colour. entered at stationers' hall. [illustration: sunset] colour as a means of art: being an adaptation of the experience of professors to the practice of amateurs. by frank howard, author of "the sketcher's manual," "the spirit of shakspeare," &c. london: henry g. bohn, york street, covent garden. mdcccxlix. dedication to sir augustus wall callcott, r.a. &c. &c. &c. dear sir, the endeavour of the present work is to fix and develope, for the benefit of the amateur and the student, some of the acknowledged general principles of colouring as a means of art, without reference to the purposes to which such art shall be applied,--without reference to poetical expression or character, or to the imitation of the details of nature, which are requisite for the production of great works. and i have much pleasure in being permitted to dedicate it to you, who have so recently shown that the capability to execute in the higher walks of art does not depend, as is erroneously supposed, upon mechanical skill attained by constant practice and devotion to one class of subjects; but upon intellectual qualifications and mental refinement, which has ever been conspicuous in your treatment of the subjects generally adorned by your pencil. i have the honour to remain, your obedient servant, frank howard. contents. page preface v introduction 17 chapter i. colouring as a means of art 25 _section 1._--harmony 27 _section 2._--tone 31 chapter ii. rules for producing pictures in colour 35 _section 1._--cuyp's principle 39 _section 2._--both's principle 41 _section 3._--hobbima and ruysdael's principles 43 _section 4._--teniers and ostade's principles 45 _section 5._--the principles of titian and the venetian school 47 _section 6._--ludovico caracci's principle 49 _section 7._--another principle of titian 51 _section 8._--ruben's principle 53 _section 9._--turner's principle 55 _section 10._--another principle of turner 57 _section 11._--modern manner 59 _section 12._--abstract principles to which these arrangements may be referred 61 chapter iii. fine colouring 69 _section 1._--principles of colouring objects 71 _section 2._--colours of lights and shadows 99 _section 3._--sunshine 101 _section 4._--sunset 103 _section 5._--moonlight 105 _section 6._--grey daylight 107 list of plates. frontispiece. sunset. (to face title page.) page 1. cuyp's principle 39 2. both's principle 41 3. ruysdael and hobbima's principle 43 4. tenier's and ostade's principle 45 5. titian and the venetian school 47 6. ludovico caracci's principle 49 7. another principle of titian 51 8. ruben's principle 53 9. turner's principle 55 10. another principle of turner 57 11. modern manner 59 12. the neri 88 13. the bianchi 93 14. the dutch school 94 15. sunshine 101 16. moonlight 105 17. grey daylight 107 preface. in the sketcher's manual, the general principles of making pictures in black and white, or, as it is technically termed, in chiaroscuro, have been briefly, but it is hoped distinctly, explained. the following work on colouring proceeds upon the same method. it treats first of the arrangements of masses of colours which have been established by various masters or schools, and which have been recognized as satisfactory or agreeable by the public voice; it then points out the abstract principles to which these several arrangements may be referred; and finally directs attention to the qualities of colouring in art which are requisite as regards the imitation of nature. it does not profess to descend to details, for these require a considerable advance in the art, and consequently could not possibly be rendered intelligible in any publication, because they would require the exercise of first-rate powers, to colour every individual impression of the plates. for examples of the details of colouring, the amateur and the student must be referred to the best pictures of the several masters whose general principles are herein exhibited. but it should be observed, that although the several masters, whose names have been brought forward in the present work, and in the sketcher's manual, as the originators of the several principles of chiaroscuro and colour, are generally distinguished by some exercise of the principles to which their names are attached, they have produced many and valuable works in other and very different styles. it is not intended to imply that all the works of these masters are constructed upon the same principles; still less is it intended to imply that the principal merit of these masters resides in the particular principle of picture-making, which they have mainly, if not entirely, contributed to develope; for this would reduce the art of painting to a "mechanical trade," or mere means of gratifying the eye. least of all has it been intended to afford to critics a means of attack upon the modern masters, whose names have been introduced into these little works, as "painters of pictures on receipt, or on a principle of manufacture." the development of a new principle of art, whether relating to composition, chiaroscuro, or colour, is as meritorious and worthy of distinction as, if not more so than, the production of an able work upon the principles of art previously established by others. the author is fully sensible that _he_ must submit to criticism with respect to whatever he may place before the public; nor is he in the least disposed to complain of any censure of the _matter contained_ in the works, or of the _manner_ in which that matter is placed before the public. he can even afford to smile at the criticism that a work addressed to the amateur and the student on picture-making in chiaroscuro, "will not make a raffaelle or a titian," particularly as the great merit of the latter was colouring; and he may observe that he does not expect that even the present work, which is solely devoted to colouring, "will make a titian." it will be sufficient if he shall have placed in a tangible shape before the reader _some_ of the principles by which the effects of colouring, and light and shade have been made, by certain masters, subservient to higher purposes;--the art is but the means to an end. but the author feels that he has a right to complain of a criticism of his work, in which the _censures_ of the _critic_ upon _third_ parties are made to appear to have proceeded from the author; and he now begs to disclaim having said anything disrespectful either of mr. stanfield or mr. roberts, either directly or indirectly, as will be evident upon the inspection of the sketcher's manual. and the author feels it necessary to remove an erroneous impression with respect to the nature and intention of these works, by stating, that they are expressly intended for the amateur or the beginner in art; that they are not intended to be argumentative or controversial; nor are any matters introduced that require the support of argument, evidence, or authority, although these could easily be adduced, if requisite; but the desire of the author has been to lay before the amateur such principles of art as have received the sanction of years, and are universally appreciated by the public in their effects: and the only merit claimed is that of having brought them together in such a form as to distinguish them clearly; and to render the principles as evident as possible. but there is no pretension of limiting the whole art of colouring to the principles of colouring contained herein. for the method in which the plates of the present work have been executed, i am indebted to a recent improvement in lithography, made by mr. hullmandell. it is capable of producing more nearly the effects of painting than any other style of engraving; but from these plates professing only to represent masses of colour and general tone, and being the first that have been attempted in this particular application, they are not calculated to display mr. hullmandell's improvement to advantage. introduction. sir joshua reynolds in one of his discourses has stated, that the edifice of art has been gradually raised by the contributions of the great men of past ages, and that although every addition to knowledge required the exertion of a mind far in advance of its contemporaries to effect it, the results have now become the common property of all artists, and may easily be appropriated by every student--"that much may now be taught, which it required vast genius to discover." it will not be necessary to adduce any argument in support of this proposition. the difference of opinion will principally refer to "what part can be taught?" and hereon there have been as great divisions and disputes as have arisen with regard to the part of the pig that was forbidden to be eaten by the followers of mahomet; only it should be observed that the discussions have terminated in an almost opposite result; for whereas the whole pig was eaten, scarcely any of the art has been taught. numerous works have been published and numerous methods of instruction adopted; but they are almost all directed to points of mechanical execution, or the representation of individual objects, which mainly depend upon skill. skill is the natural result of practice or fortunate organization, and will, of course, differ with the perseverance or capacity of the student, which has led to the persuasion that the productions of art are dependent upon what is called natural genius. but what is _known_ of art may be as easily communicated as any other fact, and as easily acquired as a knowledge of history, or any other appeal to the memory, and is indispensable equally to the critic and to the amateur. on this subject there are few if any works; and it is rarely touched by professed teachers of the art. the method of private tuition at present in favour is, to make a drawing before the pupil, who is expected to appreciate the course of proceeding, and to imitate the effect. watching a drawing thus in progress, it will be observed that the greater part is done apparently without a thought; it appears to be literally at the "fingers' ends" of the artist: and this will be found to comprehend much, it not all that confers the effect of a picture. but in what does this consist? repeated practice, and continued study of works of art, will undoubtedly, _in time_, bring it to the "fingers' ends" of the student also, and it will insensibly become an inexplicable habit, manner or style. but this is, in fact, what may be taught or communicated in a short time; it is the knowledge resulting from the experience of ages,--the edifice built up of discoveries from time to time contributed to the fund of art by the success and failures of our predecessors. this is the _knowledge_ or science of painting, which should precede all practice or attainment of skill, and such portion as relates to colouring, it is the intention of the present work to supply. skill will follow as a result of the endeavour to make use of the means to produce the end--pictures. there has been, unfortunately, so great confusion in the use of the terms applicable to colours, that it becomes difficult to convey any distinct information respecting them, without hazarding the charge of pedantry by limiting the signification of certain words. tints, tones, and shades of colour have been, and still are, too commonly used so indiscriminately to mean the same and different things, that no definite impression can be given, unless there exist a previous knowledge of the mode in which each word is applied. it will, therefore, be necessary to explain the meanings with which each word will be used in the present work. tints are those specific and definite qualities of colours, by which the individuals of a class are distinguished from each other: as of reds; scarlet, crimson, pink, rose-colour, &c.: of greens; apple-green, olive-green, pea-green, &c.: of yellows; straw-colour, amber, &c.: of blues; sky-blue, garter-blue, indigo, &c. shades of colour imply the degree of brilliancy or depth, as bright or deep crimson; light or dark blue. tones of colour are of more general application, as indicating the general aspect of classes of tints or shades; and especially designating the degree of warmth or coldness: as cool greens, warm greys. there may be lighter and darker _shades_ of the same tone, but not of the same tint. rose-colour and crimson may be said to be lighter and darker shades of the same _tone_. the word tone is also used by itself in opposition to crudity or rawness of colour; and hence is technically descriptive of the ternary compounds, of whatever tint or shade; while the primary colours and the binary compounds, blue, red and yellow, and purple, orange and green, are technically distinguished as colour. the lighter shades of tone in this sense are technically included under the term _greys_; warm, as they contain orange; cool, as they contain purple or green. tints and tones are further classed as _pure_, as they approach purple, and those tints observed in mother of pearl, hence, also pearly tints; warm or hot as they approach orange; heavy, and unless they are exceedingly transparent, muddy, as they approach green. half-tints express those gradations of _colour_, and half-lights those gradations of _light_, between the greatest brilliancy and the shadows. colours are said to be supported by others which present some resemblance, but are inferior in brilliancy; as blues by purples, crimsons by reddish-browns, yellows by orange: --contrasted by those which are the most opposite, as blues by orange or browns, reds by green, yellows by purples: --balanced when by opposition they are so neutralized that no one appears principal or predominant. the author of a recent publication on colour is quite in error, when, in describing technical terms, he states "the balance of colouring is the harmony produced by _supporting_ one colour by _another_ introduced in _different parts_ of the picture, either _of the same colour_, or one approaching to it." this is spreading _a colour_ through the picture, and though it may _contribute_ to the balance of colouring by _contrasting_ and _neutralizing_ the _other_ colours in the work, it is in itself the very opposite of the _balance_ of _colouring_, as it consists entirely in loading one side of the beam. to this it may be added that colours are said to be supported by similar tints _adjacent_, and echoed by them when "in different parts of the picture." there are many other errors in the book above-mentioned, but as this is not intended to be a controversial disquisition, those mistakes only will be noticed which might otherwise lead to confusion; but to the correction. the definition of "mellowness," as "caused by those warm colours which, when blended, produce an agreeable _tone_ or _hue_, and would then be said to _sympathize_ and create _harmony_," is as incorrect and indefinite, as the remainder of the paragraph is without foundation:--"on the contrary, if, in mixing two or more colours, a disagreeable and harsh effect were produced, they would be said to have an _antipathy_, and create _rawness_--this adulteration of one colour by another causes what painters term a muddy effect." painters term an effect _muddy_ when it is dirty in colour and wanting in transparency. this fancy respecting the sympathy and antipathy of certain colours, which is more distinctly alluded to in the following passage:--"when, to produce a particular tint, the mixing of two colours which do not sympathize is unavoidable; one or more may be introduced whose sympathy is greater, that a pleasing and harmonious effect may be produced, &c."--this is wholly groundless. how the sympathy and antipathy alluded to are supposed to act is not very evident, but they have no existence whatever. the definition of a "pearly hue," as "obtained by softening or blending the _warm_ colours without adulterating one with the other," is equally liable to objection as untrue. the attempt at a philosophical account of the _cause_ of the colours produced at sunset and sunrise, has been incidentally exposed in the third chapter of the present work. this error undoubtedly does not originate with the professed author of the publication alluded to; and as the greater part of the book is evidently, though without acknowledgment, compiled from mr. burnett and other writers on the subject, the other errors are probably in a great measure also the result of compilation. chapter i. colouring as a means of art. colouring is the decorative part of art. it answers to rhythm and rhyme in poetry, as the means of attracting the senses. as it is a means of producing, so its indispensable qualification is,--beauty. in the higher aims of art it should be made subservient to character and expression, by according with the nature of the subject; but, still under the limitation and regulation of those principles which govern pictorial effect. under all circumstances, and to whatsoever purposes applied, the first qualification of colouring as a means of art is, that it should produce a picture. a picture has been elsewhere defined as an arrangement of one or more objects and accessories so as to afford an agreeable subject of contemplation. and the principles which regulate chiaroscuro and general arrangement for this purpose, have been pointed out. the same principles must regulate colouring as a means of art. the mere representation of any object, however accurately detailed and coloured, does not constitute a picture. it must be represented with accessories and under pictorial effect. this as regards chiaroscuro has been shown to depend upon breadth. as regards colouring it depends upon harmony. chapter i. section i. harmony. harmony is a term borrowed from the sister art of music, to denote a degree of relation or congruity between two or more colours, so as mutually to support or develope each other's beauties, as is the case with a chord or concord of sounds. the degrees of relation, or qualification for harmony, of sounds, can be ascertained by mathematical calculation incapable of erroneous results. not so, those of colours; at least in the present state of the science of optics. if it should be proved that colours are the effect of vibrations of the air, or any other fluid, as are sounds, the harmony of colours may equally become the subject of mathematical calculation, with equally certain results; at present we cannot go beyond rude approximations by guess or supposition; and are vaguely placed under the regulation of _taste_, itself as protean and undefined. the theory of the three or seven colours being all equally necessary to each other, which has been derived from the division of the ray of light by a prism, has been supposed to afford the relative proportions of the various tints necessary to harmony in a picture, _because existing in light_; and fanciful, but entirely unfounded, analogies have been drawn by enthusiasts between the seven colours and the seven notes, and the three colours and the notes of the common chord in music: but without going into the question of how far this would be likely to assist in our present inquiry, _if true_, it may be sufficient to observe that these relative proportions _vary_ with the substance of the prism by means of which the ray of light is divided; so that the whole induction falls to the ground. but were the proportions always the same, the induction would be equally untenable. for, though light may be very beautiful; and the rainbow may be very beautiful; a totally different kind of beauty is required for a picture. the colours of the rainbow may perfectly harmonize; but it is more than doubtful whether the person whose whole picture was a representation of a rainbow, would be considered to have produced a finely coloured work of art. harmony, in pictorial colour, does not depend upon any particular proportionate quantities of the different tints; nor in any particular disposition or arrangement of them; but upon the qualities and the treatment of the individual colours. a picture may be painted with every variety of the most brilliant colours; or, on the other hand, as rembrandt treated light, the work may contain only one small spark of colour, the remainder being made up of neutral tints; and even the small spark of colour may be dispensed with, and the whole picture be made up of a variety of tones. having dwelt so much in the sketcher's manual, upon the principle of breadth being indispensable for the production of pictorial effect, it will scarcely be requisite to point out that it is equally necessary that colours should be so treated as to produce _unity_; and that, as with lights and shadows, so whatever variety of tints may be introduced into a picture, they must be so blended and incorporated with each other, that they still form parts of a whole;--that whether the lights be white, and the shadows black, or differently coloured, the same necessity for graduation remains; so that colours must not be in flat patches. and in the treatment of colours, besides the graduation requisite for breadth of chiaroscuro, it is necessary to pay attention to the peculiar quality termed tone, which is indispensable in a coloured work of art. as well as breadth of chiaroscuro, there must be breadth of tone, the fundamental quality of harmony. chapter i. section ii. tone. this is a term also borrowed from the vocabulary of music, to denote a property or quality of colour, the opposite of gaudiness or harshness; and implies a richness or sobriety, inviting quiet contemplation. it confers what is technically termed _repose_. it bears that relation to colours in general, that the quality of a musical note does to that of an unmusical sound or mere noise. in music, this is known to depend upon the vibrations of the air being _isochronous_, or at regular intervals. should it be discovered that colours are also produced by vibrations, tone in its present application may prove to arise from a similar regularity. tone implies a degree of transparency, which in oil colours is attainable with great facility, by a process termed _glazing_; viz. passing a transparent colour over a previously prepared tint. there are also some other practical methods of producing it, which are more advisable in certain cases, but which need not be further noticed here. in water colours, the greater number of pigments used are transparent, and the legitimate method of using them proceeds upon the principle of working entirely in transparent media; which has, at all times, excited great hopes with regard to that branch of art, as affording a better means than oil colours (in which the light tints are all composed with opaque white) of producing the brilliancy and truth of nature, in combination with the transparency (tone) which is required in a work of art. and it is to be regretted, that in some few, and those popular instances, this advantage arising out of the legitimate use of water colours, should have been thrown away, without obtaining any equivalent, other than that of hiding or correcting blunders; and that attempts should have been made, by the use of opaque body colours, and a similar method of working, to imitate the effect of oil painting. the progress of the true art of water-colour drawing, must necessarily receive a check from the adoption of such a practice, which will doubtless be sanctioned by the idle or the hurried; and attempts to carry out the original prospects and genuine advantages of the transparent medium, will probably become rare, if they should not cease entirely. it is true that opaque water-colours are supposed to have an advantage over oil-colours, in light and brilliant parts, in consequence of the tendency of the oil (the _vehicle_, as it is technically termed) to come to the surface, and thus to give a tinge to, or obscure, the purer tints of skies and distant brilliant objects. on this account, they are said to be used by turner in these parts, when he desires to attain great clearness and purity of colour. but, however, the _union_ of water-colours with oil may be advantageous for these purposes, and thus _opaque_ water-colours may receive a partial sanction; it cannot be denied that, in the instances previously alluded to, in which the opaque water-colours are used for no other purpose than the facility of recovering half-tints that had been too much obscured, the only advantage of water-colours is abandoned, without obtaining the equivalent of _richness_, arising from texture in oil; and the purity of the one art is lost, without attaining the force of the other. a crumbly, bungling appearance is produced, and for no reason, as the practice can never be successfully employed in the parts or objects, in which the use of semi-transparent colours is so invaluable in oil. and in fact, opacity, the reverse of what is desired, tone, is produced by the very same means in water-colours, by which transparency is attained in oil. breadth of tone is obtained by a process termed _breaking the colours_, which is the same with the method of incorporating lights with each other, described in the sketcher's manual; viz. graduating each tint into those adjacent, by which means a certain degree of affinity is diffused throughout the whole picture, and harmony, or breadth of tone, is produced. the same results are effected, by a process perhaps abused in the present day, termed glazing, which consists in passing some transparent pigment of the tone desired, over the whole picture, and thus breaking all the tints in the work with the same colour which produces the affinity required. chapter ii. rules for producing pictures in colour. although harmony or pictorial colouring does not _depend_ upon any _particular_ quantities or arrangement of _particular_ tints, as the slightest consideration of the infinite variety of pictures that have been produced will prove; certain quantities and arrangements of certain colours, have been found to effect it. these discoveries have been made from time to time, and have each been adopted as principles by different artists; and though admitting of considerable variation in details, their effects have been so evidently distinguished by the public as uniform in general aspect, that they have been ranged in classes or schools, to one of which any individual work is instantly referred, by those who have even a slight acquaintance with the art. by _writers_ upon art it has been very generally contended, that there _must_ be a balance of warm and cold colours. a little consideration will show, that this, as well as _all_ restrictive regulations, such as that blue must not come in the front of the picture, &c. are unfounded, or nearly the whole of the dutch school of landscape and interiors must be condemned as wanting in harmony, or bad colourists; for ruysdael and hobbima, teniers and ostade, seem to have had a horror of warm colours, while, on the other hand, cuyp and both seem to have had an equal dread of cool tints. that a balance of warm and cold colour is _one_ principle by which pictorial harmony may be obtained, is perfectly true; and that there are various means of balancing them is also true; which affords numerous varieties of style or character of pictures. and that the principle deduced by sir joshua reynolds from the venetian school, that one-third of the picture should (may) be cool, and the remaining two-thirds warm, is also just; and will be productive of beautiful results. the error consists in making these relative proportions _indispensable_ to harmony. this chapter will contain such principles as have been found to ensure harmony. there may, perhaps, be many others in store for future discovery. these principles are of universal application, whatever objects may be the subject of the drawing or picture, whether landscape, figures, animals, flowers, or altogether; and they are wholly independent of poetical or dramatic colouring,--the application of colour to expression and character,--and of the colouring of individual objects. the art of composition, in regard to colour, consists in arranging objects in such a manner, that their true colouring will produce the combination required by the principle adopted. the art of too many of the artists of the present day, consists in introducing the colours required, without any reference to their being found in nature or not. [illustration: cuyp's principle] chapter ii. section i. cuyp's principle. the simplest arrangement and treatment of colours will be found in the style of cuyp and both; objects in shadow are relieved against a warm sunny sky. for the reasons given in the sketcher's manual, with regard to progressive execution, these are the best adapted to beginners; objects in shadow do not present much variety of tint. the whole aspect or general tone of the picture is warm. the shadows are cooler than the lights, but very far from cold; being of a sepia brown, and sometimes warmer, with some cool reflections from the air. the sky is gently graduated from a rich yellow to the most delicate warm grey. the middle ground affords some blackish-green half-tints or shadows; and some golden lights are introduced in front. cuyp treated figures, animals, and boats in this way. the points requiring attention and care are, first, the tone of the sky and yellow lights, which must be obtained from yellow and roman ochres; the sky should have a creamy quality of colour; and what little grey is introduced, must be cobalt blue, or ultramarine with carmine, or lake, so as to prevent the slightest appearance of green; secondly, the masses of shadow must be of agreeable shape and must not be too dark. plate. [illustration: both's principle] chapter ii. section ii. both's principle. the style of both is only a slight variation from that of cuyp. he adopted a different character of subject, usually contriving to relieve a mass of rock or bank, and a tree with delicate foliage against the sky; and he increased the warmth of the general aspect of the picture, by making the tree and part of another _light_ bank, of the rich brown afforded by burnt terra de sienna, and by introducing some red clouds in the sky. in some instances both has not escaped the dangers that present the difficulty to his followers; the tone of these pictures appears hot, and thereby a vulgarity is occasioned, and that refinement which is required by taste in the fine arts, is destroyed. plate. [illustration: ruysdael's and hobbima's principle] chapter ii. section iii. hobbima and ruysdael's principles. these masters have adopted a style which, though apparently as opposite to that of cuyp and both as cold is to warm, resembles it in this respect--they rarely, if ever, admit positive colours in force, and thus offer another simple principle for the treatment and arrangement of tints. in hobbima and ruysdael, who painted landscapes, dark brownish masses are relieved against a cloudy grey sky, and some white or grey light is introduced in front to carry the colour of the sky through the work. the general aspect of the picture is cold. what little warmth of tone may be admitted, is to be found in the centre of the shadows; and the only approximation to positive colour, is in the sky, a little cold feeble blue, obtained in water-colours from indigo; and a small portion of a deeper shade of the same tone of blue on mountains or trees in shadow in the distance; or a little cold green in the middle ground. if ever any red be introduced, it must be a mere speck of vermilion shaded with grey, to give value by contrast to the neutral tones, which make up the principle part of the picture. plate. [illustration: ostade's principle] chapter ii. section iv. teniers and ostade's principles. teniers and ostade have treated homely interiors upon the same principle, making up the greater part of the picture with brownish grey tones, and introducing in the light, some very feeble spots of the primary colours, carefully shaded with grey, to assimilate them with the general aspect of the work. what little warmth is admitted, is found in the shadows and reflections, as in the productions of ruysdael and hobbima. but the lights afford a greater purity of tone; so that while the works of ruysdael and hobbima would be said to have a grey tone, teniers, and particularly ostade, are said to have a silvery tone. plate. [illustration: principle of titian and the venetian school] chapter ii. section v. the principles of titian and the venetian school. the venetian school, founded by titian, adopted a combination of rich warm browns, yellows, and greens, supported by crimsons, all deep in tone, overspreading two-thirds of the picture, opposed by very rich, almost warm, blues, and animated by a point of white, sometimes accompanied by black in the front of the subject. no violent contrasts are admitted, no crude colours. the white is toned down to assimilate with flesh tints, which are again toned to accord with golden lights, gradually deepening into yellowish browns, and emerging through warm greens to join the blues, which are kept in check by the opposition in some places to rich reddish browns of the same relative shade, so that one shall not be darker than the other; the blue is graduated as it approaches the white, into which it is blended by the interposition of fleshy-coloured tints. the whole aspect of the picture is rich and warm, but subdued. the lights are golden and the shadows brown, with just so much cool green, white, and blue, as shall prevent the picture appearing rusty. but though these tints are called cool, because they are cooler than the rest of the work, as in the style of cuyp and both, they must not be cold; but above all it is requisite to take care that they are not crude. white must be toned with yellow or red; blue must incline to purple; and if black be introduced, it must not be _blue_ black. plate. [illustration: ludovico caracci's principle] chapter ii. section vi. ludovico caracci's principle. ludovico caracci followed the venetian school, but subdued the colours of the whole picture, to what sir joshua reynolds calls a "cloistered tone," the effect of a "dim religious light, through storied pane." neither white nor black are admitted: the deepest shadows do not descend below a rich brown; the brightest lights do not rise above a creamy yellow. the blue is no longer opposed to a brown of the same relative shade, but is introduced in the half-lights, and carefully blended into the shadows, by means of warm reflections, and the interposition of reddish purple shadows. the chiaroscuro is broader and more tranquil than in the works of the venetian school. plate. [illustration: another principle of titian] chapter ii. section vii. another principle of titian. titian has adopted another principle in the painted ceiling of the hall of judgment, in the ducal palace at venice. pure greys are interspersed amongst masses of bright crimson, which are opposed to some pure white and blue, broken by flesh tints. the reds and greys are supported by some warm yellows, and the whole assimilated by rich brown shadows. the contrasts of colour and chiaroscuro are vivid, and require care in the shapes, as well as the situations of the masses and points of relief. plate. this principle of colouring is applicable to gorgeous historical subjects, portraits, and flowers. sir thomas lawrence frequently adopted it with a slight variation, resulting from the combination of some portion of the following principle which was developed by rubens. [illustration: ruben's principle] chapter ii. section viii. rubens' principle. rubens is the founder of another school in which the most violent contrasts of colour and chiaroscuro are admitted in the focus of the picture. the deepest black, supported by rich yellows, crimsons, and blues, is opposed to the brightest vermilion, sometimes heightened with gold, and the purest white, which is graduated through every variety of pearly tint into bright blues, interspersed with purply greys, creamy and fleshy half-tints. great simplicity of chiaroscuro is requisite in this style of colouring. both the white and the black must graduate uninterruptedly into the half-lights, which form the greater part of the picture. the crimsons, blues, and yellows, that support the black, must all partake of the same tone. the vermilion must graduate into purply tints, which will emerge through greys and greens to the bright blue. plate. [illustration: turner's principle] chapter ii. section ix. turner's principle. turner has controverted the old doctrine of a balance of colours, by showing that a picture may be made up of delicately graduated blues and white, supported by pale cool green, and enlivened by a point of rich brownish crimson. it requires some care in the graduation and shapes of the masses of blue and white, and in the situation of the point of colour. plate. [illustration: another principle of turner] chapter ii. section x. another principle of turner. another principle adopted by turner is, to contrast rich autumnal yellows in the foreground, with a brilliant italian blue sky, graduated through a series of exquisitely delicate pearly tints, to meet the cooler green tints of the middle ground. the warm colours in the foreground are qualified by purply half-tints, and supported by warm shadows and some rich crimsons; or sometimes reduced to comparative sobriety by the opposition of the brightest orange and white. plate. [illustration: modern manner] chapter ii. section xi. modern manner. a very favourite manner of the present day is partially to relieve a tower, steeple, spire, or some upright object, rendered of a purple colour, against a white cloud which is graduated with purply greys, creamy and fleshy tints, and opposed to some bright patches of blue; the lower part of the building or object is graduated through cool greens or greys, into some warmer yellows or browns in the foreground, which are interspersed with points of bright colours, such as cobalt blue, vermilion, lake, and sometimes white and black, but always introducing in front some dull red, as of bricks or tiles, contrasted with fresh greys. plate. chapter ii. section xii. abstract principles to which these arrangements may be referred. these several styles of colouring may be reduced to certain abstract principles, which may be made the foundation for other and different arrangements, as the taste and talent of the artist or amateur may dictate. pictures may be made up of a balance, or harmonic arrangement of tones. or, of a balance, or harmonic arrangement of colours. or, of a balance, or harmonic arrangement of tones and colours. or, by relieving a spark of colour against a mass of tones. or, by relieving a spot of black or white, _the concentration of_ tones, against a general aspect of colours. pictures may be warm in tone, qualified by so much cool tint as will prevent their appearing hot. or cool, with so much warm tint as will prevent their appearing cold. a small spark of bright colour will balance a large mass of subdued tint. equal brightness will require equal masses. for the principles by which the shapes and situations of masses and points must be governed, the reader is referred to the sketcher's manual, where they will be found at length, and carefully illustrated. the same regulations that govern the distribution of several lights or shadows, must guide the positions of several masses of the same colour. if two or more are introduced, they must not be equal in size, nor similar in shape, nor must they be so placed, that a line drawn through them, would be either horizontal or vertical--parallel with either base or side. the great principle of colouring being variety within the limits of harmony, such masses of similar tints should be of different sizes and shapes, and should be interspersed at different distances through the picture, so as to suggest an undulating line, traversing all, or at least three, of the four quarters of the picture, that all the particular colour shall not be on one side, and none on the other, nor all at the lower, and none in the upper half of the picture. but if the arrangement of relieving a spark of colour against a mass of tones, or the reverse be adopted, it must not be placed in the centre of the picture, nor equidistant from either top and base, or the two sides. with regard to the beauty of individual tints, it would be difficult to come to any very strict definition, as what is pleasing to one person, is not so to another; and particularly in reference to the use of colours in art, for they then become so dependent upon the other tints by which they are surrounded, that they may be said to cease to have positive designations, and to become only comparative; and there is scarcely any tint, however disagreeable in itself, but may be made by art to appear agreeable, if not beautiful. but the object of the present work being to collect the certain or decided principles of art, for the benefit of those who desire to derive pleasure or amusement from it, the doubtful or questionable hypotheses will be left untouched, and those points only brought forward which are calculated to ensure success. for this purpose, the amateur should avoid greenish blues and greenish yellows; they both appear sickly: and never place such a green between blue and yellow as would result from the mixture of the particular tints of those two colours which are made use of. both blue and yellow become agreeable as they incline to red. red becomes rich as it inclines to blue, brilliant as it inclines to yellow. all shades and tones of purple or orange are agreeable; but of greens, those only which incline to yellow. blueish greens require either to be very pale, as shown in turner's first principle (_see plate_), or moderated with black, so as almost to cease to be colours, and become tones. all shades and tints of the tertiary compounds are agreeable in their places; they receive value by the opposition of the colour which enters least into their composition, and become difficult to manage only when they approach full blueish green. white and black give value to all colours and tones. it may be necessary to make an observation upon the foregoing warning, and almost proscription, of the use of green in art, as that colour is found to be exceedingly agreeable in nature, and is used with success in manufactures, and for other general purposes. it is found to afford great relief to weak sight, and is abstractedly so much admired, that it appears singular and paradoxical to say, that green must be sparingly used in pictures, even in landscapes, whose greatest charm in nature consist of luxuriance of vegetation: but such is the case. the general tone of a picture may be yellow, as in the works of cuyp, both, ludovico caracci (_see plates_); red, as in the second principle of titian (_see plate_); blue, as in the first principle of turner (_see plates_); grey or brown, as in the works of ruysdael and the dutch school (_see plates_); but a green picture, however true to nature, instantly excites an universal outcry as being disagreeable; and if any of the modern school, to which we shall presently advert, have been for a moment tolerated, it has arisen from the previous great reputation of the artist, or for other merits in the work, and in _spite_ of its being a green picture. the following hypothesis _may_ be the mode of accounting for this paradox, and, at the same time, _may_ throw some light upon another, which will be noticed; that although painting is an imitative art, imitation, to the extent of deception, does not constitute its highest excellence. the eye is excited by colour, and the object of painting, independent of poetical expression or character, is to excite the eye agreeably. but green is found to excite the eye _less_ than any other tint, (thereby affording some corroboration to the idea that, strictly speaking, its opposite red, is the only true _colour_,) not even excepting black; so that it acts as an opiate, and is used for counteracting the brightness of the sun, by means of parasols or glasses, and to guard weak eyes from the effects of light by means of silk shades. it is thrown out as a suggestion that, in looking at a picture in which excitement to the degree of pleasure is _expected_, a disappointment _may_ arise from finding a prevalence of those tints which do not excite, except to a very slight extent, and that _thus_ a green picture _may_ occasion dissatisfaction. in looking at nature we do not wish to be always excited, and green is admired or valued as affording repose; but in looking at a picture, the very object is excitement, within certain limits, which green has a tendency to destroy. certain tints of green become disagreeable in certain parts of pictures, from association of ideas. green in flesh, excites the idea of corruption and decay. green in skies, occasioned by blending the warm yellows of sunset with the blue, excite the impression of want of skill to prevent the one tint running into the other. but in reservation it must be repeated, that there is no tint that cannot be controlled and made available, by great skill and management, to the purposes of art. these warnings are for beginners and amateurs; and the work is intended to show them what they may do with safety; as they attain proficiency, they may attempt difficulties, which principally reside in _truth_ of detail _in combination_ with agreeable general effect. when to this is added a just subservience to poetical character, the greatest requisitions of the art have been complied with; all other difficulties, of whatever nature, being merely a species of mountebank trickery, beneath the aim of high art, and deserving of the well-known sarcasm of dr. johnson upon some difficult music, that "he wished it were impossible." chapter iii. fine colouring. having shown in the preceding chapters certain principles upon which pictorial arrangements of colours may be ensured, the attention of the reader must be directed to what other qualities are requisite to constitute fine colouring. fine colouring must not be confounded with fine colours. some of the finest colourists have avoided fine colours, and sir joshua reynolds adduces as a _proof_ that apelles was a fine colourist, the statement by pliny, that, "after he had finished his pictures, he passed an _atramentum_, or blackness, over the whole of them." nor is truth of imitation sufficient of itself to constitute fine colouring, though it always confers a value on a work of art. fine colouring, in the higher walks of art, implies an adaptation of the general aspect or style of colouring to the expression and character of the subject; it then acquires the title of poetical colouring, which is its highest commendation as a means of art. but, independent of subject, there are other abstract qualifications of fine colouring to be sought for, in the representation of objects. it not only requires such an arrangement of tints and tones as shall produce an agreeable whole, but descends to minutiã¦, and demands that such tints and tones, shall be obtained by a degree of refinement or idealization, within probability, of the ordinary appearances of nature, or by a selection of the greatest beauties she displays, and such a combination of them as shall contribute to convey the most pleasing impressions, and present _her_ under the most attractive aspect. chapter iii. section i. principles of colouring objects. proceeding to consider colouring independently of character or expression, to which it should be subservient in the higher walks of art, the attention of the reader must be directed to a circumstance connected with truth of representation. it has commonly been the practice, under the almost universal sanction of great authorities, to place the student who may be desirous of acquiring the art of painting, before some object, and to direct him to copy _what he sees_. but what does he see? we need not go into the question of _how_ impressions are produced upon the mind, through the medium of the eye; whether a species of picture of the object be, during the inspection, as it were painted upon the retina; and whether that be inverted or anywise different from the real object; or whether, and to what extent, association rectifies the imperfections of our sight. these, and other investigations into the philosophical and physical nature of vision, may be left to the consideration of those who desire to account for particular facts; we have to do with the facts themselves. in whatever manner the effect may be produced, it is indisputable, that a certain and distinct impression is produced upon the mind, through the medium of the eye, by every object which may be before it, and that impression has a strict relation to the real character of the object; for instance, a marble statue, it appears, or an impression is conveyed of, an object of one unvaried tint. how this impression is conveyed, is of no consequence; it is conveyed; and a series of tints may be artificially arranged upon paper (or any other convenient material), so as also, if not equally, to convey to the mind the impression of a marble statue of uniform whiteness. but upon examination of the drawing or painting, it would be seen, that scarcely any two parts of the _representation_ of the statue were of exactly the same tint. some parts would be delicately graduated from a point of light, through a series of darker tints, to give the appearance of roundness; while others would be made nearly black by shadow, to give the appearance of projection. the present enquiry has reference solely to colours, but the same difficulties occur with regard to forms. here there is a discrepancy, occasioned by association, which we shall scarcely find language to explain, but which will in most cases prove of serious perplexity to the student; for there are some other persons like queen elizabeth, who have no idea of shadow, unless it be the shadow of a parasol or tree, under which they may escape the intensity of a noon-day sun. the statue will appear, or an impression will be conveyed to the mind, of uniform whiteness. but pictorially speaking, one spot only, that which reflects the greatest light, will appear quite white. all the other parts will _appear_, that is, to convey the impression, they must be made, of an infinite variety of tints, from the brightest light to the deepest shadow. the statue _is_ actually uniformly white, and it appears uniformly white, yet the _appearance_ or representation which must be put upon paper, to convey an impression of that _appearance_ by drawing or painting, is totally opposite, being an infinite variety of tints. but in a statue, by reason of its convexity, the second species of _appearance_, the pictorial, is much more readily appreciated, from the strong opposition of light and shadow, than in a flat surface,--a ceiling, a pavement, or meadow, in which the perception of the modifications of colour, arising from what is termed aerial perspective, is considerably influenced, by the association above mentioned, until the eye has become educated to observe these minute and delicate gradations of tint. thus, in looking at a meadow, we know the grass to be generally of the same colour throughout, and to an uneducated eye it _appears_ equally green from one end to the other: or the ceiling of a well lighted room, we know it to be of one colour throughout, and it _appears_ of one even tint from the nearest to the most distant extremity; yet pictorially speaking, it _appears_ of an infinite variety of tints, for the effect of the atmosphere is such as to rob the grass of its colour, and to make the white ceiling grey, as they recede from the eye. it will scarcely be necessary to guard against misconception as to the use of the terms describing the effect of the atmosphere, by explaining that it is not intended to assert that an _actual change_ takes place, or that there is any _actual_ difference in the colour of those parts of objects which are at a distance from the eye; or, that the colour in the distance does not appear to be, as we know it is, the same with that nearest the eye; but that the effect of distance is the _pictorial appearance_ of a modification of tint, by the interposition of the atmosphere, perceptible only to an educated eye. we know the grass to be equally green throughout, and it appears of the tints which convey that impression; while association conceals the modification occasioned by the interposition of the atmosphere (which the generality of observers consider as only "air," and of no consequence), and excites the notion that the meadow appears of one equal flat tint. but the distant extremity of the meadow is seen through more or less atmosphere, which is more or less dense; and in proportion to its density will the colour of the grass be _apparently_ altered or changed thereby; and in some instances, as in case of a fog, entirely concealed. in looking at any object through a perfectly transparent medium, such as plate glass, we do not perceive any alteration in the real colours. but when the medium is not perfectly transparent, which is the case with the atmosphere, the colours of all objects seen through it are modified or tinged in proportion to its density, until they are sometimes lost or absorbed in the tint of the medium. the slightest possible colourless opacity gives a medium approaching to a whitish film, which is very evident when there is light behind it; as in the case of the beams of the moon. this is the clearest state of the atmosphere. as it increases in density, it becomes more and more white, until it becomes a white mist, fog or cloud. the atmosphere is sometimes coloured, as will hereafter be mentioned; at present we have to do with its colourless state. the opacity of the atmosphere, as a white film over the darkness of space, occasions the blue appearance of the sky; and in proportion to the rarity or density of the medium, is the intensity of colour, or rather depth of tone. if the atmosphere be extremely rare, as in the polar regions, or at the height of mont blanc, the sky appears almost black. and if the atmosphere be thick with vapour, the sky assumes a milky colour, and the blue tint is lost in that of the medium. when the atmosphere is just so rare as to be scarcely perceptible in its influence upon terrestrial objects,--as in italy, or the eastern climes, where the most distant buildings appear diminished in size, but almost as distinct as those close to the spectator,--yet sufficiently dense to become a veil to the expanse of space, the colour of the sky appears the most intense blue. as near as we can superficially ascertain it,--in the exact medium between such rarity of atmosphere as would afford blackness, and such opacity as would afford whiteness,--we may expect to find the most intensely blue colour in the sky. as the effect of this colourless opacity of the atmosphere is, to render the appearance of the _darkness of space_ a blue colour, so all dark terrestrial objects are similarly affected by the intervening of this medium, and, in a corresponding degree, become more or less blue. the dark mountains in wales and scotland appear of a deep blue, sometimes verging upon purple; and a slight comparison between the colour of the trees close to the spectator and those in the distance, will show how much more blue the latter become, from the influence of the medium through which they are viewed. and as objects, in proportion to their distance, are more or less affected by the interposition of the atmosphere, so, also, do the parts of the individual objects themselves, become more or less grey as they recede. the boundaries of a white object are less white, and of a black object less black, than the parts nearest the eye. a tree is most green at the prominent parts, and greyer at the top and sides. this truth is so decidedly felt by the public in general--though perhaps insensibly appreciated and but tacitly acknowledged,--that, as the atmosphere reduces the colours of all objects to a blue tint, so all blue colours convey an impression of distance, and all tints approaching to blue are accordingly designated _retiring colours_. but the atmosphere is not always colourless. the rays of the sun tinge it with yellow. the rays from a fire or candle tinge it with a colour approaching to red. the combination of smoke tinges it with black or brown; and fogs infuse various degrees of dingy yellow. all these variations affect the colours of the objects seen through the atmosphere, and modify the degree of blue, or quality of grey, tint communicated thereby. when the atmosphere is coloured by the light of the sun, the blue is modified, more or less, into a warm grey. but owing to the brilliancy resulting from the blaze of light, the tints remain of the utmost purity. all tendency to green is kept in subordination by the pearly tints of those parts which are in shadow. the atmosphere is rendered more dense at the same time that it is coloured by the light of the sun; but the light parts of the objects seen through it are rendered, by the same cause, so much more brilliant, that the density of the medium is partially compensated; while its full effect is apparent upon the shadows seen through it, over which a bright haze diffuses a beautiful blue tint, slightly warmed by the golden colour of the illuminating power. the contrast of the yellow tinge in the lights makes these shadows appear to incline to purple; and at sunset and sunrise, when by the greater quantity of the medium, rendered more dense by the aqueous vapours close to the earth, the colour of the sun's light is enriched to a deep golden hue approaching orange and red, the shadows assume a decidedly purple tint, of which the blue is supplied by the density, and the red by the colour, of the medium. as the light of the sun decreases, the colour of the atmosphere is more evidently tinged with red, until the sun has sunk so far below the horizon, that the shadows of night incorporating with the colour of the vapours, render them a dull grey, sometimes approaching a brown. in proportion as the atmosphere is illumined does it also become opaque. the sky close to the sun appears much less blue than on the opposite side of the heavens. the beams of the sun, or moon, or even the rays of a candle, become so opaque, as absolutely to conceal all objects behind them. in a glowing sunshine, the particles of the atmosphere loaded with light, produce that soft haze or _caligine_, "as the italian hath it," by which the colours of every object seen through it, are assimilated in one broad, warm, grey tone, however varied the tints of the objects in reality may be. another singular appearance takes place in remote objects, of which no one has so fully availed himself as turner, for the production of pictorial beauties, and the brilliancy of sunshine. the atmosphere, which becomes most visible when before shadows, is frequently so much illuminated by the sun's rays, as to make the shadows appear nearly equally light with the illuminated parts of the objects; and the only distinction between the lights and shadows is to be found in the difference of tint--the shadows being blue or purple, and the lights a warm yellow, or fleshy colour. the practice in art, both in oil and in water colours, has been an imitation of the process of nature, and with similar results. it is usual in oil to paint the distance stronger in colour than it is intended to remain, and when dry, to pass some very thin opaque colour (technically to scumble) over the whole. thus the most perfectly aerial tints are produced. in water colours, owing to the different quality of the materials employed, another method is adopted. white, or any opaque pigment (except when used in conjunction with oil painting), has a disagreeable effect; so it is considered advisable partially to wash out the too highly coloured distance, and aerial tints similar to those produced by the scumble are obtained. however requisite it may be philosophically to account for these appearances, it is unnecessary to perplex the reader of the present work with a questionable statement of the greater impetus of rays of certain colours enabling them to penetrate through the dense atmosphere, while others are more feeble, and are swallowed up and absorbed by the medium through which they in vain essay to pass. this may be a very pretty story to amuse children with, and such philosophers as are verging on their second childhood; but while so simple a method can be discovered of accounting for the blueness of the sky and distant objects, and one that can be so easily exemplified as that given in the previous pages, we shall not be the parties to contribute to that amusement, by writing "the history of some blue rays that were lost in a fog." nor is this the place to point out the absurdity of such theories; it will be sufficient to remark that _if_ they are correct, all distant objects must appear _red_; and the blueness of the sky can only be accounted for by the hypothesis, that the atmosphere is a sort of trap for the blue rays of all the light that has passed and is passing through it! such being the effect of the atmosphere, and such being the antagonizing influence of association in looking at nature, it has been found necessary for the purposes of art, in representation, to exaggerate the former, to overstep the modesty of nature, and thus to produce what may be termed conventional imitations or translations of nature. for, in looking at a picture, association again affects us; and as we know what is before us to be a flat surface, this can only be overcome by increasing the effects produced by atmospheric influence, reflections, refractions, &c. hence the colour of all distant objects are reduced to some tone of grey, oscillating between the extremes of bright blue or even purple, and the medium between black and white as the subject, may be in sunshine cold daylight; or, as the taste of the artist may lead him to prefer one scale of colouring to another. those who delight in the sunny skies of italy, or tropical climates, represent the distance by the purest blue that ultramarine affords. others, who delineate the village church or cathedral tower, represent them of a dark grey. mountain scenery is represented of a deep indigo blue, sometimes inclining to a decided purple, as all must remember in the drawings of the late mr. robson. if this exaggeration or pictorial license be objected to, as an unnecessary departure from truth or the beauty of nature, let the most inveterate worshipper of verisimilitude place himself before a landscape under bright sunshine, on a clear day, and make an exact representation, if he be able, of what he sees; and he will be convinced that in such an instance, something more and very different is required, to make a finely coloured picture. it cannot be that the colours of the original are deficient in beauty, but that an essential quality of the beauty of nature cannot be preserved by imitative art. he will find that it will not be possible to preserve even slightly the gradation of tints before him, without descending almost to blackness in the shadows, which will be destructive of brilliancy of sunshine, and at the same time, of that quality which is indispensable in a work of art, _breadth_. he will find that in comparison with the brightness of the sky, the trees will look as dark as they are represented by ruysdael and hobbima, but who incontestibly do not give the idea of sunshine. as in translating from one language to another, he will find that a literal version may give the bones, but not the spirit of the text; and that something more is required to transfer the full force and character of the original. herein consists a great part of the art of colouring objects. it may be that the scene being unbounded in nature, is acted upon by extraneous circumstances which cannot be called to the aid of a picture. as it is impossible with pigments to rival the brightness of light, it has been found necessary to adopt some method of forcing the effect of colours, so as to conceal or to supply a compensation for this deficiency, and _apparently_ to produce the vigour of truth. this has led to a division, which rivals in fierceness as in name, the feud of the bianchi and the neri of italy, into two great schisms or factions of colourists, of whom, it is to be regretted, too many are apt to consider those of the opposite party as lost in the depths of absurdity. the hostility and contempt are quite mutual, and equally ungrounded. a writer in blackwood's magazine of the neri faction says, "we have received a prescriptive right to make war upon the rising heresy of light pictures, and we will wage it to the knife," or some such expressions. certain tones of colour have been found to be almost universally recognized as agreeables; and by the above mentioned class of artists and critics, the neri, it is held to be "fine colouring," to reduce every representation, without consideration of propriety, to these conventionally agreeable tones. plate. sir joshua reynolds commends a picture of a moonlight scene by rubens, which is so rich in colour, that if you hide the moon it appears like a sunset. the background of the far-famed mercury, venus and cupid, by corregio, in the national gallery, and the sky of the bacchus and ariadne, by titian, in the same collection, are instances of this practice, the use of conventionally agreeable tones, which may be seen by every one. it would be difficult to say what the former was meant for, except _background_ to the figures; and no one ever saw a sky such a blue as the latter. it irresistibly brings to mind the counter-criticism of a sceptic to the admiration of a landscape by poussin, in which sir ----, a worshipper of the old masters, was indulging:--"what i like so much is, it looks so _like_ an _old picture_."--"yes," said the sceptic, "and the _sky_ looks as _old_ as the _rest_ of the _picture_, for you never see such a sky now-a-days." the neri apparently give up all hope of rivalling the brightness of nature; but by forcing the shadows and general tone of the whole picture, endeavour to produce the same _gradation_ of light and shadow as in nature, but on a lower scale. the bianchi party, on the other hand, endeavour to compensate for the want of positive brilliancy, by refining or increasing the delicacy and beauty of the tints. light is the origin, or immediate cause of _colour_, and the brighter the light, the greater variety of tints will be found or displayed. as we cannot rival the cause, the bianchi contend that we must increase the effect by introducing _colour_ in lieu of those _tints_ which in nature appear neutral; and thus conceal the weakness of our imitation of the cause, by making it apparently produce greater effects. thus all greys are rendered by pure ultramarine blue tints, or delicate pearly purple, and the greatest possible variety of beautiful and delicate colours are introduced in the light; while the shadows are generally of a neutral colour, the most decidedly contrasting with the tints in the light. but sometimes the colour is also carried through the shadows as well as the lights; positive crimson being introduced into those of leaves or grass; while those of flesh are rendered by a dull red; and those of a sandy bank by pure blue. plate. the neri complain that the bianchi want tone, and the bianchi that the neri want purity and light. each of these factions contends, that all the difficulty of fine colouring is to be found only in their own aim; while they hold in perfect contempt the productions of their opponents, as being of such facile achievement as to the sarcasm of michael angelo,--to be "fit only for children," and beneath the attention of those who profess to study the fine arts. [illustration: the neri] the main difference between the principles of these two parties or factions, will be found to lie in the treatment of the atmospheric influence and association, previously alluded to. the bianchi availing themselves of the former circumstance, as a reason for introducing a great variety of pearly greys, on the purity and beauty of which they contend fine colouring is dependent; and the neri availing themselves of the latter, as an excuse for the introduction of breadth of warm tones, and the omission of as much as possible of the cool tints, which are deemed so indispensable by their rivals; they limit the representation of atmospheric influence to the least possible degree. titian's venuses are masses of the local colour of flesh, broken with so little half-tint, that they are scarcely round, and satisfy few but critics sufficiently learned in the art, to be contented with the beauties of _art_, as a substitute for the imitation of _nature_. this class of colouring is founded upon the power of association, previously alluded to, by which, the local colour overpowers the greys of atmospheric influence; in other words, that to the eyes of the many, _flesh_ looks of a _flesh_ colour, and ought to be so represented. but the _full_ effect of association is here not allowed for. in looking at flesh, we know it to be flesh colour; and we know it to be round; and it requires some education of the eye to discover the atmospheric influence, as well as the minute gradations in form. but on the other hand, in looking at a picture, we know it to be a flat surface; and however far the _imagination_ may be willing or have a tendency to supply the deficiencies in the representation, _association_ is an _antagonist_ and not an ally. this will become evident upon making outlines of objects and filling them up with flat tints; imagination will not have power to make them appear to be round, or to recede. the beauties of this class of colouring are solely conventional. titian, giorgione, and sir joshua reynolds lead the van of the neri; rubens, vandyke, and lawrence are at the head of the bianchi; unless, indeed, we should consider turner as general-in-chief of the latter. claude was probably of the bianchi faction; but time, who is the great ally of the neri, has made him appear in some of his productions an adherent of that party. it may be added, that most historical painters lean to the neri faction, on account of the disadvantage arising from too close an approach to the common appearance of every-day nature, of which the effect is described in the proverb, that "familiarity breeds contempt," and consequently is destructive of that grandeur, solemnity, or refinement which is indispensable in high art; and they take refuge in the "cloistered tone" of ludovico caracci, so commended by sir joshua reynolds, a conventional beauty which will presently be noticed. the landscape painters, on the other hand, almost universally belong to the bianchi party; as truth or _apparent_ truth is so much more indispensable in subjects that only display the scenery of nature, and which depend upon that resemblance for producing an impression, than in subjects which appeal to the passions by the display of some stirring incident. from the nature of the materials employed, the tendency of oil painting is to the side of the neri; whilst the general inclination induced by water-colour drawing, is in favour of the bianchi party. the _alleged_ principle of the colouring of the neri is deduced from the hypothesis laid down by sir isaac newton, that neither white nor black are _colours_, therefore say the neri, "neither should appear in a finely coloured picture; the brightest lights should not be white; the deepest shadows should not be black;" nevertheless, those productions which are cited by this party as the finest specimens of colour in existence, _do_ contain both _white_ and _black_. in the celebrated picture by giorgione, copied recently by mr. ward, r.a., to the eye of the uninitiated are presented both white lights, and black shadows. the former, it is true, are reduced by _time_ or glazing; and the latter are excused as having lost their original colour. but this principle can scarcely be said to be carried out, except in such pictures as possess the "cloistered tone" of ludovico caracci alluded to. here the lights are warm and golden, as if transmitted through stained glass. the atmospheric greys are introduced to no greater extent than is indispensable to prevent the picture appearing rusty. the shadows are deep rich browns, into which are thrown still warmer reflections; and the whole picture is subdued to a soft-mysterious effect, which is admirably adapted to produce what is technically termed _repose_, and to excite gentle, reverential, solemn, and even affectionate feelings. it is a style of colouring peculiarly suited to religious subjects; and in representations of interiors, may be said to be like nature, because nature _may_ be made to appear like it. (_see plate._) [illustration: the bianchi] this principle of colouring may be carried out on a higher scale than is generally found among the productions of its advocates, and abstractedly, is undoubtedly calculated to lead to very beautiful results; though it may be questioned, whether it is sufficient to entitle the party exclusively to arrogate to themselves the designation of _colourists_, as they are in the habit of doing. for the principle of the bianchi is likewise adapted to produce exceedingly beautiful colouring; and without some rational or scientific standard by which the comparative beauty of individual colours may be determined, so as to distinguish between fine colours and fine colouring, the admirers of this class of colours may, with the greatest justice, contend that it is equally beautiful with that of the opposite party; while it has this superiority, that it will enable the artist to produce much more resemblance in the representation of _external_ nature, and will be much less artificial in the effects produced as imitation of interiors. and they derive a strong argument in favour of their mode of proceeding being correct, and most likely to stand, from the circumstance, that the pictures of vandyke, many of which are _now_ claimed by the neri as painted on their principle, when first done were frequently censured as being too _raw_ or _white_. further, it should be observed that, by too many of the neri party, their great object of worship, _tone_, is limited to the rich warm brownish yellow which is legitimately superinduced in oil pictures by the action of time, or glazing; and surreptitiously obtained by washing with tobacco-water. but an inspection of the works of the dutch school, who belong to a third party which considers both the bianchi and neri to be in the wrong, as too artificial, will show that _tone_ may be cool as well as warm, and that there is a silvery _tone_ which has as devoted admirers as those of the golden image--(_see plates of ruysdael and of ostade_). [illustration: the dutch school] it may not be becoming in the author of the present work to decide between these great disputants; but from the statement respecting vandyke's pictures, that they were considered _raw_ when fresh painted, as well as from the nature of the materials employed, it is evident, that the productions of titian, giorgione, and other celebrated colourists, were not, when first painted, of such deep tones as they exhibit now; and it may be suspected that the reputation, which was derived from the _original_ colouring of their pictures, has, to a certain extent, been attached to the colouring they at present exhibit; and that veneration of talent, and respect for authority, have given sanction to what would be repudiated by the great men whose names form the slogan of the party, and is not really entitled to commendation. that the two principles may be combined, and so produce higher qualities than either affords alone, is hardly possible, when their opposite treatment of the effects of atmospheric influence and association are taken into consideration. but this compromise may be made between them with advantage both to amateurs and artists; that the style of the neri, including that of the dutch school, may be considered as most applicable to the representation of interiors and quiet or grand subjects; while that of the bianchi may be considered as most suited to exteriors, and subjects of gaiety and animation. for the benefit of the amateur, it will be necessary to say something more upon the style of colouring adopted by the dutch school, the productions of which among the cognoscenti, are termed pictures of _tone_; tone being in this instance used in opposition to positive colour, and as implying varieties of the ternary combinations, called neutral tints, or greys, but otherwise possessing the qualities of tone in a general sense, namely, transparency. this style of colouring is peculiarly adapted to the class of subjects on which the masters of the dutch school generally exercised their pencils, homely interiors; but when applied to out-of-door scenes, although undoubtedly possessed of certain conventional beauties, such as harmonious arrangement and balance of tones, it has a tendency to look dull and heavy. the landscapes of ruysdael and hobbima do not reckon among their beauties, that of vivacity or cheerfulness. they may be clear and bright and fresh, as their admirers say, but they do not represent nature under her most bewitching aspect, nor is the style of the school adapted to do so. it leans to the side of the neri, from its dread of brilliant colours. it is unaffected, sober, and in many instances, such as interiors or close woody scenes under grey daylight, possesses great truth; but from its limited application, and unpretending effect, is scarcely to be put into competition, as a style of fine colouring, with the higher aims of the two great parties before mentioned. plate. such is the present state of the theory of fine colouring; from which it is evident, that, except in a very limited class of subjects, truth _cannot_ be made the test--that even in this class of subjects, it is disputed whether it _should_ be made the test; and that it is also disputed, to what extent a departure from truth is admissible; or rather, what quantity of resemblance to nature is indispensable, and what method may be the best of compensating the want of accurate transcription; in short, what is the true _idiom_ of fine colouring in art, so as fully to translate the beauties of nature. the fashion of the day rather leans to the bianchi party in water-colour drawings, if not in oil paintings; but the principles of _none_ of the parties are _fully_ developed in the works of their existing followers. the followers of the dutch school are sacrificing part of their truth for some, but it may be doubted whether the best, part of the conventional tones of both the other parties. the bianchi are more regardless of truth than they need be, even to develope their principles to the utmost. and the neri admit themselves to be wandering in a maze, without any fixed ideas of their own principles, and therefore are less frequently successful than the reverse; and they are equally obnoxious to the charge of departing farther from truth, than is necessary to give their own principles full play. very recently a heresy of this faction adopted a peculiarity of tone, which is not to be found in the works of any of the great men of their party; and which is obnoxious to two serious objections. it is a greenish tone that unavoidably excites the idea of corruption and decay, which, having a tendency towards the disgusting, is not tolerable in the fine arts; and the second objection is, that, in their zeal for transparency, they had lost solidity to such an extent, that a portrait of george iv. by a celebrated artist, had the appearance of a vision, or of having been spun out of green glass bottles. the beginner and the amateur have already been warned against the dangers of green in pictures. and it may now be added, that transparency should reside in the _colours_ to conceal the appearance of pigments, but that the substances represented should appear as _solid_ as in nature. chapter iii. section ii. colours of lights and shadows. whatever party of colourists may find favour in the eyes of the reader, it will be necessary for him to be aware of certain effects observed in nature, of which he will make such use as is admissible under the principle he may adopt. colours reside in the light parts of objects, if not brightest on the lightest parts, closely adjacent to them. shadows reduce, blacken, or render negative the colours of objects. the edges, extremities, or boundaries of _all_ shadows are _grey_. from the effect of contrast, shadows appear _comparatively_ of the opposite colour to that of the light. the bianchi take advantage of this circumstance, and sometimes force or increase the colour of the shadow, to bring out that of the light without really tinging it so _deeply_ as is the case in nature; whereby greater brilliancy is retained. the colours of the lights and shadows depend upon that of the illuminating power, whether sunshine, moonlight, or grey daylight. these will be separately pointed out. [illustration: sunshine] chapter iii. section iii. sunshine. the degree to which the colours of objects will be affected by that of the source of light, will very much depend upon the strength of the illuminating power. the light of the noonday sun is so vivid that it diffuses its colour over all the illumined parts of the objects under its influence. these assume a rich golden hue, through which the local colours of the objects are slightly distinguishable, but rather as modifications of the warm tone diffused by the rays of the sun, than as integral varieties of tint. as already has been noticed, the obvious effect of a yellowish light upon a blue object would be to induce a greenish tint; but in the case of sunshine, this is counteracted by the brilliancy of the light, and in representation, it is necessary for the same purpose, to infuse sufficient red into the light of blue objects under the influence of sunshine, or a disagreeable heavy effect will be produced. green, yellow, and orange objects become particularly brilliant in sunshine. the shadows of the foreground are, in nature, particularly negative or colourless; but as they recede, become gradually more blue. sir joshua reynolds has made the shadows on the arm of his sleeping girl nearly black. he is one of the neri. the bianchi would have made them partake more of the colour opposite to that of light, purply brown, broken with red reflections. the shadows on green objects in the foreground would be rendered by dark crimson. sir thomas lawrence frequently used pure lake in the shadows of his grass or shrubs. plate. chapter iii. section iv. sunset. at sunset there is even less variety of colour observable in the illumined parts of objects than when the sun is higher in the sky. this arises from the influence of the atmosphere previously alluded to. a greater quantity of the medium is loaded with light, and the local colours of the objects seen through it are consequently affected to a greater degree thereby. the colour of the light is also affected by the medium through which it passes, and it becomes much richer, and more nearly approaching to orange. the light in the sky, or illuminating power, is made yellow; but the lights on objects are rendered of a fleshy colour, which is made to appear warmer by the opposition of positive purple shadows, while those objects which do not receive any of the sun's light are kept very cool grey (the effect of reflected light from the blue sky), which by contrast throws the whole of the illuminated part of the picture into warmth. frontispiece. [illustration: moonlight] chapter iii. section v. moonlight. the light of the moon being white or silvery grey, the shadows are made comparatively warm browns. the appearance of moonlight is given by the colours on the illuminated objects in the picture, which are made to appear cooler than they really are, by the contrast with the warm shadows. by this means, much more colour may be introduced into the light than is usually observed in nature, and without impairing the effect of moonlight; and the bianchi contend that by such means greater brilliancy is obtained. the blues in the sky near the moon are kept very pure for the same purpose. plate. [illustration: grey daylight] chapter iii. section vi. grey daylight. grey daylight also affords brownish shadows, but from the greater quantity and diffusion of comparatively colourless light, the local colours of objects become more visible, while the shadows are more varied by reflection and refraction. reflections take their colours from those of the objects by which they are occasioned. the lights on objects are treated as in the case of moonlight; they are made _positively_ warmer than they appear in nature, and are rendered _comparatively_ cool by the warmth of the shadows.--plate. * * * * * the degrees to which these licences may be carried, must depend upon the style of colouring adopted. the amateur has had them placed before him, and whichever he may choose, he will be certain to meet with success in the eyes of one party; he cannot hope to please all. j. m. burton, ipswich steam press. [illustration: (_see page 41._)] elementary color by milton bradley. author of "color in the schoolroom" and "color in the kindergarten." with an introduction by henry lefavour, ph.d., professor of physics, williams college. third edition. milton bradley co., springfield, mass. copyrighted, 1895, by milton bradley co., springfield, mass. contents. page. the theory of color 9 why artists and scientists have disagreed 10 the speculations of the past 12 what the primary teacher needs to consider 13 concerning the solar spectrum 15 six spectrum standards of color 17 the color wheel and maxwell disks 18 the bradley system of color instruction 20 color definitions 23 practical experiments 31 the color wheel 31 the color top 32 use of the disks 32 how to begin the experiments 34 the old theories tested by mixture of three pigments 45 old theories tested by the color wheel or color top 46 concerning the complementary colors 50 citrines and russets 54 olives 55 vermilion, burnt sienna, raw sienna and indian red 55 classification of harmonies 56 the work of chevreul reviewed 58 simultaneous, successive and mixed contrast 61 contrasted harmony 64 color with white 64 black with white 64 color with black 65 colors with gray 65 contrast of colors 67 dominant harmonies 67 complementary harmonies 69 analogous harmonies 70 perfected harmonies 70 field's chromatic equivalents 73 colored papers 74 color teaching in the schoolroom 76 the glass prism 78 how the bradley color standards were chosen 79 paper color tablets 80 color wheel or top 82 the study of tones 85 neutral grays 89 explanation of broken colors 91 an exercise in broken colors 92 formulas for a chart of broken spectrum scales 95 certain color puzzles 96 chart of pure spectrum scales completed 98 the work of cutting and pasting 99 a variety of designs 101 analysis of color materials 106 the bradley colored papers 112 engine colored papers 116 water colors 118 color blindness 121 outline of a course in color instruction 124 the solar spectrum 125 pigmentary spectrum colors 125 study of tones 126 broken colors 127 complete chart of pure spectrum scales in five tones 127 advanced study of harmonies 128 introduction. the movement in educational reform at present is in the direction of unification. it is held that in framing the programme for any grade the interest not only of the next higher but of all higher grades must be considered. this is done not solely that those who are to enter the higher grades may be directly prepared for their more advanced studies, but especially because it is felt that better work will thus be done for those whose school training is soon to terminate. for the child's education is never finished and a mind rightly directed at the start will gather from its practical experience that with which it may develop and augment the resources and the ideas already received. no education can be sound which teaches anything that is inconsistent with the more advanced truths, however complex and profound those truths may be. there should be no unlearning in the course of an education nor any expenditure of time on that which has no permanent value. it is of importance therefore to consider in connection with the study of any special subject what the problems are which lie at the end of the educational journey and what basis will be needed in the child's maturer thought. there will thus be the inspiration of the goal to be attained and guidance in the selection of the most helpful methods. there is scarcely any subject that has so many practical and scientific aspects as the subject of color. its great importance in the arts and its contribution to the enjoyment of life are matched by the multiplicity of problems in the physical and philosophical sciences with which it is connected. without attempting to enumerate all of the scientific problems related to this subject, it may be of interest to briefly summarize those which are most prominent. at the outset we have such purely physical questions as the nature of light, the cause of its emission, the mode of its propagation, the difference in the waves which give rise to the various color sensations, the principles of absorption, of reflection and of refraction, and the nature of material surfaces whereby they acquire their characteristic colors. then comes the physiology of the eye, including its structure and its function and involving the much discussed questions of primary and secondary colors, and these are closely related to the psychological or psycho-physical study of the nature, duration and delicacy of color vision and color judgment. next to these comes the study of pigments and of the chromatic effects of their mixture, essentially a chemical and technical question, and finally, the most important of all, the purely psychological or æsthetic problem touching the harmonization and grouping of the various colors and their modifications. the recent advance made in experimental psychology has given an impetus to the study of the whole subject and we may reasonably expect that rational explanations may be found for questions in æsthetics hitherto considered purely arbitrary. it will be readily seen that there must be a well developed and carefully trained color sense at the basis of an education which is to lead to the consideration of these and similar chromatic problems. as in the development of any special perceptive power, a great deal depends upon making a beginning early in life, when the mind is most receptive and there are no preconceptions to be overcome. every means should be employed that will help the child to distinguish between principal colors and between modifications of principal colors. his attention should be directed at as early a stage as possible to the analysis of composite colors and the effects obtained by the combination of colored lights and the results of irradiant light. the principles of chromatic harmony are perhaps not simple, but a child, before whom right standards of color combinations are constantly presented, will acquire a correct æsthetic judgment that may become intuitive. the effect of such a training on the higher development of our people and on their appreciation of true art would be of the greatest value. if the instruction in color is to be systematic and efficient, it is unquestionable that there must be a simple nomenclature for the standard colors; and for the teacher's guidance at least as well as for the use of the older pupils, a scientifically accurate system of describing any required modification of these recognized standards. the system presented in this book is based on the well-known principle of the maxwell wheel and has been elaborated by one who has had in view not only the theory of the subject but also the practical possibilities of its use in preparing educational material. this fact, i feel sure, greatly enhances the value of the conclusions at which he arrives. henry lefavour. williams college, december 20, 1894. preface. ever since newton discovered the solar spectrum it has been referred to in a poetic way as nature's standard of color. but as soon as the author attempted, some twelve years ago, to use it practically by making pigmentary imitations of the spectrum colors as standards they were decried as vulgar and inartistic. under such circumstances it was a great pleasure to him to hear a celebrated art professor answer his inquiry if the solar spectrum is the proper place to look for standards of color with the emphatic assertion, "certainly, there is no other place to go." where there are no standards there can be no measurements, and if in color we have no measurements of effects, no records can be made, and hence no comparisons of results at various places and times, and consequently no discussion and little progress. because there have been no accepted standards and no measurements of color very little has thus far been decided regarding psychological color effects. in drawing, as at present taught in our best schools from the kindergarten to the university, the foundation of art in black and white is laid in form study. from the drawing teachers we learn that a good touch and a fine sense for light and shade in all their subtle relations to each other are without value, unless due care has been given to the commonplace consideration of lengths and directions of lines, that is to say to the measurement of lines and angles, and to the laws of perspective. we cannot have measurements without standards. by the foot or the metre we measure lines and by the divided circle we measure angles. geometrical forms have already been so definitely analyzed by the science of mathematics that if destroyed to-day these solids and surfaces could be reconstructed at any future time from written or printed directions. but suppose all material samples of color to be lost, it would be impossible by the ordinary system of color nomenclature to even approximately restore a single one from written or verbal descriptions. color is one of the first things to attract the attention of the infant, almost as soon as a sound and long before form appeals to him, so that a collection of colored papers will often prove more interesting and instructive than a picture book to the baby, while the graduate from a two year's course in the kindergarten may have a better color sense than is at present enjoyed by the average business or professional man. if we could determine the colors used by the great masters in the past, we could add much to our knowledge of the fine arts; and if we knew what colors chevreul, the master dyer of the gobelins tapestry works, refers to in his writings, and which he indicated by hundreds of numbered samples filed away in his cabinet, we should in this generation have a wonderful fund of information to increase our knowledge of harmonies, on which to base our study of color in the industrial arts. but alas! the paintings of the old masters have faded and the great dyer had no language in which to describe his colors in his writings, and therefore it is claimed that little or no advance in color perception has been made in modern times, if indeed we have held our own. the further assertion is made that those semi-civilized nations whose drawings are the least artistic greatly surpass us in natural color perceptions. if color is the one thing in which we are deficient and in which we are making no advance, is it not necessary that we adopt a new line of operations for our color instruction in the primary grades? it is self-evident that in primary work highest art is not expected in either literature, music, drawing or painting, but as has been the aim in literature for a long time and in drawing and music more recently, so in coloring, our instruction should be based on those principles on which highest art must rest. when through the introduction of colored papers in the kindergartens and primary schools the teachers began to call for better assortments of colors in their papers than were to be found in the market, and some of us in the field attempted to meet their wants, the solution of the problem seemed almost a hopeless task, because no two wanted the same colors; each teacher was a law to herself and one thought a color "just lovely" which another declared "perfectly horrid." according to the early theories then in vogue the first colors called for were red, yellow and blue for primaries, but no two persons were sure just what they wanted for either of these, and there was no authority to be referred to for a decision. in this strait, which was practically a serious difficulty, the artists were appealed to for a decision as to the three "primary colors," and also for examples showing in what proportions the "ideal primaries" must be mixed to produce the "ideal secondaries." but in this there was no satisfaction because hardly two agreed in the primaries and necessarily the secondaries were much less definite, which was the result that should have been expected. it is a self-evident proposition that if two indefinite primaries are combined in indefinite proportions the possible secondaries which may thus be produced must be exceedingly numerous, and if this idea is carried out in the production of tertiaries by the combination of the secondaries the resulting colors may be almost infinite. in view of the indifference of the artists and the popular ignorance regarding the subject the solution of this question and the discovery of any solid basis on which to formulate a system of elementary color instruction seemed very problematical. but after much experimenting and many conferences with artists and scientists a basis for operation was decided upon and at the end of fifteen years the efforts begun in doubt have resulted in a definite system of color instruction which it is the purpose of this book to concisely set forth. it is prepared in response to inquiries from primary school teachers for a clear and condensed explanation of the bradley system of color instruction. the aim is to offer a definite scheme and suitable material for a logical presentation of the truths regarding color in nature and art to the children of the primary schools. much of this instruction is so simple that it should be familiar to children who have had kindergarten training and has therefore already been explained in substantially the same form in "color in the kindergarten." a few years ago it might well have been thought necessary to preface a treatise on the subject with arguments to prove that color is a legitimate object for school instruction, but to-day this is not a question with thoughtful educators, whether considered from the practical, industrial or æsthetic standpoint. with the establishment of professorships of practical psychology and the equipment of laboratories, provided with delicate and expensive apparatus for making and recording tests, there comes with increasing force the demand for some means by which the experiments in color made in various localities may be unified both as to the colors used and the terms and measurements for recording the result. it is the hope of the author that the system here outlined may be the initial step in gathering together such facts regarding color effects as will form a fund of knowledge little dreamed of at the present day. [illustration] the theory of color. in order to place the study of color on a broad and safe foundation, the work must commence at the bottom with a rational presentation of the subject, based on experiments and the use of color material. we must intelligently consider the relation that exists between the pure science of light which is the source of all color and the use of color materials with their effect on our color perceptions. while it is true in all study that there is here and there found a natural genius in some line of work who seems to have such inborn perceptions as to require little or no logical instruction in his special line, it is also manifest that the masses must gain their knowledge through a systematic presentation of the subject, if they secure it at all. therefore with the growth of modern pedagogics the laboratory work of the psychologist has become a necessity. this consists in collecting and tabulating the results of hundreds and thousands of experiments regarding any subject under investigation, and the averaging of these to form theories and laws. in making these experiments there must be standards and measurements on which they may be based and some nomenclature in which to make the records; and the standards, measurements and nomenclature adopted must be common to those who desire to compare their results made in different places at different times. from the results of many physical experiments properly measured and recorded certain psychological theories are deduced. these experiments are tried on hundreds and thousands of individuals and the average results establish the theories, which will ultimately stand or fall according to the truth and accuracy with which the experiments have been made. experiments are useless for formulating any exact theories unless they can be recorded in some generally accepted terms for comparison with other experiments made under similar conditions and recorded in the same terms. so in color perceptions it is not necessary that we know anything of the theories of color in order to see colors, and if endowed by nature with a natural genius for color, education in color may not be necessary, but if there is to be education in color which can be transmitted to a second party there must be some standards of colors and some measurement of color effects which can be recorded in accepted terms. why artists and scientists have disagreed. in the realm of art there is no necessity for any purely scientific analysis of sunlight, which is the origin of natural colors, because all the practical value of color is found in its æsthetic effects on the mind, and in order to enjoy these even in the highest degree it is not necessary that we understand the scientific origin of the colors, any more than it is necessary for the artist to know the chemical composition of his pigments in order to produce best effects with them on his canvas. because of this almost self-evident fact, artists have as a rule been very impatient when any reference has been made to the science of color in connection with color education, believing that color is an exception to the general subjects of study to such a degree that it lies outside of all scientific investigations. consequently they have not been in sympathy with the physio-psychological investigations which have been prosecuted with such promising results in other lines, when such investigations have been proposed regarding color. while it is not essential for best results in his own work that an expert artist shall know anything of the science of color, still if he is to communicate his knowledge of art to any others except his personal pupils, he must have some language in which to make known his ideas, and on the same grounds if any psychological tests are to be made regarding color, it is evident that there must be some accepted terms in which to record the results, which has not hitherto been the case. when the well known newton and brewster theory of three primary colors red, yellow and blue, was advocated by those scientists there appeared to be something of interest and value in it for the artists also, because with the three pigments red, yellow and blue, they seemed to be able to confirm the truth of the scientific theories regarding the spectrum colors. but the scientists have long been convinced that there is no truth in this theory and have quite generally accepted the young-helmholtz idea of three other color perceptions red, green and violet, from which they claim all color vision is produced, and which they call fundamental colors. this more modern theory has seemed so far removed from the realm of the artists and the colorists that they have not been able to see anything in it of truth or value to them, and so have continued to repeat the old, old story of the three primaries red, yellow and blue, from which the secondaries orange, green and purple are made etc., etc., all of which is the more pernicious when accepted as a correct theory because of its seeming approximation to the facts. and yet there is not in it all any scientific truth on which to build a logical system of color education, and some of the effects which are considered prominent arguments for the system are directly opposed to well known facts in the science of color. consequently, the artist has failed to gain from the investigations of the scientists anything to aid him in his pigmentary work, and the scientist has not been interested in the æsthetic ideas of the artists which in fact he has generally been unable to fully appreciate, from lack of training and associations. the system of color instruction here presented for primary grades is based on the results of careful study and experiment for many years in which the attempt has been made to bring the scientist and the artist on to common ground, where they may work in sympathy with each other instead of at cross purposes as has been the case heretofore, and the results with children have already been such as to testify fully to the efficiency of this line of work. thus the feeling for color which every true artist has, may be to a certain extent analyzed so that it can be understood by the scientist and recorded for the benefit of fellow artists one hundred or a thousand miles away and in time an aggregation of facts regarding the psychological effects of color collected which will form the beginning of a valuable fund of color knowledge to be increased from age to age. the speculations of the past. ever since newton produced the prismatic solar spectrum, the so-called science of color as applied to pigments and coloring, has been a most curious mixture of truth, error and speculation. it was supposed by newton and brewster that in the solar spectrum the colors were produced by the over-lapping of three sets of colored rays red, yellow and blue. the red rays at one end were supposed to overlap or mix with the yellow rays to make the orange, and on the other side of the yellow the blue rays were supposed to combine with the yellow to produce green. following the same theory in pigmentary colors, it has been claimed that all colors in nature may be produced by the combination of pigments in these three colors red, yellow and blue, and hence they have been called primary colors. it is still claimed by the advocates of this theory that from the three primaries red, yellow and blue the so-called secondaries orange, green and purple can be made, and that the secondaries are complementary to the primaries in pairs; the orange to the blue, the green to the red and the purple to the yellow. by similar combinations of the secondaries it is claimed that three other colors, in themselves peculiar, and different from the first six, may be made, the orange and green forming citrines, orange and violet russets, and green and violet olives and these are called tertiaries. after having accepted this fiction as a scientific theory for so many years, it is very difficult to convince the artists and colorists that in it all there is nothing of value to any one, but such is practically a fact, because from no three pigmentary effects in red, yellow and blue can the three colors orange, green and purple of corresponding purity be produced, neither are the primary colors complementary to the secondaries as claimed nor are the so-called tertiaries new and distinct colors but simply gray spectrum colors. because the red, yellow and blue theory would not stand the test of scientific investigation the young-helmholtz theory of three other primaries red, green and violet, has been quite generally adopted by the scientists of the past generation. what the primary teacher needs to consider. all these discussions of the scientists are intensely interesting and no doubt of great importance in the line to which they pertain, but practically neither the artists nor the primary school teachers care for all these theories and discussions and because the scientists have closely confined themselves to these lines, the artists and teachers have seen nothing of value to them in their theories. in going to the solar spectrum for standards on which to base pigmentary standards, we have given little attention to these various theories in their details, but the one fact of science has received careful attention, namely, that all color effects in nature and art are produced by light reflected from material surfaces. therefore, inasmuch as the light reflected from any surface must be affected by both the material color of the surface and the color of the light which illuminates the surface, it is necessary that every one having to do with this subject be informed as to what color must be expected to result from given conditions. in order that this phase of the subject be discussed and thus more fully understood, there must be a terminology or nomenclature in which to express the results produced by given conditions, and also standards by which to analyze, measure and record these results. in selecting these standards more regard must be given to the æsthetic or psychical effect of the pigmentary standards than to the purely scientific or physical properties of colored light. this selection is of great interest to the physiological psychologist because it is only by the comparison and averaging of thousands of experiments made on different people that valuable theories can be formulated. with standards and a nomenclature, color will be placed on an equal footing with other subjects, so that perceptions of color effects may be recorded and discussed with much of the definiteness with which we treat form and tone. because this has not heretofore been possible, comparatively little advance has been made during the last two decades in the æsthetic consideration of material color _which is the only practical phase of the subject_, and if any greater progress is to be achieved in the future it evidently must be along new lines. from the nursery to the university we are constantly asking two questions, "what is it?" and "why is it?" and this is what the educator from the kindergarten to the college is called upon to answer. in his laboratory the psychologist is collecting physical facts by tests regarding the powers of the eye and the ear, the sense of touch, weight, memory, etc., and these experiments when classified, arranged and averaged, furnish a basis for formulating theories, all of which is called psychology. in vision, form and color play the principal parts, in fact cover the whole ground if we include light and shade in color where it belongs. experiments regarding form can be and have long been very definitely recorded but this has not been true with color. to froebel must be given the honor of introducing logical form study into primary education, and on this has been built the present admirable system of drawing in our higher grades of schools, and the introduction of the standard forms in solids and surfaces has brought about a definite use of geometrical terms by young children which would have seemed very unnaturally mature a generation ago. but in color no corresponding advance has been made because there have been no generally accepted standards in color to correspond to the sphere, cube, cylinder, circle, ellipse and triangle in form, nor any means for measurements to take the place of the foot or metre for lengths and the divided circle for angles. it is not expected that the children in the lowest grades will learn much of the science of color, but it is desirable that the teachers have such knowledge of it that they will not unconsciously convey to the children erroneous impressions which must be unlearned later in life. concerning the solar spectrum. more than two hundred years ago sir isaac newton discovered that a triangular glass prism would transform a beam of sunlight into a beautiful band of color. if the prism is held in a beam of sunlight which enters a moderately lighted room, there will appear on the walls, ceiling or floor, here and there, as the glass is moved, beautiful spots in rainbow colors. if the room is darkened by shutters, and only a small beam of light is admitted through a very narrow slit and the prism properly adjusted to receive this beam of light, a beautiful band of variegated colors may be thrown on to a white ceiling or screen, and this effect is called a prismatic solar spectrum. a perfect solar spectrum once seen under favorable conditions in a dark room is a sight never to be forgotten. the accompanying illustration shows the relative positions of the parts named. a is the beam of light as it enters the room. b is the triangular prism. the dotted lines represent groups of rays extending to the vertical band of colors indicated by the letters v for violet at the top, then blue, green, yellow, orange to red at the bottom. the explanation of this phenomenon is that the beam of sunlight is composed of a great number of different kinds of rays, which in passing through the prism are refracted or bent from their direct course, and some are bent more than others, the red least of all and the violet most. it is supposed that light is propagated by waves or undulations in an extremely rare substance termed ether which is supposed to occupy all space and transparent bodies. these waves are thought to be similar to sound waves in the air or the ripples on the smooth surface of a pond when a pebble is thrown into it. because so many of the phenomena of light can be satisfactorily explained by this theory, it has been very generally adopted by the scientists. the amount that rays of light are refracted from a straight line in passing through a prism is in proportion to the number of waves or undulations per second, and in inverse proportion to the length of the waves. the red waves are refracted the least and are the longest, while the violet rays are refracted the most and are the shortest. [illustration: fig. 1.] whether this theory of the spectrum formation is absolutely correct or not, the fact is established that the colors found in a prismatic solar spectrum are always the same under the same conditions and the order of their arrangement is never changed. by means of the quality of spectrum colors called the wave length, a given color can always be located in the spectrum, and hence if a spectrum color is selected as a standard it can always be determined by its recorded wave length. six spectrum standards of color. therefore it seems possible to establish certain standards of color by a series of definitely located portions of the solar spectrum and in the system here presented six have been chosen, namely red, orange, yellow, green, blue and violet. these six are more distinctly recognized than the others, and from them by combination in pairs of colors adjacent in the spectrum all the other colors can be very closely imitated, and hence these six are selected as the spectrum standards. in these standards the most intense expression of each color is chosen i.e. the reddest red, greenest green, etc. which by the closest scientific investigation have been located by their wave lengths so that if they are in doubt in future they can be re-determined by individuals or if disputed, may be corrected by any authoritatively established congress, selected for the purpose. the wave lengths of our six standards are represented by the following numbers in ten millionths of a millimeter. red, 6571; orange, 6085; yellow, 5793; green, 5164; blue, 4695; violet, 4210. having thus scientifically established these unchangeable standards the attempt is made to secure the best possible pigmentary imitation of each. to any one who has ever compared a piece of colored material with a good presentation of a spectrum color, it is unnecessary to say that the result in an attempt to match the spectrum color with the material or pigmentary color is a very weak approximation, but the one thing aimed at is to secure nearly as possible the same kind of color. for example in the red, it is the aim to obtain the same _kind_ of red, by which we mean the same location in the spectrum, i.e. a red neither more orange nor more violet than the reddest spot in the spectrum. this selection must be based on a purely æsthetic perception or impression of color. the same is true of each of the six standard colors, as for example, for orange we select the location which has seemed to a large number of good judges to best represent the feeling of orange as between the quite well defined red on one hand and the equally definite narrow band of yellow on the other, and it is quite wonderful what unanimity of opinion there is on this particular color which would naturally seem to be the one most doubtful in its location. on the other side of the yellow the green seems to offer little difficulty and the pure paris or emerald green is very nearly the standard. the violet being at the other end of the spectrum is as easily decided as the red, but the blue between the green and violet is not so easily determined, because, from the best blue the hue runs so imperceptibly into the violet on one side and the green on the other. pure ultramarine blue is the nearest approach to the spectrum standard of blue of any of the permanent pigments, but even this is a trifle too violet. for educational purposes papers coated with pigments afford at once the purest colors and the most economical and useful material, and on this plan a line of colored papers has been prepared for color instruction in the kindergartens and primary schools in imitation of the above described spectrum standards. from the pure spectrum standards it is possible by reflected light to combine the two standards to produce a color between them, for example if two small mirrors are held in a spectrum one at the "red" and the other at the "orange" and the two reflected on to the same spot on a white surface, the result is a color between the red and the orange. so also if we mix red and orange pigments together we may produce colors between the two which may be termed orange-red or red-orange; but unfortunately there is no means known by which we can measure the proportion of the red and orange color-effect which is produced by any given mixture of these two pigments, because color-effect cannot be measured by the pint of mixed paint or the ounce of dry pigment. the color wheel and maxwell disks. we, however, have another means for measuring color effect which just in this emergency seems providential. it is a fact well known to every boy that if he rapidly whirls a lighted stick the fire at the end produces the effect of a circle of light, which phenomenon is explained by a quality of the eye called retention of vision, by which the impression made by the point of light remains on the retina of the eye during an entire rotation. it is a fact, based on the same quality of vision, that if one color is presented to the eye, and instantly replaced by another the effect is a combination of the two colors. therefore if one-quarter of the surface of a disk of cardboard is covered with orange paper and three-quarters with red paper, and then the disk placed on a rapidly rotating spindle, the color effect is a mixture of red and orange, and the effect is exactly in proportion to the angular measurements of the two sectors, so that if the circumference is divided into 100 equal parts the resultant color will be definitely represented by the formula "red, 75; orange, 25." less than forty years ago an english scientist named j. clerk maxwell while making experiments with such painted disks happily conceived the idea of cutting a radial slit in each of two disks from the circumference to the center so that by joining the disks they could be made to show any desired proportion of each and hence they are called maxwell disks. with such disks made in the six pigmentary standards red, orange, yellow, green, blue and violet, the intermediate pigmentary spectrum colors may be very accurately determined by combination and rotation. if we give to each of these standards a symbol as r. for red, o. for orange, y. for yellow, g. for green, b. for blue, v. for violet, we then have the basis for a definite nomenclature of colors in imitation of the pure spectrum colors. as all pigmentary or material colors are modified by light and shade thus producing in high light tints and in shadow shades of the colors, we must seek for some means of imitating these effects, and fortunately find them in white and black disks. if with a standard color disk we combine a white disk we may have a line of tints of that color, and with a black disk, shades. giving this white disk a symbol of w. and the black disk n. we complete our nomenclature. we cannot use b for black because b has already been used for blue, and therefore we use n. for _niger_, the latin word for black. the bradley system of color instruction. briefly stated then this system of color instruction is comprised under the six general heads: spectrum standards; pigmentary standards based on the spectrum standards; maxwell rotating disks in the pigmentary standards and black and white; a color nomenclature based on the accepted standards and their disk combinations; and colored papers and water colors made in accordance with these standards. for spectrum standards, six definite locations expressing the natural æsthetic or psychological impressions of red, orange, yellow, green, blue and violet are selected. six standards are chosen instead of a larger number as for example twelve, because for the purpose of a nomenclature the smaller number is more convenient than a greater number. the six are selected rather than three, four or five, because while in the consideration of colored light alone the smaller number would possibly suffice to form by combinations imitations of all other colors, any number smaller than six is entirely inadequate to form by pigmentary or disk combinations fairly good expressions of the corresponding spectrum color combinations. in selecting the spectrum standards special prominence has been given to the psychological color perceptions of experts in determining those locations in the spectrum best expressing the color feeling of red, orange, yellow, green, blue and violet, while the purely scientific consideration of these several questions has not been ignored or lightly treated. for pigmentary standards the best possible pigmentary imitations of the six spectrum standards are secured and to these are added the nearest approach to white and black that can be produced in pigments. pigmentary standards on which to base a nomenclature are valueless without some means by which measurements of standards embraced in a given compound color can be expressed. the maxwell color disks are the only known means by which we may measure the relative proportions of color effect embodied in a given color, and therefore the eight color disks are the foundation of the original color nomenclature herein advocated. colored papers are chosen for primary color instruction because paper is a valuable medium for simple schoolroom manual training and because no other pigmentary medium is at once so economical and affords such pure colors as may be secured in specially prepared colored papers, without a glazed surface. before leaving this part of the subject we do well to remember that in the present conditions of chemistry as applied to the preparation of pigments it is not possible to establish any absolutely definite science of such color combinations. nor is it possible to establish permanent pigmentary standards without great expense, but if the locations of the standard colors in the spectrum are established by wave lengths the pigmentary standards may be re-determined at any time and produced, in the purest pigments available at the time. in art or harmony effects, the purity of the pigmentary standard is not so important as its hue, i.e. its location in the spectrum, which may always be determined by the established wave length. this last statement may be illustrated by the investigations regarding complementary harmonies. scientifically one color is not considered complementary to another unless when combined in equal quantities they produce white light, or in other words when combined by the rotation of disks each color must occupy a half circle and the result must be a neutral gray. but this is not essential in considering a complementary harmony, as harmonies in different tones and in various proportions are pleasing and as yet the proportions and tones which produce the best combinations have not been determined. the entire question of harmonies or pleasing color effects is dependent on individual color perception, and the establishment of rules and laws on these points can result only from a comparison of the opinions of many experts in various localities and at different times. this cannot occur without some means for recording these opinions in generally accepted terms. it is too late for any individual opinion to be accepted as authority regarding the relative values of two different harmonies in color and this will be still less possible as we become better educated in color and able to sense finer distinctions in color combinations. [illustration] color definitions. among other advantages to be gained by a logical study of the psychology of color is the establishment of more accurate color terms and definitions. if experiments and discussions based on accepted standards and methods of comparisons can be carried on we may hope in time to have as definite expressions of color terms as we now have in music and literature. all color terms used by artists, naturalists, manufacturers, tradesmen, milliners and the members of our households are as indefinite as one might naturally expect from the utter lack of a logical basis for the whole subject. without definitions or means for intelligently naming any color, it is not strange that the terms used in speaking of colors and color effects are so contradictory as to lose much of their force, if perchance they retain anything of their original meaning. for example, probably most people apply the term shade to any modification of a color, either a hue, tint or shade. it is true that a concise and reasonably full dictionary of color terms must be the outcome of long experience in the logical study of the science of color and its use in our every-day lives, and at the best only suggestions can be made at present. but as there must be a beginning and some terms seem to be fairly well established, the following incomplete list of definitions is offered, always subject to amendment by the majority vote, for whenever such changes indicate advance they should be welcomed. _ray of light._--the finest supposable element of light impression in the eye. _beam of light._--a number of rays. _standard colors._--as used in this system of color nomenclature, the best pigmentary imitation of each of the six spectrum colors red, orange, yellow, green, blue and violet and black and white. these are more specifically called _pigmentary standards_ in distinction from spectrum standards. _spectrum standards._--the six colors found in the solar spectrum and definitely located by their wave lengths, as follows in the ten millionths of a millimeter. red, 6571; orange, 6085; yellow, 5793; green, 5164; blue, 4695; violet, 4210. _pigmentary colors._--all colors used and produced in the arts and sciences. this is in distinction from colors seen in nature, as in flowers and the solar spectrum. the term refers not only to pigments in the strictest sense but to all surfaces coated, painted or dyed artificially. _pure colors._--a pure or full color, also called a saturated color, is the most intense expression of that color without the admixture of white or black or gray. all spectrum colors are pure, while no pigmentary color is absolutely pure, but the pigmentary color which approaches most nearly to the corresponding color in the spectrum must be selected as the pigmentary type of purity of that color. for example, the standard for green must be the best possible pigmentary imitation of the spot in the spectrum which by general consent is called green, and so not only for the six standards but for all their combinations which produce the other colors in nature. in pigmentary colors the term pure is entirely one of relative degree. as processes of manufacture are improved and new chemical discoveries made, there is good reason to believe that we shall have much more intense colors and hence much better imitations of spectrum colors than are at present possible. therefore as our pigments become purer those now accepted as full colors will in time become tints or broken colors and new standards will be adopted. _hue._--the hue of a given color is that color with the admixture of a smaller quantity of another color. an orange hue of red is the standard red mixed with a smaller quantity of orange. with the disks, pure hues are secured only by mixing two standards _adjacent_ in the spectrum circuit. for convenience in speaking and writing about colors in this system of color instruction, all the spectrum colors other than the six standard spectrum colors are designated as intermediate spectrum hues, and often for convenience in speaking of them they are called simply spectrum hues. to these are also added the colors between red and violet which are not in the spectrum. when so used the term must be considered as purely technical in this particular relation, because a color between the standard blue and the standard green is in the abstract no more a hue than either of these colors. if two standards not adjacent in the spectrum circuit are combined the result is not a _pure_ spectrum hue but always some _broken_ spectrum color. _local color._--a term applied to the natural color of an object when seen in ordinarily good daylight and at a convenient distance, as a sheet of paper at arms length, a tree at twice its height, etc. _tint._--any pure or full color mixed with white, or reduced by strong sunlight. in the disk combinations a spectrum color combined with white. _shade._--a full color in shadow, i.e., with a low degree of illumination. in disk combinations a spectrum color combined with a black disk produces by rotation a shade of that color. in pigments the admixture of black does not usually produce as satisfactory shades of a color as may be secured with some other pigments, and each artist has his own preferences in making shades of the various colors on his palette. _scale._--a scale of color is a series of colors consisting of a pure or full color at the center and graduated by a succession of steps to a light tint on one side and a deep shade on the other. _tone._--each step in a color scale is a tone of that color, and the full color may be called the normal tone in that scale. in art this word has had such a variety of meaning as to render it very convenient for amateur art critics, together with such terms as breadth, atmosphere, quality, values, etc., but in the consideration of color it should have this one definite meaning. _warm colors._--red, orange and yellow, and combinations in which they predominate. _cool colors._--usually considered to be green, blue and violet, and the combinations in which they predominate. but it is, perhaps, questionable whether green and violet may properly be termed either warm or cool. the term cool as applied to colors is quite indefinite, except in a general way, but red, orange and yellow are universally considered as warm, and blue and green-blue as cool. _neutral gray._--white in shade or shadow. pure black and white mixed by disk rotation. black and white pigments mixed do not usually produce a neutral gray, but rather a blue gray. _warm gray._--a neutral gray with the admixture of a small quantity of red, orange or yellow. _cool gray._--a neutral gray with a small quantity of blue or green-blue. _green gray._--a neutral gray having combined with it a small quantity of green. as this color could hardly be classed with either warm or cool grays this fourth class of grays is suggested as helpful in giving definiteness to the more general color expressions. _broken colors._--gray colors, often improperly called broken tints. for simplicity, a tint of a color is described as the pure color mixed with white and a shade as the color mixed with black, and the corresponding broken color is the same color mixed with both white and black or with neutral gray. a tint of a color thrown into a shadow or a shade of a color in bright sunlight gives a broken color. for various reasons a very large proportion of the colors in nature are broken. broken colors are much easier to combine harmoniously than full colors, or even tints and shades. in disk combinations when a pure color is combined with both a white and black disk the result will be a broken color. when a color is mixed with both black and white, i.e., with gray, and becomes thereby a broken color, it then belongs to a broken scale and educationally has no place in any pure scale, i.e., a scale in which the key tone is a pure color. neither has a broken scale of a color any place in a chart of pure scales or spectrum scales. _neutral colors._--a term often improperly applied to grays, white, black, silver and gold. see passive colors. _passive colors._--a term suggested as covering black, white, silver, gold and very gray colors. the term "neutral colors" is often used in this sense but this is evidently improper if we are to confine the term "neutral gray" to the representation of white in shadow because as soon as a gray has any color in it, it is no longer neutral. _active colors._--those colors neither passive or neutral. necessarily both the terms "active" and "passive" used in relation to colors must be quite indefinite. _complementary colors._--as white light is the sum of all color if we take from white light a given color the remaining color is the complement of the given color. when the eye has been fatigued by looking intently for a few seconds at a red spot on a white wall and is then slightly turned to the wall, a faint tint of a bluish green is seen, and this is called the accidental color of the red, and is supposed to be identical with its complementary color. if with the disks we determine a color which with a given color will produce by rotation a neutral gray, we have the complementary color more accurately than by any other means at present known in the use of pigmentary colors. _harmony._--two colors are said to be in harmony or to combine harmoniously if the effect is pleasing when they are in juxtaposition or are used in a composition. _spectrum circuit._--if a pigmentary imitation of the solar spectrum with the addition of violet red at the red end and red violet at the violet end be made, and the two ends joined, we shall have a spectrum circuit. this may be in the form of a circle, an ellipse or an oval. _primary colors._--in the brewster theory red, yellow and blue. in the young-helmholtz theory red, green and violet are termed primary colors because it is supposed that from these three sensations all color perceptions are experienced. in purely scientific investigations of color perceptions these last three or others which are supposed to serve the same purpose are also called fundamental colors. practically every spectrum color is a primary, because each has its own wave length. _secondary colors._--in the brewster theory orange, green and purple have been called secondary because it is claimed that they are produced by the combination of primary colors in pairs. _tertiary colors._--a term used in the brewster theory to denote three classes of colors called russet, citrine and olive, made by mixing the secondaries in pairs. these are all broken spectrum colors. the orange and purple produce russet; the orange and green form citrine; the green and purple, olive. there seems to be no good reason for perpetuating the indefinite terms secondaries and tertiaries as applied to color. _values._--this word is very freely used in discussing effects in works of art, both in color and in black and white. at present it seems to be a very difficult term to define, and yet each artist is quite sure that he can "feel" it, although few will attempt to put into words a definition satisfactory even to themselves. when an engraver, who is also an artist, attempts to interpret nature in black and white on the metal plate or wooden block, he endeavors to reproduce the "values" of the various parts of the subject before him. in doing this he, for one thing, attempts to produce a variety of neutral grays which will express to the eye by means of black and white lines the same tones of color effect as are seen in the several parts of the subject under investigation. if this were the whole problem the matter would be easily expressed by the disk nomenclature. for instance, if we are to consider a certain red object which may be represented by the standard red disk, we place a medium sized disk of that color on the spindle, and in front of it, smaller disks of white and black united. by rotation the white and black disks become a neutral gray at the center of the red disk. if this gray is made nearly white all observers will agree that the gray is lighter than the red, and if it is nearly black the opinion will be equally unanimous that it is darker than the red. consequently there evidently must be a gray somewhere between these two extremes which a large majority of experts may agree to be equal in depth or tone to the red, i.e., neither lighter nor darker. but the artist-engraver will insist that to him the term "value" expresses much more than this and that he must use different lines in the sky or distance from those which he uses in the foreground; and some engravers will also insist that two different colors in the foreground must receive different treatment with the graver in order to express their true values. we know that true values of colors are not expressed in a photograph, as the warm colors are too dark and the blue far too light. if the term "value of a color" is to be used as expressing something more than a neutral gray of such a tone as to seem equal to it, then possibly this latter quality must be expressed by the word tone, and yet this use of that word will seem to enlarge its scope beyond its present limits as it now is used to express the relations between the different localities in _one_ scale of color, while this new use will extend to the comparison of tones in various color scales, including neutral grays. _luminosity._--the luminosity of a color is determined by comparing it with a neutral gray. when a color seems to be of the same brightness as a given neutral gray, i.e., not lighter nor darker, then that gray is its measure of luminosity. a noted authority says: "no colored object can have the luminosity of a white object reflecting practically the whole of the light impinging upon it. therefore if we take absolute reflection as 100 a fraction of 100 will give the relative luminosity of any body." luminosity is another expression of the quality above described as forming a prominent feature in the term values. _potentiality._--the ability or strength of a color to affect other colors by combinations with them. for example, white has a greater potentiality than black, yellow greater than red, and violet the least of all the spectrum colors. it is a pertinent question whether any quality is involved in this term which is not found in value, tone and luminosity, but it expresses a somewhat different phase of a line of color effects. _quality._--this term seems to be used rather indefinitely when applied to color, but perhaps it is not far removed from the term hue or kind of color. [illustration] practical experiments illustrating the theory of color. in the foregoing pages an attempt is made to explain clearly and as briefly as possible the principles on which the bradley system of color instruction is based, and also to suggest a few definitions necessary to an intelligent discussion of the general subject of color. owing to the peculiar nature of the questions involved, demonstration by actual experiment is more convincing than the mere statement of theories can possibly be, and therefore a few of the following pages will be devoted to the explanation of some valuable experiments, all of which may be tried by the teacher in private, while many of them can be shown the pupils with great advantage. in this system the maxwell color disks are the means for color combinations and the basis for measurements, and therefore for a color nomenclature. for this reason the present chapter treats largely of the proper use of the wheel and incidentally the theory of red, yellow and blue primaries with combinations to produce secondaries and tertiaries. no teacher using the material connected with this color scheme can hope to meet with success without a knowledge of the principles on which it is based, and in this subject as in all others, it is essential that the teacher shall know much more of it than he or she is ever required to teach. [illustration: fig 2.] the color wheel. for most convenient use the machine should be clamped to the front of a table and near one end, so that the speaker using it can stand at the end of the table and operate it with the right hand. fig. 2 represents the normal school color wheel showing the face of the disks as seen by the audience. facility in the operation of the color wheel is rapidly acquired by practice and the exact position is easily determined by the operator after a few trials. fig. 3 shows the primary school color wheel, which has only two sizes of disks, while the largest machine has four sizes and is much finer in construction. the smaller machine does not require clamping to a table, but may be steadied by the left hand while being operated by the right hand. [illustration] the color top. many of the experiments of the color wheel can be produced with a small toy called a color top, which is shown in fig. 4. it is composed of a thick cardboard disk forming the body of the top and a central wooden spindle on which the disk closely fits. a number of colored paper disks are provided with this top so that very many of the experiments performed before a class can be repeated individually by the pupils and in this way the facts which may have been demonstrated to the class with the color wheel can be fixed in the minds of the pupils by their own experiments with the top. also as a home toy in the hands of the pupils it can be of value, not only to the children, but to the parents as well. [illustration] use of the disks. fig. 5 shows the method of joining two maxwell disks and fig. 6 their appearance when properly joined to be placed on the rotating spindle of the color wheel. in joining two or more disks for use on a color wheel or top, care should be taken to place them in such relation to each other that when rotated the radial edges exposed on the face toward the audience will not "catch the wind." with small disks on the color wheel this is not important, and if there is no whole graduated disk on the arbor behind the slitted disks there is no advantage, but in using the larger disks it is well to put the graduated disk behind the others for this purpose, as at best it is quite laborious to keep up speed when using several of the large disks, even with the best possible conditions. with the thin paper disks of the color top this is an important matter. it will be noticed that the method of joining the disks for use on the color top is the reverse of that to be observed with the disks of the color wheel as shown in fig. 5. [illustration] fig. 7 shows the same two color disks placed in front of a large white disk having its edge graduated to one hundred parts, so that the relative proportions of two or more colors to be combined can be determined accurately. as the smaller disks offer so much less resistance in rotation than the larger ones they are most desirable in private experiments or before a small class, and the largest disks of the normal school wheel are necessary only when more than three expressions of color are required to be shown at the same time. in making experiments before an audience those persons in front should if possible be at least ten feet from the color wheel. from ten to forty feet there seems to be but little difference in the color perception, but for best tests fifteen to twenty feet is the most desirable position. for private practice with the color wheel a small mirror may be placed five or six feet in front of the wheel in such position as to furnish an image of the disks to the person operating the machine. owing to a slight loss of light by reflection the closest criticism may not be possible when working with a mirror in this way, but if a plate mirror is used the results are very good and a bevel plate mirror about 7 x 9 inches without frame, can usually be procured at small cost; this method is much more satisfactory for personal experimenting than an assistant to turn the wheel. these disks have heretofore been used as a curious piece of philosophical apparatus rather than because they have been supposed to have any practical value in color training, but in establishing a color nomenclature based on six spectrum colors the disks at once assume a great value and are indispensable in a system of color instruction founded on the science of color and on the psychological perception of colors. let us suppose that the two disks shown in fig. 7 are yellow and green, 80 parts yellow and 20 parts green; then by rotation we shall have a green yellow indicated by the symbol y. 80, g. 20. no argument is necessary to prove that when an exact expression of color effect is required this is better than the simple statement that it is a greenish yellow. how to begin the experiments. for practice it is profitable to commence with the red and orange disks combined on the spindle, with a smaller red disk in front of them, the smallest being preferable. begin by introducing say five per cent of orange and notice that a change from the standard red at the center is visible. gradually increase the orange until it seems difficult to say whether the resulting color is more like red or orange, and then exchange the small red disk for an orange disk of the same size, and continue adding orange in the larger disks until the difference cannot be detected between the small disk and the larger combined disks. the standards may be combined in pairs, as has been indicated with the red and orange, to produce all the intermediate hues throughout the spectrum, but it must be remembered that these combinations are to be made by joining in pairs, colors adjacent in the spectrum, red and orange, orange and yellow, yellow and green, green and blue, blue and violet. we then shall have representations of all the spectrum colors, but there are still the colors between violet and red, known in nature and art as purples, which must be produced by uniting the red and violet disks, thus completing a circuit of colors containing all the pure colors in nature. in nature all colors are modified by light and shade, strong light producing tints and shadows more or less deep forming shades. these effects are imitated on the color wheel by the use of a white disk combined with a disk of a standard color for tints and a black disk for shades, and can be tested in the same order as indicated for the hues, by combining each standard disk with a white or a black disk in varying proportions. it will be noticed early in disk experiments that a very small amount of white produces a decided effect in the tone of a color while a comparatively large amount of black is necessary to produce a marked change. as this is exactly the reverse of the effects of white and black pigments it is always a subject of remark. in pigments these effects are imitated by the mixture of white with a color to produce tints, and black for shades, or more generally instead of black some dark natural pigment approaching the hue of the color, may be preferred because a black pigment will too often impart an unexpected and undesirable hue to the color. as for example, in making shades of red some natural brown pigment is better than black, and so various dark browns and grays are used for different colors. even with the disks it is impossible to imitate purest tints of all the standard colors, because in some of the colors, as peculiarly in red and blue, the rotation of the white disk seems to develop a slightly violet gray, for which effect there has as yet been no scientific explanation. this gray dulls the purity of the tint as compared with that which is found in the color under a bright illumination, but on the whole both tints and shades as well as the hues can be better illustrated with the disks than in any other way, and in addition, the advantage is secured of being able to measure and record the tone by the graduated disk in the same way as the hues are measured and recorded. a further advantage is secured in the use of disks in color instruction because with pigments, the only other method by which colors can be combined, much time must be lost not only in the mixing and applying of the colors but in the delay necessary to allow them to dry before the true results can be seen. the shades of yellow as shown on the wheel will not be generally accepted without criticism, but careful comparison with yellow paper in shadow will prove the substantial truth of the disk results. this experiment may be tried as follows: join two cards with a hinge of paper or cloth to form a folding screen like the covers of a book as in fig. 8. on the surface a, paste a piece of standard yellow paper and on b, a piece of yellow shade no. 1. hold these two surfaces toward the class in such a position that the strong light will fall on b, which is the yellow shade, and thus bring the face a, which is a standard yellow, in a position to be shaded from the light. by varying the angle of the covers with each other and turning them as a whole from side to side, a position will be secured in which the two faces will seem so nearly alike as to convince the class that this color which they may have thought to be green, is not green, but a color peculiar to itself, a shade of yellow; because the darker paper when in full light appears substantially the same as the standard yellow in the shade or shadow. [illustration] in our experiments thus far with the wheel we have combined the standards in pairs to produce the colors of the spectrum between the standards, which for convenience may be called intermediate spectrum hues, and also have combined a white disk with each of the standards to produce tints of the standards and a black disk to make shades. by combining a white disk with an orange and a yellow disk, for example, forming a trio of disks, a variety of tints of orange yellow and yellow orange may be made. also by the use of the black disk instead of the white a series of shades of the intermediate hues may be produced, and thus a great variety of tints and shades of many spectrum colors shown. now if the white and black disks are combined with each other the result will be a shade of white, i.e., a white in shadow, which is an absolutely neutral gray. as the experiments progress it will be seen that this neutral gray is a very important feature in the study of color, and therefore it may be well at this point to make sure that the disk combinations give the true gray of a white in shadow by a test similar to the one used for the shade of yellow, thus disarming criticism. such a test may conveniently be made by covering the reverse sides of the folding covers with white on one cover and "neutral gray paper no. 1" on the other. as the neutral gray papers are made in imitation of combinations of black and white disks this experiment is as convincing as the one regarding the yellow shade. this is but one of many examples of the value of disk combinations in the classification and analysis of colors. in an elaborate chart of colors highly recommended for primary color instruction a dozen years ago no correct understanding of the classification of colors is shown, the tints and shades being indicated by a very decided change of hue rather than a consistent modification of tone. for example, in the red scale the standard or normal red is vermilion, i.e., an orange red; shade no. 1 is simply a red less orange in hue than the standard, and shade no. 2 a shade of the standard red advocated in this system; while tint no. 1 is a broken yellow orange and tint no. 2 is much more yellow and more broken than no. 1. similar inconsistencies occur in all the other scales, showing that the author had no correct knowledge of the analysis of colors, and yet this was the best and practically the only aid offered for instruction in color at that time. neither were there any true standards for neutral grays and the term "neutral" was used in such an indefinite way as to rob it of all actual value, until by the aid of disk combinations it came to be confined to white in shadow as closely imitated by the combinations of white and black disks. [illustration] with colored papers made in imitation of the six standards and two tints and two shades of each, six scales of colors may be produced by arranging the five different tones of each color in a row, as in fig. 9, which represents the orange scale with tints at the left and shades at the right. if, in addition to these six scales, we have two scales between each two of the standards, we may have between the orange scale and the yellow scale a yellow orange scale and an orange yellow scale, and if we thus introduce the intermediate scales between each of the other two standards, and include the red violet and violet red, we shall have eighteen scales of five tones each. the eighteen scales as above named may be arranged as shown in fig. 10 to form a chart of pure spectrum scales which is very valuable for study and comparison and especially so in the study of the theory of harmonies. all these tones are called pure tones and this chart is therefore called a chart of pure spectrum scales. the idea that soft, dull, broken colors produce best harmonies when used in combination may or may not be a universally accepted truth, but there is a general belief that it is much easier to make acceptable combinations with broken colors than with pure spectrum colors and their tints and shades, and therefore the temptation has been strong to select a general assortment of colors which easily harmonize because of the pleasing effect, instead of having regard solely to the educational value of colors. truth in education requires that when colors are classified as spectrum colors they shall all be the nearest approach possible to the true spectrum colors, and in the spectrum there are no broken or impure colors. therefore, whenever the spectrum is set up as nature's standard or chart of colors and an imitation is made in pigments or papers, great care should be used to secure the most accurate imitation possible, but in the past this has not been the case, because of the prevailing idea that the colors must all be possible combinations of three primaries, and hence the orange, green and violet have often been very broken colors. while pure colors and their tints and shades may be advantageously combined with various tones of broken colors in one composition for artistic effect, they should be definitely divided when classified for educational purposes, and their differences clearly explained to students. in a scale of tones in any color the several papers will harmonize more easily if the tints and shades are not too far removed from the standard, but it is thought by many good judges that the educational advantage in learning to see the relationship of color in the more extreme tones is of greater importance in the elementary grades than the facility for making most pleasing combinations. consequently in the bradley colored papers the tints are very light and the shades quite dark. if, instead of adding either a white disk or a black disk to a spectrum color, by which we make pure tints and shades, we add both white and black, a line of gray colors or so-called broken colors is formed. this is most beautifully shown with the disks, and in this way a line of _true broken colors_ is secured, because in each case a true neutral gray has been added to the color, which cannot be insured in the mixture of gray pigments. as an example, this may be shown with the three smaller sizes of the orange disks. with the medium size of these three make the combination orange, 35; white, 10; black 55. with the larger size disks make the proportions orange, 16; white, 5; black, 79, and with the smallest size orange, 43; white, 33; black, 24. place these three sets of disks on the spindle at one time and you have the three tones of a broken orange scale. with similar combinations applied to the six standards and one intermediate hue between each two, there will be material for a chart of broken spectrum scales, as shown in fig. 11, including twelve scales of three tones each. these are the most beautiful colors in art or nature when combined harmoniously. because of the loss of color in broken colors it is not advisable to attempt so many different hues or so many tones of each hue as in pure colors, for slight differences in either hues or tones are not as readily perceived. in these two charts of color scales two distinct classes of colors are represented, namely, pure colors and broken colors. the pure colors consist of the purest possible pigmentary imitations of spectrum colors, with their tints and shades, and the broken colors are these pure colors dulled by the admixture of neutral grays in various tones. this distinction is readily recognized under proper training, so that if a broken color is introduced into a combination of colors from a pure scale it will be readily detected, which always occurs when the attempt is made to produce a series of spectrum scales by the combination of the three primary colors red, yellow and blue. by this method, if logically carried out, the orange, green and violet are dark broken colors, and hence to a less extent the intermediate colors also, because each of these is a mixture of a pure color with a broken color. the usual result, however, is that the orange made from the red and yellow seem so out of place in the warm end of the spectrum that it is modified and made much nearer the pure color, usually, however, too yellow, while the greens and violets, which are deep and rich broken colors, may seem more harmonious, but are so dark as to be out of place among spectrum colors. [illustration] if light broken colors are properly combined a beautiful imitation rainbow is produced, which is more harmonious than the spectrum made from full colors. a series of such colors combined in spectrum order produce a more pleasing effect when separated by a small space of white, black, gray, silver or gold. the reason for this may be found in the discussion of simultaneous contrasts. in nature nearly all colors are broken. first, there is always more or less vapor together with other impurities in the air, so that even in a clear day objects a few hundred feet from us are seen through a gray veil, as it were, and in a misty or hazy day this is very evident. in the case of somewhat distant foliage the general color effect is produced by the light reflected from the aggregation of leaves, some of which may be in bright sunlight and others in shadow, with a mixture of brown twigs. all these tints and shades of green and brown are mingled in one general effect in the eye. also, owing to the rounded forms and irregular illumination of objects, we see very little full or local color in nature. therefore the study of broken colors becomes the most fascinating branch of this whole subject, and it also has an added interest because nearly all the colors found in tapestries, hangings, carpets, ladies' dress goods, etc., come under this head. in fact it would be hazardous for an artisan or an artist to use any full spectrum color in his work, except in threads, lines or dots. a considerable quantity of pure standard green, for instance, would mar the effect of any landscape. it is a very interesting diversion to analyze samples of the dress goods sold each season under the most wonderful names. for example:-"ecru," a color sold a few seasons ago, is a broken orange yellow with a nomenclature o. 12, y. 15, w. 17, n. 56, while this year "leghorn" and "furet" are two of the "new" colors, the former having a nomenclature of o. 16, y. 54, w. 19, n. 11, and the latter o. 18, y. 18, w. 8, n. 56, all of which are very beautiful broken orange yellows. "ashes of roses" of past years is a broken violet red which can be analyzed as follows: r. 8-1/2, v. 2-1/4, w. 15-1/4, n. 74. "anemon" of this season is r. 28, v. 7, w. 5, n. 60, which is another broken violet red. "old rose" is a broken red: r. 65-1/2, w. 24-1/2, n. 10. "empire" of past seasons is g. 18-1/2, b. 11, w. 16-1/2, n. 54, while "neptune" of this season is g. 13-1/2, b. 2-1/2, w. 11, n. 73, both being broken blue greens. "topia," a beautiful brown, is o. 10, n. 90, a pure shade of orange, while "bolide" is a lighter yellow orange with a nomenclature of o. 18-1/2, y. 2-1/2, w. 1-1/2, n. 77-1/2. we might analyze "elephant's breath," "baby blue," "nile green," "crushed strawberry" and others common in the market, but while the names will no doubt occur each season the colors will change with the fickle demands of the goddess of fashion and the interests of the manufacturers and dealers. in writing any color nomenclature the letters should be used in the following order: r.-o.-y.-g.-b.-v.-w.-n., thus always listing the standard colors before the white or black. for example, never place y. before o. or r., and never use n. before w. if this order is strictly adhered to the habit is soon acquired and a valuable point gained. it has been shown that combined white and black disks form neutral gray, which is a white in shadow or under a low degree of illumination. if to such a gray a very small amount of color is added, as orange for example, by the introduction of an orange disk, this neutral gray becomes an orange gray, but unless the amount is considerable it can not be detected as an orange, but the gray may be termed a warm gray, denoting that it is affected by some one of the colors near the red end of the spectrum. if blue instead of orange is added to the neutral gray, a cool gray is produced. when green is added to a gray the result can not fairly be called either warm or cool, and hence we have termed it a green gray. according to this plan we have four classes of grays, neutral, warm, cool and green grays. as there may be many tones of each, and many intermediate combinations from red to green, or green to blue, the number of grays in nature is infinite, but these four classes with two tones of each in the papers form what may be called standards or stations from which to think of the grays, the same as the six standards in the spectrum constitute points from which to think of pure colors. a careful consideration of the foregoing pages, accompanied with a color wheel or even a color top, can hardly fail to give a student who will make the experiments a clear idea of the use of the disks in the system of color education in which they form such an important feature, and therefore the old theory of three primaries, red, yellow and blue, and all that it leads to can be very intelligently considered and tested by them in the experiments which follow. this old theory briefly restated is as follows: it is said "there are in nature three primary colors, red, yellow and blue; and by the mixture of these primary colors in pairs, orange, green and violet may be made." in fact leading educators have said that "in the solar spectrum, which is nature's chart of colors, the principal colors are red, orange, yellow, green, blue and violet; _of these_ red, yellow and blue are primaries from which may be made the secondaries, orange, green and violet." all such statements as heretofore made in any popular treatment of the subject are understood to mean that in a pigmentary imitation of a spectrum the secondaries as enumerated may be produced by the mixtures of the primary pigments, because pigmentary mixtures are the only combinations generally recognized. this theory has also included the statement that the primaries are complementary to the secondaries in pairs, and that the combination of the secondaries in pairs may produce a distinct class of colors called tertiaries. it will be the aim of the following pages to demonstrate that in all this there is neither scientific or æsthetic truth nor educational value. the old theories tested by mixture of three pigments. experiments in mixing the three pigments, red, yellow and blue, to produce the secondaries, orange, green and violet, have been very carefully made with interesting and instructive results. all such experiments are valueless unless made with one accepted set of primaries for the three combinations, because it is self-evident that if we select a vermilion red which is very decidedly an orange red, and choose for our yellow one of the orange yellows, the mixture will more nearly approach a true orange than if a standard red and standard yellow are used. also in making a violet, if we mix a carmine, which is a violet red, with a decidedly violet blue, of which there are many, the result will be a better violet than the combination of the standard red and blue. so also in the mixing of blue and yellow to make green, a greenish yellow and a greenish blue will necessarily produce better results than the standards. therefore, to test the matter fairly, the same pigments which are used to coat the standard red, yellow and blue papers have been combined so as to produce the best possible orange, green and violet, and these results when analyzed on the color wheel are as follows:-the orange made by mixing standard red and yellow pigments in the best proportions is equal to o. 46, w. 2, n. 52. the violet is equal to v. 20, w. 1, n. 79, and the nearest approach to a standard green is shown by disk analysis to be g. 37, w. 7, n. 56, which is better than the violet and nearly as good as the orange. these experiments show that heretofore when a line of standards of six colors has been prepared from three primaries, red, yellow and blue, even though the purest possible colors may have been selected for the primaries, the secondaries have not been in the same class of colors, and that all of them are very dark broken colors. therefore, in using educational colored papers based on such a scheme, the pupil has received no correct impressions of the relative values of the several colors involved in pure spectrum scales, but has been shown at the outset a mixture of pure and broken colors _as standards_. this is not a matter of opinion regarding best harmonies, because it is easy to demonstrate that less skill is required to combine broken colors harmoniously than pure colors, but it is a choice between truth and error in the early education of color perception. old theories tested by the color wheel or color top. while it may be impossible for the reader to secure pigments exactly like the standards, red, yellow and blue, used in the above experiments, and therefore the statement here made can not be accurately verified, any one having a color wheel or even a color top may test the same combinations by use of disks. if it is true, as claimed, that a good standard orange can be made by mixing red and yellow, then it should follow that when a red and yellow disk are combined and a smaller orange disk placed in front of them, that it ought to be possible to so adjust the proportion of red to yellow that by rotation the outer ring of color will match the central orange disk. a trial of this experiment will show that while the color resulting from the best possible combination of red and yellow is a kind of orange, it is not even an approximation to the standard orange, but is a shade of orange which may be matched by combining the smaller orange disk with a black disk in the proportion of o. 45, n. 55, the larger disks being r. 89, y. 11. in combining red and blue disks to make a violet the result is more satisfactory, while if we attempt to produce a green by combining the yellow and blue disks the result will be surprising, but probably not convincing, because the statement that yellow and blue make green has been so persistently reiterated as a fundamental axiom that people who have given the subject but little attention will feel that to doubt it is rank heresy. in a text book treating of color is found the following passage: "green substances reflect the green, i.e., the blue and yellow rays of the sunlight and absorb all the others." it is a fact, however, that in the mixture of blue and yellow light there is little or no trace of green, as a single experiment with a color top or color wheel will readily demonstrate. in response to this convincing experiment a colorist of the "old school," (and there are few others) will doubtless say, "such an assertion seems to be true when applied to these rotating disks, but we see no practical value in experiments of this kind, because in the use of color we must depend on pigmentary combinations, and in pigments yellow and blue do make green." the author of a statement of this kind is always honest in making it, and yet it is absolutely untrue, because as has already been shown, the green resulting from the mixture of yellow and blue can not be placed even approximately in the same class as the yellow and blue of which it is composed. in accepting the disk combinations of standard pigmentary colors we are assuming a system of color investigation based on the combination of colored light rather than the mixture of pigments, and to an artist who has given the subject little thought this seems quite radical, not to say startling. but, logically, why is it not the most natural as well as the correct basis for this work? art in color must be based on the imitation of natural color effects. we must first learn to see color correctly and to know what we see, and after that it is a very simple matter to learn which pigments to combine for producing any desired result which is already clearly defined in the mind. in fact the best selection of pigments must often be based on their chemical and mechanical qualities as much as on their peculiar hues. all color impressions of material substances are produced by colored light reflected from a material surface to the retina of the eye, through which by some unknown means it is conveyed to the brain. when the white sunlight falls on a material substance a portion of the rays are absorbed and others are reflected to the eye, thereby conveying impressions of color. if on a surface of yellow material we throw a strong orange light through a colored glass, some of the orange rays from the glass will mingle with the yellow rays and the two are reflected to the eye, thereby producing an orange yellow or yellow orange effect where before it was yellow. so in a summer evening landscape when there is a so-called red sunset, everything is illuminated by an orange light and each color in the landscape is affected by the orange rays which mingle with the rays of the local color and are reflected to the eyes of the observer, producing the effect of local colors mixed with orange. in a room where the windows open on to a green lawn with many trees in close proximity to the house, nearly all the light is reflected from green surfaces, and hence is green light. in such a case a correct painting of objects in that room would have a general green effect. the afternoon light in a room on the west side of a city street may be nearly all red light, reflected from an opposite red brick wall, and such a room would be ill-adapted to showing fine dress goods, because the hues of the more delicate colors would be entirely changed, and hence would give a false impression as to the relations of the several colors in combination as seen in white or clear daylight. if a piece of light blue silk is illuminated by sunlight passing through a bit of yellow glass, no trace of green effect will be produced, but a gray either slightly yellow or blue, according to the relative strength of the colors in the glass and the silk. this same effect would be secured if the yellow light of the setting sun illuminated the same material, but under such conditions everything else would be similarly affected so that the effect would not be so apparent. the idea that all color is derived from the three primaries, red, yellow and blue, is so generally believed that our best writers among artists, colorists and educators have repeated it for many years. george barnard, an english artist, in a very valuable book on water color painting, speaking of the colors of the spectrum which may be re-combined to form white light, says that if the yellow and blue rays are combined they produce green. chevreul also states in his invaluable book on color contrasts that yellow and blue threads woven into a texture, side by side, produce green. this statement is the more remarkable because the writer was a very careful investigator and is but another evidence of the strong hold which the newton and brewster theory has had on the public mind for so many years. the story is told of an artist who wished to introduce into a composition of still life a blue vase with a bit of yellow lace thrown over a portion of it, and having been educated to believe that yellow and blue made green, gave a green effect to the portion of the vase covered by the lace. had he known that blue and yellow light combined make gray instead of green he would have avoided the error. the fact that gray is the product of blue and yellow light is sometimes taken advantage of in forming backgrounds in lithographic printing, in which a stippling of alternate dots of yellow and blue, very close together but not overlapping, is used to produce a beautifully transparent gray much more pleasing than any one tint of gray. this result is due to the blending of the two colors in the eye with the same effect as the colors of two rotating disks are mingled. the fact that there is a difference between the color effects produced by mixing two pigments and the mixing of the light reflected from similar colored surfaces is a very strong argument for a system of color instruction based on disk combinations, rather than on pigmentary mixtures. in order to obtain the most truthful effects of color in nature the artist should have sufficient knowledge of the principles which govern the combination of colors by reflected light, so that his reason may aid his eyes. a little experimenting with the rotating disks and with pigments will convince any one that the disk combinations form the only possible basis at present known for logical color instruction. concerning the complementary colors. having shown that the three colors, red, yellow and blue, can not be combined to make an orange, a green or a violet of a corresponding degree of purity, we will consider the other claim which is set up by the advocates of the brewster theory, namely, that the secondaries are complementary to the primaries in pairs, the green to the red, the violet to the yellow and the orange to the blue. as all color is contained in white light, if we take from white light any given color, the color remaining is the complementary. if a small disk of standard red paper is placed on a white wall and the eyes fixed intently on it for a few seconds, and then the eyes slightly moved back and forth, a ring of a bluish green tint will be seen surrounding the red paper, or if the eyes are fixed intently on the disk for a short time and the paper suddenly removed, a disk of the same blue green tint will be seen in place of the red disk. this is called the accidental color and is supposed to be identical with the complementary color, although the image is too faint to give any very exact effect, but it is sufficient to furnish a clue to the complementary, and we may infer that a color between green and blue is that which is required. now if we can determine in what proportions red, blue and green must be united to produce white light we may solve the problem. this is not possible in the use of any pigmentary colors, because of the impurity of all pigments as compared with spectrum colors. although the mixture of colored light reflected from the disks, which are made of pigmentary colors, gives much purer color than the actual mechanical mixture of the two pigments, still, because it is a reflection of pigmentary colors, it is far lower in tone than the corresponding mixture of spectrum colors. therefore it can not be a pure white, but may be white in shade or a neutral gray, which, as already shown, can be produced by the combination of a white and a black disk. therefore if red, blue and green disks of medium size are joined on the wheel and in front of them small white and black disks are combined, we have a means for solving this problem. if these various disks can be so adjusted that when rotated the effect of the three colored disks is a neutral gray, (or white under a low degree of illumination) exactly matching a gray that may be obtained by adjusting the small black and white disks, then one step in the solution is taken, as shown in fig. 12. [illustration] with such an arrangement a very close match is produced, when the combined disks show the proportions to be r. 41-1/2, b. 22-1/2, g. 36 for the larger disks, and for the small disks w. 15, and n. 85. now if blue and green are combined in the same proportions, as indicated above and in quantities sufficient when added together to fill the entire circle of 100 parts, blue will contain 38.3 parts and green, 61.7 parts, as shown in fig. 13, and the disks when rotated will give the color which is the complementary of red: namely, a blue green. in the same way the complementary of each of the other standard colors, and in fact of any color, may be obtained. the complementary of orange is another color between the green and blue, but more largely blue. the complementary of green is a violet red, and of violet a color between yellow and green, while yellow and blue are very nearly complementary to each other. these figures furnish the results in a very well-lighted room, with a perfectly white interior. it is a well-established fact that this experiment is somewhat affected by the degrees of illumination, and also that colored light from the walls and ceiling of a room must of necessity have its effect, but all these matters are so insignificant as to be of no material consequence in the æsthetic study of the subject, and they can be very nearly eliminated when necessary by a careful selection of conditions. whenever accurate experiments in pigmentary color comparisons are to be made, either by the use of rotating disks or otherwise, it is desirable to have a very well-lighted room, with a northern exposure and to select a morning or noonday light from a slightly overcast sky. these conditions obviate the unpleasant effect of direct sunlight in the room and also the very slightly blue effect of the clear sky. these precautions are unnecessary in experiments relating to the ordinary æsthetic consideration of color combinations, but even in such work it is important to exclude all light reflected from neighboring trees or colored buildings. also the interior of the room should be as free from color as possible; a clean white surface is especially desirable. a chart of complementary colors, shown in fig. 14, has been found very valuable in fixing in the minds of teacher and pupils the complementaries of the six standards. in this chart, which is about eighteen inches in diameter, the circles at the ends of the six diameters are colored papers selected from the bradley coated papers, as approximating the true complementaries. in the majority of cases they are not far from correct, but are least satisfactory in the blue and yellow. theoretically the complementary of the ideal standard blue is a slightly orange yellow, and of the standard yellow a slightly violet blue. but there is as yet no blue pigment in the market suitable for commercial use which is free from a slightly violet effect. therefore the standard blue paper is practically as good a complementary for the standard yellow as the violet blue paper. but notwithstanding these slight imperfections which are at present unavoidable, the chart is a valuable aid in fixing in the mind the positions of the complementary pairs in the spectrum circuit. [illustration] each of the foregoing experiments furnishes an interesting class exercise, and may be very closely repeated by the pupils with their tops. also the computation of the proportion of green and blue when raised to the full circle may form a practical problem in proportion for pupils of the higher grades. taken together, these experiments prove that the complementaries of the old primaries are not found in the secondaries. the last claim of the brewster theory is that the secondaries by combination form three lines of colors peculiar to themselves, called citrines, russets and olives. it is asserted that the mixture of orange and green makes citrine; orange and violet russet; green and violet olive. although these names may be very convenient terms to express three general classes of colors, they must of necessity be too general and indefinite to be of value for accurate expression of color effects, and are in fact so vague that hardly two persons can be found in a large company who will agree as to the best expression of either of them. the following are formulas for a number of colors in each class, as made from analyses of colors coming under these names. it is an interesting exercise to produce some of these colors by means of the rotating color disks and test the opinions of the different members of a company as to which best represents to each one of them a tertiary color, as citrine, for example. for this purpose three different formulas may be shown at the same time, with three sizes of disks. citrines. o. 7. y. 13. w. 3-1/2. n. 76-1/2. y. 15. w. 4. n. 81. y. 13. w. 5. n. 76. g. 6. o. 6. y. 20. w. 4. n. 70. o. 3. y. 6. w. 8. n. 83. russets. r. 37. o. 8. w. 8. n. 47. r. 79. w. 10-1/2. n. 10-1/2. r. 33. o. 20. w. 6. n. 41. r. 36. o. 4. w. 9. n. 51. r. 47. o. 7. w. 8. n. 38. olives. g. 19. b. 11-1/2. w. 10-1/2. n. 59. g. 13. b. 6. w. 12. n. 69. g. 14. b. 12. w. 8. n. 66. g. 10-1/2. b. 15. w. 8. n. 66-1/2. g. 12-1/2. b. 5-1/2. w. 4. n. 78. the term citrine theoretically covers all possible combinations of orange and green, but as generally understood those colors which are so near the orange or the green as to very decidedly approach either the one or the other are not included, and, as shown in the above analyses, a citrine is a very broken color ranging from an orange yellow through yellow to a green yellow. although the russets would theoretically range from violet to orange, yet the general conception of russet will hardly accept a violet red, but will cover only the red and orange reds as above indicated, while olives are confined to blue greens and green blues. these tests are based on combinations of the bradley standard orange, green and violet pigments, and therefore are far stronger in color than those colors usually termed citrine, russet and olive, made by mixing the pigmentary secondaries. for example, if a yellow and blue pigment are mixed to form a green, and red and yellow pigments to make an orange, and then this green and orange are mixed to produce a citrine, the result will be very much darker and more broken than the mixture of the purer orange and green colors used as standards. restricted to these limits these names may become very useful terms for general color expressions, as covering three different classes of broken colors. if any one believes that these color formulas do not correctly represent the three classes of colors indicated, a series of experiments with even the small color top will prove very convincing. when the subject of standards as a means for identifying colors is mentioned artists frequently express the feeling that the names of pigments are good enough for them, such as ultramarine blue, prussian blue, vermilions, the siennas, indian red, etc. the following are the analyses of several samples of vermilion, burnt sienna, raw sienna, and indian red of the best tube oil colors in the market:- vermilion. r. 80. o. 14. w. 6. r. 87. o. 8. w. 5. r. 50. o. 24. w. 26. burnt sienna. r. 1-1/4. o. 6. w. 3. n. 89-1/2. r. 22-1/2. o. 11-1/2. w. 2. n. 64. r. 25. o. 12-1/2. w. 5-1/2. n. 57. raw sienna. o. 18-1/2. y. 6-1/2. n. 75. o. 17. y. 14. w. 1. n. 68. o. 8-1/2. y. 3-1/2. w. 2. n. 86. indian red. r. 11-1/2. o. 7. w. 4. n. 77-1/2. r. 13-1/2. o. 13-1/2. w. 2-1/2. n. 70-1/2. a careful examination of these formulas and a reproduction and comparison of the colors on the color top will convince any one that in no case does the commercial name determine the color with a degree of accuracy sufficient for any valuable nomenclature. classification of harmonies. the theory of the harmonies of colors is a subject which awaits very careful investigation and a general discussion by artists and expert colorists. such investigations must include many experiments based on common standards and uniform methods of measurements and records. harmonies naturally seem to fall into a few general classes which are convenient for comparison and discussion as well as for elementary instruction, but no one person can set himself or herself up to decide which are the _best_ harmonies. the practices and recommendations of noted artists who have appeared to be gifted with intuitive perceptions regarding color combinations have frequently included those for which there seemed to be no recognized authority, and yet their beauty could not be questioned. as the rules of grammar are but the correlation of the practices of the best scholars, so the rules governing color combinations must be the summary of the practices and recommendations of the best artists, if they are to be generally accepted as final, and hence we must patiently await the growth of similarly established laws by the comparison of the opinions of critics of acknowledged ability in various departments of the world of art. this has not been possible in the past and can never occur until there is a language of color through which color facts can be somewhat accurately expressed in verbal and written language, and this language cannot exist until there is an accepted alphabet of color on which it can be based. this alphabet is now in part furnished by the spectrum standards and completed by the pigmentary standards and the rotating disks made like them. together they form the basis for a nomenclature by the use of which the questions involved in harmonies can be discussed and the results expressed in written language. in the investigation of any subject with a view to elementary instruction, classification is an important factor, but one which heretofore has been almost ignored as regards color education. consequently at present the more definite division of harmonies into classes is very much a matter of personal opinion, but mr. henry t. bailey, state supervisor of drawing in massachusetts, has suggested a very useful classification in which he arranges all harmonies under these five heads: contrasted, dominant, complementary, analogous and perfected. _contrasted._--the contrasted harmonies are those in which color is contrasted with non-color, or more accurately in which an active color, that is a tone from the spectrum circuit, is contrasted with a passive color, white, black, gray or silver and gold; for example, a blue green tint with white, or green blue with warm gray no. 1. _dominant._--by dominant harmonies we mean those in which are combined different tones from one color scale. for example, red tint no. 1, and red shade no. 1, or a green blue tint, green blue, and a green blue shade. a dominant harmony composed of grays, or white, gray and black, is sometimes called a neutral harmony. _complementary._--this term refers to those harmonies in which are combined opposite or complementary colors in the spectrum circuit. the best of them show not only opposition in color but also opposition in tone. thus, tints of one color with shades of its complementary produce a more pleasing effect than do complementaries of equal value. the best complementary harmonies contain one or more passive colors. _analogous._--this name is applied to those harmonies in which are combined tones from scales of neighboring colors in the spectrum circuit. for example, in a composition of colors from that part of the spectrum containing yellow, green yellow and yellow green the following simple combination may be made: yellow tint no. 1, green yellow and yellow green shade no. 2. _perfected._--by perfected harmonies we mean those in which the general effect of one analogous harmony is complementary to that of another. the above classification of harmonies is very valuable for fixing in the mind the various effects of color combinations, and yet they may seem to somewhat merge into each other in their application, until the underlying principles which govern them are understood. it is unwise to suppose that because the above classification of harmonies is based on the science of color we can infer that it furnishes definite rules for producing best effects. the work of chevreul reviewed. the good or bad effect of two or more colors in combination in decorative designs or fine art depends very largely upon phenomena which are elaborately explained in a book entitled "the principles of harmony and contrasts of colours" by m. chevreul.[a] the first edition of this book was prepared in 1835 and published in 1838. the author had at that time been employed for a number of years as superintendent of the manufactory of gobelin tapestries in paris under the control of the french government. [a] the principles of harmony and contrasts of colours and their application to the arts. by m. e. chevreul. translated from the french by charles martel. third edition. london. george bell and sons. 1890. in this book are described in detail the results of a great number of experiments which were instigated by complaints regarding certain colors produced in the dyeing department of the manufactory, and which afford the most elaborate exposition of the subject ever published. one of the first things which led chevreul to make his investigation was the complaint that certain black yarns used as shades in blue draperies were not a full black but more or less gray. the author says in his preface, "the work i now publish is the result of my researches on simultaneous contrasts of colours; researches which have been greatly extended since the lectures i gave on this subject at the institute on the 7th april, 1828. in reflecting on the relations these facts have together, in seeking the principle of which they are the consequence, i have been led to the discovery of the one which i have named the _law of simultaneous contrast of colours_." the closing sentence of the preface to the first edition and dated 1835 is as follows:-"i beg the reader never to forget when it is asserted of the phenomena of simultaneous contrast, _that one colour placed beside another receives such a modification from it_, that this manner of speaking does not mean that two colours, or rather the two material objects that present them to us, have a mutual action, either physical or chemical; it is really only applied to the modification that takes place before us when we perceive the simultaneous impression of these two colours." it was not till three years later that a publisher could be found for this book, which is still a standard. the english translation comprises over five hundred closely printed pages with many engraved and colored plates, and yet, it has been of comparatively little value in _popular instruction_ because of the lack of a generally accepted color nomenclature or list of well defined color terms, by which the readers might have understood and repeated for themselves the experiments described. unfortunately chevreul was fully impressed with the newton-brewster idea of three primaries, red, yellow and blue, and therefore some of his deductions from his experiments seem to have been more or less influenced by the attempt to make them harmonize with this theory, and yet the subject which he has treated so exhaustively and intelligently is one of the most important in the æsthetic study and use of colors. in all expressions of colors in combination with each other, whether in nature, fine arts or the decorative and industrial arts, every color is affected by its surrounding colors, a fact which is exhaustively treated in this book. while with our present knowledge of the subject it does not seem that the material use of color can be reduced to an exact science, this should not prevent us from accepting all the natural and scientific aids which have been or may be discovered toward this desirable result. because of this lack of scientific knowledge in chevreul's time much of the worth of his experiments is lost to us, yet there is very much of value in his work, suggesting as it does experiments which may be tried with present standards and modern methods. if the use of maxwell disks had been known to chevreul his deductions from his experiments would have been quite different in their details. for example, in accepting the proposition that there are three primaries, red, yellow and blue, which may be combined in pairs to make the secondaries, orange, green and violet, he states that owing to the impurities of the pigments the secondaries are not as pure as the primaries. consequently he believes that this may account for many of the shortcomings which he was too observing to overlook; but notwithstanding such an error in theory this wonderful investigator made many practical experiments and established very valuable facts regarding color contrasts. the term simultaneous contrast seems rather restricted for a title covering such a range of effects, and the author subdivides the subject into simultaneous contrasts, successive contrasts and mixed contrasts, which he defines as follows:-simultaneous contrast. "in the simultaneous contrast of colors is included all the phenomena of modification which differently colored objects appear to undergo in their physical composition and in the height of tone of their respective colors, when seen simultaneously." successive contrast. "the successive contrast of colors includes all the phenomena which are observed when the eyes, having looked at one or more colored objects for a certain length of time, perceive, upon turning them away, images of these objects having a color complementary to that which belongs to each of them." mixed contrast. "the distinction of simultaneous and successive contrast renders it easy to comprehend a phenomenon which we may call the mixed contrast; because it results from the fact that the eye, having seen for a time a certain color, acquires an aptitude to see for another period the complementary of that color, and also a new color, presented to it by an exterior object; the sensation then perceived is that which results from this new color and the complementary of the first." these last two effects may be shown very clearly in simple experiments. there are various phenomena which may be classed as successive contrasts sometimes called "after images." the phenomena which chevreul groups under the term "simultaneous contrast of colors" belong to a class of physio-psychological effects termed after images, and more definitely to the subdivision called negative images. the positive after images are not important in the consideration of the theories of color and therefore are not described here. the specific effect most directly involved in the subject of harmonies may be observed if the eyes are fixed upon a small disk of red paper on a white wall for a few seconds and then the paper is suddenly removed, as there will appear on the wall in place of the full red disk a faint tint of a blue green. this is called an after image, and is nearly or exactly a tint of the color complementary to red. for making this experiment mount a circle of red paper, say three inches in diameter on a square white card, four or five inches across, and grasping the card by one corner hold it in front of a white wall or a sheet of white paper pinned on any support. tell the observer to look intently at the red disk for a half minute, and then without giving any notice suddenly remove it and ask what color is seen in place of it. at the first trial the result may not be entirely successful, because the eyes of the observer may naturally follow the red spot when it is removed instead of remaining fixed in the original position, but a second trial will bring the expected result. to illustrate mixed contrast, fasten on the wall a piece of red tint no. 2 paper four or five inches square. this may be very conveniently done by using a bit of beeswax on each corner of the paper, which will not soil the wall. then having the three-inch circle of standard red paper mounted on a white card somewhat larger than five inches square hold the card in front of the red tint on the wall and repeat the experiment as before. the effect now should be a three-inch disk of very light gray in the center of the pink square, which is a "mixed contrast" according to chevreul. the reason is simple. the after-image or successive contrast of light blue-green is projected on the red tint and being complementary the resulting effect is a gray. if the red tint could be exactly graded to the complementary effect in the eye the resulting gray circle would be a true neutral gray. another illustration of the same physical effect by which the complementary is induced may be shown by substituting for the tint of red a light tint of the blue-green paper retaining the full red disk as before. the same blue-green after image is now projected on to the light blue-green paper and hence a circle of more intense blue-green is produced. thus it is seen that chevreul's successive and mixed contrasts are both due to the same physiological effect, the only difference being in the ground on to which the after image is projected. it probably is unnecessary to state that these experiments may be made with any color and its complementary and that red and blue-green are used here merely as an example. another phase of the same physical effect is seen under other conditions which may at first seem to be quite different from those described, but which on examination appear somewhat similar. it is a well established fact that when two surfaces approximating each other in color, as red and orange for example, are placed side by side, both are rendered less brilliant, an effect which might be reasonably expected because in order to see both the eye is naturally directed first to one and then to the other, and in each case the after image induced is a green-blue or blue-green, which being approximately complementary to both, dulls both. or in other words, it is as though one examines for a long time a line of goods of similar colors so that the eye becomes fatigued and the color dulled. it is said that a good salesman of colored materials will endeavor to occasionally attract a customer's attention for a few moments to some other colors approximating a complementary, so that when the attention is again directed to the goods under consideration the full effect of the color may be secured. if it is true that the phenomenon of the after image is the cause of the peculiar effects expressed by the terms simultaneous, successive and mixed contrasts, and that by these effects all harmonies in color are governed, it is certainly profitable to understand them while using color material with the children, for their good as well as our own pleasure. contrasted harmony. returning to our classification of harmonies, already stated, we find the first to be contrasted harmony, which covers those combinations in which a positive color, as a spectrum color for example, is combined with white, black or gray, leaving out for the present silver and gold, which may be confusing, and can at best be used only as outlines. the simplest combinations of colors are found in this class, all of which are not equally harmonious, and some may not perhaps be entitled to be classed as harmonies, although not positively inharmonious. in this class, as in all others, there is involved contrast of tone and contrast of color, which may best be considered in several divisions. color with white. according to the results of chevreul's elaborate experiments the effect of a combination of an active color with white is to render the color more brilliant and to give to the white the effect of the complementary of the active color. he admits that the modification of white is very indefinite, but claims that, knowing what to expect, a complementary effect may be seen which otherwise would not be noticed. there is also a contrast of tone which in all cases tends to strengthen a color when used with white. black with white. white and black are both intensified by combination with each other, and this is the type of "contrast of tone." contrast of tone is very clearly shown when two or more grays of different tones are placed contiguous to each other. this experiment is easily tried by mounting side by side several strips of gray papers of different tones. if more than two are used they should be arranged in order from lightest to darkest. in this case each band will appear to be graded in tone from one edge to the other, each being lighter at the edge next to the darker paper. this effect is plainly shown on the color wheel by producing several rings of grays with white and black disks of several sizes graduated from light at the center to darker at the circumference. color with black. in consequence of this law of contrast of tone the contrast of black with active colors generally tends to intensify the black and lower the tone of the color, i.e., to weaken it as though white or light gray was mixed with it, but this effect is modified by contrast of color. contrast of color is perceptible in black when combined with color simply because the black is not perfectly black but a very dark gray, and hence there is the same complementary effect which shows in white and the lighter grays, but in a smaller degree. this effect is most clearly seen when the color used in combination is blue or blue-green, which induces in the black, yellow or red complementaries and gives the black a "rusty" appearance. on the other hand, for example, red with black adds the complementary green-blue to the black, which improves it. the orange and yellow have a similar effect by their blue complementaries to relieve the black from any rusty appearance and a green yellow induces a violet effect in the black. colors with gray. when a color is contrasted with white the light from the pure white surface is so intense as to very largely obscure the complementary effect on the white, while on the other hand the feeble light from the black is not favorable for the exhibition of a complementary. so it might naturally be inferred that some tone between the white and black would be much more favorable than either for the observance of this effect, which is proved by experiment to be the case. this fact is illustrated in the familiar experiment of placing a white tissue paper over black letters on a colored ground, by which the black is practically rendered a neutral gray and the color a light broken color, and in appearance the gray letters receive a color complementary to the color of the page on which they are printed. each color has its own tone of gray most susceptible to this complementary effect. the truth of this proposition can be perfectly shown on the color wheel by forming with three different sizes of disks a gray ring on a colored surface. for example, select small disks of orange and white of equal size, then a black and a white disk of the second size and an orange and a white disk of the third size. first place the large orange and white disks on the spindle, then join the two medium-sized white and black disks and put them in front of it, and lastly add the small orange and white disks. by rotation the result is the required neutral gray ring on a light orange surface. by the joining of the white disk with each of the orange disks the orange surface may be changed to a variety of tints for trial with the different grays which may be made from the black and white disks, so that the best tones of both orange and gray may be secured. when the best proportions are obtained the effect will be surprising, because when such disks are properly adjusted the complementary effect is so strong in the gray that it appears as a very definite color, a broken green-blue. it is said that the tone of gray should have the same relation to the tone of the color that its complementary would have in order to get best results. for the same reason if a circle of lightest neutral gray paper, say four inches in diameter, is placed on a piece of yellow paper about six inches square, and another circle just like it is put on a piece of blue paper of similar size, it will be quite difficult to convince any one who has not previously seen the experiment that both gray circles are from the same sheet of paper. the results observed in this experiment are produced by a contrast of tone which causes one to look lighter than the other, and a contrast of hue which gives one a blue and to the other a yellow hue, in contrast to the color on which it is mounted. contrast of colors. if two colors contiguous in the spectrum circuit are placed in juxtaposition the effect of the contrast of hue is to throw them away from each other. for example, if orange red and the red orange papers are put side by side the former will seem more red and the latter more orange. therefore, when colored papers are pasted up or laid in order to form a spectrum, for example, the colors not only fail to blend together but each line of contact is very disagreeably prominent. if two colors are separated by a narrow strip of light gray, gold, black or white, the effect is greatly improved. for this reason a design in analogous colors is often improved by separating certain colors by a fine line of black, gold or gray. if two colors not closely related to each other in the spectrum circuit are placed in juxtaposition, each is modified by an effect which is the complementary of the other. for example, if red and yellow are placed side by side, in contact, the red is rendered more violet by the added effect of blue, which is the complementary of yellow, and the yellow is modified by the blue-green complementary of the red, which tends to dull the yellow and change it slightly toward green. if blue and yellow are joined both are improved, as the two are so nearly complementary to each other that each is intensified by simultaneous contrast, blue being added to blue and yellow to yellow. dominant harmonies. in the use of colored papers those combinations classified as dominant harmonies are the most simple to make because they are all in one family, as the little children like to consider the relationship. the red family consists of the standard red and its tints and shades, or in other words the red scale. with the several papers ready made this harmony becomes very simple, but in the use of pigments the production of a true color scale is not a thing to be confidently undertaken by a novice. in a very elaborate color chart for primary education prepared with great care by dr. hugo magnus and prof. b. joy jeffries, and published at large expense about ten years ago with hand-painted samples in oil colors, this lack of classification of hues is very noticeable, although at that time it was by far the best publication of the kind and was not criticised on this point. for example in a scale of five tones of red the following are the analyses, beginning at the lightest tint:- tint no. 2, o.45, y.20, w.18, n.17. tint no. 1, o.69, y.3, w.7, n.21. standard, r.75, o.25. shade no. 1, r.85, o.15. shade no. 2, r.75, n.25. in this scale according to the bradley nomenclature the standard or full color is a very fine vermilion expressed by r.75, o.25, i.e. an orange red, and therefore in order to form a perfect scale both tints and shades should be in the orange reds, but in fact the tints are both broken colors, the lightest a very broken yellow-orange and the deeper tint very nearly a light broken orange. the lightest shade is a pure orange-red but with a larger proportion of red to the orange than the standard, while the darkest tone is a pure shade of red. thus in the five tones we have the following arrangement, beginning at the lightest tint:-broken yellow-orange, broken orange, orange-red; another pure orange-red but more red, and lastly red shade, thus embracing in one orange-red scale parts of four scales from yellow-orange to red. in these defects in the best chart of its kind in the market only ten years ago is seen the best possible evidence of the advance made since that time in color perception, largely due to the use of the color disks in determining scales. while in the use of colored papers the dominant harmony may be the simplest and the one in which there is least danger of really bad work, some of the combinations are much better than others, and superiority is perhaps secured as much by the relative quantities of each tone used in a composition as in the selecting of the tones. in the entire range of the spectrum even this class of harmonies involves problems too complex to be solved by a few rules, but it is a very interesting field in which the children may safely be allowed to roam and experiment. complementary harmonies. complementary harmonies may perhaps be classified next to dominant because they are more easily described and more definitely limited than those effects termed analogous harmonies. a pure complementary harmony consists of the combination of tones from two scales which are complementary to each other. for example, the red scale is complementary to the blue-green scale, as also the green to the violet-red, and so on throughout the entire range of the spectrum scales. as explained on page 50, the complementary of any color can be determined by means of the color wheel, or nearly enough for æsthetic purposes with the color top. but even though the colors complementary to each other may be determined scientifically there will always remain ample opportunity for the exhibition of color sense and artistic feeling in the choice of colors because the difference between a very beautiful composition in complementary harmony and an indifferently good one may be found in the choice of tones, or in the proportions of each and their arrangement with relation to each other. this harmony certainly contains great possibilities with comparatively few limitations. while it is perhaps approximately true that complementaries are harmonious in combination, yet best authorities do not seem to fully sustain this opinion and it is quite evident that pure tones of some complementary pairs when combined are very hard in their effects, if not positively unpleasant. this can be relieved very decidedly and oftentimes very pleasing results secured by modifying the colors to tints and shades or various broken tones. but as has before been stated, and must be constantly reiterated, all fine questions of harmonies can only be determined by a general agreement of experts in color based on accepted standards. analogous harmonies may seem to be more closely related to the dominant than the complementary and hence, logically, should perhaps be considered before the complementary, but there may be greater difficulties involved in the analogous than in the complementary because they are not so definitely limited. analogous harmonies. in an analogous harmony we may use tones from a number of scales more or less closely related in the spectrum circuit. in some parts of the spectrum it is possible to include a much wider range than in others. it is comparatively easy to produce safe compositions through that part bounded by the orange-yellow and the green scales, while from the green to the violet experiments are much less safe. in almost any section of the spectrum a range of three scales is safe if the tones are properly selected and proportioned, and in some sections as many as five or six may possibly be included, by an artist, with striking and pleasing effect. perfected harmonies. the compositions which have been classified as perfected harmonies may be defined as the combination of two analogous harmonies which as a whole are approximately complementary to each other, or in which the key tones of the analogous harmonies are complementary to each other. such compositions may be entirely composed of analogous colors with the addition of but one complementary color, and this is in fact a very safe harmony, especially if that one color is used as a border line or an outline here and there in the design, in which case it may sometimes be strong in color and tone. the chart of spectrum scales as made from colored papers cut in squares is of great value in explaining the classification of harmonies. fig. 15 is a reduced copy of the chart of pure spectrum scales shown on page 41, and which is here placed horizontally for convenience. [illustration] the black zig-zag lines are designed as graphic illustrations of the various classes of harmonies. contrasted harmonies as defined are limited to designs in one active color mounted on a background of one of the passive colors and thus need no further explanation, although experience will prove that some combinations are very much more pleasing than others. the dominant harmonies which are defined as combinations of tones from one scale cannot be made more clear by a diagram, which would be simply a straight vertical line through any one of the eighteen scales, indicating that the five tones in that scale or any selection from them may be used in a dominant harmony. the analogous harmony has given students the most trouble and the diagram is principally prepared to illustrate the great variety in harmonies of this class. commencing at the left, the first line indicates a harmony in three scales beginning with red-violet shade no. 2 and passing to shade no. 1, then to standard violet and thence to blue-violet tints no. 1 and no. 2. the next is in two scales, beginning at violet-blue shade no. 2, thence to blue shade no. 1; back to normal violet-blue; again into the blue scale at tint no. 1 and back to violet-blue tint no. 2. the next begins at green-blue shade no. 2 and ends in green tint no. 2. theoretically the line beginning in g. b. s. 2. and leading to g. t. 1. and thence to y. s. 2. may represent an analogous harmony, but it may be doubtful whether a range of such an extent in that part of the spectrum could be made very harmonious. this may be divided into two harmonies at g. t. 1. and each part may be extended to g. t. 2. the straight line from g. s. 2. to o. y. t. 2., embracing five scales, might be extended to include the joining broken line running into the y. o. scale and finishing at o. y. s. 2. the remaining lines at the red end of the chart may be considered as indicating one harmony in six tones, or two harmonies in three tones each. if the two ends of the chart of spectrum scales are joined so as to form an endless band or a cylinder, bringing the violet-red scale adjoining the red-violet, as in the spectrum circuit, the same graphic illustration could be given of harmonies extending from violet to red. the complementary harmonies require no diagrams, because they are limited to the combination of two scales complementary to each other and would be represented by two parallel vertical lines through any two complementary colors, as for example vertical lines through the red and green-blue scales. the compositions termed perfected harmonies may be fairly well illustrated in the diagram by the combination of the line in v. b. and b. with the broken line commencing in g. y. s. 2. and ending in g. y. t. 2.; or again by the line in r. v. to b. v. combined with the straight line from g. t. 1. to y. s. 2.; or the broken line g. to y. s. 2. or again, the entire range of the double combination o. s. 2., o. r. t. 2., v. r. and o. r. s. 2. with the broken line from g. b. s. 2. to g. t. 2. another sample of perfected harmony is found in the union of line o. r. s. 2., v. r., o. r. t. 2., with line g. b. s. 2. to g. t. 2. these diagrams are designed to show the range or extent which a single composition may cover under its special definition and do not imply a necessity for using at one time all the colors through which the line passes, or that they are specially good harmonies. a striking illustration in nature of a perfected harmony was seen one bright autumn morning in a species of woodbine covering the side of a red brick building, in which could be discovered an infinite variety of colors in greens and violet-reds whose tones were increased in number and intensified in effect by the reflections of the sunlight and the corresponding shadows, producing very light tints and very dark shades of various hues of the complementary colors, and forming a complicated and wonderfully beautiful effect very definitely classified as a perfected harmony. field's chromatic equivalents. so much has been said and written about field's equivalents that there is a very general impression among artists and others that they constitute an important element in harmonious compositions of color. this proposition as given in owen jones' grammar of ornament is as follows:-"the primaries of equal intensities will harmonize or neutralize each other, in the proportions of 3 yellow, 5 red and 8 blue--integrally as 16. the secondaries in the proportions of 8 orange, 13 purple, 11 green--integrally as 32. the tertiaries, citrine (compound of orange and green), 19; russet (orange and purple), 21; olive (green and purple), 24--integrally as 64." in commenting on this in "the theory of color" dr. von bezold says: "it is often maintained that the individual colors in a colored ornament should be so chosen, both as regards hues and the areas assigned to them, that the resulting mixture, as well as the total impression produced when such ornaments are looked at from a considerable distance, should be a neutral gray. starting from this idea, the attempt has been made to fix the proportional size of the areas, which would have to be assigned to the various colors usually employed in the arts, for the purpose of arriving at the result indicated. this idea was especially elaborated by field, an englishman, who gave the name of 'chromatic equivalents' to the numbers of the proportions obtained, a designation which has since been very generally adopted. in reality, however, these 'chromatic equivalents' have no value whatever." the same writer also says: "it will always remain incomprehensible that even a man like owen jones in the text accompanying his beautiful "grammar of ornament" should have adopted this proposition in the form given to it by field, since among all the ornaments reproduced in the work just mentioned there are scarcely any which will really show the distribution of colors demanded by the proposition in question."[b] [b] the theory of color in its relation to art and art industry. by dr. william von bezold. translated from the german by s. k. koehler with introduction and notes by edward c. pickering. boston; l. prang & company, 1876. in accordance with this eminent authority any one familiar with disk combinations will know by experiment that no combinations of red, yellow and blue approaching the proportion named by field can produce a neutral gray effect in the eye. colored papers. for practical study of color some economic material is absolutely necessary and nothing so well combines manual work with æsthetic cultivation as colored papers, if specially prepared in standard colors and with a dead plated surface. in the manufacture of the colored papers adopted in the bradley scheme of color instruction, the effort has constantly been to produce the closest possible imitations of natural colors consistent with the material. with this aim in view we have secured the brightest possible red, orange, yellow, green and blue and have chosen a violet which has the same relation to the other pigmentary colors that the soft beauty of the spectrum violet bears to the other parts of the spectrum. it however happens that in the pure aniline colors discovered in recent years a line of purples and violets has been found so much purer than the other pigments that we cannot with our red and violet make a perfect imitation of the brightest aniline purples used in some of the goods now in the market. purple is a general name for the several modifications of violet, red-violet and violet-red as peacock blue is a name given to the beautiful hues of blue-green and green-blue. these aniline purples are but another indication that we may expect such advance in the science of pigment manufacture in the comparatively near future that a much purer line of standards may be secured than is now possible in papers. but it does not materially affect the value of the present standards as long as they are accepted as indicating the kind of color, i.e., its location in the spectrum, and the _artists_ certainly should not object to this lack of purity, because their only present criticism is that the standards are too "raw," which is but another term for pure. in the glazed colored papers in the market we may find some of these purples, especially in the tints or "pinks" which when placed beside the unglazed surfaces of the standard papers render the latter quite subdued. but in primary color education there is no place for these purest purple papers, until chemistry discovers other colors correspondingly brilliant to complete a purer chart of spectrum colors than is now possible. [illustration] color teaching in the schoolroom. in the preceding sections of this book the author has aimed to so guide the teacher who is looking for aids in elementary color teaching that she can by actual experiment determine for herself the truths regarding color, and hence be able to choose such facts as are suited to the needs of her pupils from time to time, and to present them in such a logical order as to render them of the greatest value in practical results. it should be possible to interest the children in color more easily than in any other subject. examples are always around them at home, in the street, in the garden and the field, if perchance they are fortunate enough to see the field, and those who see no attractive colors elsewhere certainly should find them in the schoolroom. to a teacher who is in love with the subject the world will be full of examples, every day. the beautiful yellows and greens of the spring leaves, the flowers, birds and butterflies of the summer, the autumn foliage, the sunsets and blue and purple mountains of winter, are but hints of the multitude of object lessons in color all around us; and if none of these are available the more commonplace subjects found in the latest seasonable colors of dress goods and house furnishings will be almost equally valuable. when the children are once interested they will discover, through their own observation, examples of such value as to surprise one who has had experience with only the old methods of trying to teach color, or rather the utter lack of all methods heretofore in vogue. the value of kindergarten training has been so thoroughly demonstrated as to be beyond controversy, and all progressive school boards must soon recognize the necessity of adopting kindergarten methods in the lower primary grades, until such time as it may be possible to introduce the complete kindergarten for all the children, to precede the school proper. the conditions prevailing in the kindergarten are peculiarly favorable to the study of color, because of the opportunities afforded for introducing it in connection with the manual exercises of the gifts and occupations. the first gift of the kindergarten, as originally introduced by froebel, consists of six soft worsted balls in six colors, which he seems to have selected as standards without care or knowledge regarding the theory of "three primaries and three secondaries," although no doubt he may have indifferently accepted it, because it was the only one in his day suggesting any logical scheme of color combinations. the use of colored papers educationally in a systematic way originated in the kindergarten, and comprised folding, cutting, pasting and weaving, from which some color instruction was incidentally derived by the children. but with the papers formerly in the market little special training in the selecting, matching and naming of colors, such as is of so great value at the present time, was possible. the call for better colors in papers came first from the kindergartners, and the diversity of ideas expressed by them caused the writer to institute a series of investigations which have resulted in the system to which this book is devoted. the occupations of paper folding, cutting and pasting have been adopted into the primary school from the kindergarten, and there is no question but the occupation of paper mat weaving as practiced in the kindergarten should also be introduced in the lowest primary grades for those who have not had kindergarten training, because of its value in simple manual work and in designing symmetrical patterns and harmonious color combinations. by general consent colored papers have been chosen as the most available material for this work, because while relatively cheap, the purest colors possible in pigments are secured, and the material is adapted to the most elementary manual training and education in form as well as color. it is not the author's aim to here provide a definite course of lessons to be given in a perfunctory way or in a fixed order, but rather to furnish suggestions based on practical work in the schoolroom that may be of value to those who have carefully examined the preceding pages of this book and become familiar with the experiments described. the suggestions are based on the experience of teachers who have been using the system here advocated for several years and testing it in various ways, and therefore it is hoped that they may be of value to any earnest worker who is not fully satisfied with her efforts in teaching color up to date. consequently a brief outline of work is suggested for the earliest years, according to a definite order, and then further suggestions and experiments are introduced, somewhat in the order in which they may naturally present themselves. the time has passed when it is necessary to offer any argument for the study of color in the schoolroom. every child begins his school life with many color impressions which he has been acquiring since the day when his baby fingers first stretched toward some bit of color, and his development demands a clear presentation to him during the earliest school years of the fundamental facts concerning color upon which all later work must be based. the glass prism. a glass prism is one of the first requisites in the appliances for teaching color, and a prism which may be bought for a few cents will work wonders in the hands of an interested teacher, although a more perfect instrument, such as is sold with physical apparatus, will give colors which are better defined. experience in many schoolrooms has proved that a spectrum can be shown somewhere in the average room at some hour in every sunny day, especially in the longer days of spring and summer, and it is well to have the prism when not in use so fixed as to project the spectrum into the room much of the time, so that it may become familiar to the younger children. observation of the spectrum enthuses the children with a feeling for color which can be developed in no other way, and they never tire with watching the wonderful vibrating effects of the liquid colors; and by studying it the mental image of each of the six colors becomes as distinct as that of the cube after it has been handled and modeled. if the schoolroom is provided with shutters or dark curtains a much better spectrum can be produced by closing them, as even a slight change from a bright sunny daylight has a very perceptible effect in bringing out the colors. a person who has never seen a carefully prepared spectrum in a room almost perfectly dark can have no realizing sense of the purest possible expressions of color. accident once disclosed a simple means by which one teacher secured a very good spectrum. there was a deep, dark closet opening from the schoolroom and one bright day when the prism was being used the spectrum was accidentally thrown into this closet, and the sudden and enthusiastic expression of approval by those pupils who were in position to discover it was certainly interesting to the teacher of that country school, with a dark coal closet. in a spectrum such as can be produced in a dark room with the most perfect form of prism, all the various colors can be separated and carefully examined and by special appliances compared with pigmentary colors. experiments of this kind are exceedingly interesting and instructive, and demonstrate the wonderful intensity and purity of the spectrum colors as compared with the purest pigmentary colors that can be produced. such experiments were carried to a great degree of perfection when the six standard colors for the bradley colored papers were selected. how the bradley color standards were chosen. after many months of labor in securing samples of material colors, and many days spent with the spectrum, a committee of artists, scientists, teachers, and artizans unanimously decided that æsthetically and psychologically the colors adopted were the best possible material expression of the six localities in the spectrum corresponding to the feeling or psychological perception of red, orange, yellow, green, blue and violet. many subsequent experiments have apparently proved that practically the same six colors best serve the purpose of primaries from which to make all others by combination. in accordance with these selections the educational colored papers have been made, and since that time an expert scientist has accurately located each of these colors in the spectrum by its wave length. consequently after the children have come to know the six colors in the sun spectrum the six standard colors of the papers may be shown as the best imitations possible. in studying the six colors from the spectrum in a schoolroom it frequently happens that one color may be best seen on the floor, another on the wall or even the blackboard, and another on the ceiling, and after the order of the colors in the whole spectrum has been observed, it is well to get each color where it can be best secured. paper color tablets. when the spectrum has been studied so that the children have some idea of the six colors and their location relative to each other, give each of the children a package of the colored paper tablets, one inch by two inches, containing the eighteen normal spectrum colors, i.e., those in the central vertical column in the chart of pure spectrum scales, page 41, and tell them to select from the eighteen the six which they have seen in the spectrum and which may be named to them as red, orange, yellow, green, blue and violet.[c] [c] tablets of paper instead of cardboard are recommended because in primary instruction the standards or types of color presented to the child ought to be the purest possible expressions of the colors represented, and a piece of color material cannot meet this requirement after having been used one year by a child. the necessary expense of cardboard tablets practically precludes a new supply each year. but the papers can finally be used to form, by pasting, some chart or combination which the pupil may be allowed to own as a sample of his work. if a sheet of neutral gray cardboard can be secured for use on each desk all early color work will be more valuable, because of the undesirable effect of the usual yellow or orange color of the wood of the desk. if some of the pupils do not make the correct selection of the papers it may be well to let the error pass for that time and have another exhibition of the spectrum before the next trial. get as many of them as possible to make the selection of the six colors from the eighteen solely by comparison with the spectrum. later if some are still unable to succeed, a paper spectrum may be shown to them, or what is better, six bits of paper like their own, pasted on a card, with an interval as wide as two papers between each two. when every child can readily select the six standard colors from the eighteen then all of them may with advantage be told to lay the six in a row on the gray cardboard or desk, in their proper order, and sufficiently separated to allow room for two other papers between each two. when all have made the attempt and some have failed to arrange the papers correctly the card having them properly mounted may again be shown and each one in error may make the necessary corrections by comparison. in a solar spectrum such as is possible in the ordinary schoolroom the intermediate colors between the standards cannot be very distinctly seen but the child can be shown that between the red and orange, with which he is familiar, there are colors different from both and possibly he may be led to see that these colors seem to be a mixture of the two. with this impression in the minds of the children the following experiment may be a very interesting psychological test of the natural color perception of each child, or in other words his "color feeling." ask the children to arrange the remaining twelve papers between the six standards in pairs and one outside of the red and violet at the ends. this exercise will serve to bring each of the other colors to the critical attention of the children so that they may not be entirely strangers to them in the succeeding exercises. at this stage the color wheel or color top or both will be most valuable. color wheel or top. if the wheel is available let the teacher place on it combined red and orange disks of medium size and in front a small red disk. before beginning the six papers should be laid on the desk in order, separated by two spaces. call attention to the fact that the red disks are like the red sample of paper. explain how the disks are joined and that the two larger ones can be made to show more or less of the orange and the red. then introduce a small amount of orange, perhaps not enough to cause the effect to be perceived by the children when the wheel is in motion, and rotate. ask if they see any difference between the small disk at the center and the larger surface. add more orange till they see a difference, and continue to add orange to the red until nearly one-half the disk is orange or till it may be questionable whether the color made by rotation is more nearly orange or red. this point will be reached before the orange nearly equals the red, because the orange is more luminous. explain that all these colors which the children have been seeing are orange-reds and ask the pupils to select that color from their papers which is orange-red, or most like the orange and red. in the meantime set the orange and red disks to the proportion of r. 85, o. 15, which nearly or exactly matches the orange-red paper. when the children have selected the paper which they think is orange-red, put the wheel in motion and ask them if their selection is like the color on the wheel. if not, see that all understand and have selected the orange-red paper to place next the red sample. when this has been done remove the disks from the wheel and readjust the larger ones so as to show a combination that is nearly all orange; then replace them and substitute in front a small orange disk instead of the red one and proceed to show a series of red-orange colors from the orange toward the red, as previously shown from the red toward the orange. with experiments before adults this break in the order of proceeding and the change of disks would be unnecessary, but with children it is desirable to mark a distinction between the orange-red and the red-orange colors, a fact which is emphasized by the mechanical manipulation. when the children have been asked to place their red-orange paper in its proper position the disks may be set to r. 50, o. 50, and an imitation of their red-orange paper shown. if the school is provided with color tops their use may be begun at this point by allowing the children to attempt to repeat the wheel experiments with the tops and thus produce for themselves an imitation of the two intermediate spectrum hues in the papers. in all combinations of colors by disks as well as pigments there is some loss of purity and hence the colors of papers in the intermediate hues may be a little brighter in some cases than the results of two disks in combination. this suggestion for the presentation of one pair of the intermediate spectrum hues may serve to illustrate all the others, and the time which can be devoted to the whole subject must determine the detail with which each pair is treated. if the tops are provided in a school but no color wheel then the teacher must begin with a top as a substitute for the wheel and let the children follow her with their tops by dictation. at first this will be much more difficult than if the wheel could be used, but after the children have become somewhat familiar with the handling of the top by dictation the result will be quite surprising. there will be in every school some children who are exceedingly awkward in the manipulation of the top, until the happy day arrives when all school children are graduates of kindergartens. at present the average kindergarten pupil will handle the top better than the children in the lowest primary grades who have not had the advantages of kindergarten instruction. when all the hues except the red-violet and violet-red have been located, the teacher should be prepared with a chart made by pasting the eighteen paper samples, including standards and intermediate hues, in their order on a strip of paper, so that by bringing the ends together the children may see that when they place the violet-red at one end of their row and the red-violet at the other they are really completing a spectrum circuit and forming a chart of natural colors. ever since newton's day it has been fashionable to speak of the spectrum as nature's chart of colors. this expression is but partially true and is entirely false if we mean that it contains examples of all the colors in nature. the spectrum is valuable in color study only from the fact that it enables us to establish permanent standard colors from which all colors in nature and the arts may be named and by the combinations of which such colors may be imitated. unless the standard colors in a system of color instruction are the closest possible imitations of corresponding spectrum colors there is no logical relation between such a system and a chart of colors based on the spectrum, because the spectrum does not furnish a complete circuit of colors and its only value is, as before stated, in furnishing a permanent standard on which to found a nomenclature of colors. up to this time we have not suggested the practice of introducing any natural objects or calling the attention of the children to various colors found in their surroundings. each teacher must use her judgment regarding this matter, but as soon as miscellaneous colors are to be considered the two questions of hues and tones are necessarily involved, and experienced teachers have been divided in their opinions as to which should be first considered, tone or hue. when it was thought necessary to occupy a long time in presenting all the spectrum colors this question assumed greater importance than at present, but very many teachers have become convinced that we have not been giving the children credit for nearly as much ability in the recognition of colors as they deserve, and that with the methods at present in use the six standard colors and twelve hues can be learned in a few weeks, during which time it may not be necessary to discuss the complicated combinations of colors in nature and our domestic surroundings. this is not intended to mean that the child will in this time be able to name the various hues when seen separately, but that having the eighteen paper tablets he may feel their relations to each other to such an extent as to be able to lay them in their spectrum order. those pupils who seem to have no natural perception of the proper relationship of colors will require more experience than the rest of the class before they can be sure of their colors and the teacher must exercise her judgment in deciding how long to hold the class to this subject of spectrum hues on their account. as in other class work it is not necessary that the dull children perfectly comprehend all that is told them at each step, because there will always be some in a class who will comprehend and thus the others may learn by observation, and in this subject particularly every step in advance must necessarily include a continual review of all that has preceded. consequently when a teacher has given as much time to the study of hues in the arrangement of the papers as she deems profitable, considering the entire time that can be devoted to the subject during the year, she may well proceed to tones. the study of tones. it is unnecessary at the beginning to use the word tones with the children, as "light and dark" colors will be understood more clearly. the first lesson in light and shade may be given with some book bound in a bright color, as red for example, which is common in cloth bindings. for this experiment partially open the book and hold it vertically, with back toward the class, in such position that a strong light from one side of the room will fall directly on one cover while the other is in the shade. if properly manipulated this simple experiment may be made effective to an entire class by moving the book in various directions to accommodate the several members, so that at different times all the pupils may get very clearly the idea of light and dark colors in the same scale. this idea can be more clearly shown by means of a simple model very easily made for the purpose. take, for example, three pieces of standard red paper, 4×4 inches, and mount them on a piece of cardboard side by side, in a row. trim the card parallel to the edges of the papers, leaving a margin of uniform width, and with the point of a knife "score" a line partially through the card from the front, at the joining of the papers, so that it can be neatly bent to the form shown in fig. 16 which represents the model as seen by the class. by holding one of the rear edges with each hand the faces can be folded to different angles with each other and the model turned to different positions with relation to the children. possibly the windows at the rear of the room may be partially darkened to advantage; they certainly can be if they have a sunny exposure at the time. the object is to give a fair daylight on the central surface for the standard, a strong light on one side to form a tint of the standard and a shadow on the other for a shade of the same color. [illustration] by a trial before school, in company with some other teacher perhaps, the best positions for different parts of the room as well as best lighting of the room may be determined in advance and thus such a success achieved with the first experiment that the whole idea of tint and shade may be impressed on each child for all time and definitions firmly fixed in his mind for these two most abused words in our every day vocabulary. added interest may be excited by showing similar models in several other colors during the same lesson, thus avoiding the possible impression on any mind that the term tint and shade apply to any special color. tints and shades may also be shown very beautifully by some kinds of colored materials. colored satin ribbons, folded or crumpled, and velvets and plushes give good object lessons. one of the most effective exhibitions of tints and shades may be found in a material used for upholstering furniture and technically called "crushed plush," which is a worsted plush embossed in figures and very changeable in its effects as its relation to the light is changed, giving at the same time very light tints and very dark shades in different portions. having thus shown how real tints and shades in nature are produced, the color wheel may be introduced with advantage. if it were practicable to use opaque colors in the school they could be employed to show that the effect of a tint is produced in pigments by mixing white with the standard color and a shade by mixing black with it, but while the mixture of white may produce the best imitations of some tints in nature, the same result does not hold good in the use of black to form shades, and black pigments are rarely used for this purpose, because they impart various untruthful hues, according to the colors with which they are mixed. for this reason, and others which will appear later, the white and black disks of the color wheel are found to be better than any other single method for representing tones. in shades the black disk produces by far the best imitation of nature, and so does the white disk for more than half of the colors. but, as previously stated, there is an effect which has never been satisfactorily explained by which the tints of red and blue especially receive an unexpected violet gray tinge by rotation. therefore in showing tints on the wheel it is well not to show very light tints of red or blue until the class has received some impressions of tones in other colors. in the orange and violet the tints seem to be practically perfect, and in the yellow and green not far from correct, but in the green they run a trifle toward the blue and in the yellow become a little gray or broken. but in the shades the black disk has done wonders for color instruction, particularly in making standard neutral grays which cannot be imitated by white and black pigments, and in determining the shades of yellow, as has been explained. see page 36. therefore, after having shown actual tints and shades with the folded models, and perhaps the other materials suggested, place a colored disk combined with a white disk on the wheel, and in front of them a smaller colored disk of the same color as the larger one for comparison, and by changing the relative proportions show various tints. then substitute a black disk for the white and show shades. if, for example, orange is taken, all proportions of both tints and shades may be shown very truthfully, the deeper shades being very rich browns. having in this way impressed on the children the terms tints and shades, give them the paper tablets, selection no. 2, in the deepest tints and the lightest shades, reserving the lightest tints and deepest shades found in selection no. 4 for later use. let each member of the class lay the spectrum in the normal colors and then select the six tints corresponding to the six standards. when all of them think they have done this, tell them to choose the corresponding shades. if a number fail in the attempt it may be well to set up three sizes of disks on the color wheel in shade, standard and tint of red. in showing a tint of red with the disks it is not a good plan to make a tint lighter than r. 95, w. 5, which is about r. t. 1. if the wheel is not available samples of papers may be held up in the three tones so that the class can get the correct idea. there is no best method of reaching all pupils in any class, but in some way at this point in color education every pupil ought to acquire such knowledge of the subject as to be able to select at least the six standard scales in three tones, and this should be practically accomplished before much time is devoted to the consideration of such materials as flowers, fabrics and miscellaneous papers, because until the child understands both hues and tones he can do nothing in either analyzing or naming colors. as soon as these six scales are familiar to the pupil the selecting of various objects and placing them in general families may be very valuable work, but until that time the classification of colors cannot be carried out very accurately, or at best the families will be very likely to include some uncles, and cousins and aunts, and yet, on the other hand, if even the distant relatives are recognized in preference to strangers the choice will give evidence of a sympathetic feeling for color relations, favorable to future progress and indicating something of the natural color sense of the child. if such occupations as paper cutting and pasting, or weaving of mats have a place in the school, combinations in two or three tones of the six standards can now be made. at this stage names are of little importance, but they will come in play early, as it is natural to give names to everything, and as soon as the child knows the definite names which belong to colors they will be used. neutral grays. immediately following the first idea of tints and shades or tones, the grays should have attention, because in the occupations with papers they will play an important part. for this purpose white, black and the neutral gray papers are included in selection no. 2 of the paper tablets and should be made familiar to the children while the tints and shades are being studied. the suggestion that a neutral gray is a tint of black or a shade of white may or may not aid a child to better understand the relation of the neutral grays to the color chart, but it is a thought worthy of the attention of the teacher, as expressing a fact important in the consideration of color impressions. this gray may also be illustrated on the wheel by the union of white and black disks, and should be early presented in this way, because this is the only means by which we can secure standards for pigmentary neutral grays, and the fact that this special and peculiar gray is so important in all color investigation furnishes sufficient argument for making it prominent before the other grays. even at this early period in his color education a child may be shown that white in shadow is a gray, and the fact that it is a neutral gray is not essential to him, as he has no knowledge of any other gray and probably it may not be desirable to call attention to the various classes of grays until after the broken colors have been studied. a sheet of white card or heavy paper may serve to show that white in shade or shadow is a gray. for this experiment fold the card or paper very sharply and hold it with the folded edge vertical and projecting toward the class, and in such a position relative to the windows that half of the paper is in very full light and the other in shadow. a comparison of neutral gray paper no. 1 with a true shade of white or white in shadow, as explained on page 36, will serve to connect the gray papers with the shades of white. after the idea of tones is made clear to the children, so that they can readily form the six standard scales in three tones, the completing of the chart of spectrum scales in three tones will be merely a matter of drill, as no new principles are involved. when the pupils can lay the chart of pure spectrum scales in three tones correctly, the thoughtful teacher will naturally ask herself what is the next logical step, and it may at first seem as though the completion of the chart in five tones ought to immediately follow. but it is very desirable that the pupils begin as early as possible to make a practical application of their knowledge of colors to the familiar objects around them; and it is evident that before any very accurate comparison of miscellaneous colors can be intelligently undertaken the child should be able to recognize the effect of mixing gray with a color, in distinction from the pure tints and shades of that color. explanation of broken colors. very few of the common colors seen in fabrics and house furnishings are either full pure colors or their tints and shades, but nearly all are broken colors. therefore it seems desirable to introduce the study of broken colors, before considering the extreme tones of the pure colors as represented in tints and shades no. 2 in the chart of pure spectrum scales in five tones. this order of presentation seems specially advisable, because the distinguishing of the extreme tones where the color is lost to so great a degree is more difficult than anything connected with the subject of broken colors. therefore at this point paper tablets, selection no. 3 are introduced. from this collection of tablets when properly arranged a chart of broken spectrum scales of twelve colors in three tones may be made, and in addition there are tablets illustrating the several classes of grays other than neutral grays. the first result desired is a definite distinction in the mind of each pupil between a broken color and any tint or shade of the same color. in order that the explanation of this distinction shall be intelligently comprehended each child must have such a clear idea of the meaning of the terms "tints" and "shades" that he shall not fail to readily understand any statement regarding them because of confusion as to the definite meaning of these terms. the child should know clearly that a "tint" is a color in a strong light or mixed with white either in pigments or disks, while a "shade" is a color in shade or shadow, i.e. with less than the normal illumination, or mixed with black. when this has been fixed in the mind of a pupil, and he has also been shown that neutral gray, the only gray he has learned anything of, is the result of the combination of white and black, it will not be difficult for him to see that a broken color is produced by the mixture of both white and black with the pure color. much later it will be possible for him to think of a broken color as a tint thrown into a shade or shadow, as may be observed by casting a strong shade or shadow on to a piece of colored paper in some one of the _tints_ of the spectrum scales. the color wheel and tops furnish the simplest and most effective means for the presentation of broken colors, because they automatically analyze every color shown, so that the pupil sees for himself just what has been done. an exercise in broken colors. after having refreshed the minds of the class as to tints and shades and grays by a brief restatement of the conditions involved in these terms, the idea of broken colors may be shown with disks on the color wheel or top. for this experiment place on the spindle, for example, a combination of orange, white and black disks, and in front of these disks put combined orange and black disks of smaller size. make the proportions of the larger disks, o. 15, w. 4, n. 81, and the smaller, o. 26, n. 74. in rotation the larger ring will show a dark broken orange and the inner one a dark shade of orange, and the difference in quality will be readily seen and felt. the effect is more valuable as a lesson if the tones of the two are nearly equal, although this is not necessary. a very much lighter pair of colors is secured by using the following formulas, o. 43, w. 26, n. 31, and o. 77, w. 23. both these experiments may be made with the primary color wheel or color top. if the high school color wheel is in use so that the four rings of color can be shown at one time, the two larger rings may show two tones of broken color and the smaller rings a tint and shade of pure color. in the use of tops two may be spun at once as near together as possible, the two broken tones on one top and the tint and shade on another. in green similar experiments may be tried, with the following formulas:- g. 20, w. 6, n. 74. g. 36, w. 13, n. 51. g. 34, n. 66. g. 82, w. 18. practically the same methods may be adopted in the study of broken colors as were employed with the pure colors. the paper tablets contained in selection no. 3, comprising broken colors and grays, will now come into use to accompany experiments with disks in broken colors. the tablets in the broken spectrum colors number thirty-six, comprising twelve scales of three tones each, thus producing but one intermediate hue between each two standards, instead of two, as in the chart of pure colors. exercises in selection and arrangement of these tablets to form a chart may be employed to familiarize the pupils with the new kind of colors. the colors are not so pronounced as in the pure scales, and for this reason the arranging may be more difficult, but the smaller number of hues simplifies it somewhat, so that, with the better-trained color perception which the child will have acquired at this stage, no greater effort will be required than in the earlier lessons. when the chart of broken scales can be laid with reasonable accuracy by the majority of the class the two charts as far as studied, each in three tones, may be laid on the desk at the same time for comparison and thus the difference in quality or character emphasized. all kinds of materials may now be considered and classified, and great interest inspired in the subject generally. flowers, autumn leaves, dress goods and anything with color can be studied and the colors analyzed. before the study of broken colors was taken up some few flowers could be quite accurately matched with the disks and analyzed, but now very many more of the flowers and plants as well as other material can be accurately analyzed and a definite nomenclature given to each sample. selection no. 3 of tablets contains, in addition to the twelve scales of broken colors, six colored grays, which must at some stage be considered in connection with gray colors or broken colors, to which they are closely related. as has already been stated, there is a point where by the continued addition of gray to a color, the color is so far obscured that its identity is practically lost and the result becomes a colored gray. although the line between gray colors and colored grays cannot be definitely drawn there are so many grades visible beyond the point where the exact color used with the gray can be determined, that the term "colored gray," which covers the three classes, warm, cool and green grays, is convenient for common use. it is very desirable that a distinction be observed between the terms "colored grays" and "gray colors," and therefore broken colors may be a better term to apply to the gray colors because a distinction is thus more strongly emphasized between these two classes of colors. the following table furnishes formulas from which the colors of the chart of broken spectrum scales may be very nearly imitated on the high school color wheel. each scale should be shown by the three smaller sets of disks, namely, the smallest for light tone, next size for standard or medium, and the third size for darkest tone. this list of disk combinations is furnished here for the convenience of teachers who may have occasion to illustrate the compositions of the various classes of colors comprised in the chart of broken spectrum scales, which covers the entire range of the æsthetic colors and from which by modifications every subdued color in material substances can be analyzed and definitely named. owing to the color usually found on the interior of a schoolroom and the lack of pure white light from outside it is not probable that these proportions will exactly match the papers, but the formulas will enable the teacher to approximate the color, and then the more accurate match in conformity to the conditions in each case may be secured by making changes in accordance with suggestions from a majority of the class, an exercise which will afford valuable practice for the pupils. formulas for a chart of broken spectrum scales. light. medium. dark. red. r.68, w.18, n.14. r.59, w.5, n.35. r.22-1/2, w.5, n.72-1/2. orange red. r.51, o.17-1/2, w.23, n.8-1/2. r.47, o.16, w.8-1/2, n.28-1/2. r.15, o.7-1/2, w.7-1/2, n.70. orange. o.43, w.22-1/2, n.24-1/2. o.34-1/2, w.10, n.55. o.15, w.5, n.79-1/2. yellow orange. o.23, y.15, w.27, n.35. o.24-1/2, y.17-1/2, w.15, n.43. o.10, y.4-1/2, w.6, n.79-1/2. yellow. y.34, w.30-1/2, n.35-1/2. y.24, w.12-1/2, n.63-1/2. y.12-1/2, w.5, n.82-1/2. green yellow. y.24, g.13, w.28, n.35. y.25, g.10, w.17, n.48. y.11, g.13, w.10, n.66. green. g.16, w.9, n.75. g.34, w.19, n.49. g.23, w.41, n.36. blue green. g.8-1/2, b.7-1/2, w.7, n.77. g.22, b.18, w.12, n.48. g.24, b.25, w.23, n.28. blue. b.22-1/2, w.6, n.71-1/2. b.38, w.13, n.49. b.36, w.29, n.35. blue violet. b.13, v.9-1/2, w.6-1/2, n.71. b.13, v.25, w.15, n.47. b.20, v.15, w.29, n.39. violet. v.20, w.13, n.67. v.51, w.24, n.25. v.61, w.32, n.7. red violet. r.17, v.10, w.5, n.68. r.16-1/2, v.45, w.13, n.25-1/2. r.23, v.40, w.26, n.11. in preparing the papers for the chart of broken spectrum colors the selection of the tones of the several colors has been made in accordance with the æsthetic color feeling of those to whom the matter was intrusted, but the hues of the colors are based on the standards of the pure spectrum colors. if these colors are considered independently of their relation to a general system of color education, it may seem that a stronger and purer line of colors would be more beautiful; but the more broken or subdued colors have been chosen after very careful consideration, because they are intended for elementary instruction and therefore should be so far removed from the pure color scales as to impress themselves on the minds of the children as a distinct and representative class of colors. when the color sense of the pupils has been sufficiently cultivated to observe smaller distinctions, a variety of color scales much less broken may be shown with the disks. different selections for a score of charts could be made, all beautiful and representing broken colors, but after much consideration these thirty-six were selected from a very large number of hand-painted samples made for the purpose, as furnishing a sufficient number of typical broken colors for elementary color instruction, and in such hues and tones as to form a harmonious chart for comparison with the chart of pure spectrum scales. certain "color puzzles." when the children have advanced far enough to understand the analysis of a color, i.e., to correctly name a color, exercises which may be called color puzzles can be introduced from time to time with great interest and profit. the idea is simply to suddenly show to the class a series of disks in rapid rotation and ask them to guess what colors it is composed of, i.e., what the definite name of the color is. the following is a suggestion for this exercise, supposing that a broken green yellow is to be shown:-select a green, a yellow, a white and a black disk of medium size and combine them as follows: y.20, g.10, w.10, n.60. then, having previously removed the nut from the spindle of the wheel and laid it in a convenient place, take the combined disks and lay on the top of them any other disk of a larger size, with the center holes of all corresponding with each other and place all these disks on the spindle of the wheel with the larger disk still covering the face of the others. having previously furnished an assistant with a sheet of cardboard of sufficient size to conceal the disks from the class have it held in front of the wheel while the disk which conceals the combination is removed, the nut screwed to place and the disks put into rapid rotation; then order the card taken away and ask the class what color they see, still continuing the rotation. the correct answer should be broken green-yellow, and not a shade of green-yellow, a broken yellow-green, a tint of yellow or a yellow shade; for there is but one true name and that should be stated. definite expressions of color are as possible as the terms used regarding other scientific subjects, and should be encouraged. much interest can be inspired and valuable instruction imparted to the children by experiments with the color wheel, but whenever color analysis is the object in view, if disks of more than one of the standard colors are used in the same combination they must be of colors adjacent to each other in the spectrum. for example, if a blue and a yellow disk are united and placed in rotation the result may be a blue gray, a yellow gray, or perhaps very nearly a neutral gray, because blue and yellow are so nearly complementary to each other. but a nomenclature of the resulting color effect expressed in terms of blue and yellow is not of practical value, because it is evident that in the analysis of a gray-blue, yellow has no logical place. if in an attempt to match a color which seems to be a broken blue, something else besides the blue, white and black is required, it must be either green or violet, i.e., one of the two standard colors adjacent to the blue in the spectrum. in other words, every color in nature is a spectrum color, i.e., either a pure spectrum color, a tint or a shade of a spectrum color, or a broken spectrum color. hence every color can be matched, and therefore analyzed by the combination of one disk of a standard color with a white disk, a black disk or both, or else by two adjacent spectrum standards with white and black or both. there are many combinations of disks outside the limitations above named which are valuable and interesting in color investigation when not used for simple analysis, but if they are presented as pleasing experiments before the pupils can understand their logical relation to the subject of color education, the result may be entirely misleading rather than instructive. in making experiments in broken colors with the wheel the most satisfactory results are secured in orange, violet, green and yellow, while the red is fairly good and the blue less satisfactory than the others because of the slight effect of gray or violet which comes into the lighter tones by rotation, to which reference has already been made. as explained on page 54, the so-called tertiary colors, russets, citrines and olives were formerly supposed to be classes of peculiar colors to which these names were given. the fact that these are all broken spectrum colors was first demonstrated by the use of the color wheel and they are now quite generally accepted as such by those who have given heed to modern methods of color instruction. as already shown the disks have also seemed to correctly define the several scales of colors, so that in contrast to the color charts of a dozen years ago a distinction is clearly drawn between the colors in the yellow and the orange scales, or even between the yellow-orange and the orange-yellow scales, so accurately do the disks determine the hue of a color. when the pupils have progressed so far that they can arrange the paper tablets to form the chart of pure spectrum scales in three tones and also the chart of broken scales, they will be prepared to intelligently begin the use of papers in cutting and pasting designs in the several classes of harmonies, but before most effective results can be produced the lightest tints and deepest shades of the full chart of pure scales in five tones must be considered. chart of pure spectrum scales completed. the entire mastery of these extreme tones will be quite difficult because they are so far removed from the standards, and the children can hardly be expected to recognize and name them when seen separately. if a pupil is able to correctly arrange them in connection with the other tones of the chart, his accomplishment will show a high grade of color perception. but these extreme tones are introduced because their use in the more advanced work of paper cutting and pasting produces stronger and more beautiful harmonies and a higher degree of color training than would result were the tints and shades nearer the standards in tone. no detailed rehearsal of the lessons for this work is necessary to enable a teacher who has pursued the course of instruction thus far to complete it in a logical way, and relatively little time will be required by the pupils to become sufficiently familiar with these tones for practical purposes, because of their more acute color perception which will be developed at this period. the work of cutting and pasting. in the study of color the work of cutting and pasting designs in educational colored papers affords the earliest and best practical expression of the color feeling which has been acquired and stimulates the further development of color perception. the order in which the use of these papers can be most profitably taken up in the occupations of cutting and pasting may be determined by a careful consideration of the subject of harmonies as explained quite fully in the foregoing section entitled "practical experiments," pages 67 to 73. the first in order is contrasted harmony, in which cut papers in one color may be mounted on a ground of some passive color as white or gray. in selecting the gray, analogy is usually preferable to contrast, while neutral gray is fairly safe for all colors. according to this suggestion the warm grays may be used with the warm colors and the cool grays with the cool colors, and in a majority of the cases the lightest tone of gray is preferable. without question dominant harmonies or the arrangement in families are the most profitable and safe for early practice. in this class a light tint may be used for the background on which to mount any of the other tones of the same scale. beyond these two classes of harmonies the order of presentation must be determined by the teacher. if the complementary is attempted with simple geometrical forms a light tint may most safely be selected for a background in the least aggressive of the two colors and the design or pasted forms in some of the complementary tones other than the normal color. do not attempt to combine full complementary colors in elementary work. the analogous harmony may be used in simple designs with beautiful effects when judicious selections are made, but owing to the latitude necessarily involved in the definition of this class of combinations the children cannot very early be trusted to make their own selections. it is evident that nothing can be attempted in the perfected harmonies in any of the ready-cut forms, but beautiful results can be produced in this class with well-drawn and accurately cut ornamental designs in colored papers, which may even surpass in strength and beauty any effects which can be produced in water colors such as can be used by the children. for earliest practice in making designs in colored papers the ready cut forms of the kindergarten, technically called "parquetry papers" are very convenient and may be procured either with or without gum on the back. these are prepared in various geometrical forms based on the one-inch standard, among which the most useful for pasting decorative designs are the circle, half-circle, square, half-square and equilateral triangle. where models and tablets are used in form study the tablets may serve as patterns from which the children can mark out the papers which they can then cut for themselves, and thus the oval and ellipse may be added to the forms, and also practice in accurate cutting secured. in the use of tablets as patterns the outlines should be made on the backside of the paper, by holding the tablet in place with one finger and working carefully around it with a well-pointed pencil. the marking to the pattern and cutting to the line provides valuable elementary practice in manual training. as it is the prime object of these papers to treat of color no attempt is here made to give directions for designing units of ornament or for folding and cutting designs. all such exercises furnish the best possible practice in both designing and manual work, but they belong more directly to the department of drawing and are fully treated in the hand books explaining modern systems of drawing. we offer here a number of simple arrangements of such forms as may be found in ready-cut papers or may be marked from the form study tablets as before mentioned, with the addition of a few other figures which involve some very simple designs for free-hand cutting. a variety of designs. the accompanying illustrations show a number of simple arrangements of such forms as are found in ready-cut papers or may be marked from the form study tablets already mentioned, with the addition of a few other figures which include some very simple forms requiring free-hand cutting. suggestions for more elaborate designs and specific directions for paper cutting can be found in elementary books treating of decorative drawing and those devoted solely to paper cutting. [illustration] figs. 17 to 25 show arrangements of one-inch kindergarten parquetry papers in one color, used as units to form border designs in contrasted harmony on a white or a gray ground, in all of which there is repetition of form as well as color. a narrow strip of paper in the same color as the units may be used at top and bottom to finish the design. [illustration] figs. 26 to 37 show border designs, each of which is made with one form in two colors or tones in alternation. [illustration] [illustration] figs. 38 and 39 show border designs in one color, with forms marked from the elliptical and oval tablets and cut by hand. in fig. 39 borders are made by combining half-squares which may be used with or without narrow strips of the same color. [illustration] figs. 40 and 41 are made by using one form with alternation of tone and of position. fig. 41 is derived from fig. 40 by laying the dark squares with the corners in contact and placing the light squares over them. fig. 42 shows alternation of form and color or tone, which is also the scheme employed in fig. 43 in a design less simple with the addition of the half-circles. figs. 44 and 45 show two other simple and pleasing designs with alternation of both form and tone or color. figs. 46, 47, 48, and 49 comprise designs in two forms and two tones or colors, in which some hand cutting is necessary on the part of the pupils. [illustration] figs. 50 to 54 are rosettes made from parquetry papers with the addition of a small circle or square at the center cut by hand. [illustration] figs. 55 to 60 are principally hand-cut forms, and 61, 62 and 63 show surface patterns made from parquetry squares and half-squares. [illustration] [illustration] colored papers can be used more advantageously in decorative designs than in imitations of natural objects, for which water colors are much better suited, but some copies of natural flowers and autumn leaves have been made in colored papers which were exceedingly close imitations of water color paintings when seen at a little distance, rivaling in the case of the autumn leaves the best water color effects in brilliancy and depth of color. there need be no definite rules governing the continuation of color study from this point by a teacher who is interested in the subject and has tried the experiments suggested in the preceding pages. the work will become very interesting at this stage, because now all sorts of material may be introduced for analysis and classification and from this point forward, to the highest achievements of the artist, nature will furnish abundant stimulus to color thought and investigation, if the foundation has been laid according to the true theory of color perception which it is the object of this system to explain. analysis of color materials. a valuable and interesting phase of color investigation and color training may be found in the analysis and naming of the natural colors found in flowers, minerals and the plumage of birds. the necessity for a definite and adequate nomenclature which naturalists experience in this department of education has been emphasized by the publication within a few years of a book entitled "a nomenclature of colors for naturalists, and a compendium of useful knowledge for ornithologists." this book has been prepared with great care by robert ridgway of the united states national museum, and contains a large number of hand-painted plates showing nearly two hundred colors which represent selections from three hundred and fifty names of colors which are given in english, latin, german, french, spanish, italian and norwegian or danish.[d] [d] a nomenclature of colors for naturalists and compendium of useful knowledge for ornithologists by robert ridgway, curator, department of birds, national museum. boston, little, brown & co., 1886. the fact that a book involving so much technical knowledge and the expenditure of so much time and money was deemed justifiable is an evidence of the great need for some definite nomenclature. in the introduction the author says: "undoubtedly one of the chief desiderata of naturalists, both professional and amateur, is a means of identifying the various shades of colors named in descriptions, and of being able to determine exactly what name to apply to a particular tint which it is desired to designate in an original description. no modern work of this character it appears, is extant,--the latest publication of its kind which the author has been able to consult being syme's edition of 'werner's nomenclature of colors,' published in edinburgh in 1821. it is found, however, that in syme's 'nomenclature' that the colors have become so modified by time, that in very few cases do they correspond with the tints they were intended to represent." the following are the opening sentences of the preface: "the want of a nomenclature of colors adapted particularly to the use of naturalists has ever been more or less an obstacle to the study of nature; and although there have been many works published on the subject of color, they either pertain exclusively to the purely scientific or technical aspects of the case or to the manufacturing industries, or are otherwise unsuited to the special purposes of the zoologist, the botanist and the mineralogist." in the same book the chapter on principles of color opens with the following sentences: "the popular nomenclature of colors has of late years, especially since the introduction of aniline dyes and pigments, become involved in almost chaotic confusion through the coinage of a multitude of new names, many of them synonymous, and still more of them vague or variable in their meaning. these new names are far too numerous to be of any practical utility, even were each one identifiable with a particular fixed tint. many of them are invented at the caprice of the dyer or manufacturer of fabrics, and are as capricious in their meaning as in their origin; among them being such fanciful names as 'zulu,' 'crushed strawberry,' 'baby blue,' 'woodbine-berry,' 'night green,' etc., besides such nonsensical names as 'ashes of roses' and 'elephant's breath.'" these extracts from this valuable and interesting book by an author of large experience are quoted here to emphasize the practical necessity for more definite color education based on analysis and nomenclature. with the color wheel or color top, the colors of flowers and leaves as well as all other objects in nature and art may be analyzed and named, and the names definitely recorded in the terms of a nomenclature based on permanent standards. the following list of flowers and leaves of plants and trees with their analyses in terms of our nomenclature is taken from a recently published paper entitled "on the color description of flowers," by prof. j. h. pillsbury, to whom the writer is indebted for some of the earliest suggestions regarding the practical application of the scientific facts of color to color teaching, and also for valuable scientific work which he has done including the exact location of the six color standards in the solar spectrum by their wave lengths:-"with these standards to work from, i undertook to determine the color analysis of certain of our common flowers. the following results, will, i think, be interesting to botanists. the numbers given indicate per cent. of color required to produce the hue of the flower:- common forsythia, f. viridissima: pure spectrum yellow. fringed polygala, p. paucifolia: r. 48, v. 52. wistaria, w. frutescens, wings: r. 11, v. 89. wistaria, w. frutescens, standard: r. 9, v. 79, w. 12. flowering quince, cydonia japonica: r. 95, v. 2, w. 3. wild cranesbill, geranium maculatum: r. 28, v. 66, w. 6. the variations of color in the early summer foliage is also interesting. the following analyses are for the upper side of fresh and well developed healthy leaves. it is not impossible that a little attention to these variations in the color of foliage on the part of artists would save us the annoyance of some of the abominable green which we so often see in the pictures of artists of good reputation:- white oak: y. 7.5, g. 11.5, n. 81. apple: y. 5, g. 13, w. 2, n. 80. copper beech: r. 17, v. 2, n. 81. hemlock: y. 2, g. 9, n. 89. white pine: y. 2.5, g. 11, n. 86.5. white birch: y. 5.5, g. 11.5, w. 1, n. 82. hornbeam: y. 5.5, g. 12.5, n. 82. shagbark hickory: y. 4.5, g. 9.5, n. 86. these analyses were made in a moderately strong diffused light with maxwell disks of the standard hues referred to above." these are but a few of the numerous flowers the colors of which may be perfectly imitated and consequently analyzed and named with the color wheel or the top. in fact for individual work in natural history the top is more convenient than the wheel and sufficiently accurate for all practical purposes, while it is a very fascinating occupation for child or adult. in the use of disks for analyzing colors it must be remembered that every material color is some quality of some color in the spectrum circuit, and therefore may be matched with not more than two standard disks, either alone or with white or black or both. if more than two color disks, besides white and black, are used they will neutralize each other more or less, and a neutral gray or a gray and some spectrum color will be the result. for example, if yellow and blue in nearly equal parts are introduced in connection with red and orange, the yellow and blue being nearly complimentary to each other will produce practically a neutral gray, and the result will be the same as if only red, orange, white and black were used. [illustration] owing to the recent advances in the art of dyeing there are some textile goods which are too intense in color to be exactly imitated by the disk standards, but this fact need not prevent a practical analysis of such colors, because by very slightly reducing with white the color to be examined the same color is retained, the modification making it, of course, somewhat lighter. fig. 64, showing a small circle representing a disk of the material mounted on thick paper, illustrates this statement. suppose we have a piece of rich brown cloth, so intense in color that when red, orange and black are combined in the proportions of r. 22, o. 16, n. 62, the material is still a little richer in color than can be made with the disks of the color wheel. if we introduce a small amount of white into the brown of the material we may hope to match it with the disks and this may be done by cutting a bit of fairly heavy white paper in the form shown in the diagram and loosening the nut of the color wheel slightly, after which we insert the point of the triangle under the nut so that when tightened the white paper may be held in front of the brown disk, as in the illustration. trim the outer end even with the disk and then rotate. if the effect of the white is too great trim off a little from the side of the white paper to make it narrower, until a perfect match is secured. the small disk in rotation is then of the same color but not quite so intense as before, or in other words, is a very deep tint of the color. in this way the nomenclature can be recorded as follows: brown 95, w. 5, = r. 22, o. 16, n. 62. this result does not often occur, but the subject is noticed here in detail that no one may be in doubt when such cases do come to light, as they will sooner or later. the aniline colors give some purples which are much more brilliant than either the violet or red which otherwise should by combination produce them, so that with these standards they cannot be made, but must be reduced with white, or possibly with white and black. if a color wheel is not available many of these experiments may be tried on the color top, but not as satisfactorily, because of the accuracy necessary in cutting so small a disk in a woven material. in using the top for analysis of all ordinary colors, the best plan is lay the material on a table or other level surface and spin the top on it. if quite an accurate test is desired the cardboard disk of the top may be trimmed down to the size of the largest paper disk, so that there will be no intervening ring of light color to separate the color of the rotating disks from the material on which it is spun. practical applications of the color top are already being made, as for example, in the selection of house furnishings. for this purpose disks of the top are combined at home to produce the desired colors to match the wood finishings and papers or draperies in a partially completed room, the top being used as a guide in preliminary selections of additional materials from the stores. if a number of colors are required it is convenient to use several combinations of disks, each set being slightly gummed together. in this way standards for various colors with a top spindle for rotation in the salesroom may be carried in a very small space. the bradley colored papers. as every competent artisan must understand the use for which each implement is designed, in order to secure the best results with it, possibly a brief explanation of the principles on which the colors in the bradley educational colored papers are selected and classified may be of value. in the sample books of these colored papers there are four sections. the first section of the book, following the title leaf called "pure spectrum scales" consists in part of the six standard colors, red, orange, yellow, green, blue and violet, with two intermediate hues between each two standards, which eighteen colors form the central vertical column in the chart of pure spectrum scales shown on page 41. in addition to these eighteen normal spectrum colors, there are two tints and two shades of each, thus producing eighteen spectrum scales of five tones, in which the normal colors as indicated in the central column aim to be the purest possible pigmentary expressions of the spectrum colors represented. in determining the number of colors to adopt in the preparation of the papers enough have been selected to furnish types of all the colors in the spectrum, and also the hues between red and violet, but at the same time the number has been so restricted as to secure a reasonably simple nomenclature of the intermediate hues. a hue of a color is defined as the result of the admixture of that color with a smaller quantity of another color; thus a hue of red approaching the orange is an orange hue of red, or an orange-red. if a small amount of red is added to orange the result is a red hue of orange, or a red-orange. therefore in selecting two hues between each two standards, rather than a larger number, the simplest nomenclature possible is secured, and one in which no mental effort is necessary to recall the color indicated by each symbol. for example, we have four colors indicated as r, or, ro, o; red, orange-red, red-orange, orange; or more extended, red, orange hue of red, red hue of orange, orange. thus by using as symbols familiar terms, no effort of the memory is required to recall the color indicated by each symbol, as would necessarily be the case if there were a greater number of hues and therefore more arbitrary symbols. the use of rotating color disks on the wheel and the top by which an infinite variety of intermediate hues can be made and accurately named by the pupils reduces the required number of papers to those types necessary for first primary work, and thus prepares the child for the use of pigments at an earlier age than would be possible without such color instruction. the second section of the sample book contains white, black and grays as indicated on the separating fly leaf. in these the best pigmentary expression of black and white are furnished. in material colors as found in industrial products, there are various so-called blacks and whites. for black there are blue-black, green-black, and brown-black; and in white, cream-white and pearl-white. cream-white is a yellow-white and pearl-white a blue-white. in fine white papers either blue, red or yellow is generally added to the pulp to counteract or cover up the gray tone of the natural material. the standard black here presented is the best possible pigmentary imitation of a very deep black hole, as for example, the projecting end of a large iron water or sewer pipe of considerable length buried in the ground, which is the blackest thing known. the white is an imitation of new-fallen snow. neither of these standards can be very nearly approached although we often hear of things as "white as snow" and as "black as night." in the same group and following the black and white are two examples each of the four kinds of grays: green gray, warm gray, cool gray and neutral gray. a pure white in shadow is the true neutral gray and a perfect imitation of this is made by the rotation of combined black and white disks on the color wheel. if to the black and white disks we add a blue disk we have cool grays. with red, orange or yellow the warm grays are produced, while the use of a green disk gives green grays. in the papers two tones of each gray are furnished. the papers found in the first two sections comprise all the colors necessary for earliest primary color instruction, and should become familiar to the children before explanation is made of the colors in the succeeding collections. in the third section, designated "broken spectrum scales" will be found a collection of gray colors or broken colors. as has before been stated, a broken color is a pure color mixed with a neutral gray. in the combination of pigmentary colors a tint of a color is the pure color mixed with white, a shade is the color mixed with black, and a broken color is a pure color mixed with both black and white, which is a neutral gray. therefore if with red, for example, we mix a certain amount of a given neutral gray and call that the normal tone of a broken scale of red, for the tint in that scale we must mix with the standard red a lighter gray and for the shade a darker gray. when a comparatively small quantity of neutral gray is combined with a pure color the result is a "gray color," as above described, because the color is quite definitely retained, but more or less modified by the gray. on the other hand, if a relatively small quantity of color is added to a neutral gray, the resulting color is properly called a "colored gray," because it is still a gray modified by color, and in this class we have warm grays, cool grays, etc., according to the color combined with the gray. the gray colors are quite generally termed "broken colors" and this seems a very useful practice, because it avoids the confusion of the somewhat similar terms "gray color" and "colored gray." by reference to the chart of broken spectrum scales on page 41 it will be seen that we have only twelve scales and but three tones in each scale, instead of eighteen scales and five tones, as in the pure scales, for which there is a good reason. for educational purposes in the elementary grades, which is the only place where there is a legitimate use for colored papers, the steps in gradation of hue or tone must not be too short, and if the saturation or intensity of the normal colors in the several scales is reduced by adding gray, as in the broken colors, there is not the possibility for as many steps in either hues or tones without leaving those colors adjacent to each other too nearly alike. therefore in the broken colors there are but thirty-six, instead of ninety, as in the pure scales. the distinction between pure colors with tints and shades, and broken colors in various tones, should be made very plain to the children whenever the subject is brought to their notice, because it is a vital point in the classification of colors. educationally this is one of the most objectionable features in the old red, yellow and blue theory of color composition, because no distinction is observed between pure and broken colors in classification. in the bradley colored papers the distinction is made very decided for educational purposes, so that no one would for a moment tolerate the mixture of the normal colors from the pure scales with the normal colors from the broken scales in the formation of a spectrum. this may be illustrated by a selection as follows: first lay in order the normal spectrum colors with the pure colors found in the first section of the sample book, thereby forming the central vertical column of fig. 10. then substitute for the orange, green and violet, those colors selected from the collection of broken colors, and the result will seem to render the operation absurd, but it is the same in principle as the results produced in the attempt to form a spectrum by the combination of three primary pigments, red, yellow and blue, because so produced the orange, green and violet, show by disk analysis from 54 to 80 per cent of black and white and are therefore as much broken as the corresponding colors in the papers of the broken scales, but not exactly the same in tone. engine colored papers. those papers which are termed "engine colored papers" are so named from the process of manufacture as distinguished from "coated papers" which comprise the first three sections of the book. in coated papers a white paper is covered with a coating of colored pigment "fixed" with a small amount of white gum, gelatine or glue, and in this way the pure color of the pigment is obtained. in the engine colored papers the color is mixed with the paper pulp in the process of making the paper. in a paper mill the tub or vat in which the pulp is kept stirred up and perfectly mixed is called the engine, and hence this technical term has been applied to such papers as are colored in the pulp. in this class of papers both sides are alike, and for this reason in some of the folding exercises these papers are preferred, also because they are thinner and tougher. heretofore, it has been impossible to obtain engine colored papers in "families" or scales, but in this assortment the numbers from one to six, furnish six scales of three tones each, comprising the normal tones with tints and shades. following these from seven to sixteen are a collection of unclassified colors including grays which are much used. all these can be analyzed and classified by the color wheel. black and white complete this class. it is impossible to make any close approximation to a black in this class of papers, as when they are compared with the coated blacks the result is a very gray black, or very dark gray. all the colors in these papers from no. 1 a to no. 13 are quite light broken spectrum colors, but less broken than the coated papers designated as broken spectrum colors. while great care has been bestowed on the original selection of the colors of all these above-described papers and every effort is constantly exercised to keep them the same from year to year, the subject is materially complicated by the guarantee required of the manufacturers that no arsenic colors shall be used in the preparation of any of the papers. this guarantee is strictly insisted on, because, while the writer has never been able to learn of any authentic case where a child has been injured by the use of plated or glazed papers, he believes that the opinions of parents and teachers should be respected in the matter, although the arsenic colors are often the most permanent and the aniline substitutes which are necessarily used belong to a class which is the most fugitive of all colors. the line of colored papers now in use is the result of many experiments on the part of the writer and careful tests by experienced teachers for several years, and in its present condition affords but small indication of the time and care which has been expended on it. this has been inevitable, because the peculiar system on which the colors are based has been one of growth and the papers have been designed to afford the necessary material colors for this special scheme of instruction. in preparing the tints and shades in the papers many experiments have been made to determine the true effect of light and shadow on each normal color, and then to imitate these effects in the papers. all this is independent of the professional tricks which artists use to heighten their effects, some of which are legitimate, while others may be questionable on sound principles. it is a common habit with artists to introduce very warm effects into all sunlight by the use of orange or yellow in the warm colors. this extreme tendency has been intentionally avoided in the preparation of these papers, however desirable or allowable it may be considered in heightening effects. so also in the shades as in the tints, the aim has been to keep all the tones of one color in the same scale, even though artists often run the various tones of the same piece of color into two or three analogous scales. it is the object of color education to train the eye to see color wherever or however it may be produced, either by actual color reflection or contrasted effects, and in order that these effects may be understood as explained under simultaneous contrasts it is necessary that the prepared material be truthful to nature, the more so because these effects are sometimes greatly exaggerated by artists. water colors. when the subject of color was introduced into the curriculum of the common schools of this country, the use of paints was a novelty. so little was known regarding the possibilities of water colors as a means of education, that the teachers may be excused for having had grave doubts about the practicability of the scheme. very few teachers in the lower grades of schools had received at that time any definite instruction in the harmonies of colors or the manipulation of pigments; and what little thought had been given to the subject was based on the three-color theory of brewster, which was the only one available at that time. during the intervening years much has been done to make entirely feasible the introduction into school and kindergarten of this pleasing and educating occupation. color standards have been adopted, which are nothing less than selections from the solar spectrum itself, and the manufacture of pigments has improved so much that it may almost be said to be a new industry. in the training of teachers, also, color instruction is now given an important place, so that the kindergartner and primary teacher can give the attention that it deserves to a subject which is so interwoven with all that is beautiful in the material world around us. passing from one form of color work to another, it is exceedingly important that children of any grade should find the same principles obtaining in each step of the way, and also that the knowledge gained in the earliest stages of the work should be available in the higher forms. this is particularly true of color instruction as it is now found in the best schools, and the principal reason why water colors are so much better adapted to use in the schools to-day than in former years, is because paints are now made to correspond in color with the standards with which the children have become familiar in the colored papers and other material of the kindergarten. at present it is generally conceded that these six colors, red, orange, yellow, green, blue and violet, which stand out so prominently in the solar spectrum, are pre-eminently adapted to serve as standards and as the basis of an alphabet of color. there should, therefore, be no question as to the adoption of these same colors as the palette of paints for the earliest color work, even with the babes in the kindergarten, when anything beyond the colored papers and the usual kindergarten occupations is wanted. not very long ago it was the practice to give the child a box of colors and let him paint at random without any definite instruction as to the relation which each color should bear to the others. in fact, with the usual cheap box of paints then in the market there was no decided correlation of the colors nor any educational selection, both of which we have to-day. water colors are now furnished which so closely approach the standards of the colored papers that they are of the greatest assistance in developing the æsthetic taste and judgment of the pupils, and it is remarkable how early in the training of children paints can be used with advantage. in some of the previous pages of this book we have treated of the false theory of sir david brewster, who supposed that there were three primary colors in the solar spectrum and that all the other colors were produced by the overlapping or mixing of these in pairs. this error, being applied to pigments, has worked much harm and has greatly retarded the progress of color study. even now some teachers recommend the use of the red, yellow and blue palette on the ground of simplicity and economy. all the recent scientific writers on color treat this three-color scheme as already exploded, because the simplest as well as the most complex experiments with colored light prove its falsity. nevertheless, the fact that yellow and blue, which with light make very nearly white, do in the mixture of pigments produce a green, has deceived many persons. but the best green that can be so procured is a very broken color and not to be successfully compared with the beautiful and brilliant green of the spectrum. why then, should we not have in our paints imitations of the solar green, orange and violet as well as the red, yellow and blue? it is not well to sacrifice so much for alleged simplicity, and as for economy, it will take but a moment's reflection to see that it would take no more paint to cover a given surface with six colors than with three. oil colors, of course, are out of the question and pastels almost equally so, for although full colors may be produced in both these mediums, they are not suited to the use of young children, and at best are neither neat nor convenient, while colored pencils are not sufficiently satisfactory in results. therefore water colors seem to be better adapted to primary work than any other pigmentary material. of necessity the pupil must later be able to recognize any pigment he may meet and to classify it according to its color value and also to give it a definite name, other than the one by which it is sold. more than one professional artist has already worked successfully from nature in oil colors with a palette consisting of only close approximations to the six standard colors with white and a few grays. a person whose color perception has been trained by the use of the color disk in six standard colors with colored papers to correspond, will undoubtedly be able to more truthfully reproduce the colors which he sees in nature, on the canvas or paper by means of such a palette than if he had been taught by any other system and used the ordinary pigments. color blindness. the subject of color blindness has received much attention because of its practical importance in the affairs of our daily lives. the use of colored lights as signals on ships and railroads has necessitated very strict regulations regarding the employment of persons whose color vision is defective, and therefore in some states specialists have been employed by the state authorities to examine from time to time the school children regarding their perception of colors. possibly this condition of things may not at present be considered a serious reflection on the methods of color instruction, or lack of such instruction in our schools because it has become so common as to attract little attention. but if it were necessary for the same course to be pursued in any other department of our public education that fact would not fail to occasion very uncomplimentary remarks regarding the methods employed. for example, if a state official were necessary to determine whether pupils are deaf or not after they have been through our grammar schools, and preliminary to accepting positions of responsibility, it would seem that something was wrong, and yet after a child has had instruction in color according to a logical system there should be no more necessity for an examination regarding his ability to properly distinguish colors than there should regarding his ability to hear. color blindness has quite generally been divided into three classes, red, green, and violet blindness, those afflicted with red blindness being most numerous, and the cases of violet blindness being very rare, if indeed there are any which may properly be so called. this classification, known as the holmgren system, seems to have been based on the young-helmholtz theory that all color perceptions are the result of three primary effects in the eye, namely, red, green and violet, rather than on any analytical classification of actual experiments concerning color blindness. color tests should be so arranged as to detect either a defect in the brain which renders it difficult for the pupil to remember the names of the several colors, or in the eye, by which he cannot see a difference between two dissimilar colors. a person totally color blind would see in the solar spectrum a band of gray in various tones, and hence if a red and a green should seem to be of the same tone of gray he would call both either red or green, and after much experience would come to give color names to various tones of gray. such cases, however, are exceedingly rare, if in fact they exist. other scientists and physiologists have doubted the truth of the claims made by both holmgren and helmholtz, and some have made extended experiments regarding color blindness which seem to oppose the holmgren theory. in view of these conditions it does not seem necessary for a teacher in the elementary grades to attempt to grasp the situation very fully, and much less to aid in the solution of the problem. very fortunately this is unnecessary, because in all the scientific tests proposed for adults nothing is accomplished which any primary school teacher will not be easily able to determine during the first two or three years of ordinary school work, if the modern system of color instruction is pursued. there is no better material than colored papers for testing the color perceptions, and the exercises of selecting, matching and arranging the spectrum colors by means of the small color tablets generally in use in the first years of school are the very best that can be devised without regard to any of the abstract theories concerning either the cause or the possible classification of color blindness. for some reason the most common form of color blindness occasions a confusion between red and green, as for example, we are told, by some people, that in picking wild strawberries in a field the fruit can be distinguished from the leaves and grass only by the shape, and the green fruit from the ripe by the touch or taste. if a teacher discovers that a child is unable to readily give the name of a color it may not indicate want of color vision, but merely inability to remember names, and therefore various tests which will naturally suggest themselves can be made to aid in reaching a decision on this point. should the results of the tests seem to indicate some defect in color vision, the nature of the trouble should be sought and memoranda made from time to time for future reference, and if the final result shows a radical lack of color perception the parents should be informed of the fact and a physician consulted. it is probable that the number of color blind women is very much less than that of men, and much time has been spent in debating the matter, but some doubt remains as to whether this opinion does not obtain because the girls are brought so much more intimately into relation with colored materials in selecting their articles of dress, and consequently come to know the names of colors much better, and in fact enjoy a much better color education than the men. a more correct decision regarding this question can better be reached when both the boys and girls receive a systematic color education and their color sense is more equally cultivated. outline of a course in color instruction. [illustration] the course of color instruction suggested in the preceding pages is not arbitrarily divided into lessons or even years, because the conditions in the city and rural schools in the various states of this country are so varied that no uniform allotment or division of time can be suggested which will be satisfactory to all. the number of hours that can be devoted to any subject must be determined by those who prepare the school programme and the progress must be more or less rapid, with instruction correspondingly superficial or complete at each stage, according to the time allowed, the preparation of the teacher and the natural ability of the pupils. the teaching of color is usually classed with drawing because both relate directly to art, but inasmuch as color enters into our every day experiences so much more largely than the graphic arts there seems to be good reason for teaching it very fully where little attention is given to drawing. every competent teacher can and will become expert and even enthusiastic in teaching color, if she fully understands the system which it is the object of the foregoing pages to explain. the following brief outline suggests the order in which the facts concerning color may be presented and the material which can be used in an elementary course, beginning with the first primary grade pupils, who for the most part have not had kindergarten training. as a part of the material the bradley educational colored papers, cut to tablets each 1 x 2 inches, are prepared and put up in four small envelopes which are enclosed in one larger envelope. on the larger envelope these words are printed: "the bradley paper tablets for primary color education, selections 1, 2, 3, 4 for complete course." the four small envelopes are labeled in this way: "selection no. 1, eighteen pieces from chart of pure spectrum scales, the normal spectrum colors." "selection no. 2, forty pieces from chart of pure spectrum scales, tint no. 1 and shades no. 1, with white, black and neutral grays." "selection no. 3, forty-two pieces comprising complete chart of broken spectrum scales and warm, cool and green grays." "selection no. 4, thirty-six pieces from chart of pure spectrum scales, tints no. 2 and shades no. 2." the solar spectrum. material. a glass prism, the cost of which need not exceed a few cents, as almost any lamp or gas pendent in the form of a prism will serve the purpose. by the use of such a prism a small spectrum can be shown on the wall of any schoolroom having a sunny exposure during any part of the day. this spectrum will make plain the fact that sunlight is composed of many colors. method. show to the pupils the best solar spectrum that can be produced under the controlling conditions. call attention to the six colors, red, orange, yellow, green, blue and violet, and the order of their arrangement in the spectrum. present the colors separately as far as possible, selecting the best conditions available for each one. pigmentary spectrum colors. material. neutral gray or white card to cover desk top for a background. chart of pure spectrum scales. colored paper tablets, selection no. 1, embracing the six standards and the intermediate spectrum hues, eighteen pieces. color wheel or tops. method. ask the pupils to separate the six standards from the twelve spectrum hues. standards to be arranged in spectrum order. teach the names of the standards. test natural color perceptions by the attempts of the pupils to lay the spectrum in the eighteen papers. explain the intermediate hues by the color disks, and drill with the tablets. continue the practice of having the pupils lay the entire spectrum with the papers until it is familiar to them. practical occupations. pasting simple designs in either of the six standard colors, on white or gray background, with ready-cut papers. marking forms from tablets and cutting and pasting them on backgrounds. study of tones. material. folding models to show light and shade. crumpled satins and plushes. standard color disks with white and black, on wheel or tops. paper tablets, selection no. 2, tints no. 1, shades no. 1, white, black and neutral grays. method. ask each pupil to lay spectrum in eighteen normal colors. lay tints and shades of the six standards. have the children complete tints and shades no. 1 of entire spectrum circuit. illustrate neutral grays by white in shadow with folding model, also with white and black disks combined. begin to classify into families the miscellaneous color material brought by the pupils. practical occupations. pasting of ready-cut papers in standard and shade on a background of the tint of same scale. paste designs in three tones of one scale on white or neutral gray background. mat weaving in tones of one scale. mat weaving in neutral gray and one or two tones of one color. broken colors. material. disks on wheel or top. paper tablets, selection no. 3. chart of broken spectrum scales. method. illustrate broken colors by disk combinations. let the pupils lay paper tablets to form chart of broken scales. compare this chart with the chart of pure scales laid with the papers. classifying of miscellaneous materials with reference to pure and broken colors. analysis of samples of pure and broken colors in cloths and flowers. practical occupations. paper cutting and pasting to be continued. following the broken colors in three tones which form the chart of broken spectrum colors, the three kinds of colored grays, warm, cool and green, may be considered preparatory to their use in contrasted effects. complete chart of pure spectrum scales in five tones. material. paper tablets, selection no. 4. chart of spectrum scales in five tones may be introduced for observation when the children are able to lay it with their papers. method. continue the study of tones with pure spectrum scales in five tones, as was done in the first three tones. from the chart of spectrum scales the study and classification of harmonies can begin in a simple way. from this time on free-hand paper cutting and pasting may be introduced at pleasure, employing the colored papers in five tones when required. advanced study of harmonies. by taking advantage of the instruction imparted in a course of color study such as has been outlined in the preceding pages the pupil will be able to advance in his ability to perceive colors and to make definite analyses of colors in natural and manufactured material. in this way the advanced study of harmonies can be greatly facilitated so that it will be possible for the student to apprehend and appreciate many delicate and subtle color effects in art and nature never before imagined. in fact the foundation of color study will have been laid in such a logical and fascinating manner that its further advance will be but a pleasure to the pupil and teacher, so that no arbitrary plan will be necessary, because so many lines of work will suggest themselves to all who are interested in the subject. water colors. this outline would not be complete without a reference to water colors, but this is not the place to give definite instructions as to their use. kindergartners and primary teachers are now generally competent to direct the children in this work, if they will avail themselves of such aid as is furnished by recently published books on the subject. non-poisonous paints, cheap and still of fair quality, can now be obtained in standard colors and put up in various forms. the moist paints in collapsible tubes are the most convenient as well as the most economical for school use. this form should be accompanied by a small mixing palette containing several compartments, which can be bought at so small a price that each pupil can have one. the paint in the tubes can then be dealt out only as required for each day's use. $material for color instruction.$ where the price is preceded by a star the article is too large to be sent by mail. in other cases where no postage is given the goods are sent postpaid on receipt of price. $water colors.$ in ordering it will be necessary to give only the number of the box. no. price 1. an enameled box containing eight pans of semi-moist colors, six standards and two grays, one brush, per box $ .35 2. an enameled box containing ten pans semi-moist colors, six standards, black, white, cool gray and warm gray, one brush, per box .50 3. same box as above, containing five pans semi-moist colors. red, two yellows, blue and gray, one brush, per box .30 4. enameled box containing four pans semi-moist colors, red, yellow, blue and gray, one brush, per box .20 5. same as above, red, two yellows and blue, per box .20 6. a decorated box containing eight cakes of dry colors, six standards and two grays, one brush, per box .25 7. a decorated box containing four large cakes of dry colors. red, yellow, blue and gray, one brush, per box .20 8. same box as above. red, two yellows and blue, two brushes, per box .20 9. nine tubes moist colors in strong paper box. six standards, warm gray, cool gray and black, per set .90 10. photograph colors. a box of eight colors, the six standards and a chinese white and a brown, with one brush. these colors are expressly prepared for coloring photographs, half tone prints, maps, etc. .25 bradley's school colors, moist in tubes. the most economical form for school use. these colors are so prepared that they remain moist out of the tube. the set comprises the following colors: postage carmine, crimson lake, vermilion, gamboge, chinese yellow, hooker's green, no. i, hooker's green, no. ii, ultramarine, prussian blue, sepia, warm sepia, burnt sienna, payne's gray, ivory black, chinese white and the six standards, with warm, cool and neutral gray, black and white, per tube .10 little artist's complete outfit, comprising a mixing palette with its seven compartments filled with semi-moist colors and a brush, the whole enclosed in a strong cardboard case .15 .03 $accessories.$ standard mixing palette, with seven compartments for paints and two for mixing. almost indispensable in using tube colors. extra deep, per doz. .60 .25 water cups. an enameled metal cup, practically indestructible, per doz. .60 .13 camel's hair brushes, quill, per doz. .30 .02 camel's hair brushes, long handles, per doz. .60 .03 japanese school brushes, per doz. .60 .05 artists' camel hair brushes, no. 6, wooden handles, per doz. .75 .03 milton bradley co.'s water color pads--made of extra quality paper for water color work. no. 1, pad of 50 sheets, 6×9, each .10 .09 no. 2, pad of 25 sheets, 9×12, each .10 .10 $apparatus.$ high school color wheel, with disks in box *10.00 one set of disks for above, in box *2.00 primary school color wheel, with disks *3.00 one set of disks for above in portfolio .75 .06 color top, by mail, each .06 color top, by mail, per doz. .50 no. 1 prism, at buyer's risk .10 no. 2 prism, at buyer's risk .15 no. 3 prism, at buyer's risk .30 rainy day spectrum, made from colored papers, mounted on cardboard, one inch by 13, each .10 .04 large spectrum, 5 by 30 inches, mounted on cloth, each .25 .04 chart of pure spectrum scales, no. 1 x, on cardboard, 9x24 inches, hinged and folded. ninety papers one inch square, each .50 .10 chart of pure spectrum scales, no. 2 x. size, 12x48, folded and hinged. ninety papers two inches square, each .75 .15 chart of broken spectrum scales, no. 1. size, 9x12 inches, with paper 1-1/2 inches square, comprising twelve scales of three tones each .50 .10 chart of broken spectrum scales, no. 2. size, 12x48 inches, with the same papers as no. 1, three inches square, each .75 .15 chart of complementary colors. on cardboard 18 inches square, each *.50 standard color chart. on two cards 11x28 inches, hinged and eyeleted for hanging. this is a combination chart comprising "spectrum standards," "pure spectrum scales," "complementary contrasts," "broken spectrum scales," and "grays." printed suggestions for using the charts on the back, each 1.25 .15 $books on color.$ water colors in the schoolroom, by milton bradley, boards .25 a new book of practical suggestions, valuable to every one who would undertake to teach the use of water colors. elementary color, by milton bradley, cloth .75 gives the principles on which the bradley system is based and an explanation of the use of the glass prism, color wheel, maxwell disks, color top, colored papers, color charts and water colors. the little artist by marion mackenzie, cloth .75 .15 a practical book of water color work for children, with 12 beautiful, colored plates. size of book, 12 by 14 inches. color in the kindergarten, by milton bradley, paper covers .25 a manual of the theory of color and the use of color material in the kindergarten. a class book of color, by prof. mark m. maycock. teachers' edition, cloth 1.00 pupils' edition, boards .50 a very complete teachers' handbook in color. practical color work, by helena p. chace, paper .25 a handbook for the educational use of colored papers in teaching color in primary and ungraded schools. the color primer, by milton bradley, paper. teachers' edition, 80 pages .10 pupils' edition, 24 pages .05 simple and direct teachings. $miscellaneous material.$ paper tablets, set no. 1, 1x2 in. .02 paper tablets, set no. 2, 1x2 in. .02 paper tablets, set no. 3, 1x2 in. .03 paper tablets, set no. 4, 1x2 in. .04 sample book, one by four inches, containing the full assortment .05 .01 package, 4x4 papers, 100 pieces .20 .04 package, 5x5 papers, 100 pieces .30 .05 fun, physics and psychology in color. a box of material for simple experiment, each .25 .07 complementary color contrasts. a box of large material for popular experiments in color vision, each .75 .20 the dunn and curtis illustrative sewing cards, in color. two sets: a. literature illustration. b. cards for special occasions. set of eight cards .25 dozen of any design .40 $milton bradley company,$ $springfield, mass.$ transcriber's note _italic text_ has been enclosed in underscores. $bold text$ has been enclosed in dollar signs. transcriber's note italic text has been formatted as _text_ and superscript text as ^{text}. colouration in animals and plants. by the late alfred tylor, f.g.s. _edited by_ sydney b. j. skertchly, f.g.s., late of h.m. geological survey. london: printed by alabaster, passmore, and sons, fann street, aldersgate street, e.c. 1886. in memory of a friendship of many years, this book is affectionately inscribed to the right hon. george young, p.c. 1885. preface. this little book is only a sketch of what its author desired it to be, and he never saw the completed manuscript. beginning with the fundamental idea that decoration is based upon structure, he saw that this was due to the fact that in the lower, transparent, animals, colour is applied directly to the organs, and that the decoration of opaque animals is carried out on the same principle--the primitive idea being maintained. where function changes the pattern alters, where function is localized colour is concentrated: and thus the law of emphasis was evolved. symmetry was a necessary consequence, for like parts were decorated alike, and this symmetry was carried out in detail apparently for the sake of beauty, as in the spiracular markings of many larvæ. hence the reason for recognizing the law of repetition. with the developing of these ideas the necessity for recognizing some sort of consciousness even in the lowest forms of life was forced upon the author, until inherited memory formed part of his scientific faith. this he saw dimly years ago, but only clearly when mr. s. butler's remarkable "life and habit" appeared, and he was gratified and strengthened when he found mr. romanes adopting that theory in his "mental evolution." the opening chapters are designedly elementary; for the author had a wise dread of locking intellectual treasures in those unpickable scientific safes of which "the learned" alone hold keys. only a very small portion of the vast array of facts accumulated has been made use of, and the author was steadily working through the animal kingdom, seeking exceptions to his laws, but finding none, when death closed his patient and far-seeing eyes. a few days before the end he begged me to finish this abstract, for i had been at his side through all his labours. the work contains his views as clearly as i could express them, though on every page i feel they suffer from want of amplification. but i feared the work might become the expression of my own thoughts, though want of leisure would probably have prevented that unhappy result. now it is finished, i would fain write it all over again, for methinks between the lines can be seen gleams of brighter light. sydney b. j. skertchly. carshalton, _july 17th, 1886_. the coloured illustrations were drawn by mrs. skertchly chiefly from nature, and very carefully printed by messrs. alabaster, passmore, and sons. [illustration] contents. chapter page i. introductory 1 ii. inherited memory 8 iii. introductory sketch 16 iv. colour, its nature and recognition 25 v. the colour sense 32 vi. spots and stripes 39 vii. colouration in the invertebrata 49 viii. details of protozoa 56 ix. details of coelenterata 59 x. the colouration of insects 68 xi. the colouration of insects 75 xii. arachnida 82 xiii. colouration of invertebrata 85 xiv. colouration of vertebrata 88 xv. the colouration of plants 95 xvi. conclusions 97 list of woodcuts. fig. 1. part of secondary feather of argus pheasant. fig. 2. ditto wing-feather of ditto. fig. 3. diagram of butterfly's wing. fig. 4. python. fig. 5. tiger's skin. fig. 6. ditto. fig. 7. tiger's head, side view. fig. 8. ditto, crown. fig. 9. leopard's skin. fig. 10. ditto. fig. 11. leopard's head, side view. fig. 12. ditto, crown. fig. 13. lynx' skin. fig. 14. ditto. fig. 15. ocelot. fig. 16. badger. fig. 17. begonia leaf. description of plates. plate i. _kallima inachus_, the indian leaf butterfly. _p._ 28. fig. 1. with wings expanded. fig. 2. two butterflies at rest, showing their exact resemblance to dead leaves. this insect affords one of the best examples of protective resemblance. plate ii. illustration of mimicry in butterflies. _p._ 30. fig. 1. male of _papilio merope_. fig. 2. female of ditto mimicking fig. 3. fig. 3. _danais niavius._ on the african continent both species occur, but in madagascar _d. niavius_ is wanting, and the female _p. merope_ is coloured like the male. plate iii. fig. 1. _gonepteryx cleopatra._ _p._ 40. fig. 2. _gonepteryx rhamni_, male. _note._--the orange spot in fig. 2 has spread over the wing in fig. 1. fig. 3. _vanessa antiopa._ fig. 4. _panopoea hirta._ fig. 5. _acrea gea._ these two last belong to widely different genera, but are admirable examples of mimicry. plate iv. fig. 1. _leucophasia sinapis._ _p._ 42. fig. 2. ditto, var. _diniensis_. fig. 3. _anthocaris cardamines_, male. fig. 4. ditto, female. fig. 5. _anthocaris belemia._ fig. 6. _anthocaris belia._ fig. 7. ditto, var. _simplonia_. fig. 8. _anthocaris eupheno_, female. fig. 9. ditto, male. fig. 10. _anthocaris euphemoides._ fig. 11. _papilio machaon._ fig. 12. _papilio podalirius._ fig. 13. _pieris napi_, summer form. fig. 14. ditto, winter form. fig. 15. ditto, var. _bryoniæ_ (alpine form). fig. 16. ditto, summer form, underside. fig. 17. ditto, winter form, underside. fig. 18. ditto, var. _bryoniæ_, underside. figs. 13-18 illustrate admirably the variations of the yellow and black in the same species. plate v. fig. 1. _araschnia prorsa_, male. _p._ 44. fig. 2. ditto, female. fig. 3. _araschnia levana_, female. fig. 4. ditto, male. fig. 5. _paragra ægeria._ fig. 6. _araschnia porima._ fig. 7. ditto, var. _meione_. fig. 8. _grapta interrogationis._ fig. 9. ditto. fig. 10. ditto. fig. 11. _papilio ajax_, var. _walshii_. fig. 12. ditto, var. _telamonides_. fig. 13. ditto, var. _marcellus_. figs. 1-5 are all one species; _levana_ being the winter form, _prorsa_ the summer form, and _porima_ intermediate. similarly 6-7 are the same species, _meione_ being the southern form. so with 8-9 and 11-13, which are only seasonal varieties. here we can actually trace the way in which varieties are formed. _see_ weismann's work, cited in the text. plate vi. _syncoryne pulchella_, magnified. after professor allman. _p._ 62. gymnoblastic or tubularian hydroids. ray soc., 1871, pl. vi., figs. 1 and 3. fig. 1. a planoblast as seen passively floating in the water after liberation. fig. 2. the entire hydrosoma of syncoryne. _a._ the spadix. _b._ the medusæ or planoblasts in various stages of development. plate vii. _p._ 80. fig. 1. _deilephila galii_, immature. fig. 2. ditto brown variety, adult. fig. 3. _deilephila euphorbiæ._ fig. 4. _sphinx ligustri._ fig. 5. _deilephila euphorbiæ_, dorsal view. fig. 6. _orgyia antiqua._ fig. 7. _abraxas grossulariata._ fig. 8. _bombyx neustria._ fig. 9. _callimorpha dominula._ fig. 10. _euchelia jacobæa._ fig. 11. _papilio machaon._ spiders. plate viii. fig. 1. _segestria senoculata_, female. _p._ 84. fig. 2. _sparassus smaragdulus_, male. fig. 3. _lycosa piscatoria_, female. fig. 4. ---_andrenivora_, male. fig. 5. ------female. fig. 6. ---_allodroma_, male. fig. 7. ---_agretyca_, male. fig. 8. ---_allodroma_, female. fig. 9. diagram of _lycosa_, showing form and position of vessels. after gegenbaur. fig. 10. _lycosa campestris_, female. fig. 11. _thomisus luctuosus_, male. fig. 12. _salticus scenicus_, female. fig. 13. _lycosa rapax_, female. fig. 14. ---_latitans_, female. fig. 15. _theridion pictum_, female. fig. 16. _lycosa picta_, female. fig. 17. ------male. all the above are british species, and copied from blackwell's "spiders of great britain and ireland." ray soc., 1862. fishes. plate ix. fig. 1. windermere char. _salmo willughbii._ a species _p._ 88. peculiar to our north of england lakes. fig. 2. perch, _perca fluviatilis_, showing the modified rib-like markings. sunbirds. plate x. fig. 1. _nectarinea chloropygia._ _p._ 90. fig. 2. _nectarinea christinæ._ these birds illustrate regional colouration well. leaves. plate xi. fig. 1. horse chestnut, _æschulus hippocastanum_, decaying. _p._ 95. fig. 2. _coleus._ fig. 3. _begonia rex._ fig. 4. _begonia_. fig. 5. _caladium bicolor._ fig. 6. _anoechtochilus xanthophyllus._ flowers. plate xii. fig. 1. _gloxinia_, with 5 petals, showing uneven _p._ 96. colouring. fig. 2. _gloxinia_, with 6 petals, showing regular colouring. figs. 3 and 4. pelargoniums, showing the variation of the dark markings with the different sized petals. [illustration] colouration in animals and plants. chapter i. introduction. before darwin published his remarkable and memorable work on the origin of species, the decoration of animals and plants was a mystery as much hidden to the majority as the beauty of the rainbow ere newton analysed the light. that the world teemed with beauty in form and colour was all we knew; and the only guess that could be made as to its uses was the vague and unsatisfactory suggestion that it was appointed for the delight of man. why, if such was the case, so many flowers were "born to blush unseen," so many insects hidden in untrodden forests, so many bright-robed creatures buried in the depths of the sea, no man could tell. it seemed but a poor display of creative intelligence to lavish for thousands of years upon heedless savage eyes such glories as are displayed by the forests of brazil; and the mind recoiled from the suggestion that such could ever have been the prime intention. but with the dawn of the new scientific faith, light began to shine upon these and kindred questions; nature ceased to appear a mass of useless, unconnected facts, and ornamentation appeared in its true guise as of extreme importance to the beings possessing it. it was the theory of descent with modification that threw this light upon nature. this theory, reduced to its simplest terms, is that species, past and present, have arisen from the accumulation by inheritance of minute differences of form, structure, colour, or habit, giving to the individual a better chance, in the struggle for existence, of obtaining food or avoiding danger. it is based on a few well-known and universally admitted facts or laws of nature: namely, the law of multiplication in geometrical progression causing the birth of many more individuals than can survive, leading necessarily to the struggle for existence; the law of heredity, in virtue of which the offspring resembles its parents; the law of variation, in virtue of which the offspring has an individual character slightly differing from its parents. to illustrate these laws roughly we will take the case of a bird, say, the thrush. the female lays on the average five eggs, and if all these are hatched, and the young survive, thrushes would be as seven to two times as numerous in the next year. let two of these be females, and bring up each five young; in the second year we shall have seventeen thrushes, in the third thirty-seven, in the fourth seventy-seven, and so on. now common experience tells us not merely that such a vast increase of individuals does not take place, but can never do so, as in a very few years the numbers would be so enormously increased that food would be exhausted. on the other hand, we know that the numbers of individuals remain practically the same. it follows, then, that of every five eggs four fail to arrive at maturity; and this rigorous destruction of individuals is what is known as the struggle for existence. if, instead of a bird, we took an insect, laying hundreds of eggs, a fish, laying thousands, or a plant, producing still greater quantities of seed, we should find the extermination just as rigorous, and the numbers of individuals destroyed incomparably greater. darwin has calculated that from a single pair of elephants nearly nineteen millions would be alive in 750 years if each elephant born arrived at maturity, lived a hundred years, and produced six young--and the elephant is the slowest breeder of all animals. the struggle for existence, then, is a real and potent fact, and it follows that if, from any cause whatever, a being possesses any power or peculiarity that will give it a better chance of survival over its fellows--be that power ever so slight--it will have a very decided advantage. now it can be shown that no two individuals are exactly alike, in other words, that variation is constantly taking place, and that no animal or plant preserves its characters unmodified. this we might have expected if we attentively consider how impossible it is for any two individuals to be subjected to exactly the same conditions of life and habit. but for the proofs of variability we have not to rely upon theoretical reasoning. no one can study, even superficially, any class or species without daily experiencing the conviction that no two individuals are alike, and that variation takes place in almost every conceivable direction. granted then the existence of the struggle for existence and the variability of individuals, and granting also that if any variation gives its possessor a firmer hold upon life, it follows as a necessity that the most favoured individuals will have the best chance of surviving and leaving descendants, and by the law of heredity, we know these offspring will tend to inherit the characters of their parents. this action is often spoken of as the preservation of favoured races, and as the survival of the fittest. the gradual accumulation of beneficial characters will give rise in time to new varieties and species; and in this way primarily has arisen the wonderful diversity of life that now exists. such, in barest outline, is the theory of descent with modification. let us now see in what way this theory has been applied to colouration. the colours, or, more strictly, the arrangement of colours, in patterns is of several kinds, viz.:-1. _general colouration_, or such as appears to have no very special function _as_ colour. we find this most frequently in the vegetable kingdom, as, for instance, the green hue of leaves, which, though it has a most valuable function chemically has no particular use as colour, so far as we can see. 2. _distinctive colouration_, or the arrangement of colours in different patterns or tints corresponding to each species. this is the most usual style of colouring, and the three following kinds are modifications of it. it is this which gives each species its own design, whether in animals or plants. 3. _protective resemblance_, or the system of colouring which conceals the animal from its prey, or hides the prey from its foe. of this class are the green hues of many caterpillars, the brown tints of desert birds, and the more remarkable resemblances of insects to sticks and leaves. 4. _mimetic colouration_, or the resemblance of one animal to another. it is always the resemblance of a rare species, which is the favourite food of some creature, to a common species nauseous to the mimicker's foe. of this character are many butterflies. 5. _warning colours_, or distinctive markings and tints rendering an animal conspicuous, and, as it were, proclaiming _noli me tangere_ to its would-be attackers. 6. _sexual colours_, or particular modifications of colour in the two sexes, generally taking the form of brilliancy in the male, as in the peacock and birds of paradise. under one or other of these headings most schemes of colouration will be found to arrange themselves. at the outset, and confining ourselves to the animal kingdom for the present, bearing in mind the fierce intensity of the struggle for life, it would seem that any scheme of colour that would enable its possessor to elude its foes or conceal itself from its prey, would be of vital importance. hence we might infer that protective colouring would be a very usual phenomenon; and such we find to be the case. in the sea we have innumerable instances of protective colouring. fishes that lie upon the sandy bottom are sand-coloured, like soles and plaice, in other orders we find the same hues in shrimps and crabs, and a common species on our shores (_carcinus mænas_) has, just behind the eyes, a little light irregular patch, so like the shell fragments around that when it hides in the sand, with eyes and light spot alone showing, it is impossible to distinguish it. the land teems with protective colours. the sombre tints of so many insects, birds and animals are cases in point, as are the golden coat of the spider that lurks in the buttercup, and the green mottlings of the underwings of the orange-tip butterfly. where absolute hiding is impossible, as on the african desert, we find every bird and insect, without exception, assimilating the colour of the sand. but if protective colour is thus abundant, it is no less true that colour of the most vivid description has arisen for the sole purpose of attracting notice. we observe this in the hues of many butterflies, in the gem-like humming birds, in sun-birds, birds of paradise, peacocks and pheasants. to see the shining metallic blue of a brazilian morpho flashing in the sun, as it lazily floats along the forest glades, is to be sure that in such cases the object of the insect is to attract notice. these brilliant hues, when studied, appear to fall into two classes, having very diverse functions, namely sexual and warning colours. protection is ensured in many ways, and among insects one of the commonest has been the acquisition of a nauseous flavour. this is often apparent even to our grosser senses; and the young naturalist who captures his first crimson-and-green burnet moth or scarlet tiger, becomes at once aware of the existence of a fetid greasy secretion. this the insectivorous birds know so well that not one will ever eat such insects. but unless there were some outward and visible sign of this inward and sickening taste, it would little avail the insect to be first killed and then rejected. hence these warning colours--they as effectively signal danger as the red and green lamps on our railways. it may here be remarked that wherever mimickry occurs in insects, the species mimicked is always an uneatable one, and the mimicker a palatable morsel. it is nature's way of writing "poison" on her jam-pots. the other class of prominent colours--the sexual--have given rise to two important theories, the one by darwin, the counter-theory by wallace. darwin's theory of sexual selection is briefly this:--he points out in much detail how the male is generally the most powerful, the most aggressive, the most ardent, and therefore the wooer, while the female is, as a rule, gentler, smaller, and is wooed or courted. he brings forward an enormous mass of well-weighed facts to show, for example, how often the males display their plumes and beauties before their loves in the pairing season, and his work is a long exposition of the truth that tennyson proclaimed when he wrote:- "in the spring a fuller crimson comes upon the robin's breast, in the spring the wanton lapwing gets himself another crest, in the spring a livelier iris changes on the burnished dove, in the spring the young man's fancy lightly turns to thoughts of love." that birds are eminently capable of appreciating beauty is certain, and numerous illustrations are familiar to everyone. suffice it here to notice the pretty bower birds of australia, that adorn their love arbours with bright shells and flowers, and show as unmistakable a delight in them as the connoisseur among his art treasures. from these and kindred facts darwin draws the conclusion that the females are most charmed with, and select the most brilliant males, and that by continued selection of this character, the sexual hues have been gradually evolved. to this theory wallace takes exception. admitting, as all must, the fact of sexually distinct ornamentation, he demurs to the conclusion that they have been produced by sexual selection. in the first place, he insists upon the absence of all proof that the least attractive males fail to obtain partners, without which the theory must fail. next he tells us that it was the case of the argus pheasant, so admirably worked out by darwin, that first shook his faith in sexual selection. is it possible, he asks, that those exquisite eye-spots, shaded "like balls lying loose within sockets" (objects of which the birds could have had no possible experience) should have been produced ... "through thousands and tens of thousands of female birds, all preferring those males whose markings varied slightly in this one direction, this uniformity of choice continuing through thousands and tens of thousands of generations"?[1] as an alternative explanation, he would advance no new theory, but simply apply the known laws of evolution. he points out, and dwells upon, the high importance of protection to the female while sitting on the nest. in this way he accounts for the more sombre hues of the female; and finds strong support in the fact that in those birds in which the male undertakes the household duties, he is of a domestic dun colour, and his gad-about-spouse is bedizened like a country-girl at fair time. with regard to the brilliant hues themselves, he draws attention to the fact that depth and intensity of colour are a sign of vigour and health--that the pairing time is one of intense excitement, and that we should naturally expect to find the brightest hues then displayed. moreover, he shows--and this is most important to us--that "the most highly-coloured and most richly varied markings occur on those parts which have undergone the greatest modification, or have acquired the most abnormal development."[2] it is not our object to discuss these rival views; but they are here laid down in skeleton, that the nature of the problem of the principles of colouration may be easily understood. seeing, then, how infinitely varied is colouration, and how potently selection has modified it, the question may be asked, "is it possible to find any general system or law which has determined the main plan of decoration, any system which underlies natural selection, and through which it works"? we venture to think there is; and the object of this work is to develop the laws we have arrived at after several years of study. [illustration] [1] wallace, tropical nature, p. 206. [2] _op. cit._, p. 206. chapter ii. inherited memory. many of our observations seemed to suggest a quasi-intelligent action on the part of the beings under examination; and we were led, early in the course of our studies, to adopt provisionally the hypothesis that memory was inherited--that the whole was consequently wiser than its parts, the species wiser than the individual, the genus wiser than the species. one illustration will suffice to show the possibility of memory being inherited. chickens, as a rule, are hatched with a full knowledge of how to pick up a living, only a few stupid ones having to be taught by the mother the process of pecking. when eggs are hatched artificially, ignorant as well as learned chicks are produced, and the less intelligent, having no hen instructor, would infallibly die in the midst of plenty. but if a tapping noise, like pecking, be made near them, they hesitate awhile, and then take to their food with avidity. here the tapping noise seems certainly to have awakened the ancestral memory which lay dormant. it may be said all this is habit. but what is habit? is it any explanation to say a creature performs a given action by habit? or is it not rather playing with a word which expresses a phenomenon without explaining it? directly we bring memory into the field we get a real explanation. a habit is acquired by repetition, and could not arise if the preceding experience were forgotten. life is largely made up of repetition, which involves the formation of habits; and, indeed, everyone's experience (habit again) shows that life only runs smoothly when certain necessary habits have been acquired so perfectly as to be performed without effort. a being at maturity is a great storehouse of acquired habits; and of these many are so perfectly acquired, _i.e._, have been performed so frequently, that the possessor is quite unconscious of possessing them. habit tends to become automatic; indeed, a habit can hardly be said to be formed until it is automatic. but habits are the result of experience and repetition, that is, have arisen in the first instance by some reasoning process; and reasoning implies consciousness. nevertheless, the action once thought out, or reasoned upon, requires less conscious effort on a second occasion, and still less on a third, and so on, until the mere occurrence of given conditions is sufficient to ensure immediate response without conscious effort, and the action is performed mechanically or automatically: it is now a true habit. habit, then, commences in consciousness and ends in unconsciousness. to say, therefore, when we see an action performed without conscious thought, that consciousness has never had part in its production, is as illogical as to say that because we read automatically we can never have learned to read. the thorough appreciation of this principle is absolutely essential to the argument of this work; for to inherited memory we attribute not only the formation of habits and instincts, but also the modification of organs, which leads to the formation of new species. in a word, it is to memory we attribute the possibility of evolution, and by it the struggle for existence is enabled to re-act upon the forms of life, and produce the harmony we see in the organic world. our own investigations had led us very far in this direction; but we failed to grasp the entire truth until mr. s. butler's remarkable work, "life and habit," came to our notice. this valuable contribution to evolution smoothed away the whole of the difficulties we had experienced, and enabled us to propound the views here set forth with greater clearness than had been anticipated. the great difficulty in mr. darwin's works is the fact that he starts with variations ready made, without trying, as a rule, to account for them, and then shows that if these varieties are beneficial the possessor has a better chance in the great struggle for existence, and the accumulation of such variations will give rise to new species. this is what he means by the title of his work, "the origin of species by means of natural selection or the preservation of favoured races in the struggle for life." but this tells us nothing whatever about the origin of species. as butler puts it, "suppose that it is an advantage to a horse to have an especially broad and hard hoof: then a horse born with such a hoof will, indeed, probably survive in the struggle for existence; but he was not born with the larger and harder hoof _because of his subsequently surviving_. he survived because he was born fit--not he was born fit because he survived. the variation must arise first and be preserved afterwards."[3] mr. butler works out with admirable force the arguments, first, that habitual action begets unconsciousness; second, that there is a unity of personality between parent and offspring; third, that there is a memory of the oft-repeated acts of past existences, and, lastly, that there is a latency of that memory until it is re-kindled by the presence of associated ideas. as to the first point, we need say no more, for daily experience confirms it; but the other points must be dealt with more fully. mr. butler argues for the absolute identity of the parent and offspring; and, indeed, this is a necessity. personal identity is a phrase, very convenient, it is true, but still only a provisional mode of naming something we cannot define. in our own bodies we say that our identity remains the same from birth to death, though we know that our bodily particles are ever changing, that our habits, thoughts, aspirations, even our features, change--that we are no more really the same person than the ripple over a pebble in a brook is the same from moment to moment, though its form remains. if our personal identity thus elude our search in active life, it certainly becomes no more tangible if we trace existence back into pre-natal states. we _are_, in one sense, the same individual; but, what is equally important, we _were_ part of our mother, as absolutely as her limbs are part of her. there is no break of continuity between offspring and parent--the river of life is a continuous stream. we judge of our own identity by the continuity which we see and appreciate; but that greater continuity reaching backwards beyond the womb to the origin of life itself is no less a fact which should be constantly kept in view. the individual, in reality, never dies; for the lamp of life never goes out. for a full exposition of this problem, mr. butler's "life and habit" must be consulted, where the reader will find it treated in a masterly way. this point was very early appreciated in our work; and in a paper read before the anthropological institute[4] in the year 1879, but not published, this continuity was insisted upon by means of diagrams, both of animal and plant life, and its connection with heredity was clearly shown, though its relation to memory was only dimly seen. from this paper the following passage may be quoted: "if, as i believe, the origin of form and decoration is due to a process similar to the visualising of object-thoughts in the human mind, the power of this visualising must commence with the life of the being. it would seem that this power may be best understood by a correct insight into biological development. it has always excited wonder that a child, a separate individual, should inherit and reproduce the characters of its parents, and, indeed, of its ancestors; and the tendency of modern scientific writing is often to make this obscure subject still darker. but if we remember that the great law of all living matter is, that the child is _not_ a separate individual, but a part of the living body of the parent, up to a certain date, when it assumes a separate existence, then we can comprehend how living beings inherit ancestral characters, for they are parts of one continuous series in which not a single break has existed or can ever take place. just as the wave-form over a pebble in a stream remains constant, though the particles of water which compose it are ever changing, so the wave-form of life, which is heredity, remains constant, though the bodies which exhibit it are continually changing. the retrospection of heredity and memory, and the prospection of thought, are well shown in mrs. meritt's beautiful diagram." this passage illustrates how parallel our thoughts were to mr. butler's, whose work we did not then know. what we did not see at the time was, that the power of thinking or memory might antedate birth. it is quite impossible adequately to express our sense of admiration of mr. butler's work. granting then the physical identity of offspring and parent, the doctrine of heredity becomes plain. the child becomes like the parent, because it is placed in almost identical circumstances to those of its parent, and is indeed part of that parent. if memory be possessed by all living matter, and this is what we now believe, we can clearly see how heredity acts. the embryo develops into a man like its parent, because human embryos have gone through this process many times--till they are unconscious of the action, they know how to proceed so thoroughly. darwin, after deeply pondering over the phenomena of growth, repair of waste and injury, heredity and kindred matters, advanced what he wisely called a provisional hypothesis--pangenesis. "i have been led," he remarks, "or, rather, forced, to form a view which to a certain extent, connects these facts by a tangible method. everyone would wish to explain to himself even in an imperfect manner, how it is possible for a character possessed by some remote ancestor suddenly to reappear in the offspring; how the effects of increased or decreased use of a limb can be transmitted to the child; how the male sexual element can act, not solely on the ovules, but occasionally on the mother form; how a hybrid can be produced by the union of the cellular tissue of two plants independently of the organs of generation; how a limb can be reproduced on the exact line of amputation, with neither too much nor too little added; how the same organism may be produced by such widely different processes as budding and true seminal generation; and, lastly, how of two allied forms, one passes in the course of its development through the most complex metamorphoses, and the other does not do so, though when mature both are alike in every detail of structure. i am aware that my view is merely a provisional hypothesis or speculation; but until a better one be advanced, it will serve to bring together a multitude of facts which are at present left disconnected by any efficient cause."[5] after showing in detail that the body is made up of an infinite number of units, each of which is a centre of more or less independent action, he proceeds as follows:-"it is universally admitted that the cells or units of the body increase by self-division or proliferation, retaining the same nature, and that they ultimately become converted into the various tissues of the substances of the body. but besides this means of increase i assume that the units throw off minute granules, which are dispersed throughout the whole system; that these, when supplied with proper nutriment, multiply by self-division, and are ultimately developed into units like those from which they were originally derived. these granules may be called gemmules. they are collected from all parts of the system to constitute the sexual elements, and their development in the next generations forms a new being; but they are likewise capable of transmission in a dormant state to future generations, and may then be developed. their development depends on their union with other partially developed or nascent cells, which precede them in the regular course of growth.... gemmules are supposed to be thrown off by every unit; not only during the adult state, but during each stage of development of every organ; but not necessarily during the continued existence of the same unit. lastly, i assume that the gemmules in their dormant state have a mutual affinity for each other, leading to their aggregation into buds, or into the sexual elements. hence, it is not the reproductive organs or buds which generate new organisms, but the units of which each individual is composed."[6] now, suppose that instead of these hypothetic gemmules we endow the units with memory in ever so slight a degree, how simple the explanation of all these facts becomes! what an unit has learned to do under given conditions it can do again under like circumstances. memory _does_ pass from one unit to another, or we could not remember anything as men that happened in childhood, for we are not physically composed of the same materials. it is not at all necessary that an unit should remember it remembers any more than we in reading are conscious of the efforts we underwent in learning our letters. few of us can remember learning to walk, and none of us recollect learning to talk. yet surely the fact that we do read, and walk, and talk, proves that we have not forgotten how. bearing in mind, then, the fundamental laws that the offspring is one in continuity with its parents, and that memory arises chiefly from repetition in a definite order (for we cannot readily reverse the process--we cannot sing the national anthem backwards), it is easy to see how the oft-performed actions of an individual become its unconscious habits, and these by inheritance become the instincts and unconscious actions of the species. experience and memory are thus the key-note to the origin of species. granting that all living matter possesses memory, we must admit that all actions are at first conscious in a certain degree, and in the "sense of need" we have the great stimulation to action. in natural selection, as expounded by mr. darwin, there is no principle by which small variations can be accumulated. take any form, and let it vary in all directions. we may represent the original form by a spot, and the variations by a ring of dots. each one of these dots may vary in all directions, and so other rings of dots must be made, and so on, the result not being development along a certain line, but an infinity of interlacing curves. the tree of life is not like this. it branches ever outwards and onwards. the eyes of the argus pheasant and peacock have been formed by the accumulation, through long generations, of more and more perfect forms; the mechanism of the eye and hand has arisen by the gradual accumulation of more and more perfect forms, and these processes have been continued along definite lines. if we grant memory we eliminate this hap-hazard natural selection. we see how a being that has once begun to perform a certain action will soon perform it automatically, and when its habits are confirmed its descendants will more readily work in this direction than any other, and so specialisation may arise. to take the cases of protective resemblance and mimicry. darwin and wallace have to start with a form something like the body mimicked, without giving any idea as to how that resemblance could arise. but with this key of memory we can open nature's treasure house much more fully. look, for instance, at nocturnal insects; and one need not go further than the beetles (_blatta_) in the kitchen, to see that they have a sense of need, and use it. suddenly turn up the gas, and see the hurried scamper of the alarmed crowd. they are perfectly aware that danger is at hand. equally well do they feel that safety lies in concealment; and while all the foraging party on the white floor are scuttling away into dark corners, the fortunate dweller on the hearth stands motionless beneath the shadow of the fire-irons; a picture of keen, intense excitement, with antennæ quivering with alertness. on the clean floor a careless girl has dropped a piece of flat coal, and on it beetles stand rigidly. they are as conscious as we are that the shadow, and the colour of the coal afford concealment, and we cannot doubt that they have become black from their sense of the protection they thus enjoy. they do not say, as tom, the water baby, says, "i must be clean," but they know they must be black, and black they are. there is, then, clearly an effort to assimilate in hue to their surroundings, and the whole question is comparatively clear. mr. wallace, in commenting upon the butterfly (_papilio nireus_)--which, at the cape, in its chrysalis state, copies the bright hues of the vegetation upon which it passes its dormant phase--says that this is a kind of natural colour photography; thus reducing the action to a mere physical one. we might as well say the dun coat of the sportsman among the brown heather was acquired mechanically. moreover, wallace distinctly shows that when the larvæ are made to pupate on unnatural colours, like sky-blue or vermilion, the pupæ do not mimic the colour. there is no reason why "natural photography" should not copy this as well as the greens, and browns, and yellows. but how easy the explanation becomes when memory, the sense of need, and butler's little "dose of reason," are admitted! for ages the butterfly has been acquainted with greens, and browns, and yellows, they are every day experiences; but it has no acquaintance with aniline dyes, and therefore cannot copy them. the moral of all this is that things become easy by repetition; that without experience nothing can be done well, and that the course of development is always in one direction, because the memory of the road traversed is not forgotten. [illustration] [3] evolution, old and new, p. 346. [4] on a new method of expressing the law of specific change. by a. tylor. [5] animals and plants under domestication, vol. ii., p. 350. [6] animals and plants under domestication, vol. ii., p. 370. chapter iii. introductory sketch. natural science has shown us how the existing colouration of an animal or plant can be laid hold of and modified in almost infinite ways under the influence of natural or artificial evolution. it shows us, for example, how the early pink leaf-buds have been modified into attractive flowers to ensure fertilisation; and it has tracked this action through many of its details. it has explained the rich hue of the bracts of _bougainvillea_, in which the flowers themselves are inconspicuous, and the coloured flower-stems in other plants, as efforts to attract notice of the flower-frequenting insects. it has explained how a blaze of colour is attained in some plants, as in roses and lilies by large single flowers; how the same effect is produced by a number of small flowers brought to the same plane by gradually increasing flower-stalks, as in the elderberry, or by still smaller flowers clustered into a head, as in daisies and sunflowers. it teaches us again how fruits have become highly coloured to lure fruit-eating birds and mammals, and how many flowers are striped as guides to the honey-bearing nectary. entering more into detail, we are enabled to see how the weird walking-stick and leaf-insects have attained their remarkable protective resemblances, and how the east indian leaf-butterflies are enabled to deceive alike the birds that would fain devour them, and the naturalist who would study them. even the still more remarkable cases of protective mimicry, in which one animal so closely mimics another as to derive all the benefits that accrue to its protector, are made clear. all these and many other points have been deeply investigated, and are now the common property of naturalists. but up to the present no one has attempted systematically to find out the principles or laws which govern the distribution of colouration; laws which underlie natural selection, and by which alone it can work. natural selection can show, for instance, how the lion has become almost uniform in colour, while the leopard is spotted, and the tiger striped. the lion living on the plains in open country is thus rendered less conspicuous to his prey, the leopard delighting in forest glades is hardly distinguishable among the changing lights and shadows that flicker through the leaves, and the tiger lurking amid the jungle simulates the banded shades of the cane-brake in his striped mantle. beyond this, science has not yet gone; and it is our object to carry the study of natural colouration still further: to show that the lion's simple coat, the leopard's spots, and the tiger's stripes, are but modifications of a deeper principle. let us, as an easy and familiar example, study carefully the colouration of a common tabby cat. first, we notice, it is darker on the back than beneath, and this is an almost universal law. it would, indeed, be quite universal among mammals but for some curious exceptions among monkeys and a few other creatures of arboreal habits, which delight in hanging from the branches in such a way as to expose their ventral surface to the light. these apparent exceptions thus lead us to the first general law, namely, that colouration is invariably most intense upon that surface upon which the light falls. as in most cases the back of the animal is the most exposed, that is the seat of intensest colour. but whenever any modification of position exists, as for instance in the side-swimming fishes like the sole, the upper side is dark and the lower light. the next point to notice in the cat is that from the neck, along the back to the tail, is a dark stripe. this stripe is generally continued, but slighter in character across the top of the skull; but it will be seen clearly that at the neck the pattern changes, and the skull-pattern is quite distinct from that on the body. from the central, or what we may call the back-bone stripe, bands pass at a strong but varying angle, which we may call rib-stripes. now examine the body carefully, and the pattern will be seen to change at the shoulders and thighs, and also at each limb-joint. in fact, if the cat be attentively remarked, it will clearly be seen that the colouration or pattern is _regional_, and dependent upon the structure of the cat. now a cat is a vertebrate or backboned animal, possessing four limbs, and if we had to describe its parts roughly, we should specify the head, trunk, limbs and tail. each of these regions has its own pattern or decoration. the head is marked by a central line, on each side of which are other irregular lines, or more frequently convoluted or twisted spots. the trunk has its central axial backbone stripe and its lateral rib-lines. the tail is ringed; the limbs have each particular stripes and patches. moreover, the limb-marks are largest at the shoulder and hip-girdles, and decrease downwards, being smallest, or even wanting, on the feet; and the changes take place at the joints. all this seems to have some general relation to the internal structure of the animal. such we believe to be the case; and this brings us to the second great law of colouration, namely, that it is dependent upon the anatomy of the animal. we may enunciate these two laws as follows:- i. the law of exposure. colouration is primarily dependent upon the direct action of light, being always most intense upon that surface upon which the light falls most directly. ii. the law of structure. colouration, especially where diversified, follows the chief lines of structure, and changes at points, such as the joints, where function changes. it is the enunciation and illustration of these two laws that form the subject of the present treatise. in the sequel we shall treat, in more or less detail, of each point as it arises; but in order to render the argument clearer, this chapter is devoted to a general sketch of my views. of the first great law but little need be said here, as it is almost self-evident, and has never been disputed. it is true not only of the upper and under-sides of animals, but also of the covered and uncovered parts or organs. for example, birds possess four kinds of feathers, of which one only, the contour feathers, occur upon the surface and are exposed to the light. it is in these alone that we find the tints and patterns that render birds so strikingly beautiful, the underlying feathers being invariably of a sober grey. still further, many of the contour feathers overlap, and the parts so overlapped, being removed from the light are grey also, although the exposed part may be resplendent with the most vivid metallic hues. a similar illustration can be found in most butterflies and moths. the upper wing slightly overlaps the lower along the lower margin, and although the entire surface of the upper wing is covered with coloured scales, and the underwing apparently so as well, it will be found that the thin unexposed margin is of an uniform grey, and quite devoid of any pattern. the law of structure, on the other hand, is an entirely new idea, and demands more detailed explanation. speaking in the broadest sense, and confining ourselves to the animal kingdom, animals fall naturally into two great sections, or sub-kingdoms, marked by the possession or absence of an internal bony skeleton. those which possess this structure are known as _vertebrata_, or backboned animals, because the vertebral-column or backbone is always present. the other section is called the _invertebrata_, or backboneless animals. now, if we take the vertebrata, we shall find that the system of colouration, however modified, exhibits an unmistakably strong tendency to assume a vertebral or axial character. common observation confirms this; and the dark stripes down the backs of horses, asses, cattle, goats, etc., are familiar illustrations. the only great exception to this law is in the case of birds, but here, again, the exception is more apparent than real, as will be abundantly shown in the sequel. this axial stripe is seen equally well in fishes and reptiles. for our present purpose we may again divide the vertebrates into limbed and limbless. wherever we find limbless animals, such as snakes, the dorsal stripe is prominent, and has a strong tendency to break up into vertebra-like markings. in the limbed animals, on the other hand, we find the limbs strongly marked by pattern, and thus, in the higher forms the system of colouration becomes axial and appendicular. as a striking test of the universality of this law we may take the cephalopoda, as illustrated in the cuttle-fishes. these creatures are generally considered to stand at the head of the mollusca, and are placed, in systems of classification, nearest to the vertebrata; indeed, they have even been considered to be the lowest type of vertebrates. this is owing to the possession of a hard axial organ, occupying much the position of the backbone, and is the well-known cuttle-bone. now, these animals are peculiar amongst their class, from possessing, very frequently, an axial stripe. we thus see clearly that the dorsal stripe is directly related to the internal axial skeleton. turning now to the invertebrata, we are at once struck with the entire absence of the peculiar vertebrate plan of decoration; and find ourselves face to face with several distinct plans. from a colouration point of view, we might readily divide the animal kingdom into two classes, marked by the presence or absence of distinct organs. the first of these includes all the animals except the protozoa--the lowest members of the animal kingdom--which are simply masses of jelly-like protoplasm, without any distinct organs. now, on our view, that colouration follows structure, we ought to find an absence of decoration in this structureless group. this is what we actually do find. the lowest protozoa are entirely without any system of colouring; being merely of uniform tint, generally of brown colour. as if to place this fact beyond doubt, we find in the higher members a tendency to organization in a pulsating vesicle, which constantly retains the same position, and may, hence, be deemed an incipient organ. now, this vesicle is invariably tinged with a different hue from the rest of the being. we seem, indeed, here to be brought into contact with the first trace of colouration, and we find it to arise with the commencement of organization, and to be actually applied to the incipient organ itself. ascending still higher in the scale, we come to distinctly organized animals, known as the _coelenterata_; of which familiar examples are found in the jelly-fishes and sea anemonies. these animals are characterized by the possession of distinct organs, are transparent, or translucent, and the organs are arranged radially. no one can have failed to notice on our coasts, as the filmy jelly-fishes float by, that the looped canals of the disc are delicately tinted with violet; and closer examination will show the radiating muscular bands as pellucid white lines; and the sense organs fringing the umbrella are vividly black--the first trace of opaque colouration in the animal kingdom. these animals were of yore united with the star-fishes and sea-urchins, to form the sub-kingdom radiata, because of their radiate structure. now, in all these creatures we find the system of colouration to be radiate also. passing to the old sub-kingdom articulata, which includes the worms, crabs, lobsters, insects, etc., we come to animals whose structure is segmental; that is to say, the body is made up of a number of distinct segments. among these we find the law holds, rigidly that the colouration is segmental also, as may be beautifully seen in lobsters and caterpillars. lastly, we have the molluscs, which fall for our purpose into two classes, the naked and the shelled. the naked molluscs are often most exquisitely coloured, and the feathery gills that adorn many are suffused with some of the most brilliant colours in nature. the shelled molluscs differ from all other animals, in that the shell is a secretion, almost as distinct from the animals as a house is from its occupant. this shell is built up bit by bit along its margin by means of a peculiar organ known as the mantle--its structure is marginate--its decoration is marginate also. we have thus rapidly traversed the animal kingdom, and find that in all cases the system of decoration follows the structural peculiarity of the being decorated. thus in the:- structureless protozoa there is no varying colouration. radiate animals--the system is radiate. segmented " " segmental. marginate " " marginal. vertebrate " " axial. we must now expound this great structural law in detail, and we shall find that all the particular ornamentations in their various modifications can be shown to arise from certain principles, namely- 1. the principle of emphasis, 2. the " repetition. the term _emphasis_ has been selected to express the marking out or distinguishing of important functional or structural regions by ornament, either as form or colour. it is with colour alone that we have to deal. architects are familiar with the term emphasis, as applied to the ornamentation of buildings. this ornamentation, they say, should _emphasize_, point out, or make clear to the eye, the use or function of the part emphasized. they recognise the fact that to give sublimity and grace to a building, the ornamentation must be related to the character of the building as a whole, and to its parts in particular. thus in a tower whose object or function is to suggest height, the principal lines of decoration must be perpendicular, while in the body of a building such as a church, the chief lines must be horizontal, to express the opposite sentiment. so, too, with individual parts. a banded column, such as we see in early english gothic, looks weak and incapable of supporting the superincumbent weight. it suggests the idea that the shaft is bound up to strengthen it. on the other hand, the vertical flutings of a greek column, at once impress us with their function of bearing vertical pressure and their power to sustain it. this principle is carried into colour in most of our useful arts. the wheelwright instinctively lines out the rim and spokes and does not cross them, feeling that the effect would be to suggest weakness. moreover, in all our handicraft work, the points and tips are emphasized with colour. this principle seems to hold good throughout nature. it is not suggested that the colouration is applied to important parts _in order to_ emphasize them, but rather that being important parts, they have become naturally the seats of most vivid colour. how this comes about we cannot here discuss, but shall refer to it further on. it is owing to this pervading natural principle, that we find the extreme points of quadrupeds so universally decorated. the tips of the nose, ears and tail, and the feet also proclaim the fact, and the decoration of the sense organs, even down to the dark spots around each hair of a cat's feelers, are additional proofs. look, for instance, at a caterpillar with its breathing holes or spiracles along the sides, and see how these points are selected as the seats of specialized colour, eye-spots and stripes in every variety will be seen, all centred around these important air-holes. this leads us to our second principle, that of repetition, which simply illustrates the tendency to repeat similar markings in like areas. thus the spiracular marks are of the same character on each segment. the principle of repetition, however, goes further than this, and tends to repeat the style of decoration upon allied parts. we see this strongly in many caterpillars in which spiracular markings are continued over the segments which lack spiracles; and it is probably owing to this tendency that the rib-like markings on so many mammals are continued beyond the ribs into the dorsal region. upon these two principles the whole of the colouration of nature seems to depend. but the plan is infinitely modified by natural selection, otherwise the result would have been so patent as to need no elucidation. natural selection acts by suppressing, or developing, structurally distributed colour. so far as our researches have gone, it seems most probable that the fundamental or primitive colouration is arranged in spots. these spots may expand into regular or irregular patches, or run into stripes, of which many cases will be given in the sequel. now, natural selection may suppress certain spots, or lines, or expand them into wide, uniform masses, or it may suppress some and repeat others. on these simple principles the whole scheme of natural colouration can be explained; and to do this is the object of the following pages. into the origin of the colour sense it is not our province to enlarge; but, it will reasonably be asked, how are these colours of use to the creature decorated? the admiration of colour, the charm of landscape, is the newest of human developments. are we, then, to attribute to the lower animals a discriminative power greater than most races of men possess, and, if so, on the theory of evolution, how comes it that man lost those very powers his remote ancestors possessed in so great perfection? to these questions we will venture to reply. firstly, then, it must be admitted that the higher animals do actually possess this power; and no one will ever doubt it if he watches a common hedge-sparrow hunting for caterpillars. to see this bird carefully seeking the green species in a garden, and deliberately avoiding the multitudes of highly coloured but nauseous larvæ on the currant bushes, arduously examining every leaf and twig for the protected brown and green larvæ which the keen eye of the naturalist detects only by close observation; hardly deigning to look at the speckled beauties that are feeding in decorated safety before his eyes, while his callow brood are clamouring for food--to see this is to be assured for ever that birds can, and do, discriminate colour perfectly. what is true of birds can be shown to be true of other and lower types; and this leads us to a very important conclusion--that colouration has been developed with the evolution of the sense of sight. we can look back in fancy to the far off ages, when no eye gazed upon the world, and we can imagine that then colour in ornamental devices must have been absent, and a dreary monotony of simple hues must have prevailed. with the evolution of sight it might be of importance that even the sightless animals should be coloured; and in this way we can account for the decoration of coral polyps, and other animals that have no eyes; just as we find no difficulty in understanding the colouration of flowers. colour, in fact, so far as external nature is concerned, is all in all to the lower animals. by its means prey is discovered, or foes escaped. but in the case of man quite a different state of things exists. the lower animals can only be modified and adapted to their surroundings by the direct influence of nature. man, on the other hand, can utilise the forces of nature to his ends. he does not need to steal close to his prey--he possesses missiles. his arm, in reality, is bounded, not by his finger tips, but by the distance to which he can send his bolts. he is not so directly dependent upon nature; and, as his mental powers increase, his dependence lessens, and in this way--the æsthetic principle not yet being awakened--we can understand how his colour sense, for want of practice, decayed, to be reawakened in these our times, with a vividness and power as unequalled as is his mastery over nature--the master of his ancestors. [illustration] chapter iv. colour, its nature and recognition. this chapter will be devoted to a slight sketch of the nature of light and colour, and to proofs that niceties of colour are distinguished by animals. first, as to the nature of light and colour. colour is essentially the effect of different kinds of vibrations upon certain nerves. without such nerves, light can produce no luminous effect whatever; and to a world of blind creatures, there would be neither light nor colour, for as we have said, light and colour are not material things, but are the peculiar results or effects of vibrations of different size and velocity. these effects are due to the impact of minute undulations or waves, which stream from luminous objects, the chief of which is the sun. these waves are of extreme smallness, the longest being only 226 _ten-millionths_ of an inch from crest to crest. the tiny billows roll outwards and onwards from their source at inconceivable velocities, their mean speed being 185,000 miles in a second. could we see these light billows themselves and count them as they rolled by, 450 billions (450,000,000,000,000) would pass in a single second, and as the last ranged alongside us, the first would be 185,000 miles away. we are not able, however, to see the waves themselves, for the ocean whose vibrations they are, is composed of matter infinitely more transparent than air, and infinitely less dense. light, then, be it clearly understood, is not the ethereal billows or waves themselves, but only the effect they produce on falling upon a peculiar kind of matter called the optic nerve. when the same vibrations fall upon a photographic sensitive film, another effect--chemical action--is produced: when they fall upon other matter, heat is the result. thus heat, light and chemical action are but phases, expressions, effects or results of the different influences of waves upon different kinds of matter. the same waves or billows will affect the eye itself as light, the ordinary nerves as warmth, and the skin as chemical action, in tanning it. though we cannot see these waves with the material eye, they are visible indeed to the mental eye; and are as amenable to experimental research as the mightiest waves of the sea. still, to render this subject clearer, we will use the analogy of sound. a musical note, we all know, is the effect upon our ears of regularly recurring vibrations. a pianoforte wire emits a given note, or in other words, vibrates at a certain and constant rate. these vibrations are taken up by the air, and by it communicated to the ear, and the sensation of sound is produced. here we see the wire impressing its motion on the air, and the air communicating its motion to the ear; but if another wire similar in all respects is near, it will also be set in motion, and emit its note; and so will any other body that can vibrate in unison. further, the note of the pianoforte string is not a simple tone, but superposed, as it were, upon the fundamental note, are a series of higher tones, called harmonics, which give richness. now, a ray of sun-light may be likened to such a note; it consists not of waves all of a certain length or velocity, but of numbers of waves of different lengths and speed. when all these fall upon the eye, the sensation of white light is produced, white light being the compound effect, like the richness of the tone of the wire and its harmonies; or we may look upon it as a luminous chord. when light strikes on any body, part or all is reflected to the eye. if all the waves are thus reflected equally, the result is whiteness. if only a part is reflected, the effect is colour, the tint depending upon the particular waves reflected. if none of the waves are reflected, the result is blackness. colour, then, depends upon the nature of the body reflecting light. the exact nature of the action of the body upon the light is not known, but depends most probably upon the molecular condition of the surface. bodies which allow the light to pass through them, are in like manner coloured according to the waves they allow to pass. we find in nature, however, a somewhat different class of colour, namely, the iridescent tints, like mother of pearl or shot silk, which give splendour to such butterflies, as some morphos and the purple emperor. these are called diffraction colours, and are caused by minute lines upon the reflecting surface, or by thin transparent films. these lines or films must be so minute that the tiny light waves are broken up among them, and are hence reflected irregularly to the eye. dr. hagen has divided the colours of insects into two classes, the epidermal and hypodermal. the epidermal colours are produced in the external layer or epidermis which is comparatively dry, and are persistent, and do not alter after death. of this nature are the metallic tints of blue, green, bronze, gold and silver, and the dead blacks and browns, and some of the reds. the hypodermal colours are formed in the moister cells underlying the epidermis, and on the drying up of the specimen fade, as might be expected. they show through the epidermis, which is more or less transparent. these colours are often brighter and lighter in hue than the epidermal; and such are most of the blues, and greens, and yellow, milk white, orange, and the numerous intermediate shades. these colours are sometimes changeable by voluntary act, and the varying tints of the chameleon and many fishes are of this character. in this connection, dr. hagen remarks, that probably all mimetic colours are hypodermal. the importance of this suggestion will be seen at once, for it necessitates a certain consciousness or knowledge on the part of the mimicker, which we have shown, seems to be an essential factor in the theory of colouration. this author further says, that "the pattern is not the product of an accidental circumstance, but apparently the product of a certain law, or rather the consequence of certain actions or wants in the interior of the animal and in its development." this remarkable paper, to which our attention was called after our work was nearly completed, is the only record we have been able to find which recognises a law of colouration. from what has been said of the nature of light, and the physical origin of colour, we see that to produce any distinct tint such as red, yellow, green, or blue, a definite physical structure must be formed, capable of reflecting certain rays of the same nature and absorbing others. hence, whenever we see any distinct colour, we may be sure that a very considerable development in a certain direction has taken place. this is a most important conclusion, though not very obvious at first sight. still, when we bear in mind the numbers of light waves of different lengths, and know that if these are reflected irregularly, we get only mixed tints such as indefinite browns; we can at once see how, in the case of such objects as tree trunks, and, still more, in inanimate things like rocks and soils, these, so-to-say, undifferentiated hues are just what we might expect to prevail, and that when definite colours are produced, it of necessity implies an effort of some sort. now, if this be true of such tints as red and blue, how much more must it be the case with black and white, in which all the rays are absorbed or all reflected? these imply an even stronger effort, and _a priori_ reasoning would suggest that where they occur, they have been developed for important purposes by what may be termed a supreme effort. consequently, we find them far less common than the others; and it is a most singular fact that in mimetic insects, these are the colours that are most frequently made use of. it would almost seem as if a double struggle had gone on: first, the efforts which resulted in the protective colouring of the mimicked species, and then a more severe, because necessarily more rapid, struggle on the part of the mimicker. yet another point in this connection. if this idea be correct, it follows that a uniformly coloured flower or animal must be of extreme rarity, since it necessitates not merely the entire suppression of the tendency to emphasize important regions in colour, but also the adjustment of all the varying parts of the organism to one uniform molecular condition, which enables it to absorb all but a certain closely related series of light waves no matter how varied the functions of the parts. now, such "self-coloured" species, as florists would call them, are not only rare, but, as all horticulturists know, are extremely difficult to produce. when a pansy grower, for instance, sets to work to produce a self-coloured flower--say a white pansy without a dark eye--his difficulties seem insurmountable. and, in truth, this result has never been quite obtained; for he has to fight against every natural tendency of the plant to mark out its corolla-tube in colour, and when this is overcome, to still restrain it, so as to keep it within those limits which alone allow it to reflect the proper waves of light. [illustration: plate i. kallima inachus.] the production of black and white, then, being the acme of colour production, we should expect to find these tints largely used for very special purposes. such is actually the case. the sense organs are frequently picked out with black, as witness the noses of dogs, the tips of their ears, the insertion of their vibrissæ, or whiskers, and so on; and white is the most usual warning or distinctive colour, as we see in the white stripes of the badger and skunk, the white spots of deer, and the white tail of the rabbit. colour, then, as expressed in definite tints and patterns, is no accident; for although, as wallace has well said, "colour is the normal character," yet we think that this colour would, if unrestrained and undirected, be indefinite, and could not produce definite tints, nor the more complicated phenomenon of patterns, in which definite hues are not merely confined to definite tracts, but so frequently contrasted in the most exquisite manner. as we write, the beautiful red admiral (_v. atalanta_) is sporting in the garden; and who can view its glossy black velvet coat, barred with vividest crimson, and picked out with purest snow white, and doubt for an instant that its robe is not merely the product of law, but the supreme effort of an important law? mark the habits of this lovely insect. see how proudly it displays its rich decorations; sitting with expanded wings on the branch of a tree, gently vibrating them as it basks in the bright sunshine; and you know, once and for all, that the object of that colour is display. but softly--we have moved too rudely, and it is alarmed. the wings close, and where is its beauty now? hidden by the sombre specklings of its under wings. see, it has pitched upon a slender twig, and notice how instinctively (shall we say?) it arranges itself in the line of the branch: if it sat athwart it would be prominent, but as it sits there motionless it is not only almost invisible, _but it knows it_; for you can pick it up in your hands, as we have done scores of times. it is not enough, if we would know nature, to study it in cabinets. there is too much of this dry-bone work in existence. the object of nature is _life_; and only in living beings can we learn how and why they fulfil their ends. here, in this common british butterfly, we have the whole problem set before us--vivid colour, the result of intense and long continued effort; grand display, the object of that colour; dusky, indefinite colour, for concealment; and the "instinctive" pose, to make that protective colour profitable. the insect _knows_ all this in some way. how it knows we must now endeavour to find out. in attacking this problem we must ask ourselves, what are the purposes that colouration, and, especially, decoration, can alone subserve? we can only conceive it of use in three ways: first, as protection from its enemies; second, as concealment from its prey; third, as distinctive for its fellows. to the third class may be added a sub-class--attractiveness to the opposite sex. the first necessity would seem to be distinctness of species; for, unless each species were separately marked, it would be difficult for the sexes to discriminate mates of their own kind, in many instances; and this is, doubtless, the reason why species _are_ differently coloured. but protective resemblance, as in _kallima_,[7] the leaf-butterfly, and mimicry, as in _d. niavius_ and _p. merope_,[8] sometimes so hide the specific characters that this process seems antagonistic to the prime reason for colouration, by rendering species less distinct. now, doubtless, protective colouring could not have been so wonderfully developed _if the organ of sight were the only means of recognition_. but it is not. animals possess other organs of recognition, of which, as everyone knows, smell is one of the most potent. a dog may have forgotten a face after years of absence, but, once his cold nose has touched your hand, the pleased whine and tail-wagging of recognition, tells of awakened memories. even with ourselves, dulled as our senses are, the odour of the first spring violet calls up the past; as words and scenes can never do. what country-bred child forgets the strange smell of the city he first visits? and how vividly the scene is recalled in after years by a repetition of that odour! but insects, and, it may be, many other creatures, possess sense organs whose nature we know not. the functions of the antennæ and of various organs in the wings, are unknown; and none can explain the charm by which the female kentish glory, or oak egger moths lure their mates. you may collect assiduously, using every seduction in sugars and lanterns, only to find how rare are these insects; but if fortune grant you a virgin female, and you cage her up, though no eye can pierce her prison walls, and though she be silent as the oracles, she will, in some mysterious way, attract lovers; not singly, but by the dozen; not one now and another in an hour, but in eager flocks. many butterflies possess peculiar scent-pouches on their wings, and one of these, a _danais_, is mimicked by several species. it is the possession of these additional powers of recognition that leaves colouration free to run to the extreme of protective vagary, when the species is hard pressed in the struggle for life. [illustration: plate ii. mimicry.] nevertheless, though animals have other means of recognition, the distinctive markings are, without doubt, the prime means of knowledge. who, that has seen a peacock spread his glorious plumes like a radiant glory, can doubt its fascination? who, that has wandered in america, and watched a male humming-bird pirouetting and descending in graceful spirals, its whole body throbbing with ecstasy of love and jealousy, can doubt? who can even read of the australian bower-bird, lowliest and first of virtuosi, decorating his love-bower with shells and flowers, and shining stones, running in and out with evident delight, and re-arranging his treasures, as a collector does his gems, and not be certain that here, at least, we have the keenest appreciation, not only of colour, but of beauty--a far higher sense? it has been said that butterflies must be nearly blind, because they seldom fly directly over a wall, but feel their way up with airy touches. yet every fact of nature contradicts the supposition. why have plants their tinted flowers, but to entice the insects there? why are night-blooming flowers white, or pale yellows and pinks, but to render them conspicuous? why are so many flowers striped in the direction of the nectary, but to point the painted way to the honey-treasures below? the whole scheme of evolution, the whole of the new revelation of the meanings of nature, becomes a dead letter if insects cannot appreciate the hues of flowers. the bee confines himself as much as possible to one species of flower at a time, and this, too, shows that it must be able to distinguish them with ease. we may, then, take it as proven that the power of discriminating colours is possessed by the lower animals. [illustration] [7] pl. i., figs 1-3. [8] pl. ii., figs. 1-3. chapter v. the colour sense. the previous considerations lead us, naturally, to enquire in what manner the sense of colour is perceived. in thinking over this obscure subject, the opinion has steadily gathered strength that form and colour are closely allied; for form is essential to pattern; and colour without pattern, that is to say, colour indefinitely marked, or distributed, is hardly decoration at all, in the sense we are using the term. that many animals possess the power of discriminating form is certain. deformed or monstrous forms are driven from the herds and packs of such social animals as cattle, deer, and hogs, and maimed individuals are destroyed. similar facts have been noticed in the case of birds. this shows a power of recognising any departure from the standard of form, just as the remorseless destruction of abnormally coloured birds, such as white or piebald rooks and blackbirds, by their fellows, is proof of the recognition and dislike of a departure from normal colouring. authentic anecdotes of dogs recognising their masters' portraits are on record; and in west suffolk, of late years, a zinc, homely representation of a cat has been found useful in protecting garden produce from the ravages of birds. in this latter case the birds soon found out the innocent nature of the fraud, for we have noticed, after a fortnight, the amusing sight of sparrows cleaning their beaks on the whilom object of terror. many fish are deceived with artificial bait, as the pike, with silvered minnows; the salmon, and trout, with artificial flies; the glitter of the spoon-bait is often most attractive; and mackerel take greedily to bits of red flannel. bees sometimes mistake artificial for real flowers; and both they and butterflies have been known to seek vainly for nourishment from the gaudy painted flowers on cottage wall-papers. sir john lubbock has demonstrated the existence of a colour sense in bees, wasps, and ants; and the great fact that flowers are lures for insects proves beyond the power of doubt that these creatures have a very strong faculty for perceiving colour. the pale yellows and white of night-flowering plants render them conspicuous to the flower-haunting moths; and no one who has ever used an entomologist's lantern, or watched a daddy-long-legs (_tipula_) dancing madly round a candle, can fail to see that intense excitement is caused by the flame. in the dim shades of night the faint light of the flowers tells the insects of the land of plenty, and the stimulus thus excited is multiplied into a frenzy by the glow of a lamp, which, doubtless, seems to insect eyes the promise of a feast that shall transcend that of ordinary flowers, as a lord mayor's feast transcends a homely crust of bread and cheese. we take it, then, as proven that the colour sense does exist, at least, in all creatures possessing eyes. but there are myriads of animals revelling in bright tints; such as the jelly-fishes and anemones, and even lower organisms, in which eyes are either entirely wanting or are mere eye-specks, as will be explained in the sequel. how these behave with regard to colour is a question that may, with propriety, be asked of science, but to which, at present, we can give no very definite reply. still, certain modern researches open to us a prospect of being able, eventually, to decide even this obscure problem. the question, however, is not a simple one, but involves two distinct principles; firstly, as to how colour affects the animal coloured, and, secondly, how it affects other animals. in other words, how does colour affect the sensibility of its possessor? and how does it affect the sense organs of others? to endeavour to answer the first question we must start with the lowest forms of life, and their receptivity to the action of light; for, as colour is only a differentiation of ordinary so-called white light, we might _a priori_ expect that animals would show sensibility to light as distinguished from darkness, before they had the power of discriminating between different kinds of light. this appears to be the case, for engelmann has shown[9] that many of the lowest forms of life, which are almost mere specks of protoplasm, are influenced by light, some seeking and others shunning it. he found, too, that in the case of _euglena viridis_ it would seek the light only if it "were allowed to fall upon the anterior part of the body. here there is a pigment spot; but careful experiment showed that this was not the point most sensitive to light, a colourless and transparent area of protoplasm lying in front of it being found to be so." commenting upon this romanes observes, "it is doubtful whether this pigment spot is or is not to be regarded as an exceedingly primitive organ of special sense." haeckel has also made observations upon those lowest forms of life, which, being simply protoplasm without the slightest trace of organization, not even possessing a nucleus, form his division _protista_, occupying the no-man's-land between the animal and vegetable kingdoms. he finds that "already among the microscopic protista there are some that love light, and some that love darkness rather than light. many seem also to have smell and taste, for they select their food with great care.... here, also, we are met by the weighty fact that sense-function is possible without sense organs, without nerves. in place of these, sensitiveness is resident in that wondrous, structureless, albuminous substance, which, under the name of protoplasm, or organic formative material, is known as the general and essential basis of all the phenomena of life."[10] now, whether romanes be correct in doubting whether the pigment-spot in euglena is a sense organ or not, matters little to our present enquiry, but it certainly does seem that the spot, _with its accompanying clear space_, looks like such an organ. and when we are further told that after careful experiment it is found that _euglena viridis_ prefers blue to all the colours of the spectrum, the fundamental fact seems to be established that even as low down as this the different parts of the spectrum affect differently the body of creatures very nearly at the bottom of the animal scale. this implies a certain selection of colour, and, equally, an abstention from other colours. it is not part of our scheme, however, to follow out in detail the development of the organs of special sense, and the reader must be referred to the various works of mr. romanes, who has worked long and successfully at this and kindred problems. suffice it to say that in this and other cases he has been led to adopt the theory of inherited memory, though not, as we believe, in the fulness with which it must ultimately be acquired. this, however, seems certain, that the development, not only of the sense organs, but of organs in general--that is, the setting aside of certain portions for the performance of special duties, and the modifications of those parts in relation to their special duties, is closely related to the activity of the organism. thus, we find in those animals, like some of the coelenterata, which pass some portion of their existence as free-swimming beings, and the remainder in a stationary or sessile condition, that the former state is the most highly organized. this is shown to a very remarkable degree in the sea squirts (ascidians), a class of animals that are generally grouped with the lower mollusca, but which prof. ray lankester puts at the base of the vertebrata. these animals are either solitary or social, fixed or free; but even when free, have little or no power of locomotion, simply floating in the sea. their embryos are, however, free-swimming, and some of the most interesting beings in nature. some are marvellously like young tadpoles, and possess some of the distinctive peculiarities of the vertebrata. thus, the body is divided into a head and body, or tail, as in tadpoles. the head contains a large nerve centre, corresponding with the brain, which is produced backwards into a chord, corresponding to the spinal chord. in the head, sense organs are clearly distinguishable; there is a well-marked eye, an equally clear ear, and a less clearly marked olfactory organ. besides this, the spinal-cord is supported below by a rod-like structure, called the notochord. in the vertebrate embryo this structure always precedes the development of the true vertebral column, and in the lowest forms is persistent through life. we have thus, in the ascidian larva, a form which, if permanent, would most certainly entitle it to a place in the vertebrate sub-kingdom. it is now an active free-swimming creature, but as maturity approaches it becomes fixed, or floating, and all this pre-figurement of a high destiny is annulled. the tail, with its nervous cord and notochord atrophies, and in the fixed forms, not only do the sense organs pass away, but the entire nervous system is reduced to a single ganglion, and the creature becomes little more than an animated stomach. it is, as ray lankester has pointed out, a case of degeneration. in the floating forms, which still possess a certain power of locomotion, this process is not carried to such extremes, and the eye is left. now, cases of this kind are important as illustrating the direct connection between an active life and advancement; and they also add indirectly to the view wallace takes of colouration, namely, that the most brilliant colour is generally applied to the most highly modified parts, and is brightest in the seasons of greatest activity. but they have a higher meaning also, for they may point us to the prime cause of the divergence of the animal and vegetable kingdoms. in thinking over this matter, one of us ventured to suggest that probably the reason why animals dominate the world, and not plants, is, that plants are, as a rule, stationary, and animals lead an active existence. we can look back to the period prior to the divergence of living protoplasm into the two kingdoms. two courses only were open to it, either to stay at home, and take what came in its way, or to travel, and seek what was required. the stay-at-homes became plants, and the gad-abouts animals. in a letter it was thus put; "it is a truly strange fact that a free-swimming, sense-organ-bearing animal should degenerate into a fixed feeding and breeding machine. it seems to me that the power of locomotion is a _sine qua non_ for active development of type, as it necessarily sharpens the wits by bringing fresh experiences and unlooked-for adventures to the creature. i almost think, and this, i believe may be a great fundamental fact, that the only reason why animals rule the world instead of plants is that plants elected to stay at home, and animals did not. they had equal chances. both start as active elements; the one camps down, and the other looks about him." talking over this question with mr. butler, he astonished the writer by quoting from his work, "alps and sanctuaries" (p. 196), the following passage:- "the question of whether it is better to abide quiet, and take advantage of opportunities that come, or to go farther afield in search of them, is one of the oldest which living beings have to deal with. it was on this that the first great schism or heresy arose in what was heretofore the catholic faith of protoplasm. the schism still lasts, and has resulted in two great sects--animals and plants. the opinion that it is better to go in search of prey is formulated in animals; the other--that it is better, on the whole, to stay at home, and profit by what comes--in plants. some intermediate forms still record to us the long struggle during which the schism was not yet complete. "if i may be pardoned for pursuing this digression further, i would say that it is the plants, and not we, who are the heretics. there can be no question about this; we are perfectly justified, therefore, in devouring them. ours is the original and orthodox belief, for protoplasm is much more animal than vegetable. it is much more true to say that plants have descended from animals than animals from plants. nevertheless, like many other heretics, plants have thriven very fairly well. there are a great many of them, and, as regards beauty, if not wit--of a limited kind, indeed, but still wit--it is hard to say that the animal kingdom has the advantage. the views of plants are sadly narrow; all dissenters are narrow-minded; but within their own bounds they know the details of their business sufficiently well--as well as though they kept the most nicely-balanced system of accounts to show them their position. they are eaten, it is true; to eat them is our intolerant and bigoted way of trying to convert them: eating is only a violent mode of proselytizing, or converting; and we do convert them--to good animal substance of our own way of thinking. if we have had no trouble we say they have 'agreed' with us; if we have been unable to make them see things from our point of view, we say they 'disagree' with us, and avoid being on more than distant terms with them for the future. if we have helped ourselves to too much, we say we have got more than we can 'manage.' and an animal is no sooner dead than a plant will convert it back again. it is obvious, however, that no schism could have been so long successful without having a good deal to say for itself. "neither party has been quite consistent. whoever is or can be? every extreme--every opinion carried to its logical end will prove to be an absurdity. plants throw out roots and boughs and leaves: this is a kind of locomotion; and as dr. erasmus darwin long since pointed out, they do sometimes approach nearly to what is called travelling; a man of consistent character will never look at a bough, a root, or a tendril, without regarding it as a melancholy and unprincipled compromise. on the other hand, many animals are sessile; and some singularly successful genera, as spiders, are in the main liers-in-wait." this exquisitively written passage the writer was quite unaware of having read, though he possessed and had perused the work quoted, nor can he understand how such an admirable exposition could have escaped notice. had he read it: had he assimilated it so thoroughly as to be unconscious of its existence; is this a case of rapid growth of automatism? he cannot say. to return to the main point, it would seem that specialization is directly proportionate to activity, and when we compare the infinitely diverse organization of the animal with the comparative simplicity of the vegetable world, this conclusion seems to be inevitable. [illustration] [9] pflüger's archiv. f. d. ges. phys. bd. xxix, 1882, quoted by romanes. mental evolution, p. 80, 1883. _op. cit._ p. 80. [10] quoted by romanes, _op. cit._ p. 81. chapter vi. spots and stripes. bearing in mind the great tendency to repetition and symmetry of marking we have shown to exist, it becomes an interesting question to work out the origin of the peculiar spots, stripes, loops and patches which are so prevalent in nature. the exquisite eye-spots of the argus pheasant, the peacock, and many butterflies and moths have long excited admiration and scientific curiosity, and have been the subject of investigation by darwin,[11] the rev. h. h. higgins,[12] weismann,[13] and others, darwin having paid especial attention to the subject. his careful analysis of the ocelli or eye-spots in the argus pheasant and peacock have led him to conclude that they are peculiar modifications of the bars of colour as shown by his drawings. our own opinion, founded upon a long series of observations, is that this is not the whole case, but that, in the first place, bars are the result of the coalescence of spots. it is not pretended that a bar of colour is the result of the running together of a series of perfect ocelli like those in the so-called tail of the peacock, but merely that spots of colour are the normal primitive commencement of colouring, and that these spots may be developed on the one hand into ocelli or eye-spots, and on the other into bars or even into great blotches of a uniform tint, covering large surfaces. let us first take the cases of abnormal marking as shown in disease. an ordinary rash, as in measles, begins as a set of minute red spots, and the same is the case with small pox, the pustules of which sometimes run together, and becoming confluent form bars, which again enlarging meet and produce a blotch or area abnormally marked. it was these well-known facts that induced us to re-examine this question. colouration and discolouration arise from the presence or absence of pigment in cells, and thus having, as it were independent sources, we should expect colour first to appear in spots. we have already stated, and shall more fully show in the sequel, how colouration follows structure, and would here merely remark that it seems as if any peculiarity of structure, or intensified function modifying structure, has a direct tendency to influence colour. thus in the disease known as frontal herpes, as pointed out to us by mr. bland sutton, of the middlesex hospital, the affection is characterized by an eruption on the skin corresponding exactly to the distribution of the ophthalmic division of the fifth cranial nerve, mapping out all its little branches, even to the one which goes to the tip of the nose. mr. hutchinson, f.r.s., the president of the pathological society, who first described this disease, has favoured us with another striking illustration of the regional distribution of the colour effects of herpes. in this case decolouration has taken place. the patient was a hindoo, and upon his brown skin the pigment has been destroyed in the arm along the course of the ulnar nerve, with its branches along both sides of one finger and the half of another. in the leg the sciatic and saphenous nerves are partly mapped out, giving to the patient the appearance of an anatomical diagram.[14] in these cases we have three very important facts determined. first the broad fact that decolouration and colouration in some cases certainly follow structure; second, that the effect begins as spots; thirdly, that the spots eventually coalesce into bands and blotches. in birds and insects we have the best means of studying these phenomena, and we will now proceed to illustrate the case more fully. the facts seem to justify us in considering that starting with a spot we may obtain, according to the development, either an ocellus, a stripe or bar, or a blotch, and that between, these may have any number of intermediate varieties. * * * * * among the butterflies we have numerous examples of the development from spots, as illustrated in plates. a good example is seen in our common english brimstone (_gonepteryx rhamni_) fig. 2, plate iii. in this insect the male (figured) is of a uniform sulphur yellow, with a rich orange spot in the cell of each wing; the female is much paler in colour, and spotted similarly. in an allied continental species (_g. cleopatra_) fig. 1, plate iii., the female is like that of _rhamni_ only larger; but the male, instead of having an orange spot in the fore-wing, has nearly the whole of the wing suffused with orange, only the margins, and the lower wings showing the sulphur ground-tint like that of _rhamni_. intermediate forms between these two species are known. in a case like this we can hardly resist the conclusion that the discoidal spot has spread over the fore-wing and become a blotch, and in some english varieties of _rhamni_ we actually find the spot drawn out into a streak. [illustration: plate iii. butterflies.] the family of _pieridæ_, or whites, again afford us admirable examples of the development of spots. the prevailing colours are white, black and yellow: green _appears_ to occur in the orange-tips (_anthocaris_), but it is only the optical effect of a mixture of yellow and grey or black scales. the species are very variable, as a rule, and hence of importance to us; and there are many intermediate species on the continent and elsewhere which render the group a most interesting study. the wood white (_leucophasia sinapis_) fig. 1, plate iv., is a pure white species with an almost square dusky tip to the fore-wings of the male. in the female this tip is very indistinct or wanting, fig. 4, plate iv. in the variety _diniensis_, fig. 2, plate iv., this square tip appears as a round spot. the orange-tips, of which we have only one species in britain (_anthocaris cardamines_) belongs to a closely allied genus, as does also the continental genus zegris. the male orange-tip (_a. cardamines_) is white with a dark grey or black tip, and a black discoidal spot. a patch of brilliant orange extends from the dark tip to just beyond the discoidal spots. in the female this is wanting, but the dark tip and spot are larger than in the male. let us first study the dark tip. in _l. sinapis_ we have seen that it extends right to the margin of the wing in the male, but in the female is reduced to a dusky spot away from the margin. in _a. cardamines_ the margin is not coloured quite up to the edge, but a row of tiny white spots, like a fringe of seed pearls, occupies the inter-spaces of the veins. on the underside these white spots are prolonged into short bars, see plate iv. in the continental species _a. belemia_ we see the dark tip to be in a very elementary condition, being little more than an irregular band formed of united spots, there being as much white as black in the tip, fig. 5, plate iv. in _a. belia_, fig. 6, plate iv., the black tip is more developed, and in the variety _simplonia_ still more so, fig. 7, plate iv. we here see pretty clearly that this dark tip has been developed by the confluence of irregular spots. turning now to the discoidal spot we shall observe a similar development. thus in:- _a. cardamines_, male, it is small and perfect. do. female, " larger " _a. belemia_ " large " _a. belia_ " large with white centre. do. _v. simplonia_ " small and perfect. [15]_a. eupheno_, female, " nearly perfect. do. male, " a band. we here find two distinct types of variation. in _a. belia_ we have a tendency to form an ocellus, and in _a. eupheno_ the spot of the female is expanded into a band in the male. the orange flush again offers us a similar case; and with regard to this colour we may remark that it seems to be itself a development from the white ground-colour of the family in the direction of the red end of the spectrum. thus in the black-veined white (_aporia cratægi_) we have both the upper and under surfaces of the typical cream-white, for there is no pure white in the family. in the true whites the under surface of the hind-wings is lemon-yellow, in the female of _a. eupheno_ the ground of the upper surface is faint lemon-yellow, and in the male this colour is well-developed. the rich orange, confined to a spot in _g. rhamni_ becomes a flush in _g. cleopatra_, and a vivid tip in _a. cardamines_. these changes are all developments from the cream white, and may be imitated accurately by adding more and more red to the primitive yellow, as the artist actually did in drawing the plate. [illustration: plate iv. spots and stripes.] in _a. cardamines_ the orange flush has overflowed the discoidal spot, as it were, in the male, and is absent in the female. but in _a. eupheno_ we have an intermediate state, for as the figures show, in the female, fig. 8, the orange tip only extends half-way to the discoidal spot, and in the male it reaches it. moreover it is to be noticed that the flow of colour, to continue the simile, is unchecked by the spot in _cardamines_, but where the spot has expanded to a bar in _eupheno_ it has dammed the colour up and ponded it between bar and tip. an exactly intermediate case between these two species is seen in _a. euphemoides_, fig. 10, plate iv., in which the spot is elongated, and dribbles off into an irregular band, into which the orange has trickled, as water trickles through imperfect fascines. this series of illustrations might be repeated in almost any group of butterflies, but sufficient has been said to show how spots can spread into patches, either by the spreading of one or by the coalescence of several. we will now take an illustration of the formation of stripes or bars from spots, and in doing so must call attention to the rarity of true stripes in butterflies. by a true stripe i mean one that has even edges, that is, whose sides are uninfluenced by structure. in all our british species such as _p. machaon_, _m. artemis_, _m. athalia_, _v. atalanta_, _l. sibilla_, _a. iris_, and some of the browns, frittilaries and hair-streaks, which can alone be said to be striped, the bands are clearly nothing more than spots which have spread up to the costæ, and still retain traces of their origin either in the different hue of the costæ which intersect them, or in curved edges corresponding with the interspaces of the costæ. this in itself is sufficient to indicate their origin. but in many foreign species true bands are found, though they are by no means common. illustrations are given in plate iv., of two swallow-tails, _papilio machaon_, fig. 11, and _p. podalirius_, fig. 12, in which the development of a stripe can readily be seen. in _machaon_ the dark band inside the marginal semi-lunar spots of the fore-wings retain traces of their spot-origin in the speckled character of the costal interspaces, and in the curved outlines of those parts. in _podalirius_ the semi-lunar spots have coalesced into a stripe, only showing its spot-origin in the black markings of the intersecting costæ; and the black band has become a true stripe, with plain edges. had only such forms as this been preserved, the origin of the spots would have been lost to view. it may, however, be said, though i think not with justice, that we ought not to take two species, however closely allied, to illustrate such a point. but very good examples can be found in the same species. a common german butterfly, _araschnia levana_, has two distinct varieties, _levana_ being the winter, and _prorsa_ the summer form; and between these an intermediate form, _porima_, can be bred from the summer form by keeping the pupæ cold. dr. weismann, who has largely experimented on this insect, has given accurate illustrations of the varieties. plate v. is taken from specimens in our possession. in the males of both _levana_, fig. 4, and _prorsa_, fig. 1, the hind-wing has a distinct row of spots, and a less distinct one inside it, and in the females of both these are represented by dark stripes. in _porima_ we get every intermediate form of spots and stripes, both in the male and female, and as these were hatched from the same batch of eggs, or, are brothers and sisters, it is quite impossible to doubt that here, at least, we have an actual proof of the change of spots into stripes. [illustration: fig. 1. part of secondary feather of argus pheasant. _a. a._ elongated spots, incipient ocelli. _b._ interspaces. _c. c._ axial line. _d. d._ double spots, incipient ocelli. _e._ minute dottings. _f. f._ shaft. _k. k._ line of feathering.] [illustration: fig. 2. part of secondary wing feather of argus pheasant. _a._ oval. axis at right angles. _b._ round. _c. c._ shaft. _d._ imperfect ocellus. _e._ expansion of stripe. _f._ interspace. _g._ stalk. _h._ edge of feather. _k._ line of feathering.] [illustration: plate v. seasonal varieties.] the change of spots more or less irregular into eye-spots, or ocelli, is equally clear; and darwin's drawing of the wings of _cyllo leda_[16] illustrates the point well. "in some specimens," he remarks, "large spaces on the upper surfaces of the wings are coloured black, and include irregular white marks; and from this state a complete gradation can be traced into a tolerably perfect ocellus, _and this results from the contraction of the irregular blotches of colour_. in another series of specimens a gradation can be followed from excessively minute white dots, surrounded by a scarcely visible black line, into perfectly symmetrical and larger ocelli." in the words we have put in italics darwin seems to admit these ocelli to be formed from blotches; and we think those of the argus pheasant can be equally shown to arise from spots. darwin's beautiful drawings show, almost as well as if made for the purpose, that the bars are developed from spots.[17] in fig. 1 is shown part of a secondary wing feather, in which the lines _k. k._ mark the direction of the axis, along which the spots are arranged, perfectly on the right, less so on the left. the lengthening out of the spots towards the shaft is well seen on the right, and the coalescence into lines on the left. in fig. 2 we have part of another feather from the same bird, showing on the left elongated spots, with a dark shading round them, and on the right double spots, like twin stars, with one atmosphere around them. increase the elongation of these latter, and you have the former, and both are nascent ocelli. we here, then, have a regular gradation between spots, bands, and ocelli, just as we can see in insects. in some larvæ, those of the _sphingidæ_ especially, ocelli occur, and these may be actually watched as they grow from dots to perfect eye-spots, with the maturity of the larva. even in some mammals the change from spots to stripes can be seen. thus, the young tiger is spotted, and so is the young lion; but, whereas in the former case the spots change into the well-known stripes (which are really loops), in the latter they die away. the horse, as darwin long ago showed, was probably descended from a striped animal, as shown by the bars on a foal's leg. but before this the animal must have been spotted; and the dappled horses are an example of this; and, moreover, almost every horse shows a tendency to spottiness, especially on the haunches. in the museum at leiden a fine series of the java pig (_sus vittatus_) is preserved. very young animals are banded, but have spots over the shoulders and thighs; these run into stripes as the animal grows older; then the stripes expand, and, at last meeting, the mature animal is a uniform dark brown. enough has now, i trust, been said upon this point to show that from spots have been developed the other markings with which we are familiar in the animal kingdom. the vegetable kingdom illustrates this fact almost as well. thus, the beautiful leaves of the crotons are at first green, with few or no coloured spots; the spots then grow more in number, coalesce, form irregular bands, further develop, and finally cover the whole, or almost the whole, of the leaf with a glow of rich colour. some of the pretty spring-flowering orchid callitriche have sulphur-yellow petals, with dark rich sepia spots; these often develop to such an extent as to overspread nearly all the original yellow. many other examples might be given. hitherto we have started with a spot, and traced its development. but a spot is itself a developed thing, inasmuch as it is an aggregation of similarly coloured cells. how they come about may, perhaps, be partly seen by the following considerations. definite colour-pattern has a definite function--that of being seen. we may, therefore, infer that the more definite colour is of newer origin than the less definite. hence, when we find the two sexes differently coloured, we may generally assume that the more homely tinted form is the more ancient. for example, some butterflies, like the gorgeous purple emperor (_apatura iris_), have very sombre mates; and it seems fair to assume that the emperor's robes have been donned since his consort's dress was originally fashioned. that the object of brilliant colour is display is shown partly by the fact that in those parts of the wings of butterflies which overlap the brilliant colour is missing, and partly by the generally brighter hues of day-flying butterflies and moths than of the night-flying species. now, the sombre hues of nocturnal moths are not so much protective (like the sober tints of female butterflies and birds), because night and darkness is their great defender, as the necessary result of the darkness: bright colours are not produced, because they could not be seen and appreciated. in these cases it is very noticeable how frequently the colour is irregularly dotted about--irrorated or peppered over the wings, as it were. this irregular distribution of the pigment cells, if it were quite free from any arrangement, might be looked upon as primitive colouring, undifferentiated either into distinct colour or distinct pattern. if we suppose a few of the pigment cells here and there to become coloured, we should have irregular brilliant dottings, just as we actually see in many butterflies, along the costa. the grouping together of these colour dots would give rise to a spot, from which point all is clear. that some such grouping or gathering together, allied to segregation, does take place, a study of spots, and especially of eye-spots, renders probable. what the nature of the process is we do not know, nor is it easy to imagine. but let us suppose a surface uniformly tinted brown. then, if we gather some of the colouring matter into a dark spot we shall naturally leave a lighter area around it, just as we see in all our browns and ringlets. in this way we can see how a ring-spot can be formed. to make it a true eye-spot, with a light centre, we must also suppose a pushing away of the colour from that centre. a study of ocelli naturally suggests such a process, which is analogous to the banding of agates, and all concentric nodules. darwin, struck with this, seems to adopt it as a fact, for he says, "appearances strongly favour the belief that, on the one hand, a dark spot is often formed by the colouring matter being drawn towards a central point from a surrounding zone, which is thus rendered lighter. and, on the other hand, a white spot is often formed by the colour being driven away from a central point, so that it accumulates in a surrounding darker zone."[18] the analogy between ocelli and concretions may be a real one. at any rate beautiful ocelli of all sizes can be seen forming in many iron-stained sand-stones. the growth of ocelli may thus be a mechanical process adapted by the creature for decorative purposes, but the artistic colouring of many eye-spots implies greater effort. there is, however, one set of colour lines in birds and insects that do not seem to arise from spots in the ordinary way. these are the coloured feather-shafts of birds, and the coloured nerves or veins in a butterfly's wing, in these the colour has a tendency to flow all along the structure in lines. _conclusion._ the results arrived at in this chapter may be thus summarised:-spots, ocelli, stripes, loops, and patches may be, and nearly always are, developed from more or less irregular spots. this is shown both by the study of normal colouring, or by abnormal colouring, or decolouring in disease. even the celebrated case of the argus pheasant shows that the bands from which the ocelli are developed arose from spots. [illustration] [11] descent of man, vol. ii., p. 132. [12] quart. journ. sci., july 1868, p. 325. [13] studies in the theory of descent. [14] see photographs in hutchinson's illustrations of clinical surgery. [15] see plate iv. [16] desc. man, vol. ii, p. 133, fig. 52. [17] compare his figs. 56 to 58 op. cit. [18] desc. man, vol. ii., p. 134. chapter vii. colouration in the invertebrata. if the principle of the dependence of colour-pattern upon structure, enunciated in the preceding pages be sound, we ought to find certain great schemes of colouration corresponding to the great structural subdivisions of the animal kingdom. this is just what we do find; and before tracing the details, it will be as well to group the great colour-schemes together, so that a general view of the question can be obtained at a glance. the animal kingdom falls naturally into two divisions, but the dividing line can be drawn in two ways. if we take the most simple classification, we have:- 1. _protozoa_, animals with no special organs. 2. _organozoa_, animals possessing organs. practically this classification is not used, but we shall see that from our point of view it is a useful one. in the most general scheme the divisions are:- 1. _invertebrata_, animals without backbones. 2. _vertebrata_, animals with backbones. the invertebrata are divided into sub-kingdoms, of which the protozoa form one. these protozoa possess, as it were, only negative properties. in their simplest form they are mere masses of protoplasm, even lacking an investing membrane or coat, and never, even in the highest forms, possessing distinct organs. it is this simplicity which at once separates them entirely from all other animals. the other sub-kingdoms are:- _coelenterata_, of which the jelly-fishes are a type; animals possessing an alimentary canal, fully communicating with the general cavity of the body, but without distinct circulatory or nervous systems. _annuloida_, of which the star-fishes are a type; animals having the alimentary canal shut off from the body-cavity, and possessing a nervous system, and in some a true circulatory system. _annulosa_, of which worms, lobsters, and insects are types; animals composed of definite segments, arranged serially, always possessing true circulatory and nervous systems. _mollusca_, of which oysters and whelks are types; animals which are soft-bodied, often bearing a shell, always possessing a distinct nervous system and mostly with a distinct heart. in old systems of classification, the _coelenterata_ and _annuloida_ were united into one sub-kingdom, the _radiata_, in consequence of their radiate or star-like structures. as colouration, according to the views here set forth, depends upon structure, we may classify the invertebrata thus:- protozoa structureless. coelenterata } radiata. radiate structure. annuloida } annulosa segmented " mollusca marginate " the mollusca are said to be marginate in structure because, in those possessing shells--the mollusca proper--the shell is formed by successive additions to the margin or edge of the shell, by means of the margin of the mantle, or shell-secreting organ. now we shall proceed to show that the schemes of colouration follow out these structure-plans, and thus give additional force to the truth of the classification, as well as showing that, viewed on a broad scale, the present theory is a true one. we can, in fact, throw the whole scheme into a table, as follows:- systems of colouration. +--+-------------------------+------------------------+------------------+ | | system of colouring. | structure. | sub-kingdoms. | +--+-------------------------+------------------------+------------------+ | |_a. no axial decoration._|_a. no axial structure._|_a. invertebrata._| |1.| no definite system. | no definite organs. | protozoa. | |2.| radiate system. | radiate structure. | coelenterata, | | | | | annuloida.| |3.| segmental system. | segmental structure. | annulosa. | |4.| marginate system. | marginate growth. | mollusca. | | | | | | | | _b. axial decoration._ | _b. axial structure._ | _b. vertebrata._ | |5.| axial system. | axial structure. | vertebrata. | +--+-------------------------+------------------------+------------------+ _protozoa._ the protozoa are generally very minute, and always composed of structureless protoplasm. their peculiarities are rather negative than positive, there being neither body segments, muscular, circulatory, nor nervous systems. even the denser exterior portion (_ectosarc_) possessed by some of them seems to be rather a temporary coagulation of the protoplasm than a real differentiation of that material. here, then, we have to deal with the simplest forms of life, and if colouration depends upon structure, these structureless transparent creatures should lack all colour-pattern, and such is really the case. possessing no organs, they have no colouration, and are generally either colourless or a faint uniform brown colour, and through their colourless bodies the food particles show, often giving a fictitious appearance of colouring. to this general statement there is a curious and most telling exception. in a great many protozoa there exists a curious pulsating cell-like body, called the contractile vesicle, which seems to be a rudimentary organ, whose function is unknown. here, then, if anywhere, traces of colouring should be found, and here it is accordingly found, for, though generally clear and colourless, it sometimes assumes a pale roseate hue. this may be deemed the first attempt at decoration in the animal kingdom, and it is directly applied to the only part which can be said to possess structure. beautiful examples are plentiful in leidy's magnificent volume on freshwater rhizopods. _coelenterata._ these animals fall into two groups, the _hydrozoa_, of which the hydra and jelly-fishes are types, and the _actinozoa_, of which the sea-anemonies and corals are types. most of the coelenterata are transparent animals, but it is amongst them we first come across opaque colouring. of the lowest forms, the hydras, nothing need be said here, as they are so much like the protozoa in their simplicity of structure. the _corynida_, familiar to many of our sea-side visitors by their horny brown tubes (_tubularia_), attached to shells and stones, are next in point of complexity. within the tube is found a semi-fluid mass of protoplasm, giving rise at the orifice to the polypite, which possesses a double series of tentacles. these important organs are generally of a vivid red colour, thus emphasizing their importance in the strongest manner. other members of the order are white, with pink stripes. in the larval stage many of the animals belonging to the above and allied orders, are very like the true jelly-fishes. these free swimming larvæ, or _gonophores_, possess four radiating canals, passing from the digestive sac to the margins of the bell, and these are often the seat of colour. in these creatures, too, we find the earliest trace of sense organs, and consequently, the first highly differentiated organs, and they appear as richly coloured spots on the margins of the bell. the true oceanic hydrozoa again afford us fine examples of structural colouration. the beautiful translucent blue-purple _velella_, which is sometimes driven on to our shores, is a case in point; and its delicate structure lines are all emphasized in deeper hues. the true jelly-fishes (_medusidæ_) with their crystal bells and radiating canals, frequently show brilliant colour, and it is applied to the canals, and also to the rudimentary eye-specks, which are frequently richly tinted, and in all cases strongly marked. in the so-called "hidden-eyed" medusæ we find the same arrangement of colour, the same emphasized eye-specks, and the reproductive organs generally appear as a vivid coloured cross, showing through the translucent bell. turning now to the _actinozoa_, of which the sea anemonies and corals are types, we are brought first into contact with general decorative, more or less opaque colour, applied to the surface of the animal. in the preceding cases the animals have been almost universally transparent or translucent, and the colouration is often applied to the internal organs, and shows through. in the sea-anemonies we find a nearer approach to opacity, in the dense muscular body, though even this is often translucent, and the tentacles generally so, often looking like clouded chalcedony. the wealth of colour to be found in these animals gives us a very important opportunity of studying decoration, where it first appears in profusion. one of the first points that strikes even a casual observer is that amongst the sea-anemonies the colouration is extremely variable, even in the same species and in the same locality. this is in strong contrast to what we generally find amongst the higher organisms, such as insects and birds; for though considerable variation is found in them, it does not run riot as in the anemonies. it would almost appear as if the actual colour itself was of minor importance, and only the pattern essential; the precise hue is not fixed, is not important, but the necessity of colour of some sort properly arranged is the object to be attained. whether this idea has a germ of truth in it or not, it is hard to say, but when we take the fact in connection with its occurrence just where opacity begins, connecting this with the transparency of the lower organisms, and the application of vivid colour to their internal organs, one seems to associate the instability of the anemony's colouring with the transference of colour from the interior to the exterior. certain it is, that vivid colour never exists in the interior of opaque animals; it is always developed under the influence of light. the white bones, nerves and cartilages, and the uniform red of mammalian muscles, are not cases of true decorative colouring in our sense of the term, for all bodies must have some colour. all bone is practically white, all mammalian muscle red, but for these colours to be truly decorative, it would be necessary for muscles of apparently the same character often to be differently tinted, just as the apparently similar hairs on a mammal, and scales on an insect, are variously painted. this we do not find, for the shaft-bones and plate-bones, and even such odd bones as the hyoid are all one colour; and no one would undertake to tell, by its hue, a piece of striped from a piece of unstriped muscle. decorative colouring _must_ be external in an opaque animal; it _may_ be internal in a transparent one. the connection thus shown between decoration and transparency seems to suggest that hypodermal colour is the original, and epidermal the newer scheme: that the latter was derived from the former. this agrees with haagen's shrewd hint that all mimetic colour was originally hypodermal. certain it is that the protective colour that is still under personal control, as in the chameleon, &c., is always hypodermal. the common crass (_bunodes crassicornis_) is so extremely variable, that all one can say of it is, that it is coloured red and green. but this colour is distributed in accordance with structure. the base, or crawling surface, not being exposed to the light, is uncoloured. the column, or stem, is irregularly spotted, and striped in accordance with the somewhat undifferentiated character of its tissue, but the important organs, the tentacles, are most definitely ornamented, the colour varying, but the pattern being constant. this pattern is heart-shaped, with the apex towards the point of the tentacle; that is to say, the narrow part of the pattern points to the narrow part of the tentacle. in the common _actinea mesembryanthemum_, which is often blood red, the marginal bodies, probably sense-organs, are of the most exquisite turquoise blue colour, and the ruby disc thus beaded is as perfect an example of simple structural decoration as could be desired. a zone of similar blue runs round the base of the body. turning now to the corals, which are simply like colonies of single anemonies with a stony skeleton, we have quite a different arrangement of hues. no sight is more fascinating than that of a living-coral reef, as seen through the clear waters of a lagoon. the tropical gardens ashore cannot excel these sea-gardens in brilliancy or variety of colour. reds, yellows, purples, browns of every shade, almost bewilder the eye with their profusion; and here again we find structural decoration carried out to perfection. the growing points of white branching corals (_madrepores_) are frequently tipped with vivid purple, and the tiny polyps themselves are glowing gem-stars. in the white brain-corals, the polyps are vivid red, green, yellow, purple and so on; but in almost every case vividly contrasting with the surrounding parts, the colour changing as the function changes. the _alcyonariæ_, which include the sea-fans, sea-pens, and the red coral of commerce, practically bring us to the end of the _coelenterata_, and afford us fresh proof of the dependence of colour upon structure and function. the well-known organ-pipe coral (_tubipora musica_) is of a deep crimson colour, and the polyps themselves are of the most vivid emerald green, a contrast that cannot be excelled. almost equally beautiful is the commercial coral (_corallium rubrum_) whose vivid red has given a name to a certain tint. in this coral the polyps are of a milk-white colour. it must be remembered that in these cases the colour seems actually to be intentional, so as to form a real and not merely an accidental contrast between the stony polypidom and the polyp, for the connecting tissue (_coenosarc_) is itself as colourless as it is structureless. gathering together the facts detailed in this chapter we find:- 1. that the protozoa are practically colourless and structureless. 2. that in those species which possess a rudimentary organ (contractile vesicle) a slight decoration is applied to that organ. 3. that in the coelenterata the colouration is directly dependent upon the structure. 4. that in transparent animals the colouration is applied directly to the organ whether it be internal as in the canals or ovaries, or external, as in the eye-specks. 5. that in opaque animals, as in the sea-anemonies, the colouring is entirely external. 6. that it is very variable in hue, but not in pattern. 7. that the most highly differentiated parts (tentacles, eye-specks), are the most strongly coloured. 8. that in the corals an emphatic difference occurs between the colour of the polypidom (or "coral") and the polyp. [illustration] chapter viii. details of protozoa. the protozoa are divided into three orders. i.--_gregarinidæ._ ii.--_rhizopoda._ iii.--_infusoria._ i. the _gregarinidæ_ consist of minute protozoa, parasitic in the interior of insects, &c., and like other internal parasites are colourless, as we should expect. ii. the _rhizopoda_ may, for our purpose, be divided into the naked forms like _amoeba_, and those which possess a skeleton, such as the radiolaria, the foraminifera and the spongia. of these the naked forms are colourless, or uniformly tinted, excepting the flush already described as emphasizing the contractile vesicle. the _foraminifera_ are the earliest animals that possess a skeleton or shell, and though generally very small, this shell is often complex, and of extreme beauty, though their bodies retain the general simplicity of the protozoa, indeed, they are said to possess no contractile vesicle. still the complexity of their shells places them on a higher level than the naked rhizopoda. in these animals we find the first definite colour, not as a pattern, but as simple tinting of the protoplasm. the general hue is yellowish-brown (as in _amoeba_), but deep red is not uncommon. the deepest colour is found in the oldest central chambers, becoming fainter towards the periphery, where it is often almost unrecognisable.[19] the _radiolaria_ are minute organisms with still more complex skeletons, and are considered by haeckel[20] to be more highly organized than the preceding order. they consist of a central portion containing masses of minute cells, and an external portion containing yellow cells. here we have the first differentiation of parts in the external coating and internal capsule, and side by side with this differentiation we find colour more pronounced, and even taking regional tints in certain forms. we may notice the following genera as exhibiting fine colour:- _red._ eucecryphalus, arachnocorys, eucrytidium, dictyoceras. _yellow._ carpocanium, dictyophimus, amphilonche. _purple._ eucrytidium, acanthostratus. _blue._ cyrtidosphæra, coelodendrum. _green._ cladococeus, amphilonche. _brown._ acanthometra, amphilonche. examples of these may be seen in the plates of haeckel's fine work, and as an illustration of regional decoration we cite _acanthostratus purpuraceus_, in which the central capsule is seen to run from red to orange, and the external parts to be colourless, with red markings in looped chains. _spongocyclia_ also exhibits this regional distinction of colour very clearly, the central capsule being red and the external portion yellow. the _spongida_, or sponges, are, broadly speaking, assemblages or colonies of amoeba-like individuals, united into a common society. individually the component animals are low, very low, in type, but their union into colonies, and the necessity for a uniform or common government has given rise to peculiarities that in a certain sense raise them even above the complex radiolaria. some, it is true, are naked, and do not possess the skeleton that supports the colony, which skeleton forms what we usually call the sponge; but even amongst these naked sponges the necessity for communal purposes over and above the mere wants of the individual, raises them a step higher in the animal series. a multitude of individuals united by a common membrane, living in the open sea, it must have happened that some in more immediate contact with the food-producing waters, would have thriven at the expense of those in the interior who could only obtain the nutriment that had passed unheeded by the peripheral animals. but just as in higher communities we have an inflowing system of water and an out-flowing system of effete sewerage quite uncontrolled, and, alas, generally quite unheeded by the individuals whose wants are so supplied; so in the sponges we have a system of inflowing food-bearing water and an out-flowing sewage, or exhausted-water system. this is brought about by a peculiar system of cilia-lined cells which, as it were, by their motion suck the water in, bringing with it the food, and an efferent system by which the exhausted liquid escapes. these cilia-lined cells are the first true organs that are to be found in the animal kingdom, and according to the views we hold, they ought to be emphasized with colour, even though their internal position renders the colouration less likely. this we find actually to be the case, and these flagellated cells, as they are called, are often the seat of vividest colour. the animal matter, or sarcode, or protoplasm of sponges falls into three layers, just as we find the primitive embryo of the highest animals; and just as the middle membrane of a mammalian ovum develops into bone, muscle and nerve, so the middle membrane (mesosarc) of the sponges develops the hard skeleton, and in this most important part we find the colour cells prevail. sollas, one of our best english authorities upon sponges, writes, "the colours of sponges, which are very various, are usually due to the presence of pigment granules, interbedded either in the _endosarc of the flagellated cells_, or in the mesodermic cells, usually of the skin only, but sometimes of the whole body."[21] we can, then, appeal most confidently to the protozoa as illustrating the morphological character of colouration. [illustration] [19] leidy. rhizopoda of n. america, p. 16. [20] haeckel. die radiolarien, berlin, 1862. [21] sollas. spongidæ. cassell's nat. hist. vol. vi., p. 318. chapter ix. details of coelenterata. i. hydrozoa. _a. hydrida._ the hydras, as a rule, are not coloured in our sense of the term; that is to say, they are of a general uniform brown colour. but in one species, _h. viridis_, the endoderm contains granules of a green colour, which is said to be identical with the green colouring matter of leaves (_chlorophyll_). this does not occur in all the cells, though it is present in most. the green matter occurs in the form of definite spherical corpuscles, and these colour-cells define the inner layer of the integument (the endoderm), and render it distinct.[22] that portion of the endoderm which forms the boundary of the body-cavity has fewer green corpuscles, but contains irregular brown granules, thus roughly mapping out a structural region. we thus see that even in so simple a body as the hydra the colouring matter is distributed strictly according to morphological tracts. _b. tubularida._ the tubularian hydroids are the subject of an exhaustive and admirably illustrated monograph by prof. j. allman, from which the following details are culled. these animals are with few exceptions marine, and consist either of a single polypite or of a number connected together by a common flesh, or coenosarc. some are quite naked, others have horny tubes, into which, however, the polypites cannot retreat. the polypites consist essentially of a sac surrounded with tentacles; and one of their most striking characters is their mode of reproduction. little buds (_gonophores_) grow from the coenosarc, and gradually assume a form exactly like that of a jelly-fish. these drop off, and swim freely about; and are so like jelly-fishes that they have been classed among them as separate organisms. the tubulariæ are all transparent; and in them we find structural colouration finely shown, the colour, as is usual in transparent animals, being applied directly to the different organs. writing of the colour, prof. allman says: "that distinct secretions are found among the hydroida, and that even special structures are set aside for their elaboration, there cannot now be any doubt. "one of the most marked of these secretions consists of a coloured granular matter; which is contained at first in the interior of certain spherical cells, and may afterwards become discharged into the somatic fluid. these cells, as already mentioned, are developed in the endoderm;[23] in which they are frequently so abundant as to form a continuous layer upon the free surface of this membrane. it is in the proper gastric cavity of the hydranth and medusa, in the spadix of the sporosac, and in the bulbous dilatations which generally occur at the bases of the marginal tentacles of the medusæ, that they are developed in greatest abundance and perfection; but they are also found, more or less abundantly, in the walls of probably the whole somatic cavity, if we except that portion of the gastrovascular canals of the medusa which is not included within the bulbous dilatations. "in the parts just mentioned as affording the most abundant supply of these cells, they are chiefly borne on the prominent ridges into which the endoderm is thrown in these situations; when they occur in the intervals between the ridges they are smaller, and less numerous. "the granular matter contained in the interior of these cells varies in its colour in different hydroids. in many it presents various shades of brown; in others it is a reddish-brown, or light pink, or deeper carmine, or vermilion, or orange, or, occasionally, a fine lemon-yellow, as in the hydranth of _coppinia arcta_, or even a bright emerald green, as in the bulbous bases of the marginal tentacles of certain medusæ. no definite structure can be detected in it; it is entirely composed of irregular granules, irregular in form, and usually aggregated into irregularly shaped masses in the interior of the cells. it is to this matter that the colours of the _hydroida_, varying, as they do, in different species, are almost entirely due. "the coloured granular matter is undoubtedly a product of true secretion; and the cells in which it is found must be regarded as true secreting cells. these cells are themselves frequently to be seen as secondary cells in the interior of parent cells, from which they escape by rupture, and then, falling into the somatic fluid, are carried along by its currents, until, ultimately, by their own rupture, they discharge into it their contents. "we have no facts which enable us to form a decided opinion as to the purpose served by this secretion. its being always more or less deeply coloured, and the fact of its being abundantly produced in the digestive cavity, might suggest that it represented the biliary secretion of higher animals. this may be its true nature, but as yet we can assert nothing approaching to certainty on the subject; indeed, considering how widely the cells destined for the secretion of coloured granules are distributed over the walls of the somatic cavity, it would seem not improbable that the import of the coloured matter may be different in different situations; that while some of it may be a product destined for some further use in the hydroid, more of it may be simply excretive, taking no further part in the vital phenomena, and intended solely for elimination from the system."[24] here we have very definite statements by a highly trained observer of the distribution of colour in the whole of these animals, and of the conclusions he draws from them. firstly as to the colour itself. we find it true colour--brown, pink, carmine, vermilion, orange, lemon-yellow, and even emerald green; a set of hues as vivid as any to be found in the animal kingdom. it is difficult to conceive these granules to be merely excrementitious matter; for in such simple creatures, feeding upon such similar bodies, one would hardly expect the excretive matter to be so diversified in tint. moreover, excrementitious matter is not, as a rule, highly coloured, but brown. thus, we see in the rhizopods the green vegetable matter which has been taken in as food becomes brown as the process of assimilation goes on; and, indeed, colour seems almost always to be destroyed by the act of digestion. still, it by no means follows that this colour, even if it is produced for the sake of decoration, as we suggest, may not owe its direct origin to the process of digestion. the digestive apparatus is the earliest developed in the animal kingdom, and in these creatures is by far the most important; the coelenterata being, in fact, little more than living stomachs. if, then, colouration be structural, what is more likely than that the digestive organs should be the seat of decoration in such transparent creatures? secondly, as to the distribution of the colour. we find it "frequently forming a continuous layer upon the free surface of" the endoderm, in the "spadix of the sporosac," and in the "bulbous terminations" of the canals, that colour is best developed. in other words, the colour is distributed structurally, and is most strongly marked where the function is most important. prof. allman gives no hint that the colour may be purely decorative, and is naturally perplexed at the display of hues in such vigour; but if this be one of the results of the differentiation of parts, of the specialization of function, then we can, at least, understand why we find such brilliant colour in these creatures, and why it is so distributed. as an illustration of the _tubularia_ we have selected _syncoryne pulchella_, fig. 2, pl. vi., and its medusa, fig. 1. the endoderm of the spadix of the hydranths is of a rich orange colour, which becomes paler as it descends towards the less highly organized stem. medusæ are seen in various stages of development, and one, mature and free, is shown. in these the manubrium, and the bulbous terminations of the canals are also seen to be coloured orange. in these medusæ we find the first appearance of sensory organs. they consist of pigment-cells enclosed in the ectoderm, or outside covering; and are singular as presenting the first true examples of opaque colouring in the animal kingdom. they are associated with nerve cells attached to a ring of filamentous nerve matter, surrounding the base of the bell. in some important respects the pigment differs from that in other parts of the animal. it is more definite in structure; and the whole ocellus is "aggregation of very minute cells, each filled with a homogeneous coloured matter."[25] these ocelli, and similar sense organs, called _lithocysts_, are always situated over the bulbous termination of the canals. the pigment is black (as in this case), vermilion, or deep carmine. [illustration: plate vi. syncoryne pulchella.] the dependence of colour upon structure is thus shown to hold good throughout these animals in a most remarkable manner, and the acceptance of the views here set forth gives us an insight into the reasons for this colouration which, as we have seen, did not arise from the study of the question from the ordinary point of view. _c. sertularida._ these animals are very similar to the last, but they are all compound, and the polypites can be entirely withdrawn within the leathery investment or polypary. their mode of reproduction is also similar, and their colouration follows the same general plan. being so like the preceding order, it is unnecessary to describe them. _b. siphonophora._ the siphonophora are all free-swimming, and are frequently called oceanic hydrozoa. they are divided into three orders, viz.:- _a. calycophoridæ._ _b. physophoridæ._ _c. medusidæ._ _a. calycophoridæ._ these animals have a thread-like coenosarc, or common protoplasm, which is unbranched, cylindrical, and contractile. they are mostly quite transparent, but where colour exists it is always placed structurally. thus, in _diphyes_ the sacculi of the tentacles are reddish, in _sphæronectes_ they are deep red, and in _abyla_ the edges of the larger specimens are deep blue.[26] _b. physophoridæ._ these creatures are distinguished by the presence of a peculiar organ, the float, or _pneumatophore_, which is a sac enclosing a smaller sac. the float is formed by a reflexion of both the ectoderm and endoderm, and serves to buoy up the animal at the surface of the sea. the best known species is the physalia, or portuguese man-o'-war. prof. huxley, in his monograph on the oceanic hydrozoa, gives many details of the colouration; and, not having had much opportunity of studying them, the following observations are taken from his work. it will be seen that the physophoridæ illustrate the structural distribution of colour in a remarkable manner. _stephanomia amphitridis_, the hydrophyllia, colourless, and so transparent as to be almost imperceptible in water, coenosarc whitish, enlarged portions of polypites, pink or scarlet, sacs of tentacles scarlet. the enlarged portion of the polypites is marked with red striæ, "which are simply elevations of the endoderm, containing thread-cells and coloured granules." the small polypites do not possess these elevations, and are colourless. _agalma breve_, like a prismatic mass of crystal, with pink float and polypites. _athorybia rosacea_, float pink, with radiating dark-brown striæ, made up of dots; polypites lightish red, shading to pink at their apices; tentacles yellowish or colourless, with dark-brown sacculi; thread-cells dark brown. _rhizophysa filiformis_, pink, with deep red patch surrounding the aperture of the pneumatocyst. _physalia caravilla_, bright purplish-red, with dark extremities, and blue lines in the folds of the crest; polypites violet, with whitish points, larger tentacles red, with dark purple acetabula, smaller tentacles blue, bundles of buds reddish. _p. pelagica_, in young individuals pale blue, in adult both ends green, with highest part of crest purple, tentacles blue, with dark acetabula; polypites dark blue, with yellow points. _p. utriculus._ prof. huxley describes a specimen doubtfully referred to this species very fully, as follows:- "the general colour of the hydrosoma is a pale, delicate green, passing gradually into a dark, indigo blue, on the under surface. "the ridge of the crest is tipped with lake, and the pointed end is stained deep bluish-green about the aperture of the pneumatocyst. "the bases of the tentacles are deep blue; the polypites deep blue at their bases, and frequently bright yellow at their apices; the velvetty masses of reproductive organs and buds on the under surface are light green." he further remarks that the tentacles have reniform thickenings at regular intervals, and "the substance of each thickening has a dark blue colour, and imbedded within it are myriads of close-set, colourless, spherical thread-cells." it would not be possible to find a more perfect example of regional colouration. not only is each organ differently coloured, but the important parts of each organ, like the ridge of the crest, the bases of the tentacles, and the thread-cell bearing ridges of the tentacles, are also emphasized with deep colour. _velella._ this beautiful creature, which sometimes finds its way to our shores, is like a crystal raft fringed with tentacles, and having an upright oblique crest, or sail. the margins of the disk and crest are often of a beautiful blue colour, and the canals of the disk become deep blue as they approach the crest. the polypites may be blue, purple, green, or brown. _c. medusidæ._ the structure and colouration of the true medusæ are so like that of the medusiform larvæ of the other hydrozoa, that they need not be particularly described. _d. lucernarida._ of this sub-class we need only cite the _lucernaria_ themselves; which are pretty bell-shaped animals, having the power of attaching themselves to seaweeds, etc., and also of swimming freely about. round the margin are eight tufts of tentacles, opposite eight lobes, the membrane between the lobes being festooned. in _l. auricula_, a british species, the membrane is colourless and transparent, the lobes bright red, or green, and the tentacles blue. as a group the hydrozoa display regional colouration in a very perfect manner. ii. actinozoa. it is not necessary to trace the colouration through all the members of this group, but we will trace the variation of colour through two species of anemonies, which have been admirably studied by dr. a. andres.[27] the first column shows the general hue, the second the tints of that hue which are sufficiently marked to form varieties as cochineal red, chocolate, bright red, rufous, liver-coloured, brown, olive, green and glaucous. the third column gives the spotted varieties, from which it will be seen that the chocolate, liver, and green coloured forms have each coloured varieties. it will be seen that the range of colour is very great, passing from pale pink, through yellowish-brown to blue-green. -----------+-----------+-----------+--------------- prevailing | uniform | spotted | colour. |varieties. |varieties. | allied species. -----------+-----------+-----------+--------------- white. | ? | | a. candida. " | coccinea. | | " | chiocca. | tigrina. | red. | rubra. | | " | rufosa. | | yellow. | hepatica. | fragacea. | " | umbra. | | " | olivacea. | | " | viridis. | opora. | " | glaucus. | | blue. | ? | | -----------+-----------+-----------+---------------varieties of actinea cari. the following brief descriptions illustrate the distribution of the colour:-_actinea cari._ uniform varieties (_homochroma_). ----------------------+---------------+----------------+--------+---------- | column. | tentacles. |gonidia.| zone. ----------------------+---------------+----------------+--------+---------- [alpha]. _hepatica_ | red brown. | azure. | azure. | azure. [beta]. _rubra_ | crimson. | violet. | |{wanting, [gamma]. _chiocca_ | scarlet. | white. | |{or flesh | | | |{coloured. | | | | [delta]. _coccinea_ | cochineal. | yellowish. | | [epsilon]. _olivacca_ | olive-brown | azure. | azure. | | green. | | | [zeta]. _viridis_ | green. | azure. | azure. | azure. | | | | spotted varieties (_heterochroma_). | | | | [eta]. _tigrina_ |red, spotted | | | | yellow. | | | [theta]. _fragacea_ |liver, spotted | | | | clear green. | azure or white.| |indistinct. [iota]. _opora_ |green spotted, | | | | and striped | | | | yellow. | azure. | | ----------------------+---------------+----------------+--------+----------in this table the varieties above mentioned are further particularized. the column is the stalk or body, the tentacles are the arms, the gonidia the eye spots, and the zone the line round the base. it will be noticed that these regions are often finely contrasted in colour. _bunodes gemmaceus_ is another variable form, and the following varieties are recognised. _heterochroma._ [alpha]. ocracea, } peristome ochre yellow, zone black, tentacles grey, (type) } with blue and white spots. [beta]. _pallida_, peristome whitish grey unbanded, tentacles with white spots. [gamma]. _viridescens_, peristome greenish white unbanded, tentacles with white spots and rosy shades. [delta]. _aurata_, column at base golden, peristome intenser yellow with crimson flush, tentacles grey with ochreous and white spots. [epsilon]. _carnea_, column at base flesh coloured, peristome rosy, tentacles rosy, with white spots. _homochroma._ [zeta]. _rosea_, like [epsilon], but with rosy tubercles. [eta] . _nigricans_, peristome blackish, with blue and green reflexions (riflessi). a few other examples may be given, all of which can be studied in dr. andré's magnificently coloured plates. _aiptasia mutabilis_ is yellow brown, the tentacles spotted in longitudinal rows, the spots growing smaller towards the tip, thus affording a perfect example of the adaptation of colour to structure. _anemonia sulcata_ has normally long light yellow pendulous tentacles tipped with rose, but a variety has the column still yellow but the tentacles pale green, tipped with rose. _bunodes rigidus_ has the column green, with rows of crimson tubercles, the tentacles are flesh-coloured, except the outer row which are pearly; the peristome is green, with brown lips. [illustration] [22] allman's hydroids. ray. soc., p. 123. [23] compare with hydra above. [24] allman. monograph of tubularian hydroida. ray. soc., p. 135. [25] allman, _op. cit._, p. 139. [26] huxley. oceanic hydrozoa, pp. 32, 46, 50. [27] fauna und flora des golfes von neapel. die actinien. 1884. chapter x. the colouration of insects. in the decoration of insects and birds, nature has exerted all her power; and amongst the wealth of beauty here displayed we ought to find crucial tests of the views herein advocated. it will be necessary, therefore, to enter somewhat into detail, and we shall take butterflies as our chief illustration, because in them we find the richest display of colouring. the decoration of caterpillars will also be treated at some length, partly because of their beauty, and partly because amongst them sexual selection cannot possibly have had any influence. butterflies are so delicate in structure, so fragile in constitution, so directly affected by changes of environment, that upon their wings we have a record of the changes they have experienced, which gives to them a value of the highest character in the study of biology. in them we can study every variation that geographical distribution can effect; for some species, like the swallow-tail (_papilio machaon_) and the painted lady (_cynthia cardui_), are almost universal, and others, like our now extinct large copper (_lycæna dispar_), are excessively local, being confined to a very few square miles. from the arctic regions to the tropics, from the mountain tops to the plains, on the arid deserts and amidst luxuriant vegetation, butterflies are everywhere to be found. before entering into details, it will be as well to sketch some of the broad features of butterfly decoration. in the first place they are all day-fliers, and light having so strong an influence upon colour, there is a marked difference in beauty between them and the night-flying moths. a collection of butterflies viewed side by side with a collection of moths brings out this fact more strongly than words can describe, especially when the apparent exceptions are considered; for many moths are as brightly coloured as butterflies. these will be found to belong either to day-flying species, like the various burnets (_zygæna_), tiger moths (_arctia_), or evening flyers like the hawk moths (_sphyngidæ_.) the true night-flying, darkness-loving moths cannot in any way compare with the insects that delight in sunshine. we see the same thing in birds, for very few nocturnal species, so far as we are aware, are brilliantly decorated. another salient feature is the difference that generally exists between the upper and lower surfaces of the wings. as a rule, the upper surface is the seat of the brightest colour. most butterflies, perhaps all, close their wings when at rest, and the upper wing is generally dropped behind the under wing, so that only the tip is visible. the under surface is very frequently so mottled and coloured as to resemble the insect's natural surroundings, and so afford protection. it does not follow that this protective colouring need be dull, and only when we know the habit of the insect can we pronounce upon the value of such colouring. the pretty orange-tip has its under wings veined with green, and is most conspicuous in a cabinet, but when at rest upon some umbelliferous plant, with its orange tip hidden, these markings so resemble the environment as to render the insect very inconspicuous. the brilliant _argynnis lathonia_, with its underside adorned with plates of metallic silver, is in the cabinet a most vivid and strongly-marked species; but we have watched this insect alight among brown leaves, or on brown stones, outside florence, where it is very common, and find that these very marks are a sure protection, for the insect at rest is most difficult to see, even when it is marked down to its resting-place. but some butterflies have parts of the under surface as gaily decorated as the upper; and this not for protection. this may be seen to some extent in our own species, for instance in the orange-tip of the orange-tip, and the red bar in the upper wing of the red admiral (_v. atalanta_). if we watch these insects, the conviction that these are true ornaments is soon forced upon us. the insect alights, perhaps alarmed, closes its wings, and becomes practically invisible. with returning confidence it will gradually open its wings and slowly vibrate them, then close them again, and lift the upper wing to disclose the colour. this it will do many times running, and the effect of the sudden appearance and disappearance of the bright hues is as beautiful as it is convincing. none can doubt the love of display exhibited in such actions. the delicacy of their organization renders butterflies peculiarly susceptible to any change, and hence they exhibit strong tendencies to variation, which make them most valuable studies. not only do the individuals vary, but the sexes are often differently coloured. where two broods occur in a season they are sometimes quite differently decorated, and finally a species inhabiting widely different localities may have local peculiarities. we can thus study varieties of decoration in many ways, and we shall treat of them as follows:- 1. _simple variation_, in which the different individuals of a species vary in the same locality. 2. _local variation_, in which the species has marked peculiarities in different localities. 3. _sexual dimorphism_, in which the sexes vary. 4. _seasonal dimorphism_, in which the successive broods differ. [illustration: fig. 3. diagram of butterfly's wing. a. upper wing. b. lower wing. _a._ costal margin. _b._ hind margin. _c._ inner " _d._ anal angle. _e._ costa. _f._ costal nervure. _g._ sub-costal do. _g_^{1-4}. branches of do. _h._ median nervure. _i._ sub-median do. _j._ discoidal cell. _k._ discoidal veins.] in order fully to understand the bearing of the following remarks it is necessary to know something of the anatomy and nomenclature of butterflies. fig. 3 is an ideal butterfly. the wing margins are described as the _costal_, which is the upper strong edge of the wing, the _hind_ margin, forming the outside, and the _inner_ margin, forming the base. the nervures consist of four principal veins; the _costal_, a simple nervure under the costa, the _sub-costal_, which runs parallel to the costal and about halfway to the tip emits branches, generally four in number; the _median_ occupying the centre of the wing and sending off branches, usually three in number, and the _sub-median_ below which is always simple. there are thus two simple nervures, one near the costal the other near the inner margin, and between them are two others which emit branches. between these two latter is a wide plain space known as the _discoidal cell_. small veins called the _discoidal_ pass from the hind margin towards the cell, and little transverse nervures, known as sub-discoidal, often close the cell. by these nervures the wing is mapped out into a series of spaces of which one, the discoidal cell, is the most important. the nervures have two functions, they support and strengthen the wing, and being hollow serve to convey nutritive fluid and afterwards air to the wing. the wings are moved by powerful muscles attached to the base of the wings close to the body and to the inside of the thorax, all the muscles being necessarily internal. "there are two sets which depress the wings; firstly a double dorsal muscle, running longitudinally upwards in the meso-thorax;[28] and, secondly, the dorso-ventral muscles of the mesoand meta-thorax,[29] which are attached to the articulations of the wings above, and to the inside of the thorax beneath. between these lie the muscles which raise the wings and which run from the inner side of the back of the thorax to the legs."[30] when we consider the immense extent of wing as compared with the rest of the body, the small area of attachment, and the great leverage that has to be worked in moving the wings, it is clear that the area of articulation of the wing to the body is one in which the most violent movement takes place. it is here that the waste and repair of tissue must go on with greatest vigour, and we should, on our theory, expect it to be the seat of strong emphasis. accordingly we commonly find it adorned with hairs, and in a vast number of cases the general hue is darker than that of the rest of the wing, and so far as we have been able to observe, never lighter than the body of the wing. even in the so-called whites (pieris) this part of the wing is dusky, and instances are numerous on plate iv. the scales, which give the colour to the wings, deserve more than a passing notice. they are inserted by means of little stalks into corresponding pits in the wing-membrane, and overlap like tiles on a roof; occasionally the attachment is a ball and socket (_morphinæ_), in which case it is possible the insect has the power of erecting and moving its scales. the shapes are very numerous, but as a rule they are short. to this there is a remarkable exception on the wings of the males of certain butterflies, consisting of elongated tufted prominences which appear to be connected with sense-organs. they are probably scent-glands, and thus we find, even in such minute parts as scales, a difference of function emphasized by difference of ornamentation, here showing itself in variety of forms; but, as we have said, ornamentation in form is often closely allied to ornamentation in colours. in some butterflies, indeed, these scales are aggregated into spots, as in _danais_, and have a different hue from the surrounding area. the scales are not simple structures, but consist of two or more plates, which are finely striated. the colouring matter consists of granules, placed in rows between the striæ, and may exist upon the upper surface of the upper membrane (epidermal), or the upper surface of the under or middle plate (hypodermal), or the colour may be simple diffraction colour, arising from the interference of the lightwaves by fine striæ. dr. haagen, in the admirable paper before mentioned, has examined this question thoroughly, and gives the results set forth in the following table:- _epidermal colours._ metallic blues and greens } bronze } gold } silver } persistent after death. black } brown } red (rarely) } _hypodermal colours._ blue } green } yellow } milk-white } fading after death. orange and } shades between } red } the hypodermal colours are usually lighter than the epidermal, and are sometimes changed by a voluntary act. hypodermal and epidermal colours are, of course, not peculiar to insects; and, as regards the former, it is owing to their presence that the changing hues of fishes, like the sole and plaice, and of the chameleon are due. the great order lepidoptera, including butterflies and moths, seems to the non-scientific mind to be composed of members which are pretty much alike, the differences being of slight importance; but this is not in reality the case, for the lepidoptera might, with some accuracy, be compared to the mammalia, with its two divisions of the placental and non-placental animals. comparing the butterflies (rhopalocera) to the placental mammals, we may look upon the different families as similar to the orders of the mammalia. were we as accustomed to notice the differences of butterflies as we are to remark the various forms of familiar animals, we should no longer consider them as slight, but accord to them their true value. when in the mammalia we find animals whose toes differ in number, like the three-toed rhinoceros and the four-toed tapir, we admit the distinction to be great, even apart from other outward forms. so, too, the seal and lion, though both belonging to the carnivora, are readily recognized as distinct, but the seals may easily be confounded by the casual observer with the manatees, which belong to quite a different order. thus it is with the lepidoptera, for from six-legged insects, whose pupæ lie buried beneath the soil, like most moths, we pass to the highest butterflies, whose fore-legs are atrophied, and whose pupæ hang suspended in the open air; and this by easy intermediate stages. surely, if six-legged mammals were the rule, we should look upon four-legged ones as very distinct; and this is the case with the butterflies. it is necessary to make this clear at starting, in order that we may appreciate to its full value the changes that have taken place in the insects under study. butterflies (_rhopalocera_) are grouped into four sub-families, as under:- 1. _nymphalidæ_, having the fore-legs rudimentary, and the pupæ suspended from the base of the abdomen. 2. _erycinidæ_, in which the males only have rudimentary fore-legs. 3. _lycænidæ_, in which the fore-legs of the males are smaller than those of the females, and terminate in a simple hook. 4. _papilionidæ_, which have six perfect pairs of legs, and in which the pupæ assume an upright posture, with a cincture round the middle. it may, at first sight, appear curious that the imperfect-legged _nymphalidæ_ should be placed at the head of the list, but this is based upon sound reasoning. the larva consists of thirteen segments, and, in passing to the mature stage, the second segment alone diminishes in size, and it is to this segment that the first pair of legs is attached. looking now to the aerial habits of butterflies, we can understand how, in the process of evolution towards perfect aerial structure, the legs, used only for walking, would first become modified; and, naturally, those attached to the segment which decreases with development would be the first affected. when this is found to be combined with an almost aerial position of the pupæ, we see at once how such insects approach nearest to an ideal flying insect. it is a general law that suppression of parts takes place as organisms become specialized. thus, in the mammalia, the greatest number of toes and teeth are found in the lowest forms and in the oldest, simplest fossil species. a butterfly is, indeed, little more than a beautiful flying machine; for the expanse of wing, compared with the size of the body, is enormous. [illustration] [28] the middle division of the thorax. [29] hinder division of thorax. [30] dallas in cassell's nat. hist., vol. vi., p. 27. chapter xi. the colouration of insects. (_continued._) _general scheme of colouring._ so various are the patterns displayed upon the wings of butterflies, that amidst the lines, stripes, bars, dots, spots, ocelli, scalloppings, etc., it seems at first hopeless to detect any general underlying principle of decoration; and this is the opinion that has been, and is still, held by many who have made these insects a special study. nevertheless, we will try to show that beneath this almost confused complexity lie certain broad principles, or laws, and that these are expressed by the statement that decoration is primarily dependent upon structure, dependent upon the laws of emphasis and repetition, and modified by the necessity for protection or distinction. to render this subject as plain as possible, british species will be selected, as far as possible, and foreign ones only used when native forms do not suffice. the body of by far the greater number of species is either darker or of the same tint as the mass of the wings; and only in rare cases lighter. when the body has different tints, it is generally found that the thorax and abdomen differ in colour, and in many cases the base of the thorax is emphasized by a dark or light band. on the wings the functional importance of the parts attached to the body is generally darker, perhaps never lighter, than the ground of the wing, and is frequently further emphasized by silky hairs. this has already been sufficiently pointed out. the wing area may be divided into the strong costal margin, the hind margin, the nervules, and the spaces; and, however complex the pattern may be, it is always based upon these structure lines. in the majority of insects the costal margin is marked with strong colour. this may be noticed in _papilio machaon_, _p. merope_, _vanessa antiopa_, and the whites in plate iv. the extreme tip of the fore-wings is nearly always marked with colour, though this may run into the border pattern. this colour is dark or vividly bright, and we know no butterfly, not even dark ones, that has a light tip to the wings. sometimes, it is true, the light bead-border spots run to the tip, but these are not cases in point. the development of tips has been traced in chapter vi., and need not be repeated. the hind margin of both wings is very commonly emphasized by a border, of which _v. antiopa_, pl. iii. fig. 3, is a very perfect example. the border pattern may consist of one or more rows of spots, lines, bands, or scallops;[31] and there is frequently a fine fringe, which in many cases is white, with black marks, and to which the term bead-pattern may be applied. a definite relation subsists in most cases between the shape of the hind margin and the character of the border-pattern. the plain or simple bordered wings have plain border patterns, and the scalloped wings have scalloped borders; or rather scalloped borders are almost exclusively confined to scalloped wings. in our english butterflies, for instance, out of the 62 species:- 33 have plain margins to the wings. in all the border is plain, or wanting. 20 have the fore-wings plain, and the hind-wings scalloped, and in all the hind-wings are scalloped and the fore-wings plain, or with slightly scalloped border-patterns. 9 have scalloped margins and scalloped border-patterns. another relation between structure and pattern is found in those insects which have tailed hind-wings, for the tail is very frequently emphasized by a spot, often of a different colour from the rest of the wing as in the swallow-tails, plates iv. and v. yet another point may be noticed. in each wing there is a space, the discoidal cell, _j_ fig. 3, at the apex of which several nervures join, forming knots. these are points at which obstacles exist to the flow of the contents, and they are almost always marked by a distinct pattern. we thus have a discoidal spot in very many butterflies, in nearly all moths; and in the other orders of winged insects the decoration is even more pronounced, as any one may see who looks at our dragon-flies, wasps, bees, or even beetles. in some insects the decoration of the body is very marked, as in our small dragon-flies, the agrions. in one species, for example, _a. puella_, the male is pale blue banded with black, and the female bronze black, with a blue band on the segment, bearing the sexual organ; the ovipositors are also separately decorated. the male generative organs are peculiar, in that the fertilizing fluid is conveyed from one segment to a reservoir at the other end of the abdomen. both the segments bearing these organs are marked by special decoration. the peculiar arrangement of the sexual organs in dragon-flies is very variable, and certain segments are modified or suppressed in some forms, as was shown by j. w. fuller.[32] in every case the decoration follows the modification. in the thorax of dragon-flies, too, the principal muscular bands are marked out in black lines. this distinct representation of the internal structure is beautifully shown in _æschna_ and _gomphina_, and in the thorax of _cicada_, as shown by dr. haagen in the paper quoted in the last chapter. we may, then, safely pronounce that the decoration of insects is eminently structural. _simple variation._ cases of simple variation have been already cited in our description of spots and stripes, and it only remains to show that in this, as in all other cases, the variation is due to a modification of original structural decoration. to take familiar examples. newman, in his british butterflies, figures the varieties of the very common small tortoiseshell (_vanessa urticæ_). in the normal form there is a conspicuous white spot on the disc of the fore-wings, which is absent in the first variety, owing to the spreading of the red-brown ground colour. this variety is permanent on the mediterranean shores. in variety two, the second black band, running from the costa across the cell, is continued across the wing. the third variety, mr. newman remarks, is "altogether abnormal, the form and colouring being entirely altered." still, when we examine the insect closely, we find it is only a modification of the original form. the first striking difference is in the margin of the wings, which in the normal form is scalloped with scallop-markings, whereas, in the variety the margins are much simpler, and the border pattern closely corresponds with it, having lost its scalloping. in the fore-wing some of the black bands and spots are suppressed or extended, and the extensions end rigidly at nervules. the dark colouring of the hind-wings has spread over the whole wing. we thus see that the decoration, even in varieties called abnormal, still holds to structural lines, and is a development of pre-existing patterns. no one can have examined large series of any species without being impressed with the modification of patterns in almost every possible way. for instance, we have reared quantities of _papilio machaon_, and find great differences, not only in the pattern, but in the colour itself. a number of pupæ from wicken fen, cambridgeshire, were placed in cages, into which only coloured light could fall, and though these experiments are not sufficiently extended to allow us to form any sound conclusions as to the effect of the coloured light, we got more varieties than could be expected from a batch of pupæ from the same locality. the tone of the yellow, the quantity of red, the proportion of the yellow to the blue scales in the clouds, varied considerably, but always along the known and established lines. the variations in the colour of lepidoptera has been most admirably treated by mr. j. jenner weir in a paper, only too short, read before the west kent natural history society.[33] he divides variations into two sections, aberrations or heteromorphism, and constant variations or orthopæcilism, and subdivides each into six classes, as under:- _heteromorphism._ albinism ... ... white varieties. melanism ... ... black do. xanthism ... ... pallid do. sports ... ... or occasional variations not included in the above. gynandrochomism ... females coloured as males. hermaphroditism ... sexes united. _orthopæcilism._ polymorphism ... variable species. topomorphism ... local varieties. atavism ... ... reversion to older forms. dimorphism ... ... two constant forms. trimorphism ... ... three do. do. horeomorphism ... seasonal variation. in some cases, he remarks, variations are met with which may with equal propriety be classed in either section. albinism he finds to be very rare in british species, the only locality known to him being the outer hebrides. this reminds us of wallace's remark upon the tendency to albinism in islands. xanthism, he finds to be more plentiful, and quotes the common small heath (_cænonympha pamphilus_) as an illustration. in these varieties we have simply a bleaching of the colouring matter of the wings, and therefore no departure from structural lines. melanism arises from the spreading of large black spots or bars, or, as in _biston betularia_, a white moth peppered with black, dots by the confluence of small spots; for this insect in the north is sometimes entirely black. it is singular that insects have a tendency to become melanic in northern and alpine places, and this is especially the case with white or light coloured species. (_see_ plate iv., fig. 17) it has recently been suggested that this darkening of these delicate membranous beings in cold regions is for the purpose of absorbing heat, and this seems very probable.[34] of ordinary spots it is merely necessary to remark, that they are all cases in our favour. thus, in _satyrus hyperanthus_ we have "the ordinary round spots ... changed into lanceolate markings"; this takes place also in _c. davus_. the other cases of aberration do not concern us. when, however, we come to the cases in which a species has two or more permanent forms, it is necessary to show that they are in all cases founded on structure lines. the patterns, as shown in plate v., figs. 1-13, are always arranged structurally, and the fact that not only are intermediate forms known, as in _araschnia porima_, plate v., fig. 6, but that the various forms are convertible into one another, would in itself be sufficient to show that in these cases there is no departure from the general law. in _grapta interrogationis_, plate v., figs. 8-10, we see in the central figure one large spot above the median nervure, in the left-hand form this is surmounted by another spot above the lowest sub-costal branch, and in the right-hand figure this latter spot is very indistinct. we have here a perfect gradation, and the same may be said of the colouration of the lower wings. take again the three forms of _papilio ajax_ in the same plate, figs. 11-13, and we have again only modifications of the same type. in local varieties, as in seasonal forms, we have again nothing more than developments of a given type, as is well shown in plates iv. & v., figs. 13-18 & 1-13. when, however, we come to mimetic forms, whether they mimic plants, as in plate i., or other species, as in plates ii. & iii., a difficulty does seem to arise. the leaf butterfly (_kallima inachus_), plate i., offers no trouble when we view the upper surface only with its orange bands, but its under surface, so marvellously like a dead leaf that even holes and microscopic fungi are suggested, does seem very like a case in which structure lines are ignored. take, for instance, the mark which corresponds to the mid-ribs, running from the tail to the apex of the upper wing; it does not correspond to any structure line of the insect. but if we take allied and even very different species and genera of indian and malayan butterflies, we shall find every possible intermediate form between this perfect mimicry and a total lack of such characters. to cite the most recent authority, the various species of the genera discophora, amathusia, zeuxidia, thaumantis, precis, &c., figured so accurately in distant's rhopalocera malayana, will give all the steps. in the cases of true mimicry, as in figs. 1-3, plates ii. & iii., where insects as different as sheep from cats copy one another, we find that of course structure lines are followed, though the pattern is vastly changed. the _papilio merope_, fig. 1, plate ii., which mimics _danais niavius_, fig. 3, does so by suppressing the tail appendage, changing the creamy yellow to white--a very easy change, constantly seen in our own pieridæ--and diffusing the black. a similar case is seen in figs. 4-5, plate iii., where a normally white butterfly (_panopoea hirta_) mimics a normally dark one of quite a different section. here again the change is not beyond our power of explanation. where a papilio like _merope_ mimics a brown species like _danais niavius_, we have a still greater change in colour, but not in structural pattern. if we ascribe to these insects the small dose of intelligence we believe them to possess, we can readily see how the sense of need has developed such forms. local varieties present no difficulty under such explanation. the paramount necessity for protection has given the hebridran species the grey colour of the rocks, and the desert species their sandy hue. [illustration: plate vii. caterpillars.] finally, to take the case of caterpillars, weismann has admirably worked out the life history of many forms, and shows how the complex markings have arisen by development. broadly, a caterpillar consists of 13 segments, the head being one. the head is often marked with darker colour, and the last segment with its clasping feet is also very frequently emphasized, as in figs. 1 & 3, plate vii. the spiracles are generally marked by a series of spots, and often connected by a line. here the tendency to repetition shows itself strongly, for not only the spiracles themselves, but the corresponding points in the segments without spiracles are frequently spotted, and, moreover, these spots are frequently repeated in rows above the spiracular line. of this, _deilephila galii_ and _d. euphorbiæ_, figs. 1-5, plate vii., are good examples. the segmentation is also generally emphasized, as shown in all the examples on the plate, but in its simplicity in fig. 10. running down the centre of the back a more or less distinct line is often seen, as shown in the figures. this corresponds with the great dorsal alimentary canal lying just below the skin, and weismann has shown that in young larvæ this line is transparent, and the green food can be seen through the skin. we have here, perhaps, a relic of the direct colouration noticed in the transparent coelenterata. where larvæ possess horns either upon the head, as in _apatura iris_ and _papilio machaon_, or on the tail, as in many of the sphyngidæ, like figs. 1-5, plate vii., these appendages are always emphasized in colour. as they are frequently oblique, we often find that this obliquity is continued as a slanting spot, as in _d. galii_ and _euphorbiæ_, and sometimes repeated as a series of oblique stripes, as in fig. 4. it must be admitted that in insects we have strong evidence of structural decoration. [illustration] [31] in the true scallop pattern the convexity is turned towards the body of the insect. [32] j. w. fuller on the breathing apparatus of aquatic larvæ. proc. bristol nat. soc. [33] entomologist, vol. xvi., p. 169, 1883. [34] nature. r. meldola on melanism, 1885. chapter xii. arachnida. the arachnida include the scorpions and spiders, and as the former are tolerably uniform in colour, our remarks will be confined to the latter. the thorax is covered with a horny plate, while the abdomen only possesses a soft skin, and neither show any traces of segmentation. from the thorax spring four pairs of legs, and a pair of palpi, or feelers. immediately beneath the skin of the abdomen lies the great dorsal vessel, which serves as a heart. this vessel is divided into three chambers, the general aspect of which is shown in fig. 9, plate viii., taken from gegenbaur's comparative anatomy.[35] from this heart the blood passes by vessels to each of the limbs, the palpi, etc., as offsets from the double-branched aorta. the shape of this dorsal vessel is peculiar, and its importance in respect to colouration will be immediately apparent. the primary scheme of colouration in the arachnida seems to be the distinguishing of the cephalothorax from the abdomen by a different colour. thus, of the 272 species of british spiders represented in blackwell's work,[36] no less than 203 have these parts differently coloured, and only 69 are of the same hue, and even in these there is often a difference of tint. so marked is this in certain cases that the two parts form vivid contrasts. of this cases are given in the following list. cephalothorax. abdomen. _eresus cinnabarinus_, black, bright red. _thomisus floricolens_, green, brown. --- _cinereus_, brown, blue. --- _trux_, red, brown. _sparassus smaragdulus_, green, red and yellow. as a rule the abdomen is darker than the cephalothorax, and many species have the former red-brown and the latter black. the legs, usually, take the colour of the cephalothorax, and are, hence, generally lighter than the abdomen, but to this there are exceptions. where the individual legs differ in colour, the two first pairs are the darkest, and the dark hue corresponds in tint with the dark markings on the cephalothorax. the joints of the legs are in many species emphasized with dark colour, which is often repeated in bands along the limb. the most remarkable point is, however, the pattern on the abdomen, which, though varied in all possible ways, always preserves a general character, so that we might speak with propriety of a spider-back pattern. this pattern is fairly well illustrated in the genus _lycosa_, but is seen to perfection, and in its simplest form in _segestria senoculata_, plate viii., fig. 1, and in _sparassus smaragdulus_, plate viii., fig. 2. this peculiar pattern is so like the dorsal-vessel that lies just beneath, that it is difficult to avoid the conclusion that we have here an actual case of the influence of internal organs on the integument, and this we believe to be the case. no matter how curious the abdominal markings may seem to be, they never so far depart from this fundamental pattern as to appear independent of it. thus, in the genus _lycosa_, which is by no means the best for the purpose, but is chosen as illustrating gegenbaur's diagram, pl. viii., we have the dorsal-vessel well marked in _l. piscatoria_, plate viii., fig. 3, from which may be developed the other forms. in _l. andrenivora_, plate viii., fig. 4, the male shows the vessel-mark attenuated posteriorly; and in the female, fig. 5, the hinder part has become broken up into detached marks, still preserving the original shape, while the upper part remains practically unchanged. in _l. allodroma_ the disintegration of the mark has further advanced, for in the male, fig. 6, the upper portion has lost something of its shape, and the lower part is a series of isolated segments. this process is carried still further in the female, fig. 8, where the upper portion is simplified, and the lower almost gone. in _l. campestris_, fig. 10, the mark is reduced to a stripe, corresponding with the upper part of the vessel-mark only: and, lastly, in the male _l. agretyca_, fig. 7, this upper part is represented by two spots, though even here traces of the original form can be seen. a simplification of marking of another sort is seen in _l. rapax_, fig. 13, where the chamber-markings are almost obliterated, and merely an irregular stripe left. the stages by which this modification is arrived at are too obvious to need illustration. in some species the lower portion of the vessel-mark is reduced to small dots, as in _l. cambrica_, _fluviatilis_, _piratica_, and others; and the stages are very clear. starting with the isolated chamber-marks, as in _l. allodroma_, fig. 5, we get, firstly, a set of spots, as in _l. picta_, which, in the female, fig. 16, are still connected with the chamber-marks, but in the male, fig. 17, are isolated. this leads us, by easy steps, to such forms as _l. latitans_, fig. 14, which consists of a double row of spots upon dark stripes. the intimate connection thus shown to subsist between the characteristic decoration of the abdomen of spiders, and the shape of the important dorsal organ beneath, seems to be strong evidence of effect that internal structure may have upon external decoration.[37] the cephalothorax of spiders, being covered with a hardened membrane, does not show such evidence clearly, for it appears to be a law that the harder the covering tissue, the less does it reflect, as it were, the internal organs. the hard plates of the armadillo are thus in strong contrast to the softer skins of other animals. nevertheless, there does appear, occasionally, to be some trace of this kind of decoration in the cephalothorax of certain spiders, though it would be hard to prove. the blood vessels of this part (see fig. 9), though large, are not nearly so prominent as the great dorsal vessel. the chief artery enters the cephalothorax as a straight tube, forks, and sends branches to the limbs, palpi, and eyes. in many species, notably in the genus _thomisus_, a furcate mark seems to shadow the forked aorta. this is best shown in _t. luctuosus_, plate viii., fig. 11. moreover, in this and other genera, lines frequently run to the outer pair of eyes, which alone are supplied with large arteries, see fig. 9. however this may be, it is certain that the entire decoration of spiders follows structural lines, and that the great dorsal vessel has been emphasized by the peculiar pattern of the abdomen. [illustration: plate viii. spiders.] [35] elements of comparative anatomy, by c. gegenbaur. translated by jeffrey bell and ray lankester, 1878, p. 285. [36] spiders of great britain and ireland, j. blackwell. ray. soc., 1861. [37] the decoration of many of the hoverer flies and wasps is of a similar character. chapter xiii. colouration of invertebrata (_continued_). of the arthropoda, including the lobsters, crabs, shrimps, etc., little can be said here, as we have not yet been able to study them with anything like completeness. still, we find the same laws to hold good. the animals are segmented, and we find their system of colouration segmental also. thus, in the lobsters and crabs there is no dorsal line, but the segments are separately and definitely decorated. the various organs, such as the antennæ and eyes, are picked out in colour, as may be beautifully seen in some prawns. when we come to the mollusca, we meet with two distinct types, so far as our subject is concerned; the naked and the shelled. in the naked molluscs, like the slugs, we have decoration applied regionally, as is shown to perfection in the _nudibranchs_, whose feathery gills are often the seat of some of the most vivid hues in nature. the shell-bearing mollusca are proverbial for their beauty, but it is essential to bear in mind that the shell does not bear the same relation to the mollusc that the "shell" of a lobster does to that animal. the lobster's shell is part of its living body; it is a true exo-skeleton, whereas the shell of a mollusc is a more extraneous structure--a house built by the creature. we ought, on our view, to find no more relation between the decoration of a shell and the structure of its occupant, than we do in the decoration of a human dwelling-house to the tenant. the shell consists of carbonate of lime, under one or both of the forms known to mineralogists as calcite and aragonite. this mineral matter is secreted by an organ called the mantle, and the edge, or lip, of the mantle is the part applied to this purpose. the edge of the mantle is the builder's hand, which lays the calcareous stones of the edifice. the shell is built up from the edge, and the action is not continuous but seasonal, hence arise the markings known as lines of growth. in some cases the mantle is expanded at times into wing-like processes, which are turned back over the shell, and deposit additional layers, thus thickening the shell. in all the forms of life hitherto considered the colouring matter is deposited, or formed, in the substance of the organ, or epidermal covering, but in the mollusca this is not the case. the colouring matter is entirely upon the surface, and is, as it were, stencilled on to the colourless shell. this is precisely analogous to the colouring of the shells of birds' eggs. they, too, are calcareous envelopes, and the colouring matter is applied to the outside, as anyone can see by rubbing a coloured egg. in some eggs several layers of colouring matter are superimposed. in no case does the external decoration of molluscan shells follow the structure lines of the animal, but it does follow the shape of the mantle. the secreting edge may be smooth, as in _mactra_, regularly puckered, as in most _pectens_, puckered at certain points, as in _trigonia_, or thrown into long folds, as in _spondylus_. in each of these cases the shell naturally takes the form of the mantle. it is smooth in _mactra_, regularly ribbed in _pecten_, tubercled in _trigonia_, and spined in _spondylus_. where the inside of the shell is coloured as in some pectens, regional decoration at once appears and the paleal lines, and muscular impressions are bounded or mapped out with colour. it is a significant fact that smooth bivalves are not so ornate as rugose ones, and that the ridges, spines, and tubercles of the latter are the seats of the most prominent colour. similar remarks apply to univalve shells, which are wound on an imaginary vertical axis. they may be smooth, as in _conus_ and _oliva_, rugose, as in _cerithium_, or spined, as in _murex_. the structure of these shells being more complex than that of bivalves, we find, as a rule, they are more lavishly ornamented, and the prominent parts of the shell, and especially the borders, are the seat of strongest colour. in some cases, as in adult cowries (_cypræa_), the mantle is reflexed so as to meet along the median line, where we see the darkest colour. the rule amongst spiral shells is to possess spiral and marginal decoration, and this is what we should expect. the nautilus repeats in the red-brown markings of its shell, the shape of the septa which divide the chambers, though, as is often the case, they are generally more numerous than the septa. the naked cephalopoda, or cuttle-fishes, often possess a distinct dorsal stripe, and when our views were first brought before the zoological society, this fact was cited as an objection. to us it seems one of the strongest of favourable cases, for these animals possess a sort of backbone--the well-known cuttle-bone--and hence they have a dorsal line. some shells, as _margarita catenata_, have a chain-pattern, and in this case the action of the pigment cells takes place at regular and short intervals. others, as _mactra stultorum_, the stencilling forms a series of lines and spots, generally enlarging into rays. the whole subject of the decoration of shells deserves much more time than we have been able to give to it as yet. [illustration] chapter xiv. colouration of vertebrata. the vertebrata, as their name implies, are distinguished by the possession of an internal skeleton, of which the backbone is the most essential part, and the general, but not universal, possession of limbs or appendages. consequently we find that the dorsal and ventral surfaces are almost invariably coloured differently, and the dorsal is the darker in the great majority of instances. generally the spine is marked by a more or less defined central line, and hence this system of colouration may be termed axial, because it is in the direction of the axes, or applied about the axes. _fishes._ where fishes have not been modified out of their original form, as are the soles, plaice, and other flat fish, we find the dorsal region darker than the ventral, and even here the under surfaces are the lightest. even in cases like the char, fig. 1, plate ix., where vivid colour is applied to the abdomen, the dorsum is the darker. the dorsum is often marked by a more or less well-defined dark band, as in the mackerel and perch, fig. 2, plate ix. there are sometimes parallel bands at right angles to the above, as in the perch and mackerel; and this is a common feature, and apparently a very old one, as we find it in the young of fishes whose adults are without these rib-like marks, such as the trout and pike. it is only necessary to inspect any drawings of fishes to see that their colouration is on a definite principle, although rather erratic. important functional parts, like the gills, fins, and tail, are generally marked in colour more or less distinctly, as may be seen, for instance, in our common fresh-water fishes, like the roach and perch. the line of mucus-secreting glands running along the sides is usually marked by a dark line. these facts point distinctly to structural decoration. [illustration: plate ix. char and perch.] there are in some fishes, like the john dory, curious eye-like dark spots, which we cannot refer to a structural origin, though a better acquaintance with the class might reveal such significance. the amphibia have not been well studied by us, and we must leave them with the remark that they seem to bear out the view of structural decoration, as is seen in our english newts. some are, however, modified out of all easy recognition. _reptiles._ among the reptiles, the snakes, fig. 4, may be selected for illustration. snakes are practically little more than elongated backbones, and are peculiar from the absence of limbs. the colouring matter does not reside so much in the scales as in the skin beneath, so that the sloughs do not illustrate the decoration. hence, we might expect to find here a direct effect of morphological emphasis. the ornamentation of snakes is very similar throughout the class, both in water and land snakes; as may be seen by sir w. fayrer's work on venomous snakes. this ornamentation is of a vertebral pattern, placed along the dorsal surface, with cross lines, which may represent ribs. where the ribs are wanting, as in the neck, the pattern changes, and we get merely longitudinal markings. in the python, fig. 4, there are, near the central line, numerous round spots, which apparently emphasize the neural processes. there are diagonal markings on some species which illustrate the development of colour-spots already alluded to. this snake-pattern is very singular and striking. the markings are fewer in number than the vertebræ, yet their true vertebral character is most obvious. in snakes, again, we find the dorsal region is darker than the ventral. in the lizards there are patches of colour placed axially, while each patch covers a number of scales. _birds._ birds have their whole economy modified to subserve their great functional peculiarity of flight. immense muscles are required for the downward stroke of the wing, and to give attachment to these the sternum has a strongly developed keel. to bring the centre of gravity low, even the muscles which raise the wing are attached to the sternum, or breastbone, instead of to the dorsal region, as might be expected; and to brace the wings back a strong furculum--the merry-thought--is attached. the breast, then, is the seat of the greatest functional activity in birds, and, consequently, we find in a vast number of birds that the breast is the seat of vivid colour. as many birds are modified for protective purposes, the brightest species were selected to test our views, namely, the birds of paradise (paradisea), humming birds (trochilidæ), and sun birds (nectarinidæ). in these birds it is clear that colour has had full sway, untramelled by any necessity for modification. nothing is more striking than the mapping out of the surface of these birds into regions of colour, and these regions are always bounded by structural lines. take, for instance, _paradisea regia_. in this bird we find the following regions mapped in colour:- sternum brown. clavicle yellow. pelvis yellow. band brown. frontal bone black. parietal bones green. occiput yellow. a beautiful ruff emphasizes the pectoral muscles, and the tail appendages emphasize the share-like caudal vertebræ. if we turn to the other species of this genus, we find in _p. papuana_ the claret breast suddenly change to green at the furculum; and similar changes take place in _p. speciosa_, while in _p. wallacei_ and _wilsoni_ this region is decorated with a wonderful apron of metallic green. the region of the furculum is equally well marked in the toucans and sun-birds. if now we observe the back of a bird, and view the skeleton with the wings at rest, we shall find it falls into three morphological tracts. first, the shoulder, or scapular track; second, the thigh, or pelvic; third, the tail, or caudal region; and in all these birds the several tracts are beautifully marked by sudden and contrasted change of colour. in _p. wilsoni_ all the tracts are brilliant red, but they are separated by jet-black borders. in _nectarinea chloropygia_ the scapular region is red, the pelvic yellow, and the caudal green. [illustration: plate x. sun birds.] in _p. wilsoni_ we have a wonderful example of morphological emphasis. the head is bare of feathers, and coloured blue, except along the sutures of the skull, where lines of tiny black feathers map out the various bones. but morphological emphasis exists everywhere in birds. the wing-primaries, which attach to the hand, are frequently differently decorated from the secondaries, which feathers spring from the ulna; and the spur-feathers of the thumb, or pollux, are different in shape, and often in colour, from the others, as every fly-fisher who has used woodcock spur-feathers knows full well. the wing-coverts and tail-coverts are frequently mapped in colour; and the brain case is marked by coloured crests. the eye and ear are marked by lines and stripes; and so we might go on throughout the whole bird. we may remark that these very tracts are most valuable for the description and detection of species, and among ornithologists receive special names. now, this distribution of colour is the more remarkable inasmuch as the feathers which cover the surface--the contour feathers--are not evenly distributed over the body, but are confined to certain limited tracts, as shown by nitzsch; and though these tracts have a morphological origin, they are rendered quite subsidiary to the colouration, which affects the whole bird, and not these regions in particular. in fact, the colouration is dependent upon the regions on which the feathers lie, and not upon the area from which they spring. in other words, we seem to have in birds evidence of the direct action of underlying parts upon the surface. in more obscurely coloured birds, and those which seem to be evenly spotted, close examination shows that even here the decoration is not uniform, but the sizes and axes of the spots change slightly as they occupy different regions; as may be seen in woodpeckers and guinea-fowl. although the same tone of colour may prevail throughout the plumage, as in the argus pheasant, great variety is obtained by the fusion of spots into stripes. a symmetrical effect is produced by the grouping of unsymmetrical feathers; as is so often seen in plants, where irregular branches and leaves produce a regular contour. sometimes, especially on the breast and back, the feathers of one region seem to unite so as to form one tract, so far as colour is concerned. thus, if in _p. wilsoni_ the black borders of the dorsal regions were suppressed, all three areas would be of one hue. this seems to have been the case in the breast region of humming birds, where only the throat is highly coloured. in the toucans the breast and throat regions are often marked with colour; but sometimes the hue is the same and the boundaries of the regions marked with a band of another colour; if this boundary band be increased, the regions do not seem so well shown, for the boundary becomes as broad as the area; yet, in all these cases the dependence upon regional decoration is manifest. no doubt the few uniformly coloured birds were derived from species which were once variously hued; the gradation of colour being lost in transmission. _mammalia._ the axial decoration of the mammalia is very definite, and nearly all species have a dorsal tract marked with colour. the dark bands on the back of the horse, ox, and ass, are cases in point. in nearly every case the dorsal is darker than the ventral surface. if we take highly decorated species, that is, animals marked by alternate dark and light bands, or spots, such as the zebra, some deer, or the carnivora, we find, first, that the region of the spinal column is marked by a dark stripe (figs. 9 & 16); secondly, that the regions of the appendages, or limbs, are differently marked; thirdly, that the flanks are striped, or spotted, along or between the regions of the lines of the ribs; fourthly, that the shoulder and hip regions are marked by curved lines; fifthly, that the pattern changes, and the direction of the lines, or spots, at the head, neck, and every joint of the limbs; and lastly, that the tips of the ears, nose, tail, and feet, and the eye are emphasized in colour. in spotted animals the greatest length of the spot is generally in the direction of the largest development of the skeleton. this morphological arrangement can be traced even when the decoration has been modified. thus, in the carnivora we have the lion and puma, which live in open country, with plain skins, the tiger with stripes, an inhabitant of the jungle, and the leopard, ocelot, and jaguar with spots, inhabiting the forests. but the lion has a dark dorsal stripe, and the nose, etc., are emphasized in colour, and, moreover, the lion has probably lost its marked decoration for protective purposes, for young lions are spotted. the tiger's stripes start from the vertebræ, and still follow the lines of the ribs. in the tiger the decoration changes at the neck, and on the head, and the cervical vertebræ are often indicated by seven stripes. see fig. 5. the markings over the vertebræ are not in continuous lines, as in many mammals, but form a series of vertebra-like spots. this plan of decoration is continued even on the tail, which is coloured more on the upper than on the lower surface. the spotted cats have their spot-groups arranged on the flanks in the direction of the ribs, at the shoulder and haunch in curves, at the neck in another pattern, on the back of the head in another; and the pattern changes as each limb-joint is reached, the spots decreasing in size as the distance is greater from the spine. see figs. 9-15. there is in tigers, and the cat-tribe generally, a dark stripe over the dental nerve; and the zygoma, or cheek-bone, is often marked by colour. even the supraorbital nerve is shown in the forehead, and there are dark rings round the ears. in dissecting an ocelot at the zoological gardens in 1883, a forked line was found immediately over the fork of the jugular vein. the colouration in these animals seems often to be determined by the great nerves and nerve-centres, and the change from spots, or stripes, to wrinkled lines on the head are strikingly suggestive of the convolutions of the brain, falling, as they do, into two lateral masses, corresponding with the cerebral hemispheres, separated by a straight line, corresponding with the median fissure. this is well shown in the ocelot, fig. 15, and in many other cats. that the nerves can affect the skin has already been pointed out in chapter vi., in the case of herpes, and that it can affect colour is shown in the hindoo described in the same place. so marked, indeed, is this emphasis of sensitive parts that every hair of the movable feelers of a cat is shown by colour to be different in function from the hairs of the neck, or from the stationary mass of hair from which the single longer hair starts. in the badger, fig. 16, there is a bulge-shaped mass of coloured hair near the dorsal and lumbar regions, but it is axially placed. the shoulder and loins are well marked, although in a different manner from other species. in some species of deer, and other mammalia, there are white or coloured lines parallel to the spine, and also, as in birds, spots coalesce and form lines, and lines break up into spots. the great anteater has what at first seems an exceptional marking on the shoulder, but a careful examination of the fine specimen which died at the zoological gardens in 1883, we were struck with the abnormal character of the scapula, and we must remember that, as wallace and darwin have pointed out, all abnormal changes of the teeth are correlated with changes in the hair. moreover the muscles of the shoulder region are so enormously developed as to render this otherwise defenceless animal so formidable that even the jaguar avoids an embrace which tightens to a death-grip. this region is, therefore, precisely the one we should expect to be strongly emphasized. this being the case, we have really no exception in this creature. certain mammals are banded horizontally along their sides, thus losing most of their axial decoration, and this is well shown among the viverridæ, and smaller rodents. now, however conspicuous such animals may appear in collections, they are in their native haunts very difficult to detect. in all cases there is a marked dorsal line; and we suggest that the mature decoration is due to a suppression of the axial decoration for protective purposes, and a repetition of the dorsal decoration according to the law before enunciated. indeed, in one case we were able to trace this pretty clearly, in the beautiful series of _sus vittatus_ in the museum at leyden. this pig, an inhabitant of java, when mature is a dark brown animal, but in the very young state it is clearly marked in yellow and brown, with a dark dorsal stripe, and spots, taking the line of the ribs, and over the shoulder and thigh. as the animal grows older, the spots run into stripes, and it becomes as clearly banded horizontally as the viverridæ. finally the dark bands increase in width, until they unite, and the creature becomes almost uniformly brown. we have not been able to see young specimens of the viverridæ, but a similar change may there occur, or it may have occurred in former times. we must also remember that these creatures are long-bodied, like the weasels, and hence they may have a tendency to produce long stripes. in the case of our domestic animals, especially the oxen, the decoration seems often to have become irregular, but even here the emphasis of the extremities is generally clearly made out, and that of the limbs can often be traced. in horses this is better shown, and dappled varieties often well illustrate the points. most horses at some time show traces of spots. sufficient has now been said to point out the laws we believe to have regulated the decoration of the animal kingdom. the full working out of the question must be left to the future, but it is hoped that a solid groundwork has been laid down. [illustration: plate xi. leaves.] chapter xv. the colouration of plants. the general structure of plants is so simple in comparison with that of animals that our remarks upon this sub-kingdom need only be short. with regard to leaves, especially such as are brightly coloured, like the begonias, caladiums, coleus, and anoechtochilus, plate xi., the colour follows pretty closely the lines of structure. we have border decoration, marking out the vein-pattern of the border; the veins are frequently the seat of vivid colour, and when decolouration takes place, as in variegated plants, we find it running along the interspaces of the veins. these facts are too patent to need much illustration; for our zonale geraniums, ribbon grasses, and beautiful-leaved plants generally, are now so common that everyone knows their character. when decay sets in, and oxidation gives rise to the vivid hues of autumn, we find the tints taking structural lines, as is well shown in dying vine and horse-chestnut leaves, fig. 1, plate xi. this shows us that there is a structural possibility of acquiring regional colouration. we must remember, too, that the negative colouration of these dying leaves is of very much the same character as the positive colouration of flowers, for flowers are modified leaves, and their hues are due to the oxidation of the valuable chlorophyll. in leaves the tendency of spots to elongate in the direction of the leaf is very marked, as may be well seen in begonia. fig. 17, drawn to illustrate another point, shows this partly. when leaves are unsymmetrical, like the begonias, the pattern is unsymmetrical also. among parallel veined leaves we find parallel decoration. thus, in the _calatheas_ we have dark marks running along the veins. in _dracæna ferrea_ we have a dark green leaf, with a red border and tip, the red running downwards along the veins. this action may be continued until the leaf is all red except the mid-rib, which remains green. in long net-veined leaves we may cite _pavetta borbonica_, whose dark green blade has a crimson mid-rib. of unsymmetrical leaves those in the plate may suffice. when we come to flowers, the same general law prevails, and is generally more marked in wild than in cultivated forms, which have been much, and to some extent unnaturally, modified. broadly speaking, when a flower is regular the decoration is alike on all the parts; the petals are alike in size, the decoration is similar in each, but where they differ in size the decoration changes. thus, in _pelargoniums_ we may find all five petals alike, or the two upper petals may be longer or shorter than the lower three. in the first case each is coloured similarly, in the other the colour pattern varies with the size of the petal. the same may be seen in rhododendron. where the petals are united the same law holds good. in regular flowers, like the lilies, the colouration is equal. in irregular flowers, like the snapdragon and foxglove, the decoration is irregular. in gloxinia the petals may be either regular or irregular, and the decoration changes in concert. a very instructive case was noticed by one of us in _lamium galeobdolon_, or yellow archangel. this plant is normally a labiate with the usual irregular corolla, but we have found it regular, and in this instance the normal irregular decoration was changed to a regular pattern on each petal. in gamopetalous flowers the line of junction of the petals is frequently marked with colour, and we know of no case in which a pattern runs deliberately across this structure line, though a blotch may spread from it. when we remember that flowers are absolutely the result of the efforts of plants to secure the fertilizing attention of insects, and that they are supreme efforts, put forth at the expense of a great deal of vegetable energy--that they are sacrifices to the necessity for offspring--it does strike us forcibly when we see that even under these circumstances the great law of structural decoration has to be adhered to. [illustration: plate xii. flowers.] chapter xvi. conclusions. we have now, more or less fully, examined into the system of colouration in the living world, and have drawn certain inferences from the facts observed. it appears that colouration began--perhaps as a product of digestion--by the application of pigment to the organs of transparent creatures. supposing that evolution be true--and, if we may not accept this theory there is no use in induction whatever--it must follow that even the highest animals have in the past been transparent objects. this was admirably illustrated by prof. ray lankester in a lecture on the development of the eyes of certain animals, before the british association meeting at sheffield, in which it was shown that the eyes commenced below the surface, and were useful even then, for its "body was full of light." granting this, it follows that the fundamental law of decoration is a structural one. assuming, as we do, that memory has played a most important part in evolution, it follows that all living matter has a profound experience in decorating its organs--it is knowledge just as anciently acquired, and as perfectly, as the power of digestion. this colour was produced under the influence of light--so it is even in opaque animals. with a knowledge so far reaching, we might expect that even in opaque animals the colouring would still follow structural lines, and there should still be traces of this, more or less distinct. this is precisely what we do find; and, moreover, we sometimes get a very fair drawing of the important hidden parts, even where least expected, as in a cat's head, a snake's body, a dragon-fly's thorax, a spider's abdomen, a bird's skull. but if animals thus learned to paint themselves in definite patterns, we might expect that when called upon to decorate _for the sake of beauty_ certain parts not structurally emphatic, they would adopt well-known patterns, and hence arose the law of repetition. but with wider experience came greater powers, and the necessity for protection arising, the well-known patterns were enlarged, till an uniform tint is produced, as in the java pig, or some repeated at the expense of others, as in the civets. but so ingrained is the tendency to structural decoration that even where modification has reached its highest level, as in the leaf-butterflies, some trace of the plan that the new pattern was founded on is recognisable, just as the rectangular basis can be traced in the arabesque ornaments of the alhambra. the pointing out of this great fact has seemed to us a useful addition to the great law of evolution. it supplements it; it gives a reason why. could he who first saw these points have read these final pages, it would have lightened the responsibility of the one upon whom the completion of the work has fallen. but he died when the work was nearly finished. the investigation is of necessity incomplete, but nothing bears such misstatements as truth, and though specialists may demur to certain points, the fundamental arguments will probably remain intact. [illustration: finis.] glossary. acetabula. lat. _acetabulum_, a little vessel. sucking discs as on the tentacles of _physalia_. aorta. gr. the chief artery. cephalothorax. gr. _kephale_, head; _thorax_, chest. the anterior division of the body in crustacea and arachnida, composed of the amalgamated segments of the head and thorax. cilia. lat. _cilium_, an eyelash. microscopic filaments having the power of vibratory movement. c[oe]nosarc. gr. _koinos_, common; _sarx_, flesh. the common stem uniting the separate animals of compound hydrozoa, &c. corpuscle. lat. _corpusculum_, a little body. small coloured bodies, as in the endoderm of hydra, p. 59. differentiated. modified into definite organs, or parts; as distinct from structureless protoplasm. ectoderm. gr. _ektos_, outside; _derma_, skin. the internal layer or skin of the coelenterata. efferent. lat. _effero_, to carry out. a vessel which carries fluids out of the body is said to be efferent. endoderm. gr. _endon_, within; _derma_, skin. the inner layer or skin of coelenterata. _see_ ectoderm. endosarc. gr. _endon_, within; _sarx_, flesh. the inner layer of sponges. epidermal. gr. _epi_, upon; _derma_, skin. relating to the outer layer of skin. as applied to colour, surface pigment as distinct from hypodermal, or deep-seated colour. gastrovascular canal. gr. _gaster_, belly; lat. _vasculum_, a little vessel. the canals or vessels in the umbrella (_manubrium_) of hydrozoa. gonidia. gr. _gonos_, offspring; _oidos_, like. reproductive bodies in sea-anemones. hydranth. gr. _hudor_, water; _anthos_, flower. the bodies or polypes of hydroids which exercise nutritive functions. they were called polypites by huxley. hydrophyllia. gr. _hudor_ and _phyllon_, a leaf. leaf-like organs protecting the polypites of hydrozoa. hydrosoma. gr. _hudor_ and _soma_, body. the entire organism of a hydrozöon. hypodermal. gr. _hypo_, beneath; _derma_, skin. in colour, such as lies beneath the surface, as distinct from epidermal. lythocysts. gr. _lythos_, stone, _kystis_, a bladder. sense organs in hydroids, consisting of transparent capsules inclosing round transparent concretions. manubrium. lat. a handle. the central polypite suspended from the interior of the umbrella of hydroids. mesoderm. gr. _mesos_, intermediate; _derma_, skin. the middle layer of sponges, &c. mesothorax. gr. _mesos_ and _thorax_. the middle division of the thorax in insects, carrying the second pair of legs. peristome. gr. _peri_, about; _stoma_, a mouth. the area surrounding the mouth in sea-anemones. pneumatocyst. gr. _pneuma_, air; _kystis_ a bladder. the air-sac contained in the pneumatophore, see below. pneumatophore. gr. _pneuma_; _phero_, to carry. the float of certain hydrozoa (_physophoridæ_.) polypite. gr. _polus_, many; _pous_, foot. the separate animal or zöoid of a hydrozöon. _see_ hydranth. protoplasm. gr. _protos_, first; _plasso_, i mould. the jelly-like matter which forms the basis of all tissues. it is identical with the _sarcode_ or flesh of protozoa. sac. lat. _saccus_, a bag, a small cell. sarcode. gr. _sarx_, flesh; _eidos_, form. the protoplasm of protozoa, &c., which see. spadix. lat. _spadix_, a broken palm branch. in zoology a hollow process occupying the axis of the generative buds of hydrozoa. sporosac. gr. _spora_, a seed, and _sac_. the body containing the ova of hydrozoa. somatic fluid. gr. _soma_, the body. the fluid which contains digested food, and taking the place of blood, circulates through the body of hydrozoa. tentacles. lat. _tentaculus_, a little arm. the arms or prehensile organs of sea-anemones, &c. thread cells. cells containing an extensible microscopic thread, possessing stinging properties, common among the _coelenterata_. thorax. gr. a breastplate. the chest. index. page _abyla_ 63 _acanthometra_ 57 _actinea cari_, varieties of 66 ---_mesembryanthemum_ 54 _acanthostratus_ 57 _actinozoa_ 51, 52 _æschna_ 77 _agalma breve_ 64 _agrion puella_ 77 _aiptasia mutabilis_ 67 albinism in butterflies 79 _alcyonariæ_ 54 allman, prof., on hydroids 59, 60 "alps and sanctuaries" quoted 36 _amoeba_ 56 amphibia 89 _amphilonche_ 57 andres, dr., on hydrozoa 65 _anemonia sulcata_ 67 anemones, sea 52 animals and plants, origin of 36 ---classification of 49 _anoechtochilus_ 95 anteater 93 _anthocaris belemia_ 41 ---_belia_ 42 ---_cardamines_ 41, 42 ---_euphemoides_ 43 ---_eupheno_ 42 ---_simplonia_ 42 _apatura iris_ 46 ---larvæ of 81 _arachnida_ 82 _araschnia levana_ 43, 45 ---_porima_ 43, 45, 79 ---_prorsa_ 43, 45 _arctia_ 69 _arachnocorys_ 57 argus pheasant 6, 39, 91 _argynnis lathonia_ 69 armadillo 84 arthropoda, colouration of 85 ascidians 35 automatic habits 9 _arthorybia rosacea_ 64 badger 93 _begonia_ 95 birds, colouration of 89 ---of paradise 90 _biston betularia_ 79 black and white, production of 28 blackwell, j., on british spiders 82 _blatta_ 14 bougainvillea 16 bower birds 5 _bunodes crassicornis_ 54 ---_gemmaceus_, varieties of 66 ---_rigidus_ 67 burnet moths 5, 69 butler s., on inherited memory 9, 10, 11, 15 ---on origin of animals and plants 36 butterflies, albinism in 79 ---classification of 74 ---sense organs of 30 ---varieties of 77 _caladium_ 95 _calathea_ 96 _calycophoridæ_ 63 _carcinus moenas_ 4 _carpocanium_ 57 cats, colouration of 17, 92 ---recognising form 32 caterpillars, colours of 81 ---spiracular markings 22 _cephalopoda_ 87 _cerithium_ 86 char 88 chlorophyll in hydra 59 cicada 77 _cladococeus_ 57 classification of animals 49 ---of butterflies 74 _coelenterata_ 20 ---colouration in 51 _coelodendrum_ 57 _coenonympha davus_ 79 ---_pamphilus_ 79 coenosarc 55 _coleus_ 95 colour and form 32 ---and transparency 53 ---epidermal 72 ---following structure 83, 91 ---hypodermal 53, 73 ---nature of 25 ---of day-and-night flying insects 47, 69 ---opaque 53 ---perception of 5, 23, 25, 32 ---uniform, why rare 28 colouration 3 ---laws of 21, 51 ---of desert animals 4 ---of arthropoda 85 ---of coelenterata 51, 59 ---of insects 68 ---of invertebrata 49 ---of molluscs 85 ---of plants 94 ---of protozoa 51 ---of spiders 82 ---of vertebrata 88 ---sexual 5 ---varieties of 3 contour feathers 91 _conus_ 86 _coppinia arcta_ 60 _corallium rubrum_ 54 corals 54 correlation of teeth and hair 94 _corynida_ 52 cowries 86 crab, shore 4 croton 46 cuttle-fishes 19, 87 _cyllo leda_ 45 _cynthia cardui_ 68 _cypræa_ 86 _cyrtidosphæra_ 57 dallas, w. s., on butterflies 71 _danais_ 72 ---niavius 30, 80 darwin, c. 1, 2, 5, 9, 11, 14, 45, 47, 94 darwin, dr. e., cited 37 deer 92 deformity, antipathy to 32 _deilephila euphorbiæ_ 81 ---_galii_ 81 descent with modification 1 desert animals, colour of 4 _dictyoceras_ 57 _dictyophimus_ 57 _diphyes_ 63 disease, markings in 39, 44 distant, w. l., on malayan butterflies 80 distinctive colouration 3 dogs recognising portraits 32 _dracæna ferrea_ 96 elephant, increase of 2 engelmann on _euglena_ 34 epidermal colour 72 _eresus cinnabarinus_ 82 _eucecryphalus_ 57 _eucrytidium_ 57 _euglena viridis_ 34 evolution 1-98 eye-spots 45, 47 fayrer, sir w., on snakes 89 feathers 91 fishes, colours of 88 foal, stripes on 46 _foraminiferæ_ 56 fuller, w. j., on aquatic larvæ 77 gamopetalous flowers 96 gegenbaur's "comparative anatomy" cited 82 general colouration 3 _gloxinia_ 96 _gomphina_ 77 _gonepteryx cleopatra_ 41, 42 ---_rhamni_ 40, 42 gonophores 52 _grapta interrogationis_ 79 _gregarinidæ_ 56 guinea-fowl 91 haagen, dr., on colour 53, 72 habits 8 haeckel, prof., on _radiolaria_ 57 hair and teeth, correlation of 94 hawk moths 69 hebrides, colours of insects in 80 heredity 2 herpes 40, 93 heteromorphism 78 higgins, rev. h. h. 39 hoverer flies 84 humming birds 90, 92 hutchinson, mr., on herpes 40 huxley, prof., on hydrozoa 63 _hydra viridis_ 59 _hydrida_ 59 hydrozoa 51, 59 hypodermal colour 53, 72 identity of offspring and parent 11 identity, personal 10 inherited memory 8 insects, colour in 68, 75 john dory 89 _kallima inachus_ 30, 80 kentish glory moth 30 _lamium galeobdolon_ 96 lankester, prof. ray, on development of eyes 97 large copper butterfly 68 larvæ, colours of 45, 81 laws of emphasis 21 ---exposure 18 ---heredity 2 ---multiplication 2 ---repetition 21, 22 ---structure 18 ---variation 2 leaf-butterfly 16, 30 leidy, prof., on _rhizopoda_ 56 leopard 17, 92 _leucophasia diniensis_ 41 ---_sinapis_ 41 "life and habit" cited 9 light, reflected 26 ---sensibility to 33 ---waves 25 _liminitis sibilla_ 43 lion 17, 92 ---stripes on young 46 lithocysts of hydroids 62 _lucernaria auricula_ 65 _lycæna dispar_ 68 _lycosa agretyca_ 83 ---_allodroma_ 83 ---_andrenivora_ 83 ---_cambria_ 84 ---_campestris_ 83 ---_latitans_ 84 ---_picta_ 84 ---_piratica_ 84 ---_rapax_ 83 mackerel 88 _mactra_ 86 ---_stultorum_ 87 madrepores 54 mammalia, colouration in 92 _margarita catenata_ 87 measles 39 medusæ 52, 65 melanism in insects 79 meldola, prof. r., on melanism 79 _melitæa artemis_ 43 ---_athalia_ 43 mimicry 3, 4 mollusca 21 ---colouration in 85 monstrosities, antipathy to 32 _morphinæ_ 72 _morpho_ 4 _murex_ 86 muscles of insects 71 _nectarinea chloropygea_ 90 newman, mr., on varieties of butterflies 77 newts 89 nitzsch on feather-tracts 91 nudibranchs 85 _nymphalidæ_ 74 oak egger moth 30 ocelli 47 ocelot 93 _oliva_ 86 opaque colouring 53 organ-pipe coral 54 origin of animals and plants 36 ----species 1 orthopoecilism 78 oxen 94 painted lady butterfly 68 pangenesis 12 _papilio ajax_ 79 ---_machaon_ 43, 68, 76, 78 ------larva of 81 ---_merope_ 30, 76, 80 ---_nireus_ 14 ---_podalirius_ 43 _paradisea papuana_ 90 ---_regia_ 90 ---_speciosa_ 90 ---_wallacei_ 90 ---_wilsoni_ 90, 91 _pavetta borbonica_ 96 _pecten_ 86 pelargonium 96 perch 88 personal identity 10 _physalia_ 63 ---_caravilla_ 64 ---_pelagica_ 64 ---_utriculus_ 64 _physophoridæ_ 63 plaice 88 plants and animals, origin of 36 ---colour in 95 pneumatophores 63 portuguese man o' war 63 protective resemblance 3 _protista_ 34 protozoa 20 ---colouration in 51, 56 python 89 _radiolaria_ 57 rarity of uniform colour 28 ray lankester, prof., on ascidians 35 red admiral butterfly 29 repetition, effects of 8 reptilia, colouration in 89 resemblance, protective 3 _rhizophora filiformis_ 64 _rhizopoda_ 56 rhododendron 96 ringlet butterflies, eye-spots of 47 roach 88 romanes, prof., cited 33, 34 _satyrus hyperanthus_ 79 scales of insects, structure of 72 scarlet tiger moth 5 sea anemones 52 ------colours of 67 seasonal dimorphism 70 sea squirts 35 _segestria senoculata_ 83 selection, sexual 5 self-coloured flowers 28 sense organs of butterflies 30 _sertularidæ_ 63 sexual colours 4 ---selection 5 ---dimorphism 70 shell, structure of 85 shore crab 4 simple variation in butterflies 77 _siphonophora_ 63 small pox 39 snakes, patterns of 89 sollas, prof., on sponges 58 soles 88 _sparassus smaragdulus_ 82 species, origin of 1 _sphæronectes_ 63 _sphingidæ_ 45, 69 spiders, structure and colour of 82 spiracles of larvæ 22 _spondylus_ 86 sponges 57 _spongida_ 57 _spongocyclia_ 57 spots and stripes 39 _stephanomia amphitridis_ 63 struggle for existence 2 sun-birds 90 _sus vittatus_ 46, 94 sutton, mr. bland, on herpes 40 swallow-tailed butterflies 68 _syncoryne pulchella_ 62 systems of colouration 51 teeth and hair, correlation of 94 _thomisus cinereus_ 82 ---_floricolens_ 82 _thomisus luctuosus_ 84 ---_trux_ 82 thrush, increase of 2 tiger 17, 92 ---moths 69 _tipula_ 33 toucans 90, 92 transparency and colour 53 _trigonia_ 86 _tubipora musica_ 54 _tubularida_ 59 tylor, a., on specific change 10 _vanessa antiopa_ 76 ---_atalanta_ 29, 43, 69 ---_urticæ_ 77 variation in insects 70 ---law of 2 ---simple, in butterflies 77 _velella_ 52, 65 vertebrata, colouration of 88 _viverridæ_ 94 wallace, a. r., on sexual selection 5, 6, 14, 15 ---on colour 29 ---on abnormal structures 94 warning colours 4 wasps 84 weir, j. jenner, on variation in insects 78 weismann, dr., on caterpillars 81 wing of butterfly, typical 70 ---patterns of 76 woodpecker 91 yellow archangel 96 zebra 92 _zygæna_ 69 [illustration] [illustration: fig. 4.--python. _showing vertebra-like markings._] [illustration: fig. 5.--tiger. _the pattern changes at the points lettered._] [illustration: fig. 6.--tiger.] [illustration: fig. 7.--tiger. _showing supra-orbital nerve mark._] [illustration: fig. 8.--tiger. _showing cerebral markings, and markings over nerves near the eyes._] [illustration: fig. 9.--leopard. _the pattern changes at the points lettered._] [illustration: fig. 10.--leopard. _the pattern changes at the points lettered._] [illustration: figs. 11, 12.--leopards' heads.] [illustration: fig. 13.--lynx. _the colour changes at the points lettered._] [illustration: fig. 14.--lynx.] [illustration: fig. 15.--ocelot. _showing changes of pattern at the joints, &c., with enlargement of head-pattern._] [illustration: fig. 16.--badger. _the colour changes at the points lettered._] [illustration: fig. 17.--begonia leaf.] transcriber's notes: variations in spelling, punctuation and hyphenation have been retained except in obvious cases of typographical error. "haeckel" and "hæckel" were used interchangeably and have been standardized to "haeckel". image tags interrupting paragraphs have been moved. footnotes have been moved to end of chapters. solutions of baryta salts, has been described as carmine-coloured and permanent. we have not found it to be so--an experience which has evidently not been confined to ourselves; and we cannot help thinking that this is one of those errors which get copied from one chemical work into another, to the special confusion of students. it is but fair, however, to add that in mr. watts' dictionary of chemistry, the latest and best work of the kind, this ferrate is said to become "brick-red after washing and drying at 100° c.," and to be only "tolerably stable." 101. _gold reds._ many organic substances added to gold solutions throw down either the metallic gold or the red oxide, which then unites with the organic compound more or less decomposed and forms a red precipitate. sugar, gum, the decoctions of cochineal, gamboge, fustic, turmeric, sumach, catechu, and brazil wood, all afford red pulverulent colours. boiled with sugar, gold solution gives first a light and then a dark red. whatever their merits, the excessive costliness of these preparations renders them inadmissible as pigments. at one time, indeed, a gold compound known as purple of cassius was so employed, but this soon became obsolete on the introduction of madder purple. 102. _iodine pink._ there may be obtained from iodine and mercury a very pretty pink colour, analogous in composition to pure scarlet. it is apt to pass into the scarlet modification, and is in other respects even less to be depended on than that variety. 103. _kermes lake_ is an ancient pigment, perhaps the earliest of the european lakes, and so called from the arabic alkermes. it is sometimes spelt _cermes_, whence probably cermosin and crimson, and kermine and carmine. in old books it is named vermilion, in allusion to the insect, or _vermes_, from which it is prepared. this insect is the "coccus ilicis," which feeds upon the leaves of the prickly oak in the south of europe. like the "coccus cacti," it is covered with a whitish dust, and yields a tinctorial matter soluble in water and alcohol. kermes and the lac of india doubtless afforded the lakes of the venetians, and appear to have been used by the earliest painters in oil of the school of van eyck. the former, under the appellation [greek: kurno kokino], is said to be employed by the modern greeks for dyeing their caps red. some old specimens of this pigment which the author obtained were in drops of a powdery texture and crimson colour, warmer than cochineal lakes, and having less body and brilliancy. they worked well, however, and withstood the action of light better than the latter, though the sun ultimately discoloured and destroyed them. in other respects, they resembled the lakes of cochineal. as a colouring matter, kermes is only about one-twelfth part as powerful as that substance. 104. _lawson's red._ in 1861 it was stated that professor lawson had prepared a new dye of great richness, in the laboratory of queen's college, canada, from an insect, a species of coccus, found the previous summer for the first time on a tree of the common black spruce (_abies nigra_), in the neighbourhood of kingston. having been but recently observed, a sufficient quantity had not been obtained for a complete series of experiments as to its nature and uses; but the habits of the insect, as well as the properties of the dye, seemed to indicate that it might become of practical importance. in colour it closely resembled ordinary cochineal, but was rather more scarlet in hue. it was described as capable of being produced in temperate countries. the colouring matter had not then been thrown upon a base, nor do we know that it has since been introduced as a pigment. if it possessed greater stability than cochineal, with equal brilliancy and depth, this dye might form one of those colours of the future, to whose possible sources we would direct attention. 105. _manganese red._ bisulphide of arsenic combines with basic metallic sulphides forming a class of sulphur-salts, called by berzelius, hyposulpharsenites. the hyposulpharsenite of manganese is a dark red precipitate, uninjured by sulphuretted hydrogen, and so far applicable as a pigment. containing arsenic, it would of course be poisonous; and would probably be found to fade on exposure to air and light. 106. _murexide._ the red obtained from this substance created a great deal of interest among printers and dyers on its introduction in 1857, or thereabouts. for purity and brilliancy of shade it was not excelled by any other colour, but not being able to stand the effects of air and light, its employment was limited. we are not aware that murexide has yet been brought forward as a pigment, and judging from its character as a dye, it would scarcely enrich the palette. dyes and pigments have much in common, and a fugitive dye cannot be expected to furnish a permanent pigment. murexide is produced by the action of ammonia on alloxan, which is itself derived from the uric acid of guano by treatment with nitric acid, and was known nearly forty years back to stain the fingers and nails red. the first murexide sent into the market was a reddish-purple powder, dissolving in water with a fine purple tint, leaving a little residue undissolved. owing to improvements in manufacture, it is now capable of being prepared almost chemically pure, and with that green metallic reflection peculiar to several coal-tar salts and the wings of certain insects. when sulphuretted hydrogen is passed through a concentrated solution of murexide, it is immediately decoloured; a fact which renders it likely that murexide pigments would be as liable to suffer from an impure atmosphere, as from exposure to light and air. when an alkaline solution of murexide is precipitated by an acid, a light shining powder results, called purpuric acid. this dissolves in alkalies, and combines with metalline bases to form various coloured compounds, termed _purpurates_. among them may be mentioned a red purpurate of lead, a purple-red and a rose-coloured purpurate of mercury, a purple-red purpurate of silver, a dark red-brown purpurate of strontia, a crystalline red purpurate of cobalt, a scarlet purpurate of platinum, a yellow purpurate of zinc, and a green purpurate of baryta. all of these, however, being more or less soluble in water, and owing their colours to murexide, would be ill adapted for pigments. 107. _paille de mil,_ or african cochineal, is a substance obtained from africa. whether it has received its name of cochineal from its appearance or origin is not clear, but it behaves more like galls and sumac than cochineal, though it does give a kind of red with alumina mordants. the colours it yields are deficient in brightness, and it has otherwise been reported unfavourably of. 108. _peganum harmala,_ the seeds of which afford a red colour, has been investigated by the french, but described as inferior to existing reds both in brilliancy and stability. 109. _persulphomolybdates._ the metallic compounds formed by the combination of persulphomolybdic acid with a base are pulverulent, in many cases of a red colour, and for the most part insoluble in water. with barium, the acid furnishes a yellowish-red powder, insoluble in, but made denser by water, which imparts to it a cinnabar colour. with calcium it is said to yield a scarlet, sparingly soluble in water. with chromium, uranium, lead, platinum, and copper, it gives a dark red; that from the last metal turning brown when collected on a filter. it likewise produces reds with zinc, cadmium, iron, mercury, and tin; of which the last is slightly soluble in water. molybdenum being a rare metal, and persulphomolybdate of potash, the salt used in the foregoing reactions, difficult to prepare, it is unlikely that the colours named will rank among the pigments of this generation. nevertheless, as we have observed before, such fancy products should not be altogether ignored, it being quite as well to have some knowledge of our resources, even though those resources be not at present available. all the rare metals afford coloured compounds: tantalum, niobium, pelopium, vanadium, tellurium, titanium, yttrium, lanthanum, didymium, glucinum, cerium, thorinum, zirconium, palladium, rhodium, iridium, ruthenium, osmium, indium, thallium, &c.; and it is just possible that some of these may one day scrape acquaintance with the palette. 110. _red chalk_, the colouring matter of which is sesquioxide of iron, is used as a crayon. some specimens are excessively hard, so much so that they are difficult to crush, even in an iron mortar; while others have the consistence of the softest iron-ochres. they vary too in tint from a fawn colour to the softest brick-red, occasionally being almost as bright as a mixture of equal weights of vermilion and venetian red. the amount of iron oxide present has been found to range from four to thirty-seven per cent, according to the depth and hardness of the samples. when a specimen of red chalk tolerably rich, but not too rich, in iron oxide is finely powdered and strongly ignited, it offers a remarkable change of colour, becoming a dull sage-green. perhaps this, if it were permanent, might prove useful in foliage tints. 111. _red precipitate_, or mercuric oxide, may be obtained either of a brick-red or orange-yellow colour. it is destroyed by impure air, and on exposure to sunshine gradually turns black, being superficially decomposed into oxygen and metallic mercury or mercurous oxide. 112. _rose pink_ is a coarse kind of lake, produced by dyeing chalk or whitening with decoction of brazil wood, peachwood, sapan, bar, camwood, &c. it is a pigment much used by paper-stainers, and in the commonest distemper painting, &c., but is too perishable to merit the attention of the artist. chevreul obtained a crystalline substance from brazil wood, which he looked upon as the pure colouring matter, or as containing the pure colouring matter, and which gave red and crimson precipitates with many salts. possibly some of these might prove more durable than the roughly made rose pink. 113. _rouge_, the rouge végétale of the french, is a species of carmine, prepared from safflower or carthamus, which is the flower of a plant growing in the north of africa, india, and other warm climates. safflower yields two colours--a valueless yellow which dissolves in cold water, and about five per cent of red, insoluble in water but dissolved by alkalies. the red, or carthamin, furnishes a pigment of exquisite beauty, marked by richness, transparency, and free working. its extreme fugacity, however, militates against its employment by artists. as a dye, its manner of fixing upon fibre is different from that of any other colouring matter; requiring no mordant, like madder or cochineal, and needing no solution, like indigo or anotta, but fixing at once as soon as the cloth is brought into contact with it. but even for a dye the colour is fugitive, fading after a few hours' exposure to sunshine, and sometimes being quite bleached in the course of a day. it is when combined with levigated talc to form the paint of the toilette that the red becomes most serviceable. possessing a peculiar softness and velvety glow, rouge is an unrivalled--and a most harmless--aid to beauty. _chinese rouge_ and _pink saucers_ have much of the qualities of, and appear to be also prepared from, the safflower. 114. _rufigallic red._ when a duly proportioned mixture of gallic acid and oil of vitriol is carefully and gradually heated to 140°, a viscid wine-red liquid results. if this be poured into cold water, after cooling, a heavy brown-red granular precipitate is formed, soluble in 3333 parts of boiling water. it dissolves in potash-ley, and to fabrics impregnated with alum or iron mordants, imparts the same shades of colour as madder; the colours so produced withstanding soap but not chlorine. whether brilliant lakes could be obtained from the potash solution of the red, and whether those reds would be stable, it might be worth while to ascertain. 115. _sandal red._ we have kept this separate from other reds derived from woods, because it is said (by professor h. dussance) to be obtainable not only equal in beauty and brightness to carmine, but of greater permanence. the process of preparation is as follows:--the powdered root exhausted by alcohol gives a solution to which hydrated oxide of lead is added in excess. the combination of colouring matter and lead oxide is then collected on a filter, washed with alcohol, dried, dissolved in acetic acid, and mixed with a quantity of water. the red being insoluble therein is precipitated, while the acetate of lead remains dissolved. after being washed, the colour is dried at a low temperature. the professor affirms that the red so produced is unaffected by sulphuretted hydrogen, or by light and air; and it is stated that the colour which was used to paint the carriages of the emperor napoleon, remained as bright at the end of nine years as when it was put on. possessing such properties, it is curious that the red has never been--in this country at least--introduced as an artistic pigment, the more especially as seventeen years have elapsed since its discovery. 116. _silver red._ by adding monochromate of potash to an acid solution of nitrate of silver, a particularly fine ochre-red is obtained. it is, however, apt to be injured both by foul air and exposure. 117. _sorgho red._ some nine years back there was found to be a carmine colouring matter in most parts of the chinese sorgho, chiefly in the unpressed stem. the red, which is extracted in an impure state, is dissolved in weak potash-ley, thrown down by sulphuric acid, and washed with water. this purified product, soluble in alcohol, caustic alkalies, and dilute acids, has been employed in austria, baden, &c., for the dyeing of silks and woollens with the common tin mordants. the colours produced from it are unchanged, they say, by warm soapsuds or light. we do not know whether the red found its way to england, but it has certainly not appeared here as a pigment. 118. _thallium red._ the orange-yellow precipitate formed by mixing a neutral salt of protoxide of thallium with bichromate of potash, is converted by nitric acid into an orange-red. the latter compound, which is a terchromate, is almost insoluble in cold water, 2814 parts being required to dissolve it. if the colour be boiled in a large excess of moderately strong nitric acid it is dissolved, yielding magnificent cinnabar red crystals on the solution cooling. these crystals likewise seem to be the terchromate. 119. _tin pink._ by igniting strongly for some hours a mixture of stannic oxide, chalk, chromate of potash, and a little silica and alumina, a dingy red mass is obtained, which acquires a beautiful rose-red colour on being washed with water containing hydrochloric acid. for the same reason that the pinks of cobalt are superfluous as artistic pigments, this tin product is commercially ineligible. having, however, the advantage of being cheap, and being probably durable, it would be well adapted for the common purposes of painting, in place of the fugitive rose pink. 120. _ultramarine red?_ in gmelin's handbook of chemistry it is remarked that "hydrogen gas passed over ignited ultramarine, colours it light red, from formation of liver of sulphur, hydrosulphuric acid gas and water being evolved at the same time." on most carefully making the experiment with a sample of native blue (the variety referred to) we did not succeed in effecting this change: no alteration to red or even to purple took place, the only result being that the colour was entirely spoilt, having assumed a leaden slate-gray hue. at our request, the trial was kindly repeated by well-known chemists, who took every precaution to ensure success. several specimens of ultramarine were acted upon, but in no case was a red or anything like a red obtained, the products ranging from a slate-gray to a drab-grey. sufficient hydrosulphuric acid gas was evolved to blacken paper moistened with acetate of lead, a fact which proved that the blue had lost some of its sulphur. seeing that not only no red was produced, but that no tendency to red was imparted, is it possible the change described by gmelin occurred under exceptional circumstances? all conversant with chemical matters will admit that results are obtained occasionally which cannot be repeated, owing it may be to some slight difference in the materials employed, or some slight variation of the process. perhaps a link, considered of no importance at the time and overlooked, has been lost, and thus the whole chain of proceeding becomes useless. it is, therefore, within the bounds of probability that the red ultramarine of the great german chemist was furnished either by a peculiar specimen of blue, or by a modified form of the method he gives. we have noticed the subject at some length because if a red ultramarine, brilliant and durable, could be obtained, the colour might prove of value. a permanent artificial compound corresponding to french blue would certainly be an acquisition. 121. _uranium red._ by treating the yellow sulphite of uranium with a prolonged current of sulphuretted hydrogen, and saturating gradually with ammonia, a red finally results. this colour is insoluble in water, and it has the objection of remaining partially suspended for an almost indefinite time, colouring the liquid light red. the product is brighter and more beautiful while moist; when dried and powdered, its tone--slightly approaching vermilion--is duller. the colour may be obtained of several degrees of brilliancy, but, apart from the question of expense, it would be inadmissible in oil, the red gradually altering by contact therewith. the most persistent tint at length resembles burnt sienna. 122. _wongshy red._ there was imported a few years ago from batavia a new colouring principle, under the name of _wongshy_, and consisting of the seed-capsule of a species of gentian. the aqueous extract, freed from the pectin which it contains, yields with barytaand lime-water yellow precipitates, from which acids separate the colouring matter of a vermilion hue. when thus prepared it is insoluble in water, and would so far be adapted for a pigment. the red has not, however, been employed as such, and we are unacquainted with its habitudes. * * * * * the concluding remarks appended to the chapter on yellow apply equally to red, and indeed to all other colours. it is not assumed that the list is exhausted: there are other reds, but they are, like some we have mentioned, ineligible as pigments, either by reason of their fugacity, their costliness, the difficulty of producing them on a scale, or the sources whence they are derived being commercially unavailable. while endeavouring throughout the work to render complete the collection of pigments actually in use, it is our object to give a selection only of numbered italicised colours; ample enough, however, to include those which have become obsolete or nearly so, and full enough to afford some insight into our resources. the nearer we approach perfection, the more eager we are to arrive at it: the path before us, therefore, cannot fail to be of interest. looking back, and noting those pigments commonly employed, we find that the reds like the yellows are divisible into three classes--the good, bad, and indifferent; or the permanent, the semi-stable, and the fugitive. among permanent reds, rank cadmium red, madder reds, mars red, the ochres, and vermilions. in the second or semi-stable class, must be placed cochineal lakes, indian lake, and red chrome. to the third division, or the fugitive, belong dragon's blood, pure scarlet, red lead, and the coal-tar reds. with regard to the foregoing classification, it must be borne in mind that the properties and effects of pigments are much influenced by adventitious circumstances. sometimes pigments are varied or altogether changed by the grounds on which they are employed, the vehicles in which they are used, the siccatives and colours with which they are mixed, and the varnishes by which they are covered. and as there is no exact and constant agreement in different specimens of like pigments, so there is no exact and constant result in their use. artists vary as much as the pigments they employ: some resemble the old masters in the delicacy with which they treat their colours, the cleanliness with which they surround them, and the care with which they compound them: in the hands of such artists pigments have every chance. some, however, are characterized by a careless manipulation, a dirty mode of working, an utter disregard for all rules of admixture: with such painters the best colours may be ruined. and here, indeed, it may be asked, whether these latter are not more properly termed painters than artists, chiefly belonging as they do to that slap-dash school which manufactures pictures simply to sell them. duly subordinated, the commercial side of art has a value which it were affectation to ignore; but to paint merely for the present, heedless of the future, is to sink art to the level of a trade, not the most honest. for it is the purchaser who suffers from the want of thought bestowed on the materials, the sloppy manipulation, the careless compounding; sins of omission and commission that cause him, on finding his picture becoming chaos, to join the detractors of modern pigments. in classifying colours therefore, those also should be classified who use them:--into artists, whose love for art would render it more lasting than themselves; and into painters, whose motto is _vita brevis est, ars quoque_. chapter x. on the primary, blue. the third and last of the primary or simple colours is _blue_, which bears the same relation to shade as yellow to light. hence it is the most retiring and diffusive of all colours, except purple and black; and all colours have the power of throwing it back in painting, to a greater or less extent, in proportion to the intimacy of their relations to light--first white, then yellow, orange, red, &c. blue alone possesses entirely the quality technically called 'coldness' in colouring, and it communicates this property variously to all other colours with which it happens to be compounded. most powerful in a strong light, it seems to become neutral and pale in a declining light, owing to its ruling affinity with black or shade, and its power of absorbing light. consequently, the eye of the artist is liable to be deceived when painting with blue in too low a light, or toward the close of day, to the endangering of the warmth and harmony of his picture. entering into combination with yellow in the composition of all _greens_, and with red in all _purples_, blue characterizes the tertiary _olive_, and is also the prime colour or archeus of the neutral _black_, &c., as well as of the semi-neutral _gray_, &c.: it therefore is changed in hue less than any other colour by mixture with black, as it is likewise by distance. blue is present subordinately in all tertiary and broken colours, and being nearest in the scale to black, breaks and contrasts powerfully and agreeably with white, as in pale blues, skies, &c. being less active than the other primaries in reflecting light, it is sooner lost as a local colour by assimilation with distance. there is an ancient doctrine that the azure of the sky is a compound of light and darkness, and some have argued hence that blue is not a primary colour, but a mixture of black and white; but pure or _neutral_ black and white compound in infinite shades, all of which are neutral also, or _grey_. it is true that a mixture of black and white is of a _cool_ hue, because black is not a primary colour, but a compound of the three primary colours in which blue predominates, a predominance which is rendered more sensible when black is diluted with white. as to the colour of the sky, in which light and shade are combined, that is likewise neutral, and never blue except by contrast; thus, the more the light of the sun partakes of a golden or orange hue, and the more parched and burnt the earth is, the bluer appears the sky, as in italy and all hot countries. in england, where the sun is cooler, and a perpetual verdure reigns, infusing blue latently into the landscape, the sky is warmer and nearer to neutrality, partaking of a diversity of greys, which beautifully melodize with blue as their key, and harmonize with the light and landscape. therefore the colour of the sky is always a contrast to the direct and reflected light of the scene: if this light were of a rose colour, the neutral of the sky would be converted into green, or if purple, the sky would become yellow. similarly would it be in all cases, according to the laws of chromatic equivalence and contrast, as may be often seen in the openings of coloured clouds at the rising and setting of the sun. in art, blue is apt to be discordant in juxtaposition with green, and less so with purple, both which are cool colours; consequently blue requires its contrast, _orange_, in equal proportion whether of surface or intensity, to compensate or resolve its dissonances and correct its coldness. in nature, however, blue is not discordant with either green or purple, nor are any two colours (as we have said before) ever found so. on the palette of nature each _colour_ is an example of _colouring_: no colour is too absolute or defined, no perfectly pure blue appears beside a perfectly pure green. a blue flower nestled in its green leaves does not offend the nicest eye, but the blue and green are not blue and green alone. there is, perhaps, but a single gleam of pure colour in each: the rest is composed of such varied hues and tints and shades, so broken and blended and beautifully harmonized, that no jarring discord is possible. hue melts into hue, tint into tint, shade into shade; and thus does the simplest weed teach a lesson in colouring the proudest painter may stoop to learn. we have spoken of blue, which is termed a cold colour, as retiring; and of yellow and red, which are called warm colours, as advancing. by this we must not be understood to mean that blue, as blue, expresses distance; or that yellow and red, as yellow and red, express nearness. colours are advancing or retiring in their _quality_--as depth, delicacy, &c., not in their hue. a blue object set side-by-side a yellow one will not look an inch farther off, but a red or orange cloud, in the upper sky, will always seem to be beyond a blue cloud close to us, as it is in reality. we grant that in certain objects, blue is a _sign_ of distance, but that is not because blue, as a mere colour, is retiring; but because the mist in the air is blue, and therefore any warm colour which has not strength of light enough to pierce the mist is lost or subdued in its blue. blue in itself, however, is no more, on this account, retiring, than brown is retiring, because when stones are seen through brown water, the deeper they lie, the browner they appear. neither blue nor yellow nor red possesses, as such, the smallest power of expressing either nearness or distance; they merely express themselves under the peculiar circumstances which render them at the moment, or in that place, signs of nearness or distance. thus, purple in a violet is a sign of nearness, because the closer it is looked at the more purple is seen; but purple in a mountain is a sign of distance, because a mountain close at hand is not purple, but green or grey. it may, indeed, be generally assumed that a tender or pale colour will more or less denote distance, and a powerful or dark colour nearness; but even this is not always so. heathery hills will usually give a pale and tender purple near, and an intense or dark purple far away: the rose colour of sunset on snow is pale on the snow at one's feet, but deep and full on the snow in the distance; and the green of a swiss lake is pale in the clear waves on the beach, but intense as an emerald in the sunstreak, six miles from shore. and in any case, when the foreground is in strong light, with much water about it or white surface, casting intense reflections, all its colours may be perfectly delicate, pale, and faint; while the distance, when it is in shadow, may relieve the whole foreground with deepest shades of purple, blue green, or ultramarine blue. there is one law, however, about distance, which has some claims to be considered constant, namely, that dulness and heaviness of colour are more or less indicative of nearness. all distant colour is pure colour: it may not be bright, but it is clear and lovely, not opaque nor soiled; for the air and light coming between us and any earthy or imperfect colour, purify or harmonize it; hence a bad colourist is peculiarly incapable of expressing distance. it is not of course meant that bad colours are to be used in the foreground by way of making it come forward; but only that a failure in colour there will not put it out of its place. a failure in colour in the distance will at once do away with its remoteness; a dull-coloured foreground will still be a foreground, though coloured badly; but an ill-painted distance will not be merely a dull distance, it will be no distance at all. this seeming digression is not out of place, as it will enable the artist better to understand that it is in their quality, not in their hue, that colours are advancing or retiring; and that he must rely on the depth, delicacy, &c., of his pigments, and not simply on their colours, to produce effects of distance. of all colours, except black, blue contrasts white most powerfully. in all harmonious combinations of colours, whether of mixture or neighbourhood, blue is the natural, prime, or predominating power. accordingly, blue is universally agreeable to the eye in due relation to the composition, and may more frequently be repeated therein, pure or unbroken, than either of the other primaries; whence the employment of ultramarine by some masters throughout the colouring of a picture. blue pigments, like blue flowers, are more rare than those of the other primary colours. in permanent blues the palette is very deficient, the list being exhausted when the native and artificial ultramarines and the cobalts have been mentioned. that there is room for new blues, durable and distinct, cannot therefore be denied. a good addition has been made of late years in the german _coëlin_, known here as cerulian blue and coeruleum. what is chiefly wanted, however, is a colour combining the wonderful depth, richness, and transparency of prussian blue with the strict stability of ultramarine. a permanent prussian blue would be the most valued gift the palette could receive. cobalt blues comprise _cerulian blue_ or _coeruleum_, _cobalt blue_, _smalt_, _royal blue_, _dumont's blue_, _saxon blue_, _thénard's blue_, _leithner's blue_, _hungary blue_, _dutch ultramarine_, _zaffre or enamel blue_, _vienna blue_, _paris blue_, _azure_, &c., and are obtained by the action of heat on mixtures of earthy or metallic bases with cobalt. they are divisible into three classes--the stannic cerulian blue, the aluminous cobalt blues, and the siliceous smalts. of these, the first possesses the least depth; the second hold a middle position; while the third are marked by exceeding richness. although not to be ranked with ultramarine, the stannic and aluminous blues may be described as durable, or at least as durable rather than semi-stable. there are, as we have before observed, different degrees of permanence, and the blues in question are not readily affected. with regard to smalts, they are, as artist's pigments, inferior in stability to other blues of cobalt. 123. cerulian blue, or _coeruleum_. under the name coëlin there has of late years been imported from germany the cobalt blue with a tin base to which reference has just been made. this comparatively new pigment--which likewise contains or is mixed with gypsum, silica, and sometimes magnesia--has the distinctive property of appearing a pure blue by artificial light, tending neither to green on the one hand nor to purple on the other. this advantage, added to its permanence, has conferred a popularity upon coeruleum which its mere colour would scarcely have gained for it. a light and pleasing blue, with a greenish-grey cast by day, it possesses little depth or richness, and is far excelled in beauty by a good aluminous cobalt. a certain chalkiness, moreover, somewhat detracts from its transparency, and militates against its use in water. it is in oil, and as a night colour, that coeruleum becomes of service, as our present system of lighting picture galleries by gas affects the purity of blues generally. if those galleries were illuminated by means of the electric light, we have it on the authority of chevreul that all colours and shades would show as well as by day: the same purpose would be answered by the magnesium light. some artificial lights are the ruin of colours; in the soda flame (alcohol and salt) for instance, yellow chromate of lead appears white, while red ochre and aniline blue appear black. like other blues of cobalt, coeruleum assumes a greenish obscurity in time, but like them it resists for a lengthened period both the action of light and impure air, although chemically it is more open to the influence of the latter, owing to its tin base. in admixture it may safely be employed, as well as in fresco or enamel. for stage skies, &c., in high-art scenery, the blue is admirably adapted. now that there are so many scene-painters who are artists--and so many artists who are scene-painters--in bringing nature to the foot-lights the effect of gas on colours is of importance. 124. cobalt blue, to which the various appellations have been given of _thénard's blue_, _vienna blue_, _paris blue_, _azure_, _cobalt-ultramarine_, &c., is the name now exclusively confined to that preparation of cobalt which has a base of alumina. it may, therefore, be not improperly called a blue lake, the colour of which is brought up by fire, in the manner of enamel blues. the discovery of this important pigment was made in 1802 by m. thénard, who obtained it by calcining a well-combined mixture of alumina and crystals of cobalt. there may be employed with the aluminous base, either the arseniate, the borate, or the phosphate of cobalt; but the latter in preference, as it produces the purest colour. the arseniate has always a violet tinge, more visible by gas-light than by day; while, on account of the arsenic, the blue is more apt to be greened by impure air, by reason of the formation of yellow sulphide of arsenic. the purity of the colour, however, does not altogether depend on the compound of cobalt used; in a great measure--as with other pigments--it rests on the purity of the materials. to obtain a perfect blue, neither inclining to purple nor green, the cobalt and alumina should be freed from iron, and the former, as much as possible, from nickel also. with the absence of these and proper skill, a true and brilliant blue may be produced, almost rivalling the finest ultramarine. apart, too, from its increased beauty, a cobalt blue containing no iron or nickel is of greater permanence than the ordinary products, being less liable to that greenness and obscurity which time confers. though not possessing the body, transparency, and depth of ultramarine, nor its natural and modest hue, commercial cobalt blue works better in water than that pigment in general does; and is hence an acquisition to those who have not the management of the latter. resisting the action of strong light and acids, its beauty declines by time, while impure air greens and ultimately blackens it. nevertheless, these changes are not readily effected, especially in well made samples full of colour, and sometimes the green tone is mechanically imparted. what wheat is to a loaf, colour is to a pigment--it has to be ground and made up for use; in the one vehicle to be mixed with gums, in the other with oils. it often happens that colours have an antipathy to the latter, and refuse to compound kindly therewith. occasionally this repugnance manifests itself in a few days, occasionally not for months. we know of a green which flatly declines to have anything to do with oils, sinking and separating therefrom in the course of a week, and leaving the clear oil on the top. repeatedly have colours to be coaxed to behave themselves as pigments, coaxed not to 'run,' to work well, to dry well, &c.; and in the humouring of their likes and dislikes the skill and patience of the artist-colourman are sometimes severely taxed. given a colour, it might puzzle most chemists to convert it into a pigment; luckily commerce lends her aid. lasting success, it is true, does not always follow, and oils will rise to the surface now and then, giving green hues to blues, orange hues to reds, and buff hues to yellows. hence changes of colour have been imputed before now to chemical alteration, when in reality the results have been physical, caused by the subsidence of the pigments, and the floating of the vehicles employed. cobalt blue dries well in oil, does not injure or suffer injury from pigments in general, and may be used with a proper flux in enamel, as well as in fresco. it affords clear bright tints in skies and distances, but is apt to cause opacity if brought too near the foreground, and to assume a violet tinge by artificial light. with madder brown it yields a range of fine pearly neutrals; and with light red, in any proportion, gives beautiful cloud tints. in combination with aureolin and sepia, or rose madder, cobalt furnishes most agreeable and delicate tints for distant trees, when under the influence of a soft light, or hazy state of the atmosphere. in water-colour painting, cobalt is tolerably firm on paper, and consequently answers better for some purposes than french blue. in middle distances, if the cobalt possess a tendency to chalkiness, the addition of a little indigo is a good corrective, especially where the blue tone is required to be sombre and dark: it should, however, be observed that the change is but temporary, indigo being a fugitive pigment. in marine painting in water-colours, cobalt is most useful for the remotest parts of seas and headlands. when dry, it can be changed by going over it with a slight wash of vermilion or light red, whereby a prismatic character is realized. any strength of tone can be obtained by repeating the washes, and should the colour be too powerful, it may be reduced by pouncing it with a soft wet sponge; or if too cold and blue, by a thin wash of burnt sienna, merely the water stained. the blues of cobalt, on whatever base they may be prepared, are distinguished from native and artificial ultramarines by not being decolorised by acids. 125. smalt, invented about the year 1540, in saxony, is a vitreous compound of cobalt and silica, in fact a blue glass. since the fifteenth century, cobalt has been used in different parts of europe to tinge glass; and so intense is the colouring power of its oxide, that pure white glass is rendered sensibly blue by the addition of one thousandth part, while one twenty-thousandth part communicates a perceptible azure tint. in common with cobalt blue, the name _azure_ has sometimes been given to it. varying exceedingly in quality and colour, the rougher kinds have been employed by the laundress, and in the making of porcelain, pottery, stained glass, encaustic tiles, &c.; as well as to cover the yellow tinge of paper. for this last purpose, however, smalt is not perfectly adapted, the colour being difficult to lay on uniformly, and the paper when written on blunting the nibs of pens. hence it has been superseded to a great extent by artificial ultramarine, the presence of which may be detected by the yellow spot which a drop of acid leaves on the paper. a coarse gritty texture is peculiar to smalt, whether it be the _powder blue_ of the washtub and _blue sand_ of the pottery, or the _dumont's_ and _royal blue_ of the artist and high-class manufacturer. but the strict stability which is a feature in smalt when used for painting on glass and enamel does not follow it to the studio: both in water and oil its beauty soon decays, as is often the case with other vitrified pigments; nor is it in other respects eligible, being, notwithstanding its richness and depth, very inferior to the cobalts preceding. it may seem a paradox that the same colour should be at once so durable and so fugitive, but we may briefly explain it by saying _when vitreous pigments are reduced to that extreme state of division which the palette requires, they lose the properties they possess in a less finely divided state_. the best smalt in lumps appears black, yields a blue powder on grinding, becomes paler on further grinding, and may be almost decolourised by continued and excessive grinding. smalt, it has been stated, is merely a blue glass; and when a piece of blue glass, or a blue crystal of sulphate of copper, is reduced to the fineness of flour, the blue is lost. in vitrified and crystallised compounds, colour depends on cohesion: sufficiently separate the particles, and the colour more or less disappears. not only, moreover, does grinding effect an optical change in vitreous pigments, but it imposes further alteration. that colour which was safe when locked up in a mass, crushed to minute atoms is no longer so: imbedded in glass or enamel it will endure for ages, but ground to impalpable powder becomes as liable to influence as though it had never been subjected to heat at all. to sum up, vitreous pigments are durable in a coarse or compact form, but are not more stable than others when reduced to extreme division. as far as regards artists' colours, therefore, vitrification does _not_ impart permanence. the grittiness to which we have referred is one of the defects of smalt, which cannot, consistently with preserving its colour be entirely freed from that drawback--an objection which pertains to vitreous pigments in general. hence it does not wash well, and in mural decoration is sometimes applied to work by strewing the dry powdered colour upon a flat ground of white or blue oil paint immediately after the latter is laid on, whilst it yet remains wet. of little body, it is a vivid and gorgeous blue; bright, deep, and transparent, bordering on the violet hue. it is chiefly employed in illumination and flower painting. the inferior kinds of smalt are occasionally adulterated with chalk. 126. cyanine. beckmann is fully convinced that the _cyanus_ of theophrastus and the _coeruleum_ of pliny were a blue copper earth. however that may be, in these days both names signify cobalt compounds, coeruleum being a stannate of cobalt, and cyanine a mixture of cobalt and prussian blue. unlike the former, cyanine, being composed of two old colours, can lay no claim to originality. in the fourth chapter it was observed, "it is quite possible for the artist to multiply his pigments unnecessarily. colours are sometimes brought out under new names which have no claim to be regarded as new colours, being, indeed, mere mixtures. compound pigments like these may most frequently be dispensed with, in favour of hues and tints composed extemporaneously of original colours upon the palette." whether these remarks are applicable to cyanine or not is a question for artists to decide: in our opinion, with so many semi-stable original pigments, the introduction of semi-stable compounds is to be deprecated. cyanine is a rich, deep, transparent blue, but its richness and depth, as well as to a great extent its transparency, depend upon prussian blue, which is not strictly stable. hence the peculiar properties of cyanine remain unchanged only so long as the prussian blue itself, the pigment losing its colour by degrees on exposure to air and light, and gradually assuming the tint of the paler but more permanent cobalt. a mixture, be it remembered, necessarily partakes of the qualities of its constituents, and if one of these be fugitive, the compound cannot preserve its original hue. within the last few years, a compound similar to cyanine has appeared, under the name of _leitch's blue_. 127. indigo, or _indian blue_, was known to the ancients under the name of _indicum_, whence its present appellation. in modern europe, it first came into extensive use in italy; but about the middle of the sixteenth century, the dutch began to import and employ it in considerable quantity. present in the woad plant, which is a native of great britain, indigo is chiefly derived from a genus of leguminous plants called _indigofera_, found in india, africa, and america. the colouring matter of these is wholly in the cellular tissue of the leaves, as a secretion or juice; not, however, in the blue state in which one is accustomed to see indigo, but as a colourless substance, which continues white only so long as the tissue of the leaf remains perfect: when this is by any means destroyed, oxygen is absorbed from the atmosphere, and the principle becomes blue. the best indigo is so light as to swim upon water, but the commercial article seldom contains more than 50 per cent. of blue colouring matter or true indigo, the remainder consisting of either accidental or intentional impurities. in painting, indigo is not nearly so bright as prussian blue, but it is extremely powerful and transparent, and may be described as a prussian blue in mourning. of great body, it glazes and works well both in water and oil. its relative permanence as a dye has obtained it a false character of extreme durability as a pigment, a quality in which it is nevertheless very inferior even to prussian blue. by impure air it is injured, and in glazing some specimens are firmer than others, but not durable; while in tint with white lead they are all fugitive. employed in considerable body in shadow, it is more permanent, but in all respects prussian blue is superior. despite this want of stability, indigo is a favourite colour with many artists, who sacrifice by its use future permanence to present effect. it is so serviceable a pigment for so many purposes, especially in admixture, that its sin of fugacity is overlooked. hence we find indigo constantly mentioned in works on painting, their authors forgetting or not caring to remember that wholesome axiom, a fugitive colour is not rendered durable by being compounded. artistically, it is adapted for moonlights, and when mixed with a little lamp black, is well suited for night clouds, distant cliffs, &c. with a little raw umber and madder it is used for water in night effects. with the addition of a little madder it forms a good gray; and with madder and burnt sienna is useful for dark rocks, this combination, with raw sienna, being also eligible for boats. for these and other mixed tints, however, prussian blue saddened by black with a suspicion of green in it, is equally fitted, and is more permanent. indeed, it would be perhaps justifiable to introduce such a compound, under the name say, of factitious indigo. indigo in dust, or in small bits, is often adulterated with sand, pulverized slate, and other earthy substances. that indigo is best which is lightest, brightest, most copper-coloured, most fine-grained, and inodorous. 128. intense blue is indigo refined by solution and precipitation. by this process, indigo becomes more durable, and, being separated from impurities, is rendered much more powerful, transparent, and deep. it washes and works admirably in water; in other respects it possesses the common properties of indigo. it is apt, however, to penetrate the paper on which it is employed, if not well freed by washing from the acid and saline matter used in its preparation. this is not always easily effected, and we cannot help thinking that in the manufacture of intense blue a dry method would be preferable. indigo may, by cautious management, be volatilized, and therefore be most thoroughly purified without the aid of acids and alkalies. the best mode of subliming this substance is to mix one part of indigo with two parts of plaster of paris, make the whole into a paste with water, spread it upon an iron plate, and, when quite dry, heat it by a spirit lamp. the volatilization of the indigo is aided by the vapour of water disengaged from the gypsum, and the surface of the mass becomes covered with beautiful crystals of pure indigo, which may be readily removed by a thin spatula. at a higher temperature, charring and decomposition take place. 129. prussian blue, otherwise called _berlin blue_, _paris blue_, _prussiate of iron_, _ferrocyanide of iron_, &c., was accidentally discovered in 1710 by diesbach, a colour-maker at berlin. it is a compound of iron and cyanogen, of varying composition, formed by adding yellow prussiate of potash to a persalt of iron, or by oxidizing the precipitate obtained from the prussiate and a protosalt. the finest blue is furnished by sesquinitrate of iron, but the salt almost exclusively employed is the protosulphate, the freedom of which from copper is essential to the colour of the blue. as is the case with other pigments, prussian blue differs considerably in colour, in depth, and in permanence, according to the purity of the materials, the mode of manufacture, and the absence of adulterants. like smalt, it is known in the washtub as well as in the studio; and in the cheaper varieties, alumina, starch, chalk, oxide of iron, &c., are often largely present. a good unsophisticated sample in the dry state is intense blue, almost black, hard and brittle, much resembling in appearance the best indigo, and having a similar copper-red fracture. it does not effervesce with acids, as when adulterated with chalk; nor become pasty with boiling water, as when sophisticated with starch. further, it feels light in the hand, adheres to the tongue, is inodorous, tasteless, not poisonous, and is insoluble in water. forming a bulky mass while moist, prussian blue shrinks to a comparatively small compass when well washed and dried by gentle heat; and, when once dried, being difficult to reduce again to the state of extreme division which it possessed while wet, it is frequently sold and used in paste for common purposes. we have said that a good sample of prussian blue is insoluble in water, and for artistic use it should certainly be so, as otherwise it has a tendency to stain the fabric on which it is employed, a defect formerly very prevalent. all prussian blues, however, are not insoluble, and these are not only liable to the drawback named, but are less to be depended on for permanence. improper proportions, for instance, of sesquichloride of iron and potash-ferrocyanide will yield a blue which, when washed even with cold water, continually imparts to it a yellow or green colour, through the partial solution of the prussiate. all commercial prussian blue, and indeed that which is prepared by careful chemical processes, give up the ferrocyanide to boiling water, thereby colouring it greenish yellow; but a sample which parts with its prussiate to _cold_ water is quite unfitted for the palette, for which the most perfect specimen is none too stable. in spite of the learned researches of professor williamson, whose name is as closely connected with the pigment as are the names of schunck and de la rue with madder and cochineal, prussian blue is not yet entirely understood. complex and uncertain in composition, uncertain too in its habitudes, our best course perhaps will be not to attempt a complete survey, but to state briefly those facts which bear on the artist's craft. prussian blue is a colour of vast body and wonderful transparency, with a soft velvety richness, and of such intense depth as to appear black in its deepest washes. notwithstanding it lasts a long time under favourable circumstances, its tints fade by the action of strong light; becoming white, according to chevreul, in the direct rays of the sun, but regaining its blue colour in the dark; hence that subdued light which is favourable to all colours is particularly so to this blue. its colour has the singular property of fluctuating, or of coming and going, under certain conditions; and which it owes to the action and reaction by which it acquires or relinquishes oxygen alternately. it also becomes greenish sometimes by a development of the oxide of iron; and is purpled, darkened, or otherwise discoloured by damp or impure air. time has a neutralizing tendency upon its colour, which forms tints of much beauty with white lead, though they are not equal either in purity, brilliancy, or permanence to those of cobalt and ultramarine. when carefully heated, prussian blue gives off water and assumes a pale green hue; its colour, therefore, depending on the presence of water, must not be exposed to a high temperature. and as it is likewise injured or destroyed by alkalis, which decompose it into oxide of iron and a soluble prussiate, the blue should be avoided in fresco, on account of the lime; neither should it be employed with pigments of an alkaline nature, nor with hard water containing bicarbonate of lime in solution, but with clean rain or distilled water, either of which is preferable for colours generally. prussian blue dries and glazes well in oil, but its great and principal use is in painting deep blues, in which its body helps to secure its permanence, and its transparency gives force to its depth. it is also valuable in compounding deep purples with lake, and is a powerful neutralizer and component of black, to the intensity of which it adds considerably. prussian blue borders slightly on green, a quality which militates against its use in skies and distances. in spite, however, of its want of, or deficiency in, durability, the old water-colour painters so employed it, neutralized by the addition of a little crimson lake. it is serviceable in mixed tints of greens, affording with light red a sea-green neutral. dissolved in oxalic acid, the blue is available as an ink, or for tinting maps. besides the preceding, there is a _basic prussian blue_, formed by simply submitting to the air the bluish-white precipitate which falls on adding yellow prussiate of potash to green vitriol. this compound dissolves entirely by continued washing with water, yielding a beautiful deep blue solution, from which the colour may be thrown down in a solid form by the addition of any salt. probably it was this basic preparation, so cheaply and easily made, that conferred upon prussian blue the character of staining paper. in name, there is also another variety of this pigment, known as _native prussian blue_; which is really a native phosphate of iron, occurring as a blue earthy powder, or as a white powder that becomes blue by exposure. 130. antwerp blue, _haerlem blue_, _berlin blue_, _mineral blue_, is a lighter and somewhat brighter prussian blue, with less depth and less permanence. it is a species of lake, having a considerable proportion of aluminous base, to which its paler tint is due. as the stability of prussian blue rests in a great measure on the marvellous amount of latent colour the pigment contains, when its particles of colour are set farther apart by the intervention of the alumina, the permanence of its hue is endangered. it was remarked, with respect to vitrified pigments, that colour depends on cohesion. more or less, this holds good as regards all pigments; but not only, as was also observed, does colour rest on cohesion, in many instances durability depends likewise. it is only when a colour is stable in itself that its particles will bear separating: native ultramarine, for example, may be weakened almost to white, and will still preserve its hue. if, however, a colour be naturally fugitive, and rely chiefly on its extreme depth for what permanence it possesses, that colour cannot with impunity be paled: witness the cochineal lakes, which the deeper they are, the more durable they are found; and so it is with prussian blue. antwerp blue is distinguished from the latter by its more earthy fracture. 131. turnbull's blue, or _ferricyanide of iron_, is formed by adding the red prussiate of potash to a protosalt of iron. this blue is lighter and more delicate than ordinary prussian blue, and is believed to resist the action of alkalies longer. it is a question whether the common prussian blue obtained by oxidizing the precipitate yielded by green vitriol and the yellow prussiate is not in reality this variety. however that may be, there is, as far as permanence goes, little or no difference between the two kinds. ultramarines. artificial ultramarines comprise the varieties known as _french ultramarine_, _french blue_, _brilliant ultramarine_, _factitious ultramarine_, _guimet's ultramarine_, _new blue_, _permanent blue_, _gmelin's german ultramarine_, _bleu de garance_, _outremer de guimet_, &c. the unrivalled qualities of native ultramarine prepared from the lapis lazuli rendered it most desirable to obtain an artificial compound which, while possessing similar properties, could be produced in quantity, and at a less costly rate. in demolishing some furnaces employed in making soda, by means of decomposing sulphate of soda, some earth had been found impregnated with a light blue, which was proved to have so close a resemblance to ultramarine as to foster hopes of success. as a stimulus, there was offered a prize of six thousand francs or £500 for the production of artificial ultramarine by the _société d'encouragement_ of paris, which was won in 1828 by m. guimet. it is fitting that the discoverer of a colour should excel in its manufacture, and to this day guimet's ultramarine is the finest made. as an instance of how the researches of different men may, almost simultaneously, lead to the same results, it is curious that very shortly after the problem was also solved by gmelin. the cause of the blue colour of ultramarine was long a matter of controversy, but was believed generally to be due to iron. when, however, the discovery of artificial ultramarine was made, this assumption was shown to be false, by the fact that a blue could be obtained with materials perfectly free from iron. the absolutely necessary constituents of ultramarine are silica, alumina, sulphur, and soda; and there is little doubt that the colouring matter consists of hyposulphite of soda and sulphide of sodium: it is certain that the blue colour is dependant on the soda, inasmuch as potash yields an analogous compound which is purely white. a number of substances, such as iron, lime, magnesia, and potash, may be present as impurities, and were, in part at least, purposely added to the earlier manufactures; but they are found to be superfluous. nevertheless, as regards iron, it is probable that a very small portion, such as is usually contained in the ingredients, greatly facilitates the production of the blue, and may even be essential in some cases. the colour of ultramarine is brought out by successive heatings. green portions, more or less in quantity, are often formed in the crucibles, especially on the first ignition. on repeated heating they pass into a blue tint. artificial ultramarines are said to be seldom entirely freed from all traces of the green modification, and are therefore less beautiful than the natural varieties, having a shade of green or grey. this defect, however, is certainly not discernible in guimet's products, which sometimes incline so much to purple as to require neutralizing with a little prussian blue. depth for depth, the artificial are darker and less azure than the natural varieties, but the superiority of the latter consists not so much in their greater purity of hue, although this is considerable, as in their far greater transparency. the finest french ultramarine is never so transparent as the native; it is brilliant, it is powerful, it is permanent, it is nearly--but only nearly--transparent. possessing in a subdued degree the characteristics and qualities of the genuine, it works, washes, and dries well; and is useful either in figures, draperies, or landscape. rivalling in depth, although not equalling in colour, the pure azure of native ultramarine, it answers to the same acid tests, but is sometimes distinguished therefrom by the effervescence which ensues on the addition of an acid. not a bubble escapes in such case from the natural blue; unless, indeed, as occasionally happens, it retain a portion of alkali, with which it may have been combined in the preparation, but from which it should have been freed. darkened as a rule by fire, factitious ultramarine becomes dingy blue, and at last white, when strongly ignited for a long time; and is, like the true variety, decolourised by ignition in an atmosphere of hydrogen gas. at a high temperature, this effect is even produced by silica, whence the unfitness of ultramarine for painting on glass or porcelain; and simply by a prolonged red heat the blue is rendered white. being unaffected by alkalis, it is eligible in mural decoration, and is particularly adapted to siliceous painting, on account of the silica and alumina which it contains, two substances with which a soluble silicate readily unites. if artificial ultramarine be mixed with a soluble silicate, for example silicate of potash, and be laid on a properly prepared ground, it will become so firmly fixed, says mr. barff, that no amount of washing nor the slow action of moisture will remove it, or affect its brilliancy. judging from the behaviour of ultramarine, therefore, if the colours employed in siliceous painting contain silica and alumina, they should adhere as firmly to the surface on which they are placed; and this is really the case. it is possible to produce a mixed solution of aluminate and silicate of potash which will remain liquid for twenty-four hours. if, while in the liquid state, colours are saturated with this solution and allowed to dry, their particles will be very intimately mixed with silica and alumina chemically combined with potash. according to the author quoted, the admixture of silica and alumina does not interfere with the brilliancy or depth of the colours, and the method may be used for all those which are not injured by potash, and are in themselves adapted to the art. with respect to permanence, the finer varieties of artificial ultramarines may, undoubtedly, be pronounced stable; but, like all other colours, these blues are apt to vary in quality, and inferior kinds are liable to lose their purity in a measure, and become grayer. moreover, they are made by different processes, and the mode adopted for the manufacture of a pigment not only tells upon the colour, but may influence to some extent its durability. from the following experiment of an ingenious artist and friend of the author, it is evident that the production of artificial ultramarine was not carried in its early days to that state of perfection at which it has now arrived. he took a picture, the sky of which had been recently painted in the ordinary manner with prussian blue and white; and having painted over the clear part of the sky uniform portions with tints formed of the best factitious ultramarine, cobalt blue, and genuine ultramarine, so as to match the ground of the sky, and to disappear to the eye thereon by blending with the ground, when viewed at a moderate distance, he set the picture aside for some months. upon examination, it appeared that the colour of these various blue pigments had taken different ways, and departed from the hue of the ground: the factitious ultramarine had _blackened_, the cobalt blue _greened_, the genuine ultramarine remained a _pure azure_, like a spot of light, while their ground, the prussian blue sky, seemed by contrast with the ultramarine of a _grey_ or _slate colour_. other things being equal, those artificial ultramarines are most durable which possess the most colour; and all are, perhaps, most permanent in water. if used in that vehicle, care should be taken to employ a gum free from acid; also, whether in water or oil, not to compound the blue with a pigment which may possibly contain acid, such as constant white. acid, as we have said, is the great test for ultramarine; whence if a sample be sophisticated with cobalt, its blue colour will not be entirely destroyed. with high-class artistic pigments, however, adulteration is the exception and not the rule. it is as a powder-blue for the washtub that ultramarine gets disguised, when it is ground up with soda-ash, chalk, gypsum, &c., and sold sometimes under its own name, but more frequently as superfine saxon smalts. 132. brilliant ultramarine, lately called _factitious ultramarine_, is a specially fine preparation of m. guimet, presenting the nearest approach to the natural product of any artificial ultramarine, both in transparency, purity of hue, and chemical characteristics. equalling in depth and power the ordinary french ultramarine, it possesses greater clearness, beauty, and brightness; and has, in a subdued degree, that quality of light in it, and of the tint of air, which forms so distinguishing a feature in the native blue. 133. french ultramarine, or _french blue_, is a rich deep colour, but less transparent and vivid than the preceding variety, which is preferable in unmixed tints. for compound hues, french blue is sufficiently well adapted, and is extremely useful. with aureolin and burnt sienna, or vandyke brown, it affords valuable autumn greens; and with lamp black, or lamp black and light red, good stormy clouds. a sombre gray for distant mountains is furnished by french blue and madder brown, with a very little gamboge; and a deep purple for sunsets, by the blue and purple madder, or indian red and rose madder. with cadmium and orient yellows, sepia, viridian, and many other colours, this ultramarine is of service. 134. new blue is confined to water-colour painting, and is an artificial ultramarine, holding a middle position between french blue and permanent blue, being less deep than the one and less pale than the other. it may be said to hover in tint between a rich ultramarine and cobalt. 135. permanent blue is a pale ultramarine, with a cobalt hue; and, in spite of its name, less permanence than belongs to the richer and deeper sorts. what antwerp blue is to prussian blue, this is to french blue--that is, as regards colour. with respect to durability, however, permanent and antwerp blues cannot be compared; the former being a weakened variety of a stable, and the latter a weakened variety of a semi-fugitive, pigment. hence permanent blue justifies its name, although that name would be more suited to the brilliant, or french, ultramarine. 136. genuine ultramarine, _native ultramarine_, _natural ultramarine_, _real ultramarine_, _true ultramarine_, _ultramarine_, _pure _ultramarine_, _azure_, _outremer_, _lazuline_, _lazulite blue_, and _lazurstein_. this most costly, most permanent, and most celebrated of all pigments, is obtained by isolating the blue colouring matter of the _lapis lazuli_, a stone chiefly brought from china, thibet, and the shores of lake baikal. about the antiquity of the stone, and its colour, much has been written, and many conflicting statements have been made; but there is little doubt that our lapis lazuli was the sapphire of the ancients; and that the first certain mention of ultramarine occurs in a passage of arethas, who lived in the eleventh century, and who, in his exposition of a verse in the book of revelation, says, the sapphire is that stone of which _lazurium_, as we are told, is made. it has been common to confound ultramarine with the _cyanus_ and _coeruleum_ of the ancients; but their cyanus, or armenian blue, was a kind of mineral or mountain blue, tinged with copper; and their coeruleum, although it may sometimes have been real ultramarine, was properly and in general a copper ochre. that ultramarine was known to the ancients there seems every probability, for it is certain they were acquainted with the stone; and modern travellers describe the brilliant blue painting still remaining in the ruins of temples of upper egypt as having all the appearance of ultramarine. whether it is so or not, however, could only be proved by analysis; for, be it recollected, although the colour had preserved its hue during so many centuries, it had been completely buried, and therefore most perfectly secluded from light and air. mr. layard, in his 'nineveh,' referring to some painted plaster, remarks that "the colours, particularly the blues and reds, were as brilliant and vivid when the earth was removed from them as they could originally have been; but, on exposure to the air, they faded rapidly." in all likelihood, these were of organic, or semi-organic, origin, prepared in some such manner as that mentioned by pliny, who speaks of an earth which, when boiled with plants, acquired their blue colour, and was in some measure inflammable. as a pigment, cobalt was unknown to the ancients; but to these vegetable and copper blues of theirs, a third blue may perhaps be added. experiments made upon blue tiles, found in a roman tesselated foot-pavement at montbeillard, showed that the colour was due to iron. m. gmelin has proved that a blue tint can be imparted to glass and enamel by means of iron; and it is probable that the ancients were first induced by the blue slag of their smelting-houses to study the colouring of glass with iron; that in this art they acquired a dexterity not possessed at present, and that they employed their iron-smalt as a pigment, as we do our smalt of cobalt. to sum up, there are grounds for believing that the ancients were acquainted with copper blues, vegetable blues, and iron blues; and that, consequently, the blue described by travellers as having all the appearance of ultramarine may, or may not, be that pigment. lapis lazuli, or lazulite, is usually disseminated in a rock, which contains, among other substances, a fine white lazulite. in the _musée minéralogique_ of paris are two splendid specimens of the stone, in which is seen the transition from the azure to the white. according to the quantity and quality of blue present, the lapis varies from an almost uniform tint of the deepest indigo-blue to grayish-white, dotted and streaked at intervals with pale blue. the exceeding beauty of good samples has caused the lazulite to be much sought after, both as a gem for adorning the person, and for inlaid works in ornamental decoration. in china the stone is highly esteemed, being worn by mandarins as badges of nobility conferred only by the emperor; and in the apartments of a summer palace near st. petersburg, the walls are covered with amber, interspersed with plates of this costly lapis. besides the colouring principle of the lazulite, there are always more or less mica and iron pyrites, the latter a lustrous yellow bisulphide of iron, which has often been mistaken for pellets of gold. having chosen portions of the stone most free from these impurities, it is simply requisite to reduce them to an impalpable powder to obtain a blue pigment; and probably this was the original mode of preparing it before the discovery of the modern process. this curious method, which is mechanical rather than chemical, depends for its success on the character and proportions of the materials employed, as well as on the nicety of working. when well carried out, it perfectly isolates the blue from all extraneous matter, yielding the colour at first deep and rich, then lighter and paler, and lastly of that gray tint which is known by the name of ultramarine ash. the refuse, containing little or no blue, furnishes the useful pigment, mineral gray. the immense price of ultramarine--or, as it was at first called, azurrum ultramarinum, blue beyond-the-sea--was almost a prohibition to its use in former times. it is related that charles i. presented to mrs. walpole, and possibly to vandyke also, five hundred pounds worth of ultramarine, which lay in so small a compass as only to cover his hand. even in these days, despite the introduction of artificial ultramarines, the native product continues costly, commanding in proportion to its intensity and brightness, from two to eight guineas an ounce. to say, however, that the merits of the blue at least equal its expense, is to give the genuine ultramarine no more than its due. it has, indeed, not earned its reputation upon slight pretensions, being, when of fine quality, and skilfully prepared, of the most exquisitely beautiful blue, ranging from the utmost depth of shadow to the highest brilliancy of light and colour,--transparent in all its shades, and pure in all its tints. a true medial blue, when perfect, partaking neither of purple on the one hand, nor of green on the other, it sustains no injury either by damp and impure air, or by the intensest action of light, and is so eminently durable, that it remains unchanged in the oldest paintings. drying well, working well in oil and fresco, ultramarine may be safely compounded with pigments generally, excepting only an acid sulphate of baryta or constant white. the blue has so much of the property of light in it, and of the tint of air--is so purely a sky-colour, and hence so singularly adapted to the direct and reflex light of the sky, and to become the antagonist of sunshine--that it is indispensable to the painter. moreover, it is so pure, so true, so unchangeable in its tints and glazings, as to be no less essential in imitating the marvellous colouring of nature in flesh and flowers. to this may be added that it enters so admirably into purples, blacks, greens, grays, and broken hues, that it has justly obtained the character of clearing or carrying light and air into all colours, both in mixture and glazing, as well as gained a sort of claim to universality throughout a picture. nevertheless, ultramarine is not always entitled to the whole of this commendation. frequently it is coarse in texture, in which case it is apparently more deep and valuable; yet such blue cannot be used with effect, nor ground fine without injuring its colour. again, it is apt to be separated in an impure state from the lapis lazuli, which is an exceedingly varying and compound mineral, abounding with earthy and metallic parts in different states of oxidation and composition: hence ultramarine sometimes contains iron as a red oxide, when it has a purple cast; and sometimes the same metal as a yellow oxide, when it is of a green tone; while often it retains a portion of black sulphuret of iron, which imparts a dark and dusky hue. occasionally, it is true, artists have preferred ultramarine for each of these tones; still are they imperfections which may account for various effects and defects of this pigment in painting. growing deeper by age has been attributed to ultramarine; but it is only such specimens as would acquire depth in the fire that could be subject to the change; and it has been reasonably supposed that in pictures wherein other colours have faded, it may have taken this appearance by contrast. ultramarine, prepared from calcined lapis, is not liable to so deepen; but this advantage may be purchased at some sacrifice of the vivid, warm, and pure azure colour of the blue produced from unburnt stone. we have frequently found ultramarine to be darkened, dimmed, and somewhat purpled by ignition; and the same results ensue, in many instances, when the lazulite is calcined. in burning the stone, the sulphur of the pyrites is in a great measure expelled, and during its expulsion has probably a deteriorating influence on the beauty of the colour: our belief in this being so is strengthened by the fact that certain samples of ultramarine, ignited with sulphur, were not improved thereby. similar effects are likewise caused by a careless or improper mode of treatment, for the finest lapis may yield dingy blues, containing particles of mica, metal, &c., and possessing a dull green, black, or purple hue. of course the perfection of the pigment is dependant to a large extent upon the quality of the stone itself. though unexceptionable as an oil-colour, both in solid painting and glazing, it does not work so well as some other blues in water; nor is it, unless carefully prepared, so well adapted for mixed tints, on account of a gritty quality, of which no grinding will entirely divest it, and which causes it to separate from other pigments. when extremely fine in texture, however, or when a considerable portion of gum, which renders it transparent, can be employed to give connexion or adhesion while flowing, it becomes no less valuable in water than in oil; but when its vivid azure is to be preserved, as in illuminated manuscripts and missals, little gum must be used. the fine greens, purples, and grays of the old masters, are often unquestionably compounds of ultramarine; and formerly it was the only blue known in fresco. pure ultramarine varies in shade from light to dark, and in hue from pale warm azure to the deepest cold blue. native ultramarine consists of silica, alumina, sulphur, and soda; its colouring matter seeming to be due to hyposulphite of soda and sulphide of sodium. in these respects, as well as in that of being decolourised by acids, the natural product resembles the artificial. as a precious material, the former has been subject to adulteration; and it has been dyed, damped, and oiled to enrich its appearance; attempts of fraud, however, which may be easily detected. in the preceding edition of this work the author adds--"and the genuine may be as easily distinguished from the spurious by dropping a few particles of the pigment into lemon-juice, or any other acid, which almost instantly destroys the colour of the true ultramarine totally, and without effervescence." with this statement, so far as it pretends to be a test for the two kinds, we are not inclined to agree. genuine ultramarine is always decolourised by acids; but it depends on the mode and nicety of its preparation whether it is decolourised without effervescence: that this is the case the author himself admits in his article on artificial ultramarine. moreover, the "violent effervescence" which he describes as ensuing on the latter being dropped into an acid, does not of necessity take place: in m. guimet's finest variety, the brilliant ultramarine, acid produces little or no effervescence. seeing, therefore, that both sorts are decolourised by acids, and that both may or may not effervesce therewith, the acid test must be considered fallacious. experiments made with different samples of each, showed that native ultramarines offered greater resistance to acid than the artificial, taking longer to decolourise; and that the residues of the first were in general of a purer white than those of the last. it was also found that the brilliant ultramarine, above referred to, was less readily decolourised than other french or german kinds. * * * * * 137. _blue carmine._ in a former edition of this work there appeared the following:--"blue carmine is a blue oxide of molybdenum, of which little is known as a substance or as a pigment. it is said to be of a beautiful blue colour, and durable in a strong light, but is subject to be changed in hue by other substances, and blackened by foul air: we may conjecture, therefore, that it is not of much value in painting." in his estimate of this colour the author was certainly right. it is formed when a solution of bichloride of molybdenum is poured into a saturated, or nearly saturated, solution of molybdate of ammonia. a blue precipitate falls, which is a molybdate of molybdic oxide, hydrated, and abundantly soluble in water. when dried, it furnishes a dark blue powder, resembling powdered indigo, having a bitter, rough, metallic taste, and reddening litmus strongly. the solubility of this hydrated oxide is alone fatal to its employment as a pigment. it may, indeed, be rendered comparatively insoluble in water by ignition; but the anhydrous oxide so obtained is nearly black, and as a colour worthless. a more eligible preparation is the molybdate of baryta, produced by mixing solutions of molybdate of potash and acetate of baryta. a white, flocculent precipitate results, which rapidly condenses to a crystalline powder, and turns blue on ignition. it is, however, a costly compound, of little merit, and not likely to come into use. it is insoluble in water. 138. _blue ochre_, which has been improperly called native prussian blue, is a native hydrated phosphate of iron of rare occurrence, found with iron pyrites in cornwall, and also in north america. what indian red is to the colour red, and oxford ochre to yellow, this pigment is to the colour blue, being sober and subdued rather than brilliant. it has the body of other ochres, more transparency, and is of considerable depth. both in water and oil it works well, dries readily, and does not suffer in tint with white lead, nor change when exposed to the action of strong light, damp, or impure air. as far as its powers extend, therefore, it is an eligible pigment, though not generally employed nor easily procured; it may, however, be artificially prepared. answering to similar acid tests as ultramarine, it is distinguished therefrom by assuming an olive-brown hue on exposure to a red heat. 139. _cobalt prussian blue._ gmelin states that yellow prussiate of potash yields with a solution of oxalate of sesquioxide of cobalt a blue resembling prussian blue--that, in fact, there can be obtained a prussian blue with a base of cobalt instead of iron. in the moist state, the similarity is sufficiently great, but when washed and dried, the product is, with us, a dingy slate colour. possibly, if such a blue could be produced, it might exceed in permanence the ferroand ferri-cyanides of iron. of course the compound would be much more expensive. _copper blues_ are now seldom or never employed as artists' pigments. the following are the principal varieties:-140. _bice_, blue bice, iris, terre bleu, was prepared, when true, from the armenian stone, which is a calcareous kind of stone coloured with copper. it was of a light bright hue, but is completely superseded by pale ultramarine. the persian lazur appears to have been a similar pigment, being a sort of copper ore, which, when the stone was pounded and sifted, furnished a fine paint, very bright and pleasant. it could not, however, stand the effects of the atmosphere like the tartarian lazur or lapis lazuli, in the course of time becoming of a dark and dismal colour. ground smalts, blue verditer, and other pigments, have passed under the name of bice. 141. _blue ashes_, or _mountain blue_, are both hydrated carbonates of copper, the first being artificially prepared, and the second found native in cumberland. neither is durable, especially in oil; and, as pigments, both are precisely of the character of verditer. by treating the natural malachite green with an alkali, it may be converted into blue. 142. _blue verditer_, or verditer, is an oxide of copper, formed by precipitating nitrate of copper with lime. it is of a beautiful light blue colour, little affected by light, but greened and ultimately blackened by time, damp, and impure air--changes which ensue even more rapidly in oil than in water. it is mostly confined to distemper painting and paper-staining. 143. _egyptian blue_, called by vitruvius, coeruleum, is frequently found on the walls of the temples in egypt, as well as on the cases enclosing mummies. count chaptal, who analysed some of it discovered in 1809 in a shop at pompeii, found that it was blue ashes, not prepared in the moist manner, but by calcination. he considers it a kind of frit, of a semi-vitreous nature; and this would appear to be the case from sir h. davy obtaining a similar colour by exposing to a strong heat, for two hours, a mixture of fifteen parts of carbonate of soda, twenty of powdered flints, and three of copper. the colour is very brilliant when first made, and retains its hue well in distemper and decorative painting; but it has the common defect of copper blues of turning green in oil, when ground impalpably for artistic use. one remarkable effect of this copper smalt--for it is nothing else--is, that by lamp-light it shows somewhat greenish, but shines by day with all the brightness of azure. mérimée believes that paul veronese employed this sort of blue in many of his pictures where the skies have become green. 144. _saunders blue_, a corrupt name from _cendres bleues_, the original denomination probably of ultramarine ashes, is of two kinds, the natural and artificial. the first is a blue mineral found near copper mines, while the last is simply a verditer. 145. _schweinfurt blue_, or reboulleau's blue, is prepared by fusing together equal weights of ordinary arseniate of protoxide of copper and arseniate of potash, and adding one-fifth its weight of nitre to the fused mass. the result is, so to speak, a sort of blue scheele's green, into which latter colour it soon passes when rubbed with oil. 146. _cotton seed blue._ cotton seed oil is bleached by treatment with either carbonate of soda or caustic lime. in both cases, a considerable residue is left after drawing off the bleached oil. this residue is treated with sulphuric acid, and distilled at a high temperature, when there is left a compact mass of a deep greenish-blue colour. on further treatment of this mass with strong sulphuric acid, the green tint disappears, and a very intense pure blue colour is produced. the blue mass is a mixture of the coloured substance with some sulphuric acid, sulphate of soda, and fats. the two former may be removed by washing with water; the latter by treatment with naptha. alcohol now dissolves the blue colour, and water precipitates it from the solution chemically pure. this blue has not been introduced as a pigment; and of its permanence, and other attributes, we know nothing. 147. _gold blue._ gold purple, under the name of purple of cassius, was once very well known: a like compound of tin and gold may be made to yield a blue. resembling indigo, the colour is not remarkably brilliant, and, unless several precautions are carefully observed, is rather violet than blue. when obtained, the colour must be quickly washed by decantation, or it changes first to violet and then to purple. its costliness, lack of brightness, and tendency to redden, are against its employment on the palette. in enamelling it would doubtless preserve its colour, and in exceptional cases might be useful. 148. _iodine blue._ it is curious that iodine, which gives a yellow with lead, should also afford a blue with the same metal. when a solution of iodine in aqueous soda (carbonate of soda is not so good) is added to nitrate or acetate of lead-oxide, a transient violet-red precipitate falls, which decomposes spontaneously under water, yielding iodine and a beautiful blue powder. the colour, however, is exceedingly fugitive, even the carbonic acid of the air separating iodine from it and forming a lead salt. bearing in mind the scarlet iodide of mercury, iodine is capable of furnishing the three primary colours, distinguished alike by their brilliancy and fugacity. 149. _iridium blue._ the rare metal iridium affords a blue which is a mixture of the oxide and the sesquioxide. but being slightly soluble in water and decolourised by sulphuretted hydrogen, it would not, other considerations apart, be an acquisition. 150. _manganese blue._ an aqueous solution of permanganate of potash yields with baryta-water a violet mixture, which afterwards becomes colourless, and deposits a blue precipitate. this retains its colour after washing and drying, but cannot be recommended as a pigment, being liable to suffer in contact with organic substances, which deoxidize and decolourize the manganates and permanganates. 151. _platinum blue._ with mercurous nitrate, the platinocyanide of potassium forms a thick smalt blue, and the platinidcyanide a dark blue precipitate. the compound is a mixture of platinoor platinidcyanide of mercury and mercurous nitrate. upon the presence of the latter the colour seems to depend, for on washing with cold water containing nitric acid, the nitrate is not removed nor the blue affected; but boiling water extracts the nitrate and leaves a white residue. a blue containing mercurous nitrate must necessarily be injured by impure air, and be otherwise objectionable. 152. _tungsten blue_ is an oxide formed by the action of various deoxidizing agents on tungstic acid. it remains unaltered in the air at ordinary temperatures, is opaque, and of a blackish indigo-blue colour. as a pigment, there is little to recommend it. 153. _wood-tar blue._ the colours obtained from coal-tar have become household words, and it is not impossible that those from wood-tar may be some day equally familiar. at present wood-tar is comparatively unexplored, but the fact that picamar furnishes a blue is at least as suggestive and hopeful as that transient purple colouration by which aniline was once chiefly distinguished. as aniline is a product of coal-tar, so picamar is a product of wood-tar; and as the former gives a purple with hypochlorites, so the latter yields a blue with baryta-water. both are distinguished by coloured tests, but there is this advantage in the picamar blue--it is comparatively permanent. picamar blue is produced when a few drops of baryta-water are added to an alcoholic solution of impure picamar, or even to wood-tar oil deprived of its acid. the liquor instantly assumes a bright blue tint, which in a few minutes passes into an indigo colour. from [greek: pitta] pitch, and [greek: kallos] ornament, the blue is named _pittacal_. the mode of separating pittacal has not been clearly described. dumas states, that when precipitated in a flocculent state from its solutions, or obtained by evaporation, it closely resembles indigo, and, like it, acquires a coppery hue when rubbed. it is inodorous, tasteless, and not volatile; and is abundantly soluble in acetic acid, forming a red liquid, which, when saturated by an alkali, becomes of a bright blue. it is represented as a more delicate test of acid and alkalis than litmus. with acetate of lead, protochloride of tin, ammonio-sulphate of copper, and acetate of alumina, it yields a fine blue colour with a tint of violet, said not to be affected by air or light, and therefore recommended for dyeing. like indigo, pittacal is believed to contain nitrogen, but its ultimate composition has not been accurately determined. dumas considers it identical with a blue product obtained in 1827 from coal-tar by mm. barthe and laurent. if this be the case, its greater stability over coal-tar blues and colours generally admits of doubt. that, however, has yet to be ascertained. our object in noticing this blue has been two-fold: first, to direct attention to wood-tar as a possible source of colour; and secondly, to point to pittacal as a possible substitute for indigo, possessing greater durability. 154. _zinc-cobalt blue._ cobalt, as furnishing a blue colour, is usually associated with alumina, silica, or tin; and, as furnishing a green colour, with zinc. but there is obtainable a compound of zinc and cobalt which gives a blue not only free from green, but inclining rather to red. it is made by adding to a solution of ordinary phosphate of soda in excess a solution first of sulphate of zinc and then of sulphate of cobalt, and washing and igniting the precipitate. the result is a vitreous blue with a purple cast, of little body, and exceedingly difficult to grind. altogether, it is not unlike smalt, over which it has no advantages as an artistic pigment either in colour or permanence. for tinting porcelain, however, it is admirably adapted, imparting thereto a very pure dark blue of extraordinary beauty. this blue is distinguished from smalt by dissolving in acetic acid. * * * * * compared with the wide range of yellows, or even with reds, the artist finds the number of his blues limited. the perfect native and excellent artificial ultramarines, the good blues of cobalt, the fair prussian blue, and the doubtful indigo, are the four varieties he has for years been in the habit of using, and is still mainly dependent on. our division, therefore, into permanent, semi-stable, and fugitive, is easily effected. in the front rank, pre-eminent among blues as among pigments generally, stands genuine ultramarine. behind it, are the artificial ultramarines; and behind them again, cobalt and cerulian blue. to a greater or less extent, all these are durable. among the semi-stable, must be classed cyanine or leitch's blue, smalt, and prussian blue. to the fugitive, belong indigo and the somewhat more permanent intense blue, antwerp blue, and the copper blues. in this list of blues, which grace or disgrace the palette of the present day, there is one colour which, although not permanent, is almost indispensable. as yet, the chemist cannot in all cases lay down the law as to what pigments may or may not be employed. the painter who unnecessarily uses fugitive colours must have little love for his craft, and a poor opinion of the value of his work; but, even with the best intentions and the utmost self-esteem, the artist cannot always confine himself to strictly stable pigments. he has no right to use orpiment instead of cadmium yellow, or red lead instead of vermilion, or copper blue instead of cobalt: he has no business to employ indigo when prussian blue saddened by black will answer his purpose; but--what pigment can he substitute for prussian blue itself? none. in its wondrous depth, richness, and transparency, it stands alone: there is no yellow to compare with it, no red to equal it, no blue to rival it. in force and power it is a colour among colours, and transparent beyond them all. the great importance of transparent pigments is to unite with solid or opaque colours of their own hues, giving tone and atmosphere generally, together with beauty and life; to convert primary into secondary, and secondary into tertiary colours, with brilliancy; to deepen and enrich dark colours and shadows, and to impart force and tone to black itself. for such effects, no pigment can vie with prussian blue. what purples it produces, what greens it gives, what a matchless range of grays; what velvety glow it confers, how it softens the harshness of colours, and how it subdues their glare. no; until the advent of a perfect palette, the artist can scarcely part with his prussian blue; nor can the chemist, who has nothing better to offer, hold him to blame. it is for art to copy nature with the best materials she possesses: it is for science to learn the secrets of nature, and turn them to the benefit of art. chapter xi. on the secondary, orange. orange is the first of the secondary colours in relation to light, being in all the variety of its hues composed of _yellow_ and _red_. a true or perfect orange is such a compound of red and yellow as will neutralize a perfect blue in equal quantity either of surface or intensity; and the proportions of such compound are five of perfect red to three of perfect yellow. when orange inclines to red, it takes the names of _scarlet_, _poppy_, &c.: in gold colour, &c., it leans towards yellow. combined with green it forms the tertiary _citrine_, and with purple the tertiary _russet_: it also furnishes a series of warm semi-neutral colours with black, and harmonizes in contact and variety of tints with white. orange is an advancing colour in painting:--in nature it is effective at a great distance, acting powerfully on the eye, diminishing its sensibility in accordance with the strength of the light in which it is viewed. it is of the hue, and partakes of the vividness of sunshine, as it likewise does of all the powers of its components, red and yellow. pre-eminently a _warm_ colour, being the equal contrast of or antagonist to blue, to which the attribute of _coolness_ peculiarly belongs, it is discordant when standing alone with yellow or with red, unresolved by their proper contrasts or harmonizing colours, purple and green. as an archeus or ruling colour, orange is one of the most agreeable keys in toning a picture, from the richness and warmth of its effects. if it predominate therein, for the colouring to be true, the violet and purple should be more or less red, the red more or less scarlet, the yellow more or less intense and orange, and the orange itself be intense and vivid. further, the greens must lose some of their blue and consequently become yellower, the light blues be more or less light grey, and the deep indigo more or less marrone. although the secondary colours are capable of being obtained by admixture of the primaries in an infinitude of hues, tints, and shades; yet simple original pigments of whatever class--whether secondary, tertiary, or semi-neutral--are, it has been said before, often superior to those compounded, both in a chemical and artistic sense. hence a thoroughly good original orange is only of less value and importance than a thoroughly good original yellow, a green than a blue, or a purple than a red. to produce pure and permanent compound hues requires practice and knowledge, and we too often see in the works of painters combinations neither pleasing nor stable. colours are associated with each other which do not mix kindly, and compounds formed of which one or both constituents are fugitive. as a consequence, mixed tints are frequently wanting in clearness, and, where they do not disappear altogether, resolve themselves into some primary colour; orange becoming red by a fading of the yellow, green yellow by a fading of the blue, and purple blue by a fading of the red. again, with regard to compound tints, there is the danger of one colour reacting upon and injuring another, as in the case of greens obtained from chrome yellow and prussian blue, where the former ultimately destroys the latter. of course a mixture of two permanent pigments which do not react on each other will remain permanent; the green, for instance, furnished by aureolin and native ultramarine lasting as long as the ground itself. to produce, however, the effects desired, the artist does not always stop to consider the fitness and stability of his colours in compounding, even if he possess the needed acquaintance with their physical and chemical properties. at all times, therefore, but especially when such knowledge is slight, good orange, &c., pigments are of more or less value, as by their use the employment of inferior mixtures is to a great extent avoided. in mingling primary with primary, if one colour does not compound well with the other, or is fugacious, the result is failure; but a secondary is not so easily affected by admixture: a green, for example, is seldom quite ruined by the injudicious addition of blue or yellow; and even if either of the latter be fugitive, the green will remain a green if originally durable. thus the secondaries, if they are not already of the colour required, may be brightened or subdued, deepened or paled, with comparative impunity. the artist who, from long years of experience, knows exactly the properties and capabilities of the colours he employs, may in a measure dispense with secondary pigments, and obtain from the primaries mixed tints at once stable, beautiful, and pure; but even he must sometimes resort to them, as when a green like emerald or viridian is required, which no mixture of blue and yellow will afford. the primaries, by reason of their not being able to be composed of other colours, occupy the first place on the palette, and are of the first importance; but the secondaries are far too useful to be disregarded, and have a value of their own, which both veteran and tyro have cause to acknowledge. the list of original orange pigments was once so deficient, that in some old treatises on the subject of colours, they are not even mentioned. this may have arisen, not merely from their paucity, but from the unsettled signification of the term orange, as well as from improperly calling these pigments reds, yellows, &c. in these days, however, orange pigments are sufficiently numerous to merit a chapter to themselves; they indeed comprise some of the best colours on the palette. 155. burnt sienna, or _burnt terra di sienna_, is calcined raw sienna, of a rich transparent brown-orange or orange-russet colour, richer, deeper, and more transparent than the raw earth. it also works and dries better, has in other respects the qualities of its parent colour, and is a most permanent and serviceable pigment in painting generally. for the warm tints in rocks, mud banks, and buildings, this colour is excellent. when mixed with blue it makes a good green; furnishing a bright green with cobalt, and one much more intense with prussian blue. for the foresea, whether calm or broken by waves, it may be employed with a little madder; while compounded with a small portion of the latter and lamp black, it meets the hues of old posts, boats, and a variety of near objects, as the tints may be varied by modifying the proportions of the component colours. used with white, it yields a range of sunny tones; and with aureolin or french blue and aureolin will be found of service, the last compound giving a fine olive green. similar but fugitive greens are afforded by admixture of burnt sienna with indigo and yellow or roman ochre, or raw sienna; tints which may be saddened into olive neutrals by the addition of sepia, and rendered more durable by substituting for indigo prussian blue and black. mixed with viridian, it furnishes autumnal hues of the utmost richness, beauty, and permanence; and, alone, is valuable as a glaze over foliage and herbage. for the dark markings and divisions of stones a compound of payne's gray and burnt sienna will prove serviceable; while for red sails the sienna, either by itself, with brown madder, or with indian red, cannot be surpassed. for foregrounds, banks and roads, cattle and animals in general, burnt sienna is equally eligible, both alone and compounded. it has a slight tendency to darken by time. 156. cadmium orange was first introduced to the art-world at the international exhibition of 1862, where it was universally admired for its extreme brilliancy and beauty, a brilliancy equalled by few of the colours with which it was associated, and a beauty devoid of coarseness. we remember well the power it possessed of attracting the eye from a distance; and how, on near approach, it threw nearly all other pigments into the shade. it has in truth a lustrous luminosity not often to be met with, added to a total absence of rankness or harshness. a simple original colour, containing no base but cadmium, it is of perfect permanence, being uninjured by exposure to light, air or damp, by sulphuretted hydrogen, or by admixture. having in common with cadmium sulphides a certain amount of transparency, it is invaluable for gorgeous sunsets and the like, either alone or compounded with aureolin. of great depth and power in its full touches, the pale washes are marked by that clearness and delicacy which are so essential in painting skies. as day declines, and blue melts into green, green into orange, and orange into purple, the proper use of this pigment will produce effects both glowing and transparent. transparency signifies the quality of being seen through or into; and in no better way can it be arrived at than by giving a number of thin washes of determined character, each lighter than the preceding one. with due care in preserving their forms, from the commencement to the termination, such washes of orange will furnish hues the softest and most aerial. for bits of bright drapery, a glaze over autumn leaves, and mural decoration, this colour is adapted; while in illumination it supplies a want formerly much felt. "with the exception of scarlet or bright orange," said mr. bradley, nine or ten years since, in his manual of illumination, "our colours are everything we could wish." as an original pigment, a permanent scarlet does not yet exist; but the brilliancy of cadmium orange cannot be disputed, nor its claim to be the only unexceptionable bright orange known. it even assists the formation of the other colour: remarks the author mentioned, "brilliancy is obtained by gradation. suppose a scarlet over-curling leaf, for example. the whole should be painted in pure orange, with the gentlest possible after-touch of vermilion towards the corner under the curl. when dry, a firm line--not wash--of carmine, (of madder, preferable.--_ed._), passed within the outline on the shade side only of the leaf, will give to the whole the look of a bright scarlet surface, but with an indescribable superadded charm, that no merely flat colour can possess." in the same branch of art, illumination, cadmium orange, opposed to viridian, presents a most dazzling contrast, especially if relieved by purple. 157. chinese orange belongs to the coal-tar colours, and ought strictly to have been classed therewith. we have preferred, however, to keep it separate, because, as chinese orange, it was introduced as a pigment, and has not been employed as a dye. in colour, it somewhat resembles burnt sienna, enriched, reddened, brightened, and made more transparent, by admixture with crimson lake. from its behaviour, it would seem to be composed of yellow and red, such a compound as magenta and aniline yellow would afford. its pale washes are uncertain, being apt to resolve themselves into red and yellow, of which the latter appears the most permanent; for, on exposure to light and air, the red more or less flies, leaving here a yellow, and there a reddish-yellow ground: in places both red and yellow disappear. like all fugitive colours, it is comparatively stable when used in body; but even then it entirely loses its depth and richness, and in a great measure its redness, becoming faded and yellowish. in thin washes or glazing it is totally inadmissible; and, being neither a red, an orange, nor a brown, is unsuited to pure effects. nevertheless, where it need not be unduly exposed; in portfolio illuminations, for instance, the richness, subdued brilliancy, and transparency of this pigment, justify its adoption. it is not affected by an impure atmosphere. aniline colours may be adapted for oil painting by dissolving them in the strongest alcohol, saturating the solution with dammar resin, filtering the tincture, and pouring the filtrate either on pure water or solution of common salt, stirring well all the time. the water or brine solution must be at least twenty times the bulk of the tincture. the colour after being collected on a filter, washed, and dried, can be ground with linseed oil, poppy oil, or oil varnishes. 158. chrome orange, _orange chrome_, or _orange chromate of lead_, is a sub-chromate of lead of an orange-yellow colour, produced by the action of an alkali on chrome yellow. like all the chromates of lead, it is characterized by power and brilliancy; but also by a rankness of tone, a want of permanence, and a tendency to injure organic pigments. by reason of its lead base it is subject to alteration by impure air, but is on the whole preferable to the chrome yellows, being liable in a somewhat less degree to their changes and affinities. as, however, a colour has no business to be used if a better can be procured, the recent introduction of cadmium orange renders all risk unnecessary. 159. mars orange, _orange de mars_, is a subdued orange of the burnt sienna class, but without the brown tinge that distinguishes the latter. marked by a special clearness and purity of tone, with much transparency, it affords bright sunny tints in its pale washes, and combines effectively with white. being an artificial iron ochre it is more chemically active than native ochres, and needs to be cautiously employed with pigments affected by iron, such as the lakes of cochineal and intense blue. 160. mixed orange. orange being a compound colour, the place of original orange pigments can be supplied by mixtures of yellow and red; either by glazing one over the other, by stippling, or by other modes of breaking and intermixing them, according to the nature of the work and the effect required. for reasons lately given, mixed pigments are apt to be inferior to the simple or homogeneous both in colour, working, and other properties; yet some pigments mix and combine more cordially and with better results than others; as is the case with liquid rubiate and gamboge. generally speaking, the compounding of colours is easier in oil than in water; but in both vehicles trouble will be saved by beginning with the predominating colour, and adding the other or others to it. perhaps in this, our first chapter on the secondary colours, and consequently on colours that can be compounded, a few remarks on mixed tints from a chemical point of view will not be deemed superfluous. there are two ways, we take it, of looking at a picture--from a purely chemical, and from a purely artistic, point of view. regarded in the first light, it matters little whether a painting be a work of genius or a daub, provided the pigments employed on it are good and properly compounded. the effects produced are lost sight of in a consideration of the materials, their permanence, fugacity, and conduct towards each other. painting is essentially a chemical operation: with his pigments for reagents, the artist unwittingly performs reaction after reaction, not with the immediate results indeed of the chemist in his laboratory, but often as surely. as colour is added to colour, and mixture to mixture, acid meets alkali, metal animal, mineral vegetable, inorganic organic. with so close a union of opposite and opposing elements, the wonder is not so much that pictures sometimes perish, but that they ever live. it behoves the artist, then, not only to procure the best and most permanent pigments possible, but to compound them in such a manner that his mixed tints may be durable as well as beautiful. to effect or aid in effecting this, although he may not always be able to act upon them, the following axioms should be borne in mind:-1. if they do not react on each other, a permanent pigment added to a permanent pigment yields a permanent mixture. 2. if they do react on each other, a permanent pigment added to a permanent pigment yields a semi-stable or fugitive mixture. 3. a permanent pigment added to a semi-stable pigment yields a semi-stable mixture. 4. a permanent pigment added to a fugitive pigment yields a fugitive mixture. consequently-5. a permanent pigment may be rendered fugitive or semi-stable by improper compounding. 6. a semi-stable or fugitive pigment is not rendered durable by being compounded. 7. as a chain is only as strong as its weakest link, so a mixture is only as permanent as its least durable constituent. to give illustrations-1. ultramarine added to chinese white yields a permanent mixture. 2. ultramarine added to an acid constant white yields a semi-stable or fugitive mixture. 3. ultramarine added to prussian blue yields a semi-stable mixture. 4. ultramarine added to indigo yields a fugitive mixture. except in the second instance, where the blue is either partially or wholly destroyed--in time, be it remembered, not at once--according to the quantity and strength of the acid in the white, the ultramarine remains unchanged. hence at first sight our third and fourth conclusions may appear wrong; inasmuch as, it may be argued, a blue mixture cannot be semi-stable or fugitive when blue is left. to this we reply, unless both constituents are fugitive, a mixture will always more or less possess colour; but, if even one constituent be semi-stable or fugitive, a mixture will slowly but surely lose _the_ colour for which it was compounded, and be _as a mixture_ semi-stable or fugitive. it need hardly be observed that the number of permanent orange, green, and purple hues which the artist can compound, depends mainly on the number of permanent yellows, reds, and blues at his disposal. in mixed orange, therefore, a selection of durable yellows and reds is of the first importance. it should, however, be remarked that mixed orange, more sober and less decided, is obtainable by the use of citrine and russet; in the former of which yellow predominates, and in the latter, red: consequently orange results when yellow is added to russet, red to citrine, or citrine to russet. permanent yellows. | permanent reds. | aureolin. | cadmium red. cadmium, deep. | liquid rubiate. cadmium, pale. | madder carmine. lemon yellow. | rose madder. mars yellow. | mars red. naples yellow, modern. | ochres. ochres. | vermilions. orient yellow. | raw sienna. | none of these pigments react on each other, and from them can be produced the most durable mixed orange that yellow and red will afford. 161. neutral orange, or _penley's neutral orange_, is a permanent compound pigment composed of yellow ochre and the russet-marrone known as brown madder: it is chiefly valuable in water-colour. paper, being white, is too opaque to paint upon, without some wash of colour being first passed over it; otherwise the light tones of the sky are apt to look crude and harsh. it must, therefore, be gone over with some desirable tint, that shall break, in a slight degree, the extreme brilliancy of the mere paper. for this purpose, a thin wash of the orange is to be put over the whole surface of the paper with a large flat brush, care being taken never to drive the colour too bare, _i.e._ never to empty the brush too closely, but always to replenish before more is actually required. this first wash of colour not only gives a tone to the paper, but secures the pencil sketch from being rubbed out. the reason why, in this compound, yellow ochre, as a yellow, is preferred to any of the others, is, that it is a broken yellow, that is, a yellow slightly altered by having another hue, such as red, or brown, in its composition. it is somewhat opaque too, and hence, from this quality, is especially adapted for distances. brown madder also is a subdued red, which, when in combination with the former, produces a neutral orange, partaking of the character of soft light. as a general rule, yellow ochre is to predominate in broad daylight, and brown madder in that which is more sombre and imperfect: hence the pigment can be yellowed or reddened, by the addition of one or the other. for a clear sunset, the neutral orange must be repeated, with a preponderance of ochre at the top, assisted by a little cadmium yellow near the sun; the madder being added downwards. in treating of distant mountains, a distinction is to be made between them and the clouds, the former requiring solidity, while the latter are only to be regarded as vapour and air. mountains, being opaque bodies, are acted upon by atmosphere more or less, according to their position, their distance, and the state of the weather. to express this distinction, recourse must be had to an under tint, except where the tone is decidedly blue--an uncommon case. no mixture can give this with such truth as the neutral orange. a wash, therefore, should be passed over the mountains, with nearly all yellow in the high lights, or in the gleams of sunshine, and, on the contrary, almost all brown madder for the shadows. these two degrees of tone must be run into each other while the drawing is wet. a beautiful and soft under tone will thus be given to receive the greys. 162. orange, or burnt roman ochre, called also _spanish ochre_, is a very bright yellow or roman ochre burnt, by which operation it acquires warmth, colour, transparency, and depth. moderately bright, it forms good flesh tints with white, dries and works well both in water and oil, and is a very good and eligible pigment. it may be used in enamel painting, and has all the properties of its original ochre in other respects. a redder hue is imparted by mixing the ochre with powdered nitre before ignition, the orange red being subsequently washed with hot water. * * * * * 163. _anotta_, annotto, annatto, arnotto, arnotta, terra orellana, rocou, &c., is met with in commerce under the names of cake anotta, and flag or roll anotta. the former, which comes almost exclusively from cayenne, should be of a bright yellow colour: the latter, which is imported from the brazils, is brown outside and red within. it is prepared from the pods of the _bixa orellana_, and appears generally to contain two colouring matters, a yellow and a red, which are apt to adhere to each other and produce orange. anotta dissolves with difficulty in water, but readily in alcohol and alkaline solutions, from which last it may be thrown down as a lake by means of alum. being, however, exceedingly fugitive and changeable, it is not fit for painting; but is chiefly employed in dyeing silk, and colouring varnishes and cheese. very red cheese should be looked upon with suspicion, for although the admixture of anotta is in no way detrimental to health provided the drug be pure, it is commonly adulterated with red lead and ochre. several instances are on record that gloucester and other cheeses have been found contaminated with red lead, through having been coloured with anotta containing it, and that this contamination has produced serious consequences. _bixine_ is a purified extract of anotta made in france, and used by dyers. 164. _antimony orange_, golden sulphur of antimony, or golden yellow, is a hydro-sulphuret of antimony of an orange colour, which is destroyed by the action of strong light. it is a bad dryer in oil, injurious to many pigments, and in no respect eligible either in water or oil. 165. _chromate of mercury_ has been improperly classed as a red with vermilion, for though it is of a bright ochrous red in powder, when ground it becomes a bright ochre-orange, and affords with white very pure orange tints. nevertheless it is a bad pigment, since light soon changes it to a deep russet colour, and foul air reduces it to extreme blackness. 166. _damonico_, or monicon, is an iron ochre, being a compound of raw sienna and roman ochre burnt, and having all their qualities. it is rather more russet in hue than the pigment known as orange or burnt roman ochre, has considerable transparency, is rich and durable in colour, and furnishes good flesh tints. as in orange ochre, powdered nitre may be employed in its preparation. notwithstanding its merits, it is obsolete or nearly so; doubtless because burnt sienna mixed with burnt roman ochre sufficiently answers the purpose. 167. _gamboge orange._ on adding acetate of lead to a potash solution of gamboge, a rich bright orange is precipitated, which may be washed on a filter till the washings are colourless, and preserves its hue with careful drying. the orange which we thus obtained stood well in a book, but it cannot be recommended as an artistic pigment. perhaps in dyeing, the lead and gamboge solutions might be worth a trial. 168. _laque minérale_ is a french pigment, a species of chromic orange, similar to the orange chromate of lead. this name is likewise given to orange oxide of iron. 169. _madder orange_, or orange lake. it has been said that the yellows so-called produced from madder are not remarkable for stability, differing therein from the reds, purples, russets, and browns. like them, this 'orange' is of doubtful colour and permanence, and not to be met with, brilliant and pure, on the palette of to-day. the russet known as rubens' madder has a tendency to orange. 170. _orange lead_, of a dull orange colour, is an orange protoxide of lead or massicot. like litharge, it may be employed in the preparation of drying oils, and, being a better drier than white lead, may be substituted for it in mixing with pigments which need a siccative, as the bituminous earths. minium sometimes leans to orange; and there is made from ceruse a peculiar red, _mineral orange_. _orange orpiment_, or realgar, has also been called red orpiment, improperly, since it is a brilliant orange, inclining to yellow. there are two kinds, a native and an artificial, of which the former is the _sandarac_ of the ancients, and is rather redder than the latter. they possess the same qualities as pigments, and as such resemble yellow orpiment, to which the old painters gave the orange hue by heat, naming it alchemy and burnt orpiment. orange orpiment contains more arsenic and less sulphur than the yellow, and is of course highly poisonous. it is often sophisticated with brickdust and yellow ochre. 172. _thallium orange_ is produced when bichromate of potash is added to a neutral salt of the protoxide of thallium, as an orange-yellow precipitate. the scarcity of the metal precludes their present introduction as pigments, but if the chromates of thallium were found to resist the action of light and air, and not to become green by deoxidation of the chromic acid, they might possibly prove fitted for the palette. it is a question whether their _very_ slight solubility in water would be a fatal objection; and, although they would be liable to suffer from a foul atmosphere, we are inclined to think the effects would not be so lasting as in the chromates of lead. like lead sulphide, the sulphide of thallium ranges from brown to brownish-black, or grey-black; and, like it too, is subject to oxidation and consequent conversion into colourless sulphate. it is, however, much more readily oxidized than sulphate of lead; and hence the thallium chromates would doubtless soon regain their former hue on exposure to a strong light. mr. crookes, who discovered this new metal in 1861, believes that the deep orange shade observable in some specimens of sulphide of cadmium is due to the presence of thallium. he has frequently found it, he says, in the dark-coloured varieties, and considers the variations of colour in cadmium sulphide to be owing to traces of thallium. that thallium affects the colour is most probable, but it is not necessarily the cause of the orange hue. the tint of cadmium sulphide is a mere matter of manufacture, seeing that from the same sample of metal there can be obtained lemon-yellow, pale yellow, deep yellow, orange-yellow, and orange-red. with deference to the opinion of a chemist so distinguished, we hold that thallium rather impairs the beauty of cadmium sulphide than imparts to it an orange shade, the thallium being likewise in the form of sulphide, and therefore more or less black. on chromate of cadmium, made with bichromate of potash, thallium would naturally confer an orange hue. 173. _uranium orange_ is obtainable by wet and dry methods as a yellowish-red, or, when reduced to powder, an orange-yellow, uranate of baryta. it is an expensive preparation, superfluous as a pigment. 174. _zinc orange._ when hydrochloric acid and zinc are made to act on nitro-prusside of sodium, a corresponding zinc compound is formed of a deep orange colour, slightly soluble in water, and not permanent. * * * * * for a secondary colour, orange is well represented on the modern palette, and can point to some pigments as good and durable as any to be found among the primaries. burnt sienna, cadmium orange, mars orange, neutral orange, and orange or burnt roman ochre, are all strictly permanent. the so-called orange vermilions were, it will be remembered, classed among the reds. as semi-stable, must be ranked chrome orange; and as fugitive, chinese orange, orange orpiment, and orange lead. from the foregoing division, the predominance of eligible orange pigments over those less trustworthy is manifest. unfortunately, with many painters it is not so manifest that their secondary and compound colours should receive as much attention as the primaries, and that it is their duty, not only to the art which they practice, but to the patrons for whom they practice it, that their orange and green and purple hues, should be as durable as their yellows, reds, and blues. for such, the introduction of a new permanent pigment is of little interest, unless its colour be primary; so wedded are they to that passion for compounding which the chemist views with dismay. with dismay, because he knows that the rules of mixture are severe, and cannot with impunity be altered; that, although disguised in oil or gum, each pigment is a chemical compound, with more or less of affinity and power, more or less likely to act or be acted upon. because he knows that, except with the most experienced artists, compounding leads to confusion; and that in it the temptations to use semi-stable or fugitive colours are strong. look at those tables of mixed tints of which artist-authors are so fond, and tell us whether they always bear scrutiny--surely not. admirable, perfect as these tints may be in an artistic sense, how often is their beauty like the hectic flush of consumption, which carries with it the seeds of a certain death. will that orange where indian yellow figures ever see old age, or that green with indigo, or purple with cochineal lake? will they not rather spread over the picture the upas-tree of fugacity, and kill it as they die themselves! chapter xii. on the secondary, green. green, which occupies the middle station in the natural scale of colours and in relation to light and shade, is the second of the secondary colours. it is composed of the extreme primaries, _yellow_ and _blue_, and is most perfect in hue when constituted in the proportions of three of yellow to eight of blue of equal intensities; because such a green will exactly neutralize and contrast a perfect red in the ratio of eleven to five, either of space or power. of all compound colours, green is the most effective, distinct, and striking, causing surprise and delight when first produced by a mixture of blue and yellow, so dissimilar to its constituents does it appear to the untutored eye. compounded with orange, green converts it into the one extreme tertiary _citrine_; while mixed with purple, it becomes the other extreme tertiary _olive_: hence its relations and accordances are more general, and its contrasts more agreeable with all colours, than those of any other individual colour. accordingly it has been adopted very wisely in nature as the common garb of the vegetal creation. it is, indeed, in every respect a central or medial colour, being the contrast, compensatory in the proportion of eleven to five, of the middle primary _red_, on the one hand, and of the middle tertiary _russet_, on the other; while, unlike the other secondaries, all its hues, whether tending to blue or yellow, are of the same denomination. these attributes of green, which render it so universally effective in contrasting colours, cause it also to become the least useful in compounding them, and the most apt to defile other colours in mixture. nevertheless it forms valuable semi-neutrals of the olive class with _black_, for of such subdued tones are those greens by which the more vivid tints of nature are opposed. accordingly, the various greens of foliage are always more or less semi-neutral in hue. as green is the most general colour of vegetal nature and principal in foliage; so red, its harmonizing colour, with compounds of red, is most general and principal in flowers. purple flowers are commonly contrasted with centres or variegations of bright yellow, as blue flowers are with like relievings of orange; and there is a prevailing hue, or character, in the green colour of the foliage of almost every plant, by which it is harmonized with the colours of its flowers. the chief discord of green is blue; and when they approximate or accompany each other, they require to be resolved by the opposition of warm colours. it is in this way that the warmth of distance and the horizon reconciles the azure of the sky with the greenness of a landscape. its less powerful discord is yellow, which needs to be similarly resolved by a purple-red, or its principles. in tone, green is cool or warm, sedate or gay, either as it inclines to blue or to yellow; yet in its general effects it is cool, calm, temperate, and refreshing. having little power in reflecting light, it is a retiring colour, and readily subdued by distance: for the same reason, it excites the retina less than most colours, and is cool and grateful to the eye. as a colour individually, green is eminently beautiful and agreeable, but it is more particularly so when contrasted by its compensating colour, red, as it often is in nature, even in the green leaves and young shoots of plants and trees. "the autumn only is called the painter's season," remarks constable, "from the great richness of the colours of the dead and decaying foliage, and the peculiar tone and beauty of the skies; but the spring has, perhaps, more than an equal claim to his notice and admiration, and from causes not wholly dissimilar,--the great variety of tints and colours of the living foliage, accompanied by their flowers and blossoms. the beautiful and tender hues of the young leaves and buds are rendered more lovely by being contrasted, as they now are, with the sober russet browns of the stems from which they shoot, and which still show the drear remains of the season that is past." the number of pigments of any colour is in general proportioned to its importance; hence the variety of greens is very great, though the classes of those in common use are not very numerous. of the three secondaries, green is the colour most often met with, and, consequently, the most often compounded: for this last reason, perhaps, the palette is somewhat deficient in really good original greens--more deficient than there is any necessity for. chrome oxides. by numerous methods both wet and dry, oxides of chromium are obtainable pale and deep, bright and subdued, warm and cool, opaque and transparent: sometimes hydrated, in which case they cannot be employed in enamelling; and sometimes anhydrous, when they are admissible therein. but whatever their properties may be, chemical, physical, or artistic, they are all strictly stable. neither giving nor receiving injury by admixture, equally unaffected by foul gas and exposure to light, air, or damp, these oxides are perfectly unexceptionable in every respect. for the most part they are eligible in water and oil, drying well in the latter vehicle, and requiring in the former much gum. they have long been known as affording pure, natural, and durable tints; but, until within the last few years, have been rather fine than brilliant greens. lately, however, processes have been devised, yielding them almost as bright, rich, and transparent, as the carmine of cochineal itself. 175. oxide of chromium, _opaque oxide of chromium_, _green oxide of chromium_, _chrome oxide_, _true chrome green_, _native green_, _&c._, is found native in an impure state as chrome ochre, but is always artificially prepared for artistic use. obtained anhydrous by dry modes, this is the only chrome oxide available in enamelling, and is the one seen on superior porcelain. it is a cold, sober sage green, deep-toned, opaque, and, although dull, agreeable to the eye. its tints with white are peculiarly delicate and pleasing, possessing a silvery luminous quality, and giving the effect of atmosphere. being very dense and powerful, it must be employed with care to avoid heaviness, and is preferably diluted with a large quantity of white, or compounded with transparent yellow. in the hands of a master, this gray-green furnishes lustrous hues with brown pink, italian pink, and indian yellow; three beautiful but fugitive pigments, of which the two last may be replaced by aureolin. of this mr. penley observes, "as adapted for the colouring of foliage and herbage, it is impossible to say too much in its praise. it imparts the vividness and freshness of nature to every colour with which it is combined;" and he brackets oxide of chromium with aureolin as a compound hue "extremely useful." in flat tints, the oxide sometimes does not wash well in water. 176. transparent oxide of chromium being deficient in body, is only eligible in oil. a very pale greyish-white green in powder, it gives an agreeable yellowish green of some depth in oil, moderately bright, but not very pure or clear. we are acquainted with another transparent chrome oxide of far greater beauty, brightness, purity, and clearness than the above. of a bluish green hue, a difficulty in getting it to mix with oil renders it at present unavailable. 177. veronese green, or _french veronese green_, is a comparatively recent introduction, similar in colour and general properties to the following; beside which, however, it appears dull, muddy, and impure. it is often adulterated with arsenic to an enormous extent, which interferes with its transparency, mars its beauty, and renders it of course rankly poisonous. 178. viridian is a still later addition to the palette, and the only permanent green which can be described as gorgeous, being not unlike the richest velvet. pure and clear as the emerald, it may be called the prussian blue of greens, of such richness, depth, and transparency is it. in hue of a bluish-green, its deepest shades verge on black, while its light tints are marked by transparent clearness unsurpassed. no compound of blue and yellow will afford a green at once so beautiful and stable, so gifted with the quality of light, and therefore so suited for aerial and liquid effects. used with aureolin, it gives foliage greens sparkling with sunshine; and, fitly compounded, will be found invaluable for the glassy liquidity of seas, in painting which it becomes incumbent to employ pigments more or less transparent. "the general failing in the representation of the sea is, that instead of appearing liquid and thin, it is made to bear the semblance of opacity and solidity. in order to convey the idea of transparency, some object is often placed floating on the wave, so as to give reflection; and it is strange that we find our greatest men having recourse to this stratagem. to say it is not true in all cases, is saying too much; but this we do assert, that as a general principle it is quite false, and we prove it in this way: water has its motion, more or less, from the power of the wind; it is acted upon in the mass, and thus divided into separate waves, and these individually have their surface ruffled, which renders them incapable of receiving reflection. the exception to this will be, where the heaving of the sea is the result of some gone-by storm, when the wind is hushed, and the surface becomes bright and glassy. in this state, reflections are distinctly seen. another exception will be in the hollow portion of the waves, as they curl over, and dash upon the shore." as viridian, like the sea, is naturally "liquid and thin, bright and glassy," the extract we have quoted from mr. penley, points to this green as a pigment peculiarly adapted for marine painting; in which, it may be added, its perfect permanence and transparency will be appreciated in glazing. its fitness for foliage has been remarked; but in draperies the colour will prove equally useful, and in illumination will be found unrivalled. in the last branch of art, indeed, viridian stands alone, not only through its soft rich brilliancy, but by the glowing contrast it presents with other colours: employed as a ground, it throws up the reds, &c., opposed to it, in a marvellous manner. like the three preceding oxides of chromium, viridian neither injures nor is injured by other pigments; is unaffected by light, damp, or impure air; and is admissible in fresco. in enamelling it cannot be used; the colour, depending on the water of hydration, being destroyed by a strong heat. copper greens are commercially known as _emerald green_, _malachite green_, _scheele's green_, _schweinfurt green_, _verdigris_, _green bice_, _green verditer_, _brunswick green_, _vienna green_, _hungary green_, _green lake_, _mineral green_, _patent green_, _mountain green_, _marine green_, _saxon green_, _french green_, _african green_, _persian green_, _swedish green_, _olympian green_, _imperial green_, _mitis green_, _pickle green_, &c. the general characteristics of these greens are brightness of colour, well suited to the purposes of house-painting, but seldom adapted to the modesty of nature in fine art; considerable permanence, except when exposed to the action of damp and impure air, which ultimately blacken most of them; and good body. they have a tendency to darken by time, dry well as a rule in oil, and are all more or less poisonous, even those not containing arsenic. 179. emerald green, _schweinfurt green_, _vienna green_, _imperial green_, _brunswick green_, _mitis green_, &c., is a cupric aceto-arsenite, prepared on the large scale by mixing arsenious acid with acetate of copper and water. it differs from scheele's green, or cupric arsenite, in being lighter, more vivid, and more opaque. powerfully reflective of light, it is perhaps the most durable pigment of its class, not sensibly affected by damp nor by that amount of impure air to which pictures are usually subject: indeed it may be ranked as permanent both in itself and when in tint with white. it works better in water than in oil, in which latter vehicle it dries with difficulty. bearing the same relation to greens generally as pure scarlet bears to reds, its vivid hue is almost beyond the scale of other bright pigments, and immediately attracts the eye to any part of a painting in which it may be employed. too violent in colour to be of much service, it has the effect, when properly placed, of toning down at once, by force of contrast, all the other greens in a picture. if discreetly used, it is occasionally of value in the drapery of a foreground figure, where a bright green may be demanded; or in a touch on a gaily painted boat or barge. when required, no mixture will serve as a substitute. compounded with aureolin, it becomes softened and semi-transparent, yielding spring tints of extreme brilliancy and beauty. 180. scheele's green, or _swedish green_, resembles the preceding variety in being a compound of copper and arsenic, and therefore rankly poisonous; but differs from it in containing no acetic acid, in possessing less opacity, and in having a darker shade. it is a cupric arsenite, with the common attributes of emerald green, under which name it is sometimes sold. of similar stability, it must not be employed with the true naples yellow or antimoniate of lead, by which it is soon destroyed. upon the lavish use of this dangerous pigment in colouring toys, dresses, paper-hangings, artificial leaves, and even cheap confectionery, it is not our province to enlarge: the constant-recurring diseases and deaths, which, directly or indirectly, result from the employment of arsenical pigments, are such every-day facts that they are merely deplored and forgotten. with arsenic on our heads, our clothes, our papers, our sweets, our children's playthings, we are so accustomed to live--and die--in a world of poison, that familiarity with it has bred contempt. into the fatal popularity, therefore, of arsenical colours for decorative purposes, we shall not further enter; but it behoves us to deprecate their presence, and the presence of all poisonous pigments, in colour-boxes for the young. it is one of the pleasures of childhood to suck anything attractive that comes in its way, openly if allowed, furtively otherwise: and as in early life we have a preference for brilliancy, so vivid a pigment as scheele's green is an object of special attention. artistically, it matters little whether a pigment is noxious or not, but we hold that poison should not be put into the hands of the young; and indeed are of opinion that a box of colours is about the worst present a child can receive. 181. malachite green, or _mountain green_, is met with in cumberland, and is also found in the mountains of kernhausen, whence it is sometimes called _hungary green_. it is prepared from malachite, a beautiful copper ore employed by jewellers, and is a hydrated dicarbonate of copper, combined with a white earth, and often striated with veins of mountain blue, to which it bears the same relation that green verditer bears to blue verditer. the colour, which may be extracted from the stone by the process followed for native ultramarine, varies from emerald-green to grass-green, and inclines to grey. it has been held in great esteem by some, and considered strictly stable, on the assumption, probably, that a pigment obtained from a stone like ultramarine, and by the same method, could not be otherwise than permanent. that it is so, with respect to light and air, there is no denying; but the green, when separated from the ore and purified for artistic use, is merely a carbonate of copper, and therefore subject to the influence of damp and impure air, in common with other non-arsenical copper colours. as a pigment, native malachite green has the same composition, or very nearly the same, as that which can be artificially produced, and answers to the same tests. water-rubs of the two varieties which we exposed to an atmosphere of sulphuretted hydrogen became equally blackened by the gas. practically, there is little or no difference between them: both preserve their colour if kept from damp and foul air, both are injured by those agents, and both are liable to darken in time, especially when secluded from light. the artificial, however, can be obtained of a much finer colour than the natural, which it may be made to resemble by admixture with mineral gray. on the whole, they can scarcely be recommended for the palette, and are certainly inferior in durability to scheele's and schweinfurt greens. in fresco painting they have been pronounced admissible; but, apart from the question of damp, we should deem the conjunction of lime with carbonate of copper not favourable to permanence. by the action of alkalies, even the native green malachite may be converted into blue; and it becomes a question whether the dingy greenish-blue on some ancient monuments was not originally malachite green. 182. verdigris, or _viride æris_, is of two kinds, common or impure, and crystallized or _distilled verdigris_, or, more properly, refined verdigris. the best is made at montpellier in france, and is a sub-acetate of copper of a bright green colour inclining to blue. the least durable of the copper greens, it soon fades as a water-colour by the action of light, &c., and becomes first white and ultimately black by damp and foul gas. in oil, verdigris is permanent with respect to light and air, but moisture and an impure atmosphere change its colour, and cause it to effloresce or rise to the surface through the oil. it dries rapidly, and is exceptionally useful with other greens or very dark colours. in varnish it stands better; but cannot be considered safe or eligible, either alone or compounded. vinegar dissolves it, forming a solution used for tinting maps, and formerly much employed for colouring pickles, &c. the painters, who lived at the time when the arts were restored in italy, used this pigment; and the bright greens seen in some old pictures are made by glazings of verdigris. it is often largely adulterated with chalk and sulphate of copper. 183. mixed green green, being a compound of blue and yellow, may be got by combining those colours in the several ways of working--by mixing, glazing, hatching, or otherwise blending them in the proportions of the various hues required. to obtain a _pure_ green, which consists of blue and yellow only, a blue should be chosen tinged with yellow rather than with red, and a yellow tinged with blue. if either a blue or a yellow were taken, tinged with red, this latter colour would go to produce some grey in the compound, which would tarnish the green. the fine nature-like greens, which have lasted so well in some of the pictures of the italian schools, appear to have been compounded of ultramarine, or ultramarine ashes and yellow. whatever pigments are employed on a painting in the warm yellow hues of the foreground, and blue colouring of the distance and sky, are advantageous for forming the greens in landscape, &c., because they harmonize better both in colouring and chemically, and impart homogeneity to the whole: a principle conducive to a fine tone and durability of effect, and applicable to all mixed tints. in compounding colours, it is desirable not only that they should agree chemically, but that they should have, as far as possible, the same degree of durability. in these respects, aureolin and ultramarine, gamboge and prussian blue, indian yellow and indigo, are all judicious mixtures, although not all to be recommended. permanent yellows. | permanent blues. | aureolin. | cerulian blue. cadmium yellow, pale. | cobalt blue. cadmium yellow, deep. | genuine ultramarine. lemon yellow. | brilliant ultramarine. mars yellow. | french ultramarine. naples yellow, modern. | new blue. ochres. | permanent blue. orient yellow. | raw sienna. | the foregoing yellows and blues are in no wise inimical to each other, and yield the best mixed greens, chemically considered, the palette can afford. in an artistic sense, we confess, the result is not so satisfactory: the list of blues, it must be admitted, being somewhat scant. among the latter there is no pigment with the wonderful depth, richness, and transparency of prussian blue, and none consequently which will furnish with yellow a green of similar quality. that the artist, therefore, will dispense with prussian blue, it would be too much to expect. there is, however, less necessity for it since the introduction of viridian, a green resembling that which is produced by admixture of prussian blue and yellow, and which may be varied in hue by being compounded with aureolin or ultramarine. our object in this work is to give precedence to the chemical rather than the artistic properties of pigments, to separate the strictly stable from the semi-stable, and the semi-stable from the fugitive. a colour or a mixture may be chemically bad but artistically good, and vice versâ; but the chemist looks upon no pigment or compound with favour unless it be perfectly permanent, and ignores its mere beauty when void of durability. hence, all artistic considerations are set aside in our lists of permanent pigments: if it be possible to use them alone, so much the better for the permanence of painting; if not, so much the worse will it be, according to the degree of fugacity of the colours employed. 184. bronze, and the three succeeding varieties, are greens resembling each other in being semi-stable, and more or less transparent. bronze is a species of prussian green, of a dull blue-black hue. in its deep washes it appears a greenish-black with a coppery cast. it is used in ornamental work, and sometimes as a background tint for flower pieces. 185. chrome greens, commonly so called, are compounds of chromate of lead and prussian blue, a mixture which is also known as _brunswick green_. fine bright greens, they are suited to the ordinary purposes of mechanic painting, but are quite unfit for the artist's craft, chrome yellow reacting upon and ultimately destroying prussian blue when mixed therewith. for the latter, cheap cobalts and ultramarines are preferably substituted, although they do not yield greens of like power and intensity. under the names of english green, green cinnabar, &c., 'new' green pigments have been from time to time introduced, which have turned out mixtures of prussian blue and chromate of lead; not made, however, by compounding the two, but directly by processes similar to the following:--a mixed solution of the acetates of lead and iron is added to a mixed solution of the yellow prussiate and chromate of potash, the necessary acetate of iron being obtained by precipitating a solution of acetate of lead by sulphate of iron, and filtering the supernatant liquid. or; to a solution of prussian blue in oxalic acid, first chromate of potash is added, and then acetate of lead. by the last process, superior and more permanent chrome greens may be produced, free from lead, by using chloride of barium or nitrate of bismuth in place of the acetate of lead. chromate of baryta, or chromate of bismuth is then formed, neither of which acts on the prussian blue. it should be added that where the latter pigment is present, no green will serve for painting walls containing lime, as its action alters the tint of the prussian blue. 186. hooker's green is a compound of prussian blue and gamboge, two pigments possessing a like degree of stability, and perfectly innocuous to each other. it is a mixture more durable and more transparent than chrome greens made with chromate of lead. there are two varieties in common use--no. 1, a light grass green, in which the yellow predominates; and no. 2, a deeper and more powerful green, with a larger amount of blue. 187. prussian green, like the preceding, is composed of prussian blue and gamboge; but contains a very great excess of the former, and is therefore a bluish-green of the utmost depth and transparency, verging on black in its deep washes. yellow ochre may be employed instead of gamboge, but is not so eligible. a true prussian green, which has been recommended as a pigment, can be produced as a simple original colour, with a base wholly of iron. it is got by partially decomposing the yellow oxalate of protoxide of iron with red prussiate of potash. we have made this green and given it a fair trial, but our verdict is decidedly against it. in colour it is far from being equal to a good compound of prussian blue and gamboge, and it assumes a dirty buff-yellow on exposure to light and air, the film of blue on the oxalate more or less disappearing. another prussian green, with a base of cobalt, is obtained by precipitating the nitrate of that metal with yellow prussiate of potash. according to the mode adopted, and the degree of heat, either a light or dark green results; but this also is inferior in colour, and presents no advantage as to permanence. 188. sap green, _verde vessie_, or _iris green_, is a vegetal pigment prepared from the juice of the berries of the buckthorn, the green leaves of the woad, the blue flowers of the iris, &c. it is usually preserved in bladders, and is thence sometimes called _bladder green_. when good, it is of a dark colour and glossy fracture, extremely transparent, and a fine natural yellowish green. this gummy juice, inspissated and formed into a cake, is occasionally employed in flower painting. it is, however, a very imperfect pigment, disposed to attract the moisture of the atmosphere, and to mildew; while, having little durability in water and less in oil, it is not eligible in the one and is totally useless in the other. similar pigments, obtained from coffee-berries, and named venetian and emerald greens, are of a colder colour, equally defective and fugitive, and now obsolete. 189. terre verte, or _green earth_, is a sober bluish green with a grey cast. it is a species of ochre, containing silica, oxide of iron, magnesia, potash, and water. not bright and of little power, it is a very durable pigment, being unaffected by strong light or impure air, and combining with other colours without injury. it has not much body, is semi-transparent, and dries well in oil. veins of brownish or reddish ochre are often found mixed with terre verte, to the detriment of its colour; and there are varieties of this pigment with copper for their colouring matter, which, although generally brighter, are inferior in other respects, and not true terre vertes. verona green and verdetto or holy green, are ferruginous native pigments of a warmer hue. these are met with in the mendip hills, france, italy, and the island of cyprus, and have been used as pigments from the earliest times. rubens has availed himself much of terre verte, not in his landscapes merely, but likewise in the carnation tints in his figures of a dead christ. it is evident that much of the glazing is done with this colour: it is, in fact, most useful in glazing; because, having only a thin substance, it can be rendered pale by a small portion of white; although in the end it becomes darker by a concentration of its molecules. mérimée states that in the greater part of alexander veronese's works--in his death of cleopatra, in the louvre, for instance--there are some demi-tints which are too green, and which it is certain were not so originally. terre verte, therefore, must be employed with caution; and it would be well to ascertain beforehand whether a mineral colour will in time become darker than when first laid on the picture, by putting a drop of oil on the powder in its natural state. if the tone this gives to it be more intense than that which it acquires by being ground up, it may fairly be assumed that it will attain to the same degree of strength whenever, having completely dried, its molecules shall have re-united as closely as it is possible. umber and terra di sienna are of this class. in combination with indian red and naples yellow, terre verte forms a series of mild russet greens, of much use in middle distance. * * * * * 190. _chrome arseniate_ is an agreeable apple-green colour, prepared from arseniate of potash and salts of chromic oxide. it is durable, but possesses no advantages over the chrome oxides, and is of course poisonous. 191. _cobalt green_, rinman's green, vert de zinc or zinc green. true cobalt green is made by igniting a very large quantity of carbonate of zinc with a very small quantity of carbonate of cobalt. to give a green tint to an enormous proportion of the former, an inappreciable amount of the latter will suffice. some samples which were analysed, consisted almost entirely of zinc, there being only two or three per cent. of cobalt present. this green presents an example of a pigment being chemically good and artistically bad, or at least indifferent. it is a moderately bright green, apt to vary in hue according to the mode of manufacture, permanent both alone and compounded, but so sadly deficient in body and power, as to have become almost obsolete. with other physical defects, and a colour inferior to the chrome oxides, cobalt green has never been a favourite with artists, though justly eulogised by chemists. 192. _copper borate_ is obtained by precipitating sulphate of copper with borax, washing the residue with cold water, and, after drying, igniting it, fusion being carefully avoided. in this manner, a pretty yellowish green is produced, which upon longer ignition assumes a dark green shade: the mass is levigated for use. the compound has the objection of being glassy, and possessing little body, but is preferable to verdigris as to permanence. 193. _copper chrome_ may be prepared by several methods, but the colour is in no case so fine as scheele's or schweinfurt green, nor is it as stable. 194. _copper stannate_, or tin-copper green, equals in colour any of the copper greens free from arsenic. the cheapest way of making it is to heat 59 parts of tin in a hessian crucible with 100 parts nitrate of soda, and dissolve the mass when cold in a caustic alkali. to the clear solution, diluted with water, a cold solution of sulphate of copper is added: a reddish-yellow precipitate falls, which on being washed and dried, becomes a beautiful green. on the palette it would be superfluous, but for common purposes might be found of service. 195. _elsner's green_ is also a combination of tin and copper. it is made by adding to a solution of sulphate of copper a decoction of fustic, previously clarified by a solution of gelatine. to this mixture are added ten or eleven per cent. of protochloride of tin, and lastly an excess of caustic potash or soda. the precipitate is then washed and dried, whereupon it takes a green colour tinged with blue, but without the brightness or durability of the preceding stannate. 196. _green bice_, or green verditer, is the same in substance as blue verditer, which is converted into green verditer by boiling. this pigment is one of the least eligible of copper greens. 197. _green ochre._ by partially decomposing yellow ochre with prussiate of potash, we have produced a fine dark blue-green, resembling prussian green, of great depth and transparency. there are, however, difficulties in the process; and the results do not warrant us in pronouncing this green superior or equal to a mixture of the ochre and prussian blue. 198. _green ultramarine_ is french or artificial ultramarine before the final roasting. it is a somewhat bright bluish-green, becoming a dull greenish-blue on continued exposure. chemically, it is not a bad colour; but artists generally have decided against it. 199. _manganese green_, or cassel green. by several methods, manganate of baryta may be obtained either as an emerald-green, a bluish-green, or a pale green. the manganates, however, are decomposed by contact with organic matter; and hence the green would be liable to suffer from the vehicles employed, as well as by being compounded with animal or vegetal pigments. 200. _mineral green_ is the commercial name of _green lakes_, prepared from sulphate of copper. these vary in hue and shade, have all the properties of the common non-arsenical copper-greens, and, not being subject to change of colour by oxygen and light, stand the weather well, and are excellent for the use of the house-painter, &c. having a tendency to darken and blacken by time and foul air, they are not eligible in the nicer works of fine art. another mineral green adopted in germany as a substitute for the poisonous schweinfurt green, is composed of chromate of lead, carbonate of copper, oxide of iron, and chalk. valueless for the palette, it has not the beauty of schweinfurt green, but is recommended as being free from arsenic. it is not, however, altogether harmless, and should not be used in confectionery or the like. 201. _molybdenum green._ a clear malachite green colour, when dried, is produced from molybdate of soda and potash-chrome-alum, or from the molybdate and alum with ammonia. being more expensive than the chrome oxides and not better, its introduction, for use by artists, would be attended with no advantage. there is likewise obtainable a copper molybdate, by adding neutral molybdate of soda in excess to sulphate of copper. the precipitate is a very pale green colour, flocculent at first, but crystalline after washing. like the chrome molybdate it would be superfluous as a pigment. 202. _quinine green_ is rather adapted for a dye than an artist-colour. it is furnished by acting on quinine with hypochlorite of lime, hydrochloric acid, and ammonia, successively. thus prepared, the green resembles a resin, insoluble in water, but soluble in alcohol, and turned blue by acetic acid. its alcoholic solution dyes silk green, and also woollen and cotton when mordanted with albumen. 203. _roman green_, brought from rome some years back by a president of the royal academy, appeared to be a mixture of prussian blue and dutch or italian pink. it was a fugitive compound, which became blue in fading. 204. _silicate of baryta._ one part of silica heated to whiteness with three parts of baryta, yields a pale green solid mass, permanent, but deficient in colour when ground. it might be employed in enamelling. 205. _titanium green_ has been proposed as a substitute for the green arsenical pigments in common use; but, apart from its expense, the colour is very inferior to scheele's green, &c. titanium green is a ferrocyanide of that metal, produced by adding yellow prussiate of potash to a solution of titanic acid in dilute hydrochloric acid, and heating the mixture to ebullition rapidly. the dark green precipitate is washed with water acidulated with hydrochloric acid, and dried with great care, since it decomposes at temperatures above 100°. 206. _uranium green_ is an oxide of a deep dull green colour, inclining to olive, and nearly black when in lumps. a durable but unattractive preparation, equalled in permanence and far surpassed in beauty by many cheaper compounds. 207. _vanadium green_ falls when ferrocyanide of potassium is added to vanadic acid dissolved in a strong acid. it is a beautiful green precipitate, but at present simply a curiosity, owing to the rarity of the metal vanadium. * * * * * adopting our usual custom of separating the wheat from the chaff, we point to the opaque and transparent oxides of chromium, veronese green, viridian, emerald green, scheele's green, and terre verte, as more or less worthy of being dubbed durable. as semi-stable, malachite green, bronze, hooker's green, and prussian green, must be classed. verdigris, chrome greens, and sap green, should be branded as fugitive: the chrome greens, because they are always commercially composed of chromate of lead and prussian blue, two compounds which are semi-stable in themselves, but become fugacious when compounded. a reference to the numbered italicised greens will show that there are many not known to the palette, which are nevertheless very greatly superior, as regards permanence, to some that disgrace it. why these latter are suffered to hold their position is a mystery not easily explained: it is hard to reconcile the deplored degeneracy of modern pigments with the popularity of semi-stable and fugitive colours. pictures do not stand, is the common cry; therefore, says the public, there are no good pigments now-a-days. to which we answer, newly built houses are constantly falling down; therefore there are no good bricks in these times. of a truth, one conclusion is as reasonable as the other: in either case, if rotten materials be used, the result cannot be lasting; but in neither case does it follow, because such materials are employed, that there are no better obtainable. a well-built house implies a conscientious builder, and a well-painted picture implies a conscientious artist. it is because, we fear, that there are so few conscientious artists, that there are so few permanent paintings; not, certainly, because there are no good pigments. in this last belief, however, the public is encouraged by certain painters, who seek thereby to excuse their own shortcomings, forgetting that it is a bad workman who finds fault with his tools. it has been well observed that when artists speak regrettingly of lost 'systems,' or pigments enjoyed by the mediævalists and unattainable now, it would be far better were they to make the best use of existing materials, and study their further development. there is no need for this cant cry of fugacity, which casts such a blight on modern art. durable pigments are not yet obsolete, they have only to be employed and employed properly to furnish paintings equal in permanence to those of the old masters. "titian," says haydon, "got his colours from the colour shops on the rialto, as we get ours from brown's; and if apelles or titian were living now, they would paint just as good works with our brushes and colours as with their own." chapter xiii. on the secondary, purple. purple, the third and last of the secondary colours, is composed of _red_ and _blue_, in the proportions of five of the former to eight of the latter; proportions which constitute a perfect purple, or one of such a hue as will neutralize and best contrast a perfect yellow, in the ratio of thirteen to three, either of surface or intensity. when mixed with its co-secondary colour, green, purple forms the tertiary _olive_; and, when compounded with the remaining secondary, orange, it constitutes in like manner the tertiary _russet_. of the three secondary colours it is the coolest, as well as the nearest in relation to _black_ or shade; in which respect, and in never being a warm colour, it resembles blue. in other respects also, purple partakes of the properties of blue, which is its archeus, or ruling colour; hence it is to the eye a retiring colour, that reflects light little, and loses rapidly in power in a declining light, and according to the distance at which it is viewed. by reason of its being the mean between black and blue it becomes the most retiring of all positive colours. nature employs this hue beautifully in landscape, as a sub-dominant, in harmonizing the broad shadows of a bright sunshine ere the light sinks into deep orange or red. girtin, who saw nature as she is, and painted what he saw, delighted in this effect of sunlight and shadow. as a ruling colour, whether in flesh or otherwise, purple is commonly too cold, or verges on ghastliness, a fault which is to be as much avoided as the opposite extreme of viciousness in colouring, stigmatized as foxiness. yet, next to green, purple is the most generally pleasing of the consonant colours; and has been celebrated as a regal or imperial colour, as much perhaps from its rarity in a pure state, as from its individual beauty. romulus wore it in his trabea or royal mantle, and tullus hostilius, after having subdued the tuscans, assumed the pretexta or long robe, broadly striped with purple. under the roman emperors, it became the peculiar emblem or symbol of majesty, and the wearing of it by any who were not of the imperial family, was deemed a "treasonable usurpation," punishable by death. at the decline of the empire, the tyrian purple was an important article of commerce, and got to be common in the clothing of the people. pliny says, "nepos cornelius, who died in the reign of augustus cæsar, when i was a young man, assured me that the light violet purple had been formerly in great request, and that a pound of it usually fetched 100 denaria (about £4 sterling): that soon after the tarentine or reddish purple came into fashion; and that this was followed by the tyrian dibapha, which could not be bought for less than 1000 denaria (nearly £40 sterling) the pound; which was its price when p. lentulus spinter was ædile, cicero being then consul. but afterwards, the double-dyed purple became less rare, &c." the tyrian purple alluded to was obtained from the purpuræ, a species of shell-fish adhering to rocks and large stones in the sea adjoining tyre. on account, probably, of its extreme costliness, it was frequently the custom to dye the cloth with a ground of kermes or alkanet, previous to applying the tyrian purple. this imparted to the latter a crimson hue, and explains doubtless the term, double-dyed. the greeks feigned the ancient purple to be the discovery of hercules tyrius, whose dog, eating by chance of the fish from which it was produced, returned to him with his mouth tinged with the dye. alexander the great is said to have found in the royal treasury, at the taking of susa, purple to the enormous value of 5000 talents,[a] which had lain there one hundred and ninety-two years, and still preserved its freshness and beauty. when inclining to red, purple takes the name of _crimson_, &c.; and when leaning to blue, the names of _violet_, _lilac_, _mauve_, _&c._ blue is a colour which it serves to mellow, or follows well into shade. the contrast or harmonizing colour of purple is yellow on the side of light and the primaries; while purple itself is the harmonizing contrast of the tertiary _citrine_ on the side of shade, and less perfectly so of the semi-neutral _brown_. as the extreme primaries, blue and yellow, when either compounded or opposed, afford, though not the most perfect harmony, yet the most pleasing consonance of the primary colours; so the extremes, purple and orange, yield the most pleasing of the secondary consonances. this analogy extends likewise to the extreme tertiary and semi-neutral colours, while the mean or middle colours furnish the most agreeable contrasts or harmonies. in nature pure purple is not a common colour, and on the palette purple pigments are singularly few. they lie under a peculiar disadvantage as to apparent durability and beauty of colour, owing to the neutralizing power of yellowness in the grounds upon which they are laid; as well as to the general warm colour of light, and the yellow tendency of almost all vehicles and varnishes, by which the colour of purple is subdued. 208. burnt carmine is the carmine of cochineal partially charred till it resembles in colour the purple of gold, for which, in miniature and water-painting, it is substituted. it is a magnificent reddish purple of extreme richness and depth, eligible in flower-painting and the shadow of draperies. as it is generally impossible, however, to alter the nature of a pigment by merely changing its colour, burnt carmine is scarcely more permanent than the carmine from which it is produced. if used, therefore, it should be in body, and not in thin washes or as a glaze. durable pigments are admissible in any form; but semi-stable pigments (gamboge excepted) should only be employed in body. 209. burnt lake holds the same relation to crimson lake as burnt carmine to ordinary carmine; and is hence a weaker variety of the preceding, with less richness, and likewise less permanence. 210. indian purple is prepared by precipitating an extract of cochineal with sulphate of copper. it is a very deep-toned but rather cold and subdued purple, neither so red nor so brilliant as burnt carmine; and is chiefly of service in draperies. it is apt to lose its purple colour in a great measure on exposure to light and air, and assume an inky blackness; a defect which becomes less apparent when the pigment is used in bulk. 211. mars violet, _violet de mars_, _purple ochre_, or _mineral purple_, is a dark ochre, native of the forest of dean in gloucestershire. it is of a murrey or chocolate colour, and forms cool tints of a purple hue with white. it is of a darker colour than indian red, which has also been classed among purples, but has a similar body and opacity, and generally resembles that pigment. it may be prepared artificially, and some natural red ochres burn to this colour. being difficult and sometimes impossible to procure, mars violet is often compounded; in which case it is liable to vary both in hue and stability. as, however, indian red is always taken for its basis, the mixture is never wholly fugitive, nor exhibits any very glaring contrast on exposure. 212. mixed purple. purple being a secondary colour, composed of _blue_ and _red_, it follows of course that any blue and red pigments, which are not chemically at variance, may be employed in producing mixed purples of any required hue, either by compounding or grinding them together ready for use, or by combining them in the various modes of operation in painting. in such compounding, the more perfect and permanent the original colours are, the more perfect and permanent will be the purple obtained. to produce a pure purple, neither the red nor the blue must contain or incline to yellow; while to compound a durable purple, both the red and the blue must be durable also. ultramarine and the reds of madder yield beautiful and excellent purples, equally stable in water or oil, in glazing or tint, whether under the influence of light or impure air. cobalt blue and madder red likewise afford good purples; and some of the finest and most delicate purples in ancient paintings appear to have been composed of ultramarine and vermilion, which furnish tints equally permanent, but less transparent than the above, and less easily compounded. facility of use, and other advantages, are obtained at too great a sacrifice by the employment of perishable mixtures, such as the lakes of cochineal with indigo. permanent reds. | permanent blues. | cadmium red. | cerulian blue. liquid rubiate. | cobalt blue. madder carmine. | genuine ultramarine. rose madder. | brilliant ultramarine. mars red. | french ultramarine. ochres. | new blue. vermilions. | permanent blue. it should be noted that all the above reds do not afford pure purples with blue; those which contain more or less yellow, as cadmium red and orange vermilion, furnish purples partaking more or less of olive, which is a compound of purple and green. to those reds may be added the russet rubens madder and the marrone madder brown, two pigments which are alike eligible for mixed purple and mixed orange. no purple, it will be remarked, equal in gorgeous richness to that produced from crimson lake and prussian blue is obtainable from the colours given; just as no mixed green is of such depth and power if that blue be wanting as a constituent. but, as our compound tints are given rather as examples of durability than beauty, all semi-stable or fugitive mixtures are of necessity ignored. 213. purple madder, _field's purple_, or _purple rubiate_, is the only durable organic purple the palette possesses. marked by a soft subdued richness rather than by brilliancy, it leans somewhat towards marrone, and affords the greatest depth of shadow without coldness of tint. unfortunately, in the whole range of artistic pigments there is no colour obtainable in such small quantity as madder purple; hence its scarcity and high price cause it to be confined to water-colour painting, in which the clearness and beauty of its delicate tones render it invaluable in every stage of a drawing. with raw sienna and indigo or prussian blue, subdued by black, it gives beautiful shadow tints, and will be found useful in sky and other effects compounded with cobalt, rose madder, french blue and sepia, yellow ochre and cobalt, lamp black and cobalt, light red, vandyke brown, burnt sienna, or aureolin. with great transparency, body, and depth, it is pure and permanent in its tints, neither gives nor sustains injury on admixture, dries and glazes well in oil, works well, and is altogether most perfect and eligible. for fresco it is admirably adapted, being quite uninjured by lime. there is a lighter and slightly brighter sort, containing less colouring matter and more base, which has all the properties of the above with less intensity of colour. for the sake of cheapness, the purple is sometimes compounded in oil, generally of brown madder and a blue. provided the latter be stable, transparent, and mix kindly, no greater objection can be taken to this than to the neutral orange of brown madder and yellow ochre. 214. violet carmine is a brilliant bluish purple of much richness, employed in draperies and the like. it is prepared by precipitating an alcoholic extract of the root of the _anchusa tinctoria_, commonly known as alkanet, a plant growing in the levant, and some other warm countries. it was used by the ancients as a dye, or as a groundwork to those stuffs which were to be dyed purplish-red: the ladies in ancient times also employed it as a paint. its colouring matter or _anchusin_ has the character of a resin, and is dark-red, softened by heat, insoluble in water, soluble in alcohol and alkalis, and freely so in ether, fats, and volatile oils, to all of which it imparts a brilliant red hue. to obtain anchusin, all the soluble matters are first abstracted from the bruised root by water: it is then digested in a solution of carbonate of potash, from which it may be readily precipitated by an acid. its alcoholic solution yields with different reagents crimson, flesh-coloured, blue, and violet precipitates, none of which, however, can be classed as durable. the variety under notice, violet carmine, resembles the other colours afforded by alkanet in not being able to withstand the action of light. on continued exposure, it loses its beauty and brightness, together with much of its colour, and, like indian purple, assumes an inky blackness. hence it is unsuited to permanently pure effects, and should only be used in body. * * * * * 215. _archil purple._ archil may be regarded as the english, cudbear as the scotch, and litmus as the dutch name for one and the same substance, extracted from several species of lichens by various processes. these lichens, which are principally collected on rocks adjacent to the sea, are cleaned and ground into a pulp with water, treated from time to time with ammoniacal liquor, and exposed with frequent agitation to the action of the atmosphere. peculiar principles existing in the lichens are, by the joint instrumentality of the air, water, and ammonia, so changed as to generate colouring matter, which, when perfect, is expressed. soluble in water and alcohol, this colouring principle yields by precipitation with chloride of calcium a compound known as 'solid french purple', a pigment more stable than the archil colours generally, but all too fugitive for the palette. 216. _bismuth purple._ a purple powder is capable of being produced from bismuth by passing chlorine gas through the hydrated oxide suspended in a saturated solution of potash. as soon as the oxide becomes brown-red, the mixture is boiled and the liquid decanted off at once, the residue being immediately washed first with alcohol and then with water. on the whole, the result is not, for an artistic pigment, worth the trouble involved in the preparation. 217. _burnt madder_ is obtained by carefully charring madder carmine until it becomes of the hue required. bearing the same relation to madder carmine as burnt carmine to the carmine of cochineal, burnt madder is a permanent and perfectly unexceptionable pigment. by reason, probably, of its great price, it is not mentioned in trade catalogues, and must be held as commercially unknown. 218. _cobalt purples_ are obtainable ranging from the richest crimson purple to the most delicate violet. we have produced them by wet and dry methods, varying in brilliancy and beauty, but characterised generally by want of body, and frequently by a smalt-like grittiness. chemically, good and stable colours, they are not received with favour on the palette, and certainly may be very well replaced by mixtures of cobalt blue and madder red. when a permanent compound is obtainable equal in colour to an original pigment, and superior in its physical attributes, no objection can fairly be taken to its artistic preference. there are other things to be considered in a pigment besides permanence, or even permanence and colour combined. the two together do not constitute a perfect pigment, that is, a material of practical utility and value. in the last chapter, allusion was made to a green which possesses both the one and the other, and yet is--at present, at least--quite unfitted for artistic use. hence, with a strong partiality for simple original pigments, we are bound to confess there are cases where mixtures are justifiably preferred. all we contend for is, that each constituent of such mixtures should be stable, and neither give nor receive injury by being compounded. 219. _gold purple_, purple of cassius, or cassius's purple precipitate, was discovered in 1683 by cassius of leyden. it is a compound of tin and gold, best formed by mixing aqueous perchloride of iron with aqueous protochloride of tin, till the colour of the liquid has a shade of green, and then adding this liquid, drop by drop, to a solution of perchloride of gold, which is free from nitric acid and very dilute: after twenty-four hours the purple is deposited. when recently prepared, the colour is brightened by boiling nitric acid. not brilliant, but rich and powerful, this purple varies in hue according to the mode of manufacture from deep crimson to murrey or dark purple: it also differs in degrees of transparency. working well in water, it is an excellent though costly pigment, once popular in miniatures, but at present rarely, if ever used, as purple madder is cheaper, and perfectly well supplies its place. retaining its colour at a high red heat, it is now confined to enamel and porcelain painting, and to tinging glass of a fine red. if, whilst in its hydrated state, it be washed with ammonia, a bright purple liquid results, from which a violet colour, somewhat less expensive, can be produced, by combining the gold purple with alumina, and calcining the product in the same way that is practised with cobalt. this compound may be exposed to the action of the sun's rays for a year without being sensibly affected. 220. _prussian purple._ a prussiate of iron is obtainable of a violet hue, affording good shadow tints and clear pale washes. it has not, however, been introduced as a pigment, as ordinary prussian blue tinged with red furnishes a similar colour. 221. _sandal wood purple._ sandal wood contains about 16 per cent. of colouring matter, soluble with difficultly in water, but readily dissolved by alcohol. from the latter solution, chloride of tin throws down a purple, and sulphate of iron a deep violet precipitate; neither of which is remarkable for permanence. 222. _tin violet._ by heating chromate of stannic oxide to bright redness, a dark violet mass is obtained, which is better adapted to enamel painting than to the palette. it communicates in glazings a variety of tints, from rose-red to violet. * * * * * so scant is the number of good purples in common use, that there are but two which can be classed as durable, namely, purple madder and the true mars violet. foremost in the second group stands burnt carmine. as there are different degrees both of permanence and fugacity, so are there different degrees of semi-stability. burnt carmine, burnt lake, indian purple, and violet carmine, all belong to this division; but the first certainly is more permanent than the rest. rich and beautiful as it is, purple madder cannot be called brilliant; while mars violet is, of course, ochrous. unlike green and orange, therefore, purple can point to no original pigment at once vivid and durable: as regards purple, brilliancy implies a semi-stability that borders more or less closely on fugacity. until the advent of a perfect palette, however, brilliancy and semi-stability will doubtless hold their own. their present popularity may be seen by a glance at the lists of artist-colours--lists compiled, be it remembered, in obedience to the law of demand and supply. if art were really so much honoured as some of its disciples pretend, none but durable colours would be employed. in our opinion, if a picture be worth painting at all, it is worth painting with permanent pigments; but many evidently think otherwise. deploring an error neither flattering to the craft they practise nor to themselves, we would urge such to bear in mind this axiom, semi-stable pigments become fugitive when used in thin washes. even in body they do not preserve their primitive hue, but in glazing and the like, their colour altogether flies or is wholly destroyed. it is this semi-stability, recommended to the thoughtless and indifferent by the beauty which generally accompanies it, that is the bane of modern art. even our greatest painters have yielded to its fascination. who has not gazed upon one of turner's fading pictures with still more of sadness than enjoyment, that anything so grand, so beautiful, so true, should slowly but surely be passing away? a feeling akin to pity is conjured up at the sight of the helpless wreck, abandoned amid the treacherous materials employed, and sinking deeper and deeper. mournful, indeed, is that mighty ruin of mind amid matter; mournful the thought that in years to come, the monument sought for will not be found. footnotes: [a] a talent of money, _i.e._, a talent's weight of silver, was equal to nearly £244. chapter xiv. on the tertiary, citrine. citrine, or the colour of the citron, is the first of the tertiary class of colours, or ultimate compounds of the primary triad, yellow, red, and blue; in which yellow is the archeus or predominating colour, and blue the extreme subordinate. for citrine being an immediate compound of the secondaries, _orange_ and _green_, of both which yellow is a constituent, the latter colour is of double occurrence therein, while the other two primaries enter singly into its composition. the mean or middle hue comprehends eight blue, five red, and six yellow, of equal intensities. hence citrine, according to its name, which is that of a class of colours and used commonly for a dark yellow, partakes in a subdued degree of all the powers of its archeus yellow. in estimating, therefore, its properties and effects in painting, it is to be regarded as participating of all the relations of yellow. by some this colour is improperly called brown, as almost all broken colours are. the harmonizing contrast of citrine is a _deep purple_, which may be seen beautifully opposed to it in nature, when the green of summer declines. as autumn advances, citrine tends towards its orange hues, including the colours termed aurora, chamoise, and others before enumerated under the head of yellow. it is the most advancing of the tertiary colours, or nearest in relation to light; and is variously of a tender, modest, cheering character. to understand and relish the harmonious relations and expressive powers of the tertiary colours, require a cultivation of perception and a refinement of taste for which study and practice are needed. to a great extent the colourist, like the poet, is born not made; but although he must have an innate sense of the beautiful and the true, hard work alone, with his head, his eyes, and his hands, will enable him to learn and turn to account the complex beauties and relations of tertiary colours. they are at once less definite and less generally evident, but more delightful--more frequent in nature, though rarer in common art, than the like relations of the secondaries and primaries. there is very little pure colour in the world: now and then a gleam dazzles us, like a burst of sunshine through grey mists; but as a rule, nature prefers broken colours to absolute hues. most pure in spring, most full in summer, most mellow in autumn, most sober in winter, her tints and shades of colour are always more or less interlaced, from white and the primaries to the semi-neutral and black. of original citrine-coloured pigments there are only a few, unless we include several imperfect yellows which might not improperly be called citrines. the following are best entitled to this appellation:-223. brown pink, _brown stil de grain_, _citrine lake_, or _quercitron lake_ is usually prepared from the berries of avignon (ramnus infectorius), better known as french, persian, or turkey berries; but a more durable and quicker drying species is obtained from the quercitron bark. if produced from the former, it must be branded as fugitive, but if from the latter, it may be termed semi-stable. in either case it is a lake, precipitated from the alkaline decoction by means of alum, in such proportions that the alkali shall not be more than half saturated. the excess of soda or potash employed imparts a brown hue; but the lake being in general an orange broken by green, falls into the class of citrine colours, sometimes inclining to greenness, and sometimes towards the warmth of orange. it works well both in water and oil, in the latter of which it is of great depth and transparency, but its tints with white lead are very fugitive, and in thin glazing it does not stand: the berry variety dries badly. a fine rich colour, more beautiful than eligible, it is popular in landscape for foliage in foregrounds. modified by admixture with burnt sienna or gamboge, it yields a compound which, with the addition of a small quantity of indigo, gives a warm though not very durable green. in many of the flemish pictures the foliage has become blue from the yellowish lake, with which the ultramarine was mixed, having faded. it has been remarked that the alteration made by time in semi-stable pigments is not so observable when they are employed in full body. their use generally has been deprecated, but in shadows such vegetable colours as brown pink are sometimes of advantage, as they are transparent, lose part of their richness by the action of the air, and do not become black. moreover, if mixed with pigments which have a tendency to darken, they mitigate it very much. this last, indeed, is the most legitimate purpose to which semi-stable pigments whose colour fades on exposure can be put. 224. mars brown, or _brun de mars_, is either a natural or artificial ochre containing iron, or iron and manganese. of much richness and strict permanence, it resembles raw umber in being a brown with a citrine cast, but is generally marked by a flush of orange which is not so observable in the latter pigment. 225. mixed citrine. what has been before remarked of the mixed secondary colours is more particularly applicable to the tertiary, it being more difficult to select three homogeneous substances of equal powers as pigments than two, that shall unite and work together cordially. hence the mixed tertiaries are still less perfect and pure than the secondaries; and as their hues are of extensive use in painting, original pigments of these colours are proportionably estimable to the artist. nevertheless there are two evident principles of combination, of which he may avail himself in producing these colours in the various ways of working; the one being that of combining two original secondaries; and the other, of uniting the three primaries in such a manner that the archeus shall predominate. thus in the case of citrine, either orange and green may be directly compounded; or yellow, red, and blue be so mixed that the yellow shall be in excess. these colours are, however, obtained in many instances with best and most permanent effect, not by the intimate combination of pigments upon the palette, but by intermingling them, in the manner of nature, on the canvas, so as to produce the appearance at a proper distance of a uniform colour. thus composed is the _citrine_ colour of fruit and foliage, on inspecting which we distinctly trace the stipplings of orange and green, or of yellow, red, and green. the truth and beauty resulting from such stipplings in art may be seen in the luscious fruit-pieces of the late w. hunt, where the bloom on the plum, the down of the peach, &c., are given with wondrous fidelity to nature. in the _russet_ hues of autumn foliage, where purple and orange have broken or superseded the summer green, this interlacing of colour appears; and also in the _olive_ foliage of the rose-tree, formed in the individual leaf by the ramification of purple in green. besides the durable yellows, reds, and blues, the following orange and green pigments are eligible for mixed citrines. they may likewise, however, be safely and simply compounded by slight additions, to an original brown, of that primary or secondary tone which is requisite to give it the required hue. permanent orange. | permanent green. | burnt roman ochre. | oxide of chromium, opaque. burnt sienna. | oxide of chromium, transparent. cadmium orange. | veronese green. mars orange. | viridian. neutral orange. | emerald green. | scheele's green. | terre verte. 226. raw umber, or umber, is a natural ochre, chiefly composed of oxide of manganese, oxide of iron, silica, and alumina. it is said to have been first brought from ancient ombria, now spoleto, in italy. found in england, and in most parts of the world, that which comes from cyprus, under the name of turkish or levant umber, is the best. of a quiet brown-citrine colour, semi-opaque, it dries rapidly, and injures no other good pigment with which it may be mixed. by time it grows darker, a disadvantage which may be obviated by compounding it with colours which pale on exposure. for light shadow tones and delicate grays it is extremely useful, and yields with blue most serviceable neutral greens. to mud walls, tints for stone, wood, gray rocks, baskets, yellow sails, and stormy seas, this citrine is suited. some artists have painted on grounds primed with umber, but it has penetrated through the lighter parts of the work. mérimée states that there are several of poussin's pictures so painted; that fine series, "the seven sacraments," being clearly among the number. * * * * * 227. _cassia fistula_ is a native vegetal pigment, though it is more commonly employed as a medicinal drug. it is brought from the east and west indies in a sort of cane, in which it is naturally produced. as a pigment it is deep, transparent, of an imperfect citrine colour, inclining to dark green, and diffusible in water without grinding, like gamboge and sap green. once sparingly used in water as a sort of substitute for bistre, it is not now to be met with on the palette. 228. _citrine brown._ from boiling, hot, or cold solutions of bichromate of potash and hyposulphite of soda in excess, we have obtained an agreeable citrine-brown colour, varying in hue and tint according to the mode of preparation and proportions of materials employed. it is a hydrated oxide of chromium which, when washed and carefully dried, yields a soft floury powder. transparent, and affording clear, delicate pale washes, the oxide has not been introduced as a pigment; partly owing to certain physical objections, and partly to a tendency to greenness. this tendency is peculiar to all the brown chrome oxides of whatever hue, whether hydrated or anhydrous; and indeed distinguishes more or less nearly all the compounds of chromium. green, in fact, is the natural colour of such compounds, the colour which they are constantly struggling to attain; and hence it is that the green oxides of chromium, being clothed in their native hue, are of such strict stability. the inclination to green which the citrine under notice possesses, may be seen by washing the precipitate with boiling water. it has been supposed that hydrated brown oxide of chromium is not a distinct compound of chromium and oxygen, but a feeble union of the green oxide with chromic acid. if this be the case, the citrine cast of the brown oxide is easily explained, as well as the gradual addition to its green by the deoxidation of the chromic acid. in mixed tints for autumn foliage and the like, the tendency to green of this citrine brown would be comparatively unimportant; but whether the oxide be adapted to the palette or not, we believe the colour might be utilized. in dyeing, for instance, the solutions of bichromate of potash and hyposulphite of soda would be worth a trial, the liquids of course being kept separate, and the brown washed with cold water. various patterns could be printed with the bichromate on a ground previously treated with hyposulphite. * * * * * several other browns, and ochrous earths, partake of a citrine hue, such as cassel earth, bistre, &c. but in the confusion of names, infinity of tones and tints, and variations of individual pigments, it is impossible to arrive at an unexceptionable or universally satisfactory arrangement. we have therefore followed a middle and general course in distributing pigments under their proper heads. of the three citrines in common use, mars brown and raw umber are strictly stable; while brown pink, the purest original citrine the palette possesses, is either semi-stable or fugitive, according to the colouring substance used in its preparation. chapter xv. on the tertiary, russet. russet, the second or middle tertiary colour, is, like citrine, constituted ultimately of the three primaries, red, yellow, and blue; but with this difference--instead of yellow as in citrine, the archeus or predominating colour in russet is red, to which yellow and blue are subordinates. for _orange_ and _purple_ being the immediate constituents of russet, and red being a component part of each of those colours, it follows that red enters doubly into russet, while yellow and blue appear but once therein. the proportions of its middle hue are eight blue, ten red, and three yellow, of equal intensities. thus composed, russet takes the relations and powers of a subdued red; and many pigments and dyes of the latter denomination are strictly of the class of russet colours. in fact, nominal distinction of colours is only relative; the gradation from hue to hue, as from tint to tint, and shade to shade, being of such unlimited extent, that it is impossible to pronounce absolutely where one hue, tint, or shade ends, and another begins. the harmonizing, neutralizing, or contrasting colour of russet, is a _deep green_; or when the russet inclines to orange, a _gray_ or _subdued blue_. these are often beautifully opposed in nature, being medial accordances or in equal relation to light, shade and other colours, and among the most agreeable to sense. russet, as we have said, partakes of the relations of red, but it is a hue moderated in every respect, and qualified for greater breadth of display in the colouring of nature and art; less so, perhaps, than its fellow-tertiaries in proportion as it is individually more beautiful. the powers of beauty are ever most effective when least obtrusive; and its presence in colour should be chiefly evident to the eye that seeks it--not so much courting as being courted. of the tertiary colours, russet is the most important to the artist; and there are many pigments classed as red, purple, &c., which are of russet hues. but there are few true russets, and only one original pigment of that colour is now known on the palette, to wit-229. rubens' madder, _orange russet_, _russet rubiate_, or _field's russet_. this is a very rich crimson russet with a flush of orange; pure, transparent, and of a middle hue between orange and purple. prepared from the madder root, it is not subject to change by the action of light, time, or mixture of other pigments. although not so much employed as the marrone madder brown, it is serviceable both as a local and auxiliary colour in compounding and producing with yellow the glowing hues of autumnal foliage, &c.; and with blue, the beautiful and endless variety of grays in skies, flesh, &c. a good glazing colour, its thin washes afford fine flesh tints in water: as an oil pigment it dries indifferently, and requires to be forced by the addition of a little gold size or varnish. cappah brown and burnt umber sadden it to the rich tones adapted for general use in shadows. so saddened, this lake meets admirably the dark centres of the upper petals of certain fancy geraniums, while alone its pale washes are equally well suited to the lower leaves. 230. mixed russet. what has been remarked in the preceding chapter upon the production of mixed citrine colours, is likewise applicable to mixed russet. by the immediate method of producing it materially from its secondaries, good and durable colours are obtained by compounding the following orange and purple pigments- permanent orange. | permanent purple. | burnt roman ochre. | mars violet, true. burnt sienna. | purple madder. cadmium orange. | mars orange. | neutral orange. | many other less eligible duple and triple compounds of russet are obvious upon principle, and it may be produced by adding red in due predominance to some browns; but these, like most mixtures, are inferior to original pigments. to the orange colours there may be added cadmium red and the orange vermilions, pigments which were classed among the reds, but which contain sufficient yellow to render them adapted for either compound russets or compound citrines. and as of original purple pigments there are two only which are stable, such mixtures as madder red and french blue will help to swell the list of available permanent purples. rubens' madder itself may be changed in hue by being first mixed with blue and then with orange. * * * * * 231. _prussiate of copper_ differs chemically from prussian blue only in having copper instead of iron for its basis. it varies in hue from russet to purple brown, is transparent and deep, but, being very liable to change in colour by the action of light and by other pigments, has never been much used, and is now obsolete. the compound has the objection of containing free prussiate of potash, not removable by continued washing--sometimes as much as five per cent. * * * * * there are several other pigments which enter imperfectly into, or verge upon, the class of russet, which, having obtained the names of other classes to which they are allied, will be found under other heads; such are some of the ochres, as indian red. burnt carmine is often of the russet hue, or convertible to it by due additions of yellow or orange; as are burnt sienna and various browns, by like additions of lake or other reds. the one pigment in this chapter known to the modern palette, rubens' madder, is permanent. chapter xvi. on the tertiary, olive. olive is the third and last of the tertiary colours, and nearest in relation to shade. like its co-tertiaries, citrine and russet, it is composed of the three primaries, blue, red, and yellow; but is formed more directly of the secondaries, _purple_ and _green_, in each of which blue is a constituent: hence blue occurs twice in the latter mode of forming olive, while red and blue enter therein singly and subordinately. blue is, therefore, in every instance the archeus or predominating colour of olive; its perfect or middle hue comprehending sixteen of blue to five of red and three of yellow. it partakes in a proportionate measure of the powers, properties, and relations of its archeus: accordingly, the antagonist or harmonizing contrast of olive is a _deep orange_. like blue, olive is a retiring colour, the most so of all the colours, being the penultimate of the scale, or nearest of all in relation to black, and last, theoretically, of the regular distinctions of colours. hence its importance in nature and painting is almost as great as that of black; it divides the office of clothing the face of creation with green and blue; with both which, as with black and grey, it enters into innumerable compounds and accordances, changing its name as either hue prevails, into green, gray, ashen, slate, &c. thus the olive hues of foliage are called green, and the purple hues of clouds are called gray, &c.; but such terms are general only, and unequal to the infinite particularity of nature. this infinity, or endless variation of hue, tint, and relation, of which the tertiaries are susceptible, gives a boundless license to the revelry of taste, in which the genius of the pencil may display the most captivating harmonies of colouring, and the most chaste and delicate expressions; too subtle to be defined, too intricate to be easily understood, and often too exquisite to be felt by the untutored eye. nature always melodizes by imperceptible gradations, while she harmonizes by distinct contrasts. at different seasons we have blossoms of all hues, variously subordinated; and when the time of flowers may be considered past, as if she had no further use for her fine colours, or were willing to display her ultimate skill and refinement, nature lavishes the contents of her palette, not disorderly, but in multiplied relations, over all vegetal creation, in those rich and beautiful accordances of broken and finishing colours with which autumn is decorated ere the year decays and sinks into olive darkness. as a rule, no colour exists in nature without gradation, which is to colours what curvature is to lines. the difference in mere beauty between a gradated and ungradated colour may be seen by laying an even tint of rose-colour on paper, and putting a rose leaf beside it. the victorious beauty of the rose, as compared with other flowers, depends wholly on the delicacy and quantity of its colour gradations, all other flowers being either less rich in gradation, not having so many folds of leaf; or less tender, being patched and veined instead of flushed. it is not enough, however, that colour should be gradated in painting by being made simply paler or darker at one place than another. generally, colour changes as it diminishes, and is not only darker at one spot, but also purer at one spot than elsewhere; although it does not follow that either the darkest or the lightest spot should be the purest. very often the two gradations more or less cross each other, one passing in one direction from paleness to darkness, another in another direction from purity to dulness; but there will almost always be both of them, however reconciled. hence, every piece of blue, say, laid on should be quite pure only at some given spot, from which it must be gradated into blue less pure--greyish blue, or greenish blue, or purplish blue--over all the rest of the space it occupies. in turner's largest oil pictures, there is not one spot of colour as large as a grain of wheat ungradated; and it will be found in practice that brilliancy of hue, vigour of light, and even the aspect of transparency in shade, are essentially dependent on this character alone; hardness, coldness, and opacity, resulting far more from equality of colour than from nature of colour. given some mud off a city crossing, some ochre out of a gravel pit, a little whitening, and some coal-dust, and a luminous picture might be painted, if time were allowed to gradate the mud, and subdue the dust. but not with the red of the ruby, the blue of the gentian, snow for the light, and amber for the gold, could such a picture be produced, if the masses of those colours were kept unbroken in purity, and unvarying in depth. olive being usually a compound colour both with the artist and mechanic, there are few olive pigments in commerce. 232. mixed olive may be compounded in several ways; directly, by mixing green and purple; or indirectly, by adding to blue a smaller proportion of yellow and red, or by breaking much blue with little orange. cool black pigments, combined with yellow ochre, afford eligible olives; hues which are called _green_ in landscape, and _invisible green_ in mechanic painting. it is to be noted that in producing these and other compound colours on the palette or canvass, those mixtures will most conduce to the harmony of the performance which are formed of pigments otherwise generally employed in the picture. thus, presuming aureolin to be the principal yellow used, the same yellow should be chosen for compounding orange and green, or for obtaining indirectly citrine, russet, and olive. permanent green. | permanent purple. | oxide of chromium, opaque. | mars violet, true. oxide of chromium, transparent. | purple madder. veronese green. | viridian. | emerald green. | scheele's green. | terre verte. | as in the case of russet, there may be added to the two original purples, mixtures composed of durable reds and blues. there are so many ways of producing the tertiaries, that no difficulty can be found in compounding them with stable pigments. each tertiary may be represented as follows:- citrine = orange + green. " = (yellow + red) + (yellow + blue.) " = 2 yellow + red + blue. russet = orange + purple. " = (yellow + red) + (red + blue.) " = 2 red + yellow + blue. olive = green + purple. " = (yellow + blue) + (red + blue.) " = 2 blue + yellow + red. from the above equations, and by consulting the lists given of permanent primary and secondary colours, the artist will at once see how easily and safely he may vary his mode of compounding the tertiaries. 233. olive green, sometimes called _dewint's green_, is an arbitrary compound, or mixed green, of a fine deep olive colour and sober richness. advisedly or not, it is used in landscape, sketching, &c.; but only in water, olive lake supplying its place in oil. like many other compound pigments, it is either permanent, semi-stable, or fugitive, according to the constituents of which it is composed. generally speaking, it is more beautiful than durable, and is often decidedly fugacious, fading on exposure. it is impossible for a writer to pronounce an absolute opinion on the stability of all mixtures sold in a separate form, inasmuch as the compounds of one firm may differ from those of another. we have before expressed our dislike to such pigments, and this uncertainty with regard to their composition serves to strengthen it. nevertheless, as there are exceptions to every rule, it must be admitted that the palette possesses compounds always to be relied upon. 234. olive lake is in commerce exclusively an oil colour. when true, it is a lake prepared from the green ebony, or laburnum, and is of considerable permanence, transparency, and depth, both in water and oil; in which latter vehicle it dries well. this variety, however, may be said to be obsolete; having given way to a mixture, usually semi-stable, and liable to blacken. * * * * * 235. _burnt verdigris_ is what its name expresses, and is an olive-coloured oxide of copper deprived of acid. it dries remarkably well in oil, is more durable than the original verdigris, and is in other respects an improved and more eligible pigment, although not to be recommended. 236. _olive oxide of chromium._ an olive oxide of this metal is obtainable, transparent, of strict stability, and altogether superior to any original or compound olive pigment as yet known. eligible either in water or oil, it is admirably adapted for autumn foliage, where a quiet, subdued, nature-like green is required. it has not, however, been introduced, partly because of its expense, and partly because a mixture of other pigments with the ordinary chrome oxides sufficiently answers the purpose. there are more good colours in the world than are dreamt of in the palette's philosophy, but either they are not wanted, or are too costly to sell. in a great measure, both art and science are dependent on commerce. 237. _olive rinman's green._ a compound analogous to cobalt green may be made, of an olive hue, with more body, and equally stable. 238. _olive scheele's green._ cupric arsenite, when heated, gives off arsenious acid and water, leaving a residue of arsenide of copper and copper arseniate. a series of olive colours is so afforded, which are as durable as their original pigment, and might with advantage be substituted for the doubtful compounds at present in use. 239. _olive schweinfurt green_ is likewise furnished by gentle calcination. it may be directly prepared by mixing boiling aqueous solutions of equal parts of crystallised verdigris and arsenious acid. an olive-green precipitate is immediately formed, which is apt, without due precaution, to pass into an emerald green. a durable copper colour. 240. _olive terre verte._ we have obtained a very beautiful olive from terre verte by simply changing its hue. in oil, especially, the colour so produced would be found of service for autumn foliage, or richly painted foregrounds. a simple original pigment, consisting wholly of the earth, it resembles ordinary terre verte in being unaffected by strong light or impure air, and uninjured by admixture; but differs from it in not darkening by time. semi-transparent, of sober richness and drying well in oil, it is, according to its powers, a perfectly unexceptionable colour, of strict stability. * * * * * of the two olive colours in common use, olive lake and olive green, the first is generally semi-stable, and apt to blacken; while the second is usually fugitive, and liable to fade: both are compounds. the palette, therefore, possesses no original olive pigment, good or bad. a glance at the numbered italicised olives will show that the doubtful mixtures referred to might with advantage be superseded. it is clear that the olive pigments which the palette does not know, are better than those with which it is acquainted. chapter xvii. on the semi-neutral, brown. as colour, according to the regular scale descending from white, ceases properly with the last of the tertiaries, olive, in theory the neutral black would here form a fitting conclusion. practically, however, every coloured pigment, of every class or tribe, combines with black as it exists in pigments--not simply being deepened or lowered in tone thereby, but likewise defiled in colour, or changed in class. hence there arises a new series or scale of coloured compounds, having black for their basis, which, though they differ not theoretically from the preceding order inverted, are yet in practice imperfect or impure. these broken compounds of black, or coloured blacks and greys, we have distinguished by the term, semi-neutral, and divided them into three classes: brown, marrone, and gray. what tints are with respect to white, they are with regard to black, being, so to speak, black tints or shades. the first of the series is brown, a term which, in its widest acceptation, has been used to include vulgarly every kind of dark broken colour, and is, in a more limited sense, the rather indefinite name of a very extensive class of colours of warm or tawny hues. accordingly there are browns of every denomination except blue; to wit, yellow-brown, red-brown, orange-brown, purple-brown, citrine-brown, russet-brown, &c. but there is no such thing as a blue-brown, nor, strictly, any other coloured brown in which blue predominates; such predominance of a cold colour at once carrying the compound into the class of gray, ashen, or slate. brown comprises the hues called dun, hazel, auburn, feuillemort, mort d'ore, &c.; several of which have been already mentioned as allied to the tertiary colours. the term _brown_, then, denotes rightly a warm broken colour, of which _yellow_ is a chief constituent: hence brown is in some measure to shade what yellow is to light. hence, also, proper quantities of either the three primaries, the three secondaries, or the three tertiaries, produce variously a brown mixture. browns contribute to coolness and clearness by contrast when opposed to pure colours, and rubens more especially appears to have employed them upon this principle; although the same may be said of titian, correggio, paulo veronese, and all the best colourists. being a sort of intermedia between positive colours and neutrality, browns equally contrast colour and shade. this accounts for their vast importance in painting, and the necessity of preserving them distinct from other colours, to which they give foulness in mixture; and to this is due their use in backgrounds and in relieving of coloured objects. the tendency in the compounds of colours to run into brownness and warmth is one of the common natural properties of colours which occasions them to deteriorate or defile each other in mixture. brown by consequence is synonymous with foul or dirty, as opposed to fair or clean; and hence brown, which is the nearest of the semi-neutrals in relation to light, is to be avoided in mixture with light colours. yet is it an example of the wisdom of nature's author that brown is rendered, like green, a prevailing hue, and in particular an earth colour, as a contrast which is harmonized by the blueness and coldness of the sky. this tendency will likewise explain the use of brown in harmonizing and toning, as well as the great number of natural and artificial pigments and colours so called. it was the fertility and abundance of browns that caused our great landscape-colourist wilson, when a friend went exultingly to tell him that he had discovered a new brown, to check him in his characteristic way, with--"i'm sorry for it: we have gotten too many of them already." nevertheless, fine transparent browns are obviously very valuable. if red or blue in excess be added to brown, it falls into the other semi-neutral classes, marrone or gray. the wide acceptation of the term brown has occasioned much confusion in the naming of colours, since broken colours in which red, &c. predominate, have been improperly called brown. that term, therefore, should be confined to the semi-neutral colours, compounded of, or like in hue to, either the primary _yellow_, the secondary orange, or the tertiary _citrine_, with a _black_. the general contrast or harmonizing colour of such compounds will consequently be more or less purple or blue. the number of browns is great, as may be seen by the following list. this list, however, is good, and includes a considerable proportion of permanent pigments. 241. asphaltum, _asphalt_, _bitumen_, _mineral pitch_, _jew's pitch_, _antwerp brown_, _liquid asphaltum_, &c., is a sort of mineral pitch or tar which, rising liquid to the surface of the lacus asphaltites or asphaltic lake (the dead sea) concretes there by the natural action of the atmosphere and sun, and, floating in masses to the shores, is gathered by the arabs. the french give it an additional name from the region of the lake, to wit, bitumen of judea; and with the english, from the same cause, it has the alias of jew's pitch. asphaltum is not so called, however, after the lake, as is asserted by a writer in the encyclopædia: it is just the reverse--pliny says, "the asphaltic lake produces nothing but bitumen (in greek, asphaltos); and hence its name." a substance resembling asphalt is found at neufchâtel in switzerland, and in other parts of europe. a specimen of the native bitumen, brought from persia, and of which the author made trial, had a powerful scent of garlic when rubbed. in the fire it softened without flowing, and burnt with a lambent flame; did not dissolve by heat in turpentine, but ground easily as a pigment in pale drying oil, affording a fine deep transparent brown colour, resembling that of commercial asphaltum; dried firmly almost as soon as the drying-oil alone, and worked admirably both in water and oil. asphaltum may be used as a permanent brown in water, for which purpose the native is superior to the artificial. the former, however, is now seldom to be met with, the varieties employed on the palette being the residua of various resinous and bituminous matters, distilled for the sake of their essential oils. these residua are all black and glossy like common pitch, which differs from them only in having been less acted upon by fire, and thence in being softer. at present asphaltum is prepared in excessive abundance as a product of the distillation of coal at the gas manufactories, and is chiefly confined to oil-painting, being first dissolved in turpentine, which fits it for glazing and shading. its fine brown colour and perfect transparency are lures to its free use with many artists, notwithstanding the certain destruction that awaits the work on which it is much employed, owing to its tendency to contract and crack by changes of temperature and the atmosphere; but for which, and a slight liability to blacken, it would be a most beautiful, durable, and eligible pigment. the solution of asphaltum in turpentine, united with drying oil by heat, or the bitumen torrefied and ground in linseed or drying-oil, acquires a firmer texture, but becomes less transparent and dries with difficulty. if common asphaltum, as usually prepared with turpentine, be used with some addition of vandyke brown, umber, or cappah brown ground in drying oil, it will gain body and solidity which will render it much less disposed to crack. nevertheless, asphaltum is to be regarded in practice rather as a dark varnish than as a solid pigment, and all the faults of a bad varnish are to be guarded against in employing it. it is common to call the solution in turpentine _asphaltum_, and the mixture with drying-oil _bitumen_: the latter is likewise known as _antwerp brown_. a preparation for the use of water-colour artists is employed under the name of _liquid asphaltum_. 242. bistre is extracted by watery solution from the soot of wood fires, whence it derives a strong pyroligneous scent. it is a very powerful citrine-brown, washes well, and has a clearness suited to architectural subjects. its use is confined to water-colour painting, in which it was much employed by the old masters for tinting drawings and shading sketches, before the general application of indian ink to such purposes. of a wax-like texture, it is perfectly durable, but unfitted for oil, drying therein with the greatest difficulty. a substance of this kind collects at the back of fire-places in cottages where peat is the constant fuel burnt; which, purified by solution and evaporation, yields a fine bistre, similar to the scotch. all kinds of bistre attract moisture from the atmosphere. 243. bone brown and _ivory brown_ are obtained by roasting bone and ivory until by partial charring they become of a brown colour throughout. though much esteemed by some artists, they are not quite eligible pigments, being bad driers in oil, the only vehicle in which they are now used. moreover, their lighter shades are not permanent either in water or oil when exposed to the action of strong light, or mixed in tint with white lead. the palest of these colours are the most opaque: the deepest are more durable, and most so when approaching black. neither bone nor ivory brown is often employed, but the former may be occasionally applied in forming clear, silvery, warm grays, in combination with zinc white. 244. burnt umber is what its name denotes, and has a deeper shade with a more russet hue than the raw umber. a quiet brown, it affords clear and warm shadows, but is apt to look rather turbid if used in great depth. it washes and works capitally in water, and dries quickly in oil, in which it is employed as a siccative. perfectly stable in either vehicle, it may sometimes be substituted for vandyke brown, is eligible in fresco, and invaluable in buildings. where the lakes of madder require saddening, the addition of burnt umber increases their powers, and improves their drying in oil. it contains manganese and iron, and may be produced artificially. the old italians called it _falsalo_. 245. caledonian brown is a permanent native pigment, the use of which is confined to oil. a magnificent orange-russet brown of considerable transparency, it is marked by great depth and richness, and will be found serviceable where a powerful brown of the burnt sienna class is required. 246. cappah brown, or _cappagh brown_, is likewise a colour peculiar to oil. it is a species of bog-earth or peat, mixed with manganese in various proportions, and found on the estate of lord audley at cappagh, near cork. the specimens in which the peat earth most abounds are of light weight, friable texture, and dark colour; while those which contain more of the metal are heavy and paler. as pigments, the peaty cappah brown is the most transparent and rich in colour. a prompt drier in oil, its surface rivels during drying where it lies thick. the other and metallic sort is a more opaque, a lighter and warmer brown pigment, which dries rapidly and smoothly in a body or thick layer. the first may be regarded as a superior vandyke brown, the second as a superior umber. the two extreme kinds should be distinguished as light and deep cappah browns; the former excellent for dead colouring and grounds, the latter for glazing and graining. these pigments work well in oil and varnish; they do not, however, keep their place while drying in oil by fixing the oil, like the driers of lead, but run. under the names of _euchrome_ and _mineral brown_, they have been introduced into commerce for civil and marine painting. 247. cassel earth, _terre de cassel_, or, corruptly, _castle earth_, is specially an oil pigment, similar to burnt umber but of a more russet hue. it is an earth containing bitumen, a substance which, with pit-coal, lignite or brown coal, jet, petroleum or rock oil, naphtha, &c., is looked upon as a product of the decomposition of organic matter, beneath the surface of the earth, in situations where the conditions of contact with water, and almost total exclusion of atmospheric air, are fulfilled. deposited at the bottom of seas, lakes, or rivers, and subsequently covered up by accumulations of clay and sand, the organic tissue undergoes a kind of fermentation by which the bodies in question are slowly produced. the true bitumens appear to have arisen from coal or lignite by the action of subterranean heat; and very closely resemble some of the products yielded by the destructive distillation of those bodies. rich as is the tone of colour of cassel earth, it is apt to lose this in some measure on exposure to light. mérimée remembers to have seen a head, the brown hair of which had been painted partly with the earth alone, and partly with a mixture of the earth and white; yet the hair where the white was employed was darker than that painted solely with the brown, the white having fixed the colour. to compensate for its thus fading, it should be mixed with pigments that are permanent, such as umber and lamp black. like all bituminous earths, it needs the strongest drying oil. by calcination, a greater degree of intensity may be imparted to the colour, and perhaps a little more solidity. in landscapes it is of much service for the most vigorous portions of foregrounds and the trunks of trees, as well as for painting cavernous rocks or deep recesses in architecture. compounded with burnt lake and a little prussian blue, it gives a black the most profound. 248. chalon's brown is a water-colour pigment, transparent and inclining to red; deep, full, and very rich. on exposure to light it becomes less russet, but is otherwise strictly stable. 249. cologne earth, incorrectly called _cullen's earth_, is a native bituminous earth, containing less bitumen than cassel earth, and therefore drying more quickly. darker than that variety, it is less transparent, and covers better. in its general qualities it resembles vandyke brown, except that in combination with white, it affords a range of cooler brown tints. useful for the shadows of buildings, it does not wash so well as sepia, and is preferred occasionally on that account. by some it has been called durable, by others branded as fugacious. according to bouvier, brown hair represented by this colour has been known to disappear in six months, all the brown vanishing, and nothing remaining but a few black lines of the sketch. as it is similar in composition to cassel earth, the safest course would be to mix it with umber, and not to employ it alone. calcined, it acquires a reddish hue. 250. indelible brown ink. although this cannot be classed as a pigment, yet, being very useful in water-colours, it may be proper to describe its qualities. the ink is a rich brown fluid, and, as its name imports, is indelibly fixed on the paper as soon as it is dry; thus allowing the artist to work or wash over it repeatedly, without its being disturbed. if diluted with water to its faintest tint, it still continues to retain its indelible properties undiminished. it is generally used with a reed pen, and employed chiefly in architectural details and outlines. various brown inks, principally solutions of bistre and sepia, were adopted in sketching by claude, rembrandt, and many of the old masters. in modern times, a beautiful transparent brown for water-colour artists, known as _liquid prout's brown_, has been extensively employed. this contains less fixative than the indelible ink, and is the vehicle with which nearly all samuel prout's drawings were executed. 251. leitch's brown is a permanent pigment peculiar to water painting. a most beautiful olive brown, soft and rich, it is admirably adapted for autumnal foliage tints and the like, either alone or compounded with burnt sienna or cadmium orange. transparent and clear in its washes, this is a most serviceable colour in landscape generally. 252. mixed brown can be produced in endless variety, either by adding a warm colour to black, such as yellow, orange, or citrine, or else by combining the three primaries, secondaries, or tertiaries in suitable proportions. by consulting the lists given of permanent pigments belonging to those classes, and by referring to the chapter on black, it will be seen that no difficulty exists in obtaining durable mixed browns when required. for example, there may be formed from the primaries, a compound of aureolin, rose madder, and ultramarine; or from the secondaries, a mixture of cadmium orange, viridian, and madder purple. of course, as with other mixed tints, the brown hue can be furnished not only by direct compounding of the colours on the palette, but by laying one colour over the other on the paper or canvass, or by stippling. 253. mummy, _mummy brown_, or _egyptian brown_, is a bituminous product mixed with animal remains, brought from the catacombs of egypt, where liquid bitumen was employed three thousand years ago in embalming. by a slow chemical change, it has combined during so many ages with substances which give it, as a rule, a more solid and lasting texture than simple asphaltum. generally resembling the latter in its other properties and uses as a pigment, mummy is often substituted for it, being less liable to crack or move on the canvass. it must be remembered, however, that mummy varies exceedingly both in its composition and qualities; and as from its very nature and origin nothing certain can be said of it, but little reliance should be placed on this brown. mummy belongs to the class of pigments which are either good or bad, according as they turn out. on the whole, we agree with the american artist, who has been more than once quoted in these pages, that nothing is to be gained by smearing one's canvass with a part, perhaps, of the wife of potiphar. with a preference for materials less frail and of a more sober character, we likewise hold with bouvier, that it is not particularly prudent to employ without necessity these crumbled remains of dead bodies, which must contain ammonia and particles of fat in a concrete state and so be more or less apt to injure the colours with which they may be united. the use of mummy is now confined to oil, in which, says mr. carmichael, a mixture of mummy and bitumen will dry and never crack. if this be the case, the compound would be preferable to either separate. 254. prussian brown is an iron oxide, containing more or less alumina, and prepared by calcining an aluminous prussian blue, or treating an aluminous ferrocyanide of peroxide of iron with an alkali. possessing the nature and properties of burnt sienna, it is transparent, permanent, and dries well in oil. of an orange hue, it is neither so rich nor so powerful as that pigment, and is better employed as a glaze than in body. 255. sepia, _liquid sepia_, _seppia_, or _animal æthiops_, is named after the sepia or cuttle-fish, also called the ink-fish, from its affording a dark liquid, which was used as an ink and pigment by the ancients. all the species of cuttle-fish are provided with a dark-coloured fluid, sometimes quite black, which they emit to obscure the water, when it is wanted to favour their escape from danger, or, by concealing their approach, to enable them with greater facility to seize their prey. the liquid consists of a mass of extremely minute carbonaceous particles, intermixed with an animal gelatine or glue, and is capable of being so widely spread, than an ounce of it will suffice to darken several thousand ounces of water. from this liquid, brought chiefly from the adriatic, but likewise obtainable from our own coasts, is derived the pigment sepia, as well as, partially, the indian ink of the chinese. sepia is a powerful dusky brown, of a fine texture, transparent, works admirably in water, combines cordially with other pigments, and is very permanent. it is much used as a water-colour, and for making drawings in the manner of bistre and indian ink; but is not employed in oil, as it dries therein very reluctantly. extremely clear in its pale tints, and perhaps the best washing colour known, sepia must be used with caution, or otherwise heaviness will be engendered in the shades, so strong is its colouring property. mixed with indigo, or, preferably, prussian blue and black, it is eligible for distant trees, for a general shadow tint in light backgrounds, and for the shade of white linen or white draperies. with madder red it forms a fine hue, somewhat resembling brown madder, and with crimson lake and indigo gives an artistically excellent black. sometimes alone and sometimes in combination with lamp black, or madder red and prussian blue saddened by the black, it will be found useful in dark foreground boats, rocks, near buoys, sea-weed, &c. compounded with aureolin, sepia yields a series of beautiful and durable neutral greens for landscape; and mixed with prussian blue, affords low olive greens, which may be deepened into very cool dark greens by the addition of black. for hills and mountains in mid-distance, sepia combined with cobalt and brown madder is of service; or, for the dark markings and divisions of stones in brooks and running streams, the same compound without the cobalt. mixed with purple madder, it furnishes a fine tint for the stems and branches of trees; and with french blue and madder red gives a really good black. compounds of sepia and yellow ochre, gamboge, raw sienna, or cobalt and aureolin, are severally useful. a rich and strong brown is formed by the admixture of madder red, burnt sienna, and sepia; a tint which may be modified by omitting the sepia or the sienna, or reducing the proportions of either. for dutch craft, this tint and its variations are of great value. a wash of sepia over green very agreeably subdues the force of the colour. 256. warm sepia is the natural sepia warmed by mixture with other browns of a red hue, and is intended for drawings where it would be difficult to keep the whole work of the same tint, unless the compound were made in the cake of colour. 257. roman sepia is a preparation similar to the preceding, but with a yellow instead of a red cast. 258. vandyke brown. this pigment, hardly less celebrated than the great painter whose name it bears, is a species of peat or bog-earth of a fine, deep, semi-transparent brown colour. the pigment so much esteemed and used by vandyke is said to have been brought from cassel; an assertion which seems to be justified by a comparison of cassel earth with the browns of his pictures. gilpin in his essays on picturesque beauty, remarks that "in the tribe of browns--in oil-painting, one of the finest earths is known, at the colour shops, by the name of castle-earth, or vandyke's brown." the vandyke brown of the present day is a bituminous ochre, purified by grinding and washing over. apt to vary in hue, it is durable both in water and oil, but, like all bituminous earths, dries tardily as a rule in the latter vehicle. clear in its pale tints, deep and glowing in shadows, in water it has sometimes the bad property of working up: for this reason, where it is necessary to lay on a great body of it, the moist tube colour should be preferred to the cake. with madder red, the brown gives a fine tint, most useful as a warm shadow colour; and with prussian blue, clear, very sober neutral greens for middle distances. in banks and roads, vandyke brown is the general colour for dragging over the surface, to give roughness of texture: compounded with yellow ochre, it affords a good ground tint, and with purple madder a rich shadow colour. in sunrise and sunset clouds, a mixture of the brown with cobalt yields a cold neutral green, adapted for those clouds at the greatest distance from the sun. for foliage tints, aureolin, french blue, and vandyke brown, will be found of service; or as a glaze over such tints, the yellow and the brown. with raw sienna, brown madder, payne's gray, gamboge, and roman ochre, this brown is useful. in a water-colour winter scene, when the trees are denuded of foliage, the net work of the small branches at the tops of them may be prettily given with cobalt and vandyke brown, used rather dry, and applied with a brush having its hairs spread out either by the fingers or by drawing them through a fine-tooth comb before working. grass is likewise represented readily by this means, and so are small trees on the summit of a cliff or in like positions. the campania brown of the old italian painters was a similar earth. 259. verona brown, a pigment peculiar to oil painting, is a native ferruginous earth. a citrine brown of great service in tender drab greens, it forms with terre verte and the madder lakes rich autumnal tints of much beauty and permanence. 260. yellow madder, _cory's yellow madder_, or _cory's madder_, is classed among the browns for the same reason that italian pink was ranked among the yellows. it was stated in the eighth chapter that no true madder yellow, brilliant and pure, exists as a pigment at the present day, and certainly this preparation can lay no claim to the title. except in name, it is an orange-brown of the burnt sienna hue, and might therefore with more reason have been called orange madder. it is a good and permanent colour, rich and transparent, at present used only in oil, we believe, and chiefly as a glaze. * * * * * 261. _cadmium brown_. by igniting the white carbonate of cadmium, among other methods, a cinnamon-brown oxide is obtainable, of a very clear and beautiful colour if the process be well conducted. it is, however, not eligible as a pigment, owing to the rapidity with which the oxide is acted upon by the air. in water, especially, we have found this brown so eagerly absorb carbonic acid from the atmosphere as to become in a few months once more a carbonate, and as purely white as before. the same result is observable when the powder is exposed: some shown at the international exhibition of 1862, on a glass stand, had to be removed, its label marked 'cadmium brown' being at last found attached to a sample of cadmium white. in oil, the conversion takes place less readily, that vehicle having the property of protecting, to some extent, pigments from oxidation. it is curious that even in a book a water-rub of the brown slowly but surely changes to white. 262. _catechu browns._ catechu is an extract of the khair tree or _acacia catechu_ of bombay, bengal, and other parts of india. with the exception of such earthy matters as are communicated to it during the preparation, or are added purposely as adulterants, catechu is entirely soluble both in water and alcohol. an aqueous solution has a reddish-brown colour, and gives the following results:--protosalts of iron thrown down olive-brown and persalts greenish-brown precipitates; salts of tin and lead yield brownish-yellow and brick-coloured deposits respectively; while acetate of copper or bichromate of potash furnishes brown residues. to our knowledge, none of these have been introduced as pigments, but a brown prepared by dr. lyon playfair some years back from the catechu bark has been described as exceedingly rich, transparent, and beautiful; and recommended for painting _if not too thinly applied_. 263. _chrome browns_ are produced by various methods of several hues, tints, and shades, both by wet and dry processes. we have obtained them by many methods, of different degrees of permanence. some very intense in colour have stood well, while others paler and more delicate have gradually greened, but none possessed the strict stability of the green oxides. presuming a paucity of browns, these preparations of chromium would be worth further attention; but, with the objection of being--for browns--somewhat expensive, they have the far more fatal objection of not being wanted. 264. _copper brown_, varying in hue, is obtainable, in the form of prussiate, &c., but cannot be recommended, however made. 265. _french prussian-brown._ according to bouvier, a colour similar to that of bistre, and rivalling asphaltum in transparency, is produced by partially charring a moderately dark prussian blue; neither one too intense, which gives a heavy and opaque brownish-red, nor one too aluminous and bright, which yields a feeble and yellowish tint. yielding to a rapture we cannot wholly share, he describes its qualities in the warmest terms. in his opinion, it has the combined advantages of asphaltum, mummy, and raw sienna, without their drawbacks. "i cannot," he says, "commend too highly the use of this charming bistre-tint: it is as beautiful and good in water as in oil, perfectly transparent, of a most harmonious tone, and dries better than any other colour suitable for glazing. closely resembling asphaltum in tint as well as in transparency, this brown is preferable to it in every point of view." as the colour is very quickly and easily obtained, the artist can judge for himself of its proper value. m. bouvier's process is, to place upon a clear fire a large iron spoon, into which, when red hot, some pieces of the prussian blue are put about the size of a small nut: these soon begin to crackle, and throw off scales in proportion as they grow hot. the spoon is then removed, and allowed to cool: if suffered to remain too long on the fire, the right colour will not be produced. when the product is crushed small, some of it will be found blackish, and the rest of a yellowish brown: this is quite as it should be. chemically, the result is a mixture of oxide of iron and partly undecomposed or carbonised prussiate. 266. _gambogiate of iron._ dr. scoffern read a paper at the meeting of the british association of science, in 1851, describing this combination as a rich brown, like asphaltum, but richer, as well as more durable in oil. it has not been, however, employed as a pigment, or at least is not at present. 267. _hypocastanum_, or chestnut brown, is a brown lake prepared from the horse-chestnut. this now obsolete pigment is transparent and rich in colour, warmer than brown pink, and very durable both in water and oil; in the latter of which it dries moderately well. 268. _iron browns_, native or artificial, are well represented on the palette, but nothing would be easier than to increase their number. of all metals, iron is the richest source of colour, capable of affording all colours with the exception of white. none of them, however, are so numerous as the browns, a description of which would fill this chapter. suffice it to state they are obtainable of every hue, tint, and shade, and are generally permanent. they are made on a large scale and sold under various names for house-painting, &c. 269. _manganese brown_ is an oxide of manganese, which is quite durable both in water and oil, and dries admirably in the latter. a fine, deep, semi-opaque brown of good body, it is deficient in transparency, but might be useful for glazing or lowering the tone of white without tinging it, and as a local colour in draperies, &c. 270. _nickel brown._ a very pleasing yellowish brown is obtainable from nickel, bright and clear in its pale washes, and of some richness in oil. unless thoroughly washed, it has a tendency to greenness in time. 271. _ochre browns._ the slight affinity of sulphur for yellow ochre, with its merely temporary effect thereon, was observed in the eighth chapter, where allusion was made to the action of sulphuretted hydrogen and sulphide of ammonium on the earth. sulphur alone, and in the dry state, ignited with yellow or other native ochres converts them into browns, varying in hue, and of greater or less durability. those browns, however, which we have made by this process, although standing well in a book, have not withstood exposure to light and air. they have all become pale, whitish, or of a drab cast, evidently through the oxidation of the sulphur, or rather the sulphide of iron formed during the calcination. practically, therefore, ochres have an antipathy to sulphur, moist or dry, by itself or in combination; and are, so to speak, the disinfectants of the palette. ever waging war against sulphurous vapours, the native earths serve to protect a picture from the damaging influence of impure air, whether they be used alone, or employed in admixture with such pigments as are injured thereby. 272. _purple brown_ is a refuse manufacture from indian red washings. a dull, heavy, coarse colour, it belongs to the class of common pigments which are unexceptionable for decorative painting, but scarcely suited to the higher branches of art. as this work professes simply to treat of artistic pigments, that have been, are, or might be, more than a passing reference to those colours exclusively adopted by house-painters, &c., would be out of place. 273. _rubens' brown_, still in use in the netherlands under this appellation, is an earth of a lighter colour and more ochrous texture than the vandyke brown of english commerce: it is also of a warmer or more tawny hue than the latter pigment. beautiful and durable, it works well both in water and oil, and much resembles the brown employed by teniers. 274. _uranium brown._ yellow, red, orange, green, have been previously noticed as being derived from uranium, and to this list of colours may now be added brown. a warm rich hue of the utmost intensity may be produced, which possesses considerable permanence, although not equal to that of uranium yellow. 275. _zinc brown._ a yellow-brown, so yellow that it might fairly have been classed with the ochrous colours of that denomination, is made by combining zinc with another metal by the aid of heat. experience tells us that it is, chemically, a thoroughly good and stable pigment. safely to be used in admixture, it is a clear, bright colour, affording good greens by compounding with blue. of no great power, and semi-opaque, this yellow-brown or brown-yellow is superior to some of the pigments at present used, but is probably too much like them in hue and other properties to be of any special value. * * * * * besides the preceding, there are those browns of a citrine or russet cast which are elsewhere described, such as raw umber, madder brown, &c. moreover, there are numberless other varieties, obtainable from most of the metals, from many organic substances, and from a combination of the two. of all colours, a 'new' brown is the most easily discovered: success may not be met with in seeking a yellow, red, or blue, or an orange, green, or purple; but it is strange if in the course of one's experiments a brown does not turn up. no difficulty, therefore, would have been found in greatly extending the present list; but it was felt that no advantage could have accrued by further multiplying the notices of a colour, with which we are already furnished so abundantly by nature and art, and which is capable of being produced in such profusion by admixture. with the exception of ivory and bone browns, and perhaps cassel and cologne earths, all the browns commonly employed may be considered more or less durable. chapter xviii. on the semi-neutral, marrone. we have adopted the term marrone, or _maroon_ as it is sometimes called, for our second and middle semi-neutral, as applicable to a class of impure colours composed of black and red, black and purple, or black and russet, or of black and any other denomination in which red predominates. it is a mean between the warm, broken, semi-neutral _browns_, and the cold, semi-neutral _grays_. marrone is practically to shade, what red is to light; and its relations to other colours are those of red, &c., when we invert the scale from black to white. it is therefore a following, or shading, colour of red and its derivatives; and hence its accordances, contrasts, and expressions agree with those of red degraded; consequently red added to dark brown converts it into marrone if in sufficient quantity to prevail. in smaller proportions, red gives to lighter browns the names of bay, chestnut, sorrel, &c. owing to confused nomenclature, most of the colours and pigments of this class have been assigned to other denominations--puce, murrey, morelle, chocolate, columbine, pavonazzo, &c., being variously ranked among reds, browns, and purples. this vagueness also accounts for pigments having been ranged under heads not suited to the names they bear, and explains why brown ochre has been classed among the yellows, italian pink among the same, brown pink among the citrines, &c. as adapted to the walls of a picture gallery, marrone, more or less deep and inclined to crimson, is one of the best colours known. for the reason that each colour has its antagonist, and consequently may affect a picture well or ill, according to its tone or general hue, there can be no universally good colour for such a purpose. what suits one picture or style of painting may not suit another: with a blood-red sunset, for instance, or portrait with crimson drapery, marrone would be out of place. but as it is impossible to provide each picture with a separate background, all that can be done in large collections is to study the general effect, sacrificing the interests of the few to the good of the many. if cool-coloured landscapes predominate, with blue skies and green foliage, it will be found that the orange-yellow of the frames agreeably contrasts the former, and the crimson-marrone of walls as agreeably sets off the latter. if portraits and historic paintings prevail, which are in general of a warm advancing nature, then a modest green may prove eligible. and if engravings form the staple, the grey hue of the print is best opposed by a bright fawn colour. where several rooms are devoted to pictures, a suitable wall colour is most easily secured by classifying the paintings as far as possible according to their general hue, and placing them in different chambers: in each there will be a prevailing character in the colouring of its pictures, and each can be painted or papered accordingly. however, whether this plan is adopted or not--and it may be objected to as involving a certain monotony--care should be taken to have a wall colour of some sort or other, that is, to let it be seen. pictures crammed together kill each other: without a pin's point between them, a speck of wall space visible, much of the illusion is destroyed. "it is only," says chevreul, "the intelligent connoisseur and amateur who, on seeing a picture exhibited in a gallery, experience all the effect which the artist has wished to produce; because they alone know the best point of view, and because, while their attention is fixed on the work they are observing, they alone end by no longer seeing the surrounding pictures, or even the frame of that one they contemplate." amid a moving crowd of people, inseparable from nearly all public exhibitions, it becomes difficult for the visitor, intelligent or otherwise, thus to concentrate his attention on one work. as far, therefore, as space will allow, paintings should be kept separate: larger rooms, or fewer pictures, are what is wanted.[b] from this digression, pardonable, let us hope, because in the interests of art, we will pass on to a consideration of marrone pigments. 276. brown madder is an exceedingly rich marrone or russet-marrone brown, bearing the same relation to the colour marrone that raw umber bears to the colour citrine. one of the most valuable products of the madder root, it has supplied a great desideratum, and in water especially is indispensable, both as a local and auxiliary colour. of intense depth and transparency, if made with skill, it affords the richest description of shadows, either alone or compounded with blue, and the most delicate pale tints. being quite permanent, a good drier, and working most kindly, it is a pigment which cannot be too strongly recommended to the landscape painter's notice. containing a large proportion of red, it is eligible, with yellow or blue, for mixed orange or mixed purple of a subdued tone. it may be used tolower red curtains or draperies, and for the darkest touches in flesh. mixed with cobalt, it forms a fine shadow colour for distant objects; and with indigo or prussian blue and black, is serviceable for the shades of those nearer the foreground. it is similarly useful when mixed with black, and will be found advantageous in rusty iron, as anchors, chains, &c. for the deepest and richest parts of foregrounds it may be employed alone, as also for deep dark cracks and fissures, or strong markings in other near objects, as boats and figures. with french blue, or cobalt and white, a set of beautiful warm or cold grays may be obtained, in proportion as the brown or blue predominates. compounded with blues and bright yellows such as aureolin, it gives fine autumnal russet greens. a good purple for soft aerial clouds is furnished by cobalt and brown madder, or for stormy clouds by the brown, prussian blue, and black: an equally good slate colour is obtained from cobalt, sepia, and the brown. for glazing over foliage and herbage, a mixture of the madder with aureolin or gamboge is adapted; and for brooks and running streams compounds of this brown with raw sienna, cobalt and raw sienna, vandyke brown, and french blue, will each be found useful. black sails are well represented by burnt sienna, french blue, and brown madder; and red sails by light red or burnt sienna with the brown. 277. mixed marrone. marrone is a retiring colour easily compounded in all its hues and shades by the mixture variously of red, and black or brown; or of any other warm colours in which red and black predominate. a reference to the permanent brown, black, and red or reddish pigments will show to what extent the colour marrone may safely be produced by admixture. in compounding marrone, the brown or black may be itself compounded, before the addition of the red, reddish-purple, or russet, requisite for its conversion. * * * * * 278. _chica marrone_. chica, the red colouring principle alluded to in the ninth chapter, is extracted from the _bignonia chica_, by boiling its leaves in water, decanting the decoction, and allowing it to cool, when a red matter falls down, which is formed into cakes and dried. insoluble in cold water, it dissolves in alcohol and alkalies; is precipitated from alkaline solutions by acids without alteration; and is bleached by chlorine. another variety of the same substance, obtained from para in brazil, and known as crajuru, carajuru, or caracuru, behaves in a similar manner. this is said to be superior to the former sort. a chica pigment, brought from south america, and examined by the author, was of a soft powdery texture, and rich marrone colour. somewhat resembling rubens' madder in hue, it was equal in body and transparency to the carmine of cochineal, though by no means approaching it in beauty, or even in durability. simply exposed to the light of a window, without sun, the colour was soon changed and destroyed. conclusive evidence as this is that the sample submitted to mr. field was worthless, it remains to be seen whether all the colours to be derived from chica, by different modes and from different kinds, are equally valueless as pigments. 279. _chocolate lead_, or marrone red, is a pigment prepared by calcining oxide of lead with about a third of copper oxide, and reducing the compound to a uniform tint by levigation. it is of a chocolate hue, strong opaque body, and dries freely. like all lead and copper colours, it is blackened by impure air. 280. _cobalt marrone._ there is obtainable from cobalt a very rich marrone brown, which, like many other colours, is more beautiful while moist than when dried. permanent, if carefully made and most thoroughly washed, it is an expensive compound, and must rank among those colours which are interesting in the laboratory but superfluous in the studio. 281. _madder marrone_, or marrone lake, was a preparation of madder, of great depth, transparency, and stability. working well in water, glazing and drying in oil, and in every respect a good pigment, it was one of those colours which gradually--and often, as in this case, unfortunately--become obsolete, on account of their hues being easily given by admixture of other pigments. there was likewise a deeper kind, called purple black. a good madder marrone may be produced by adding to brown madder either rose madder, madder carmine, or rubens' madder, with a slight portion of black or blue if required. 282. _mars marrone._ under the heading of a new marrone pigment there appeared some months back in a chemical journal the following:--"the blood-red compound obtained by adding a soluble sulphocyanide to a salt of iron in solution can be made (apparently at least) to combine with resin thus: to a concentrated solution of sesquichloride of iron and sulphocyanide of potassium in ether, an etherial solution of common resin is added, and the whole well shaken together. there is then mixed with it a sufficiency of water to cause a precipitate, when it will be found, after the mixture has stood a few hours, that the whole or nearly the whole of the red-coloured iron compound has united with the precipitated resin, forming the marrone-coloured pigment in question. when this coloured substance is finely powdered and mixed with water, the liquid is not the least coloured; whence it is inferred that the red iron compound has chemically united itself with the resin." the foregoing account is rather to be regarded as of scientific interest than of practical utility. the blood-red solution of sulphocyanide of iron is in itself not stable: when the red solution of this salt is so exposed to the sun, that the rays pass through the glass jar containing it, it is rendered colourless, but the colour is retained or restored when the rays pass directly from the air into the fluid; so that when a properly diluted solution is placed in a cylindrical glass vessel in direct sunshine, it loses colour in the morning till about eleven in the forenoon, when the rays beginning to fall upon the surface exposed to the air, gradually restore the colour, which attains its maximum about two o'clock. moreover, the solution is immediately decolourised by sulphuretted hydrogen and other deoxidizing agents, as well as by alkalies and many acids. it is scarcely probable that the union of the red colouring matter with the resin would suffice to secure it from change; and there is little doubt that the new marrone pigment would be a chameleon colour. * * * * * failures in the process of burning carmines, and preparing the purple of gold, frequently afford good marrones. compounds more or less of that hue are likewise furnished by copper, mercury, &c. some ochres incline to marrone when calcined: indeed we have remarked in many instances that the action of fire anticipates the effects of long continued time; and that several of the primary and secondary colours may, by different degrees of burning, be converted into their analogous secondary, tertiary, or semi-neutral colours. the one marrone or brown-marrone pigment at present employed, brown madder, is permanent. footnotes: [b] this was written previous to the opening of the new rooms of the royal academy at burlington house. in these, among other improvements, the subject of wall space has been considered. chapter xix. on the semi-neutral, gray. of the tribe of semi-neutral colours, gray is third and last, being nearest in relation to black. in its common acceptation, and that in which we here use it, gray, as was observed in the third chapter, denotes a class of cool cinereous colours faint of hue; whence we have blue grays, olive grays, green grays, purple grays, and grays of all hues, in which blue predominates; but no yellow or red grays, the prevalence of such hues carrying the compounds into the classes of brown and marrone, of which gray is the natural opposite. in this sense the _semi-neutral_ gray is distinguished from the _neutral_ grey, which springs in an infinite series from the mixture of the neutral black and white. between gray and grey, however, there is no intermediate, since where colour ends in the one, neutrality commences in the other, and vice versâ. hence the natural alliance of the semi-neutral gray--definable as a cool coloured grey--with black or shade; an alliance which is strengthened by the latent predominance of blue in the synthesis of black, so that in the tints resulting from the mixture of black and white, so much of that hue is developed as to give apparent colour to the tints. this explains why the tints of black and dark pigments are colder than their originals, so much so as in some instances to answer the purposes of positive colours. it accounts in some measure for the natural blueness of the sky, yet not wholly, for this is in part dependent, by contrast, upon the warm colour of sunshine to which it is opposed; for, if by any accident the light of nature should be rendered red, the colour of the sky would not appear purple, in consequence, but green. again, if the sun shone green, the sky would not be green, but red inclined to purple; and so would it be with all colours, not according to the laws of composition, but of contrast; since, if it were otherwise, the golden rays of the sun would render a blue sky green. the grays are the natural cold correlatives, or contrasts, of the warm semi-neutral browns, as well as degradations of blue and its allies. hence blue added to brown throws it into or toward the class of grays, and hence grays are equally abundant in nature and necessary in art: in both they comprehend a widely diffused and beautiful play of retiring colours in skies, distances, carnations, and the shadowings and reflections of pure light, &c. gray is, indeed, the colour of space, and has therefore the property of diffusing breadth in a picture, while it furnishes at the same time good connecting tints, or media, for harmonizing the general colouring. consequently the grays are among the most essential hues of the art, though they must not be suffered to predominate where the subject or sentiment does not require it, lest they cast over the painting that gloom or leaden dulness reprobated by sir joshua reynolds; yet in solemn works they are wonderfully effective, and proper ruling colours. nature supplies these hues from the sky abundantly and effectively throughout landscape, and rubens has employed them as generally to correct and give value to his colouring, with fine natural perception in this branch of his art: witness his works in the national gallery, and in that of the luxembourg. according to the foregoing relations, grays favour the effects and force of warm colours, which in their turn also give value to grays. it is hence that the tender gray distances of a landscape are assisted, enlivened, and kept in place by warm and forcible colouring in the foreground, gradually connected through intermediate objects and middle distances by demi-tints declining into gray; a union which secures full value to the colours and objects, and by reconciling opposites gives repose to the eye. as a general rule, it may be inferred that half of a picture should be of a neutral hue, to ensure the harmony of the colouring; or at least that a balance of colour and neutrality is quite as essential to the best effect of a painting as a like balance of light and shade. 283. mineral gray, or mineral gr_e_y, as it is often improperly spelt, is obtainable from the lapis lazuli, after the blue and ash have been worked out. so derived, it is a refuse article, worthless if the stone has been skilfully exhausted of its ultramarine. as this is now generally the case, the best mineral gray is no longer a waste product, but a lower species of ash, a pale whitish blue with a grey cast. possessing the permanence of ultramarine, it may be regarded in colour as a very weak variety of that blue, diluted with a large quantity of white slightly tinged by black. a pigment peculiar to oil painting, it is admirably adapted to that gray semi-neutrality, the prevalence of which in nature has been just remarked. for misty mornings, cloudy skies, and the like, this gray will be found useful. 284. mixed gray is formed by compounding black and blue, black and purple, black and olive, &c.; and is likewise produced by adding blue in excess to madder brown, sepia, &c., transparent mixtures which are much employed. it should be borne in mind that the semi-neutrals, like the secondaries and tertiaries, may be so compounded as to be permanent, semi-stable, or fugitive. the due remembrance of this cannot be too strongly insisted upon, seeing that in every picture the browns and grays are of frequent occurrence. these it is that lend such charm to the whole, flowing, as it were, like a quiet under-current of colour beneath the troubled surface of more decided hues. in the work of every true artist--between whom and the mere painter there is as much difference as between the poet and the poetaster--there is sentiment as well as colour, whether the subject be an exciting battle-scene or a bit of still life. this sentiment, as strongly felt as the colour is clearly seen, is imparted in no small degree by the skilful use of semi-neutrality, the compounding of which, as time goes on, will therefore affect a picture for good or for evil. subjoined is an analysis of the three semi-neutrals, which serves partly to show in what great variety they may be obtained by admixture. brown = black + yellow } " = " + orange } + red, purple, &c. " = " + citrine} " = 2 yellow + red + blue " = 2 orange + green + purple " = 2 citrine + russet + olive marrone = black + red " = " + purple-red " = " + russet " = 2 red } " = 2 purple-red} + dark brown or black " = 2 russet } gray = black + blue } " = " + purple-blue} + 2 white " = " + olive } " = 2 blue } " = 2 purple-blue} + light brown, or black + 2 white " = 2 olive } in the last division, the white has been added to remind the reader that grays are coloured greys, not coloured blacks; and are therefore faint of hue. this paleness, however, need not necessarily be produced by admixture with white: it can be gained by means of thin washes. as a pigment, gray may be to all appearance black in bulk. 285. neutral tint, or, more correctly, _semi_-neutral tint, is a compound shadow colour of a cool character. it is permanent, except that on exposure the gray is apt to become grey, a change which may be prevented by a slight addition of ultramarine ash. so protected, it becomes serviceable in landscape for the extreme distance, which, it may be laid down as a general principle, should be painted rather cold than otherwise. blue being the principal compound of atmosphere, it is of the utmost importance to obtain this in the first instance, particularly as, from its being only of a blue tint, not blue colour, it is so immediately altered and acted upon by subsequent washes; whereas, the blue tone once lost, it will be found very difficult to be recovered. wherever a picture is wanting in air effect, the cause will, upon examination, be seen to rest entirely upon the absence of pure grays, bordering upon a bluish tone, not tending, be it observed, to brown or purple. a bluish gray, then, of rather a cold tone, such as the neutral tint, is recommended as the prevailing hue with which to begin the extreme distances; and, as a rule, it is better to pass with this over as much of the landscape as possible, and thus lay the foundation for a general atmosphere. 286. payne's gray resembles the preceding in being a compound colour and liable to assume a grey cast by time, but differs from it in having more lilac in its hue, and being therefore of a warmer tone. giving by itself a clear violet shadow, it may be rendered more neutral by a small portion of burnt sienna, an admixture which, whether the gray or sienna predominates, affords useful tints. compounded with light red or vandyke brown, the gray is good for shipping and sails, or the stems and branches of trees; while with gamboge or aureolin it is suited to glossy leaves in high light, also to very cold tones in foregrounds, herbage, &c. yellow ochre, light red, and payne's gray form a mixture for banks and roads; the ochre, gray, and sepia, a most beautiful tint for stones; and brown madder and the gray, a fine shade for the black head and feet of cattle. alone, the gray is serviceable for slate; and compounded with light red, for bricks or tiles in shadow. 287. ultramarine ash is obtained from the stone after the richer and more intense blue has been extracted. although not equal in beauty, and inferior in strength of colour to ultramarine, it is a valuable bye-product varying in shade from light to dark, and in hue from pale azure to cold blue. with a grey cast, it affords delicate and extremely tender tints, not so positive as ultramarine, but which, as water-colours, wash much better. it furnishes grays softer, purer, and more suited to the pearly tints of flesh, skies, distances, foliage, shadows of drapery, &c. than those composed of other blues, with white and black, which the old masters were wont to employ. ultramarine, however, produces the same effects when broken with black and white, and is thus sometimes carried throughout the colouring of a picture. the ash, compounded with lamp black, gives a soft cold gray for dark louring clouds, or for twilight away from the sun's influence. alone it is adapted to very remote hills or mountains, and with orient yellow or aureolin to distant foliage. * * * * * the native phosphate of iron, which has been already described in the tenth chapter under its name of blue ochre, might have been classed among the grays, being similar in colour to the deeper hues of ultramarine ashes. powdered slate, slate clays, and several native earths, likewise rank with grays; but some of the earths we have tried are not durable, being apt to become brown by the oxidation of the iron they contain. it may be proper here to mention those other pigments, known as tints, which, being the result of the experience of accredited masters in their peculiar modes of practice, serve to facilitate the progress of their amateur pupils, while they are more or less eligible for artists. such are _harding's_ and _macpherson's tints_, composed of pigments which associate cordially, and sold ready prepared in cakes and boxes for miniature and water painting. of the four grays in use--mineral gray, ultramarine ash, neutral tint, and payne's gray--the two first are quite unchangeable, and the others sufficiently stable to be classed as permanent. chapter xx. on the neutral, grey. grey is the second and intermediate of the neutral colours, standing between _white_ and _black_. true or normal grey is only obtainable by admixture of pure white with pure black, various proportions of which afford numerous tones of pure grey. in practice it may likewise be produced by a thin wash of black over white. the neutral gr_e_y differs from the semi-neutral gr_a_y in not being coloured by any primary, secondary, tertiary, or semi-neutral; hence any blue, purple, olive, or gray added to it, at once destroys the neutrality of grey, and converts it into gray. thus easily defiled and changed in class, grey is rather a theoretical than a practical colour. to our knowledge, there has never been a true grey pigment, that is, one composed exclusively of pure white and pure black; the gr_a_ys known to the palette as mineral grey and payne's grey having been incorrectly named. practically, the nearest approach to a normal grey is furnished by black lead, which forms grey tints of greater permanence and purity than the blacks in general use, and is now employed for this purpose with approved satisfaction by experienced artists. being compounded of white and black, grey partakes in some measure of the qualities of both those colours--for colours, as a matter of convenience, they must be called; although white is often spoken of as no colour, and black as the complete extinction of all colour. with white predominant, grey is used, pure or coloured, for the general lights of a picture; just as, with black predominant, grey is employed, pure or coloured, for the shades. it helps to subdue the absolute white, and to make the absolute black conspicuous. black and white are in some respects complementary to each other, and when in contact, appear to differ more from each other than when viewed separately: both show with best effect when harmonised by a medium of grey, normal or otherwise. the primary colours, also, gain in brilliancy and purity by the proximity of grey. with dark colours, such as blue and violet, and deep tones in general, grey forms assortments of analogous harmonies; while with the luminous colours, such as red, orange, yellow, and the light tints of green, it forms harmonies of contrast. although grey never produces a bad effect in its assortments with two luminous colours, in most cases the association is dull and inferior to black and white. the only instance in which grey associates with two such colours more happily than white is that with red and orange. grey is inferior to both white and black with red and green, red and yellow, orange and yellow, orange and green, yellow and green; and is not so good as white with yellow and blue. in association with sombre colours, such as blue and violet, and with broken tones of luminous colours, grey gives rise to harmonies of analogy which have not the vigour of those with white; but if the colours do not combine well together, it has the advantage of separating them from each other. associated with two colours, one sombre, the other luminous, grey will perhaps be better than white, if white produces too strong a contrast of tone: on the other hand, grey will be preferable to black, if that has the inconvenience of increasing too much the proportion of sombre colours. grey associates more happily than black with orange and violet, green and blue, or green and violet. 288. mixed grey. when a ray of solar light (a sunbeam) is passed through a prism of flint glass, and the image or 'prismatic spectrum' received upon a screen of white paper, it is found to consist of numerous rays of different colours, which are conveniently divided into six groups--red, orange, yellow, green, blue, violet. optically, the union of red, yellow, and blue, in proper proportions, constitutes white light; whether the rays of the three separate colours are mixed, or of one with the other two in combination: the same result ensues when red is mixed with green as if it were mixed with blue and yellow, because green is composed of blue and yellow. consequently, any primary mixed with a secondary composed of the other two primaries, forms the complement of rays necessary to constitute or make up white light, and vice versâ. there is, however, a very great difference between the results arising from the mixture of the pure coloured rays of the spectrum, and those from material colours or pigments. when, by means of a convex lens, we reunite the coloured rays of the spectrum white light is reproduced; but when we mix coloured materials, blues, yellows, and reds, the compound is never white, but grey or black; even if these coloured pigments are taken in the exact proportions in which their colours exist in the spectrum. ultramarine, our purest blue, reflects red rays as well as blue rays; aureolin, our purest yellow, reflects blue as well as yellow rays; and carmine reflects yellow as well as red rays. now whenever the third primary colour is present in any mixture of coloured materials, it tends to form grey, by mixing with a sufficient quantity of the other coloured rays to neutralize it, and the presence of this grey breaks or tarnishes the pure colour. hence it is that to obtain a pure green, a blue should be taken tinged with yellow rather than with red, and a yellow tinged with blue: if there were chosen either a blue or a yellow tinged with red, this latter colour would go to form some grey in the compound, which would tarnish the green. in like manner, to produce pure orange, neither the red nor the yellow must contain blue; and similarly with pure purple, neither the blue nor red should contain yellow. as regards pigments, then, a proper mixture of yellow, red, and blue; or of yellow and purple, red and green, or blue and orange; or of orange, green, and purple, affords black if sufficiently intense, and grey if sufficiently diluted. the black may be rendered grey by spreading a thin wash over a white ground, or by the direct addition of white. it must be remembered, however, that suitable proportions of the component colours are essential. when all three of the primaries, for example, are mixed together, colour is neutralised according as they are compounded of equal strength and in right quantities: if proper proportions are observed, pure black or normal grey results; but if not, there will be produced a coloured black or a coloured grey, an excess of one or two of the primaries giving rise to brown, marrone, or gray. a reference to the lists of permanent primary and secondary pigments will show to what extent durable greys can be compounded. as these pigments differ so widely in hue and other properties, no fixed rules can be given for their admixture: to ensure neutrality, practice and a correct eye are indispensable. without perfect neutrality, difficult to attain and rarely to be met with, grey ceases to exist. in pure white, pure grey, and pure black, colour is, so to speak, conspicuous by its absence. chapter xxi. on the neutral, black. black is the last and lowest in the series or scale of colours descending--the opposite extreme from white--the maximum of colour. to be perfect, it must be neutral with respect to colours individually, and absolutely transparent, or destitute of reflective power as regards light; its use in painting being to represent shade or depths, of which black is the element in a picture and in colours, as white is of light. as there is no perfectly pure and transparent black pigment, black deteriorates all colours in deepening them, as it does warm colours by partially neutralizing them, but it combines less injuriously with cold colours. though black is the antagonist of white, yet added to it in minute portion, it in general renders white more neutral, solid, and local, with less of the character of light. impure black is brown, but black in its purity is a cold colour, and communicates a coolness to all light colours; thus it _blues_ white, _greens_ yellow, _purples_ red, and _cools_ blue. hence the artist errs with ill effect who regards black as of nearest affinity to hot and brown colours, and will do well to keep in mind--"the glow of sunshine and the _cool_ of shade." it is a fault of even some of our best colourists, as evinced by their pictures, to be too fond of black upon their palettes, and thence to infuse it needlessly into their tints and colours. with such it is a taste acquired from the study of old pictures; but in nature hardly any object above ground is black, or in daylight is rendered neutral thereby. black, therefore, should be reserved for a local colour, or employed only in the under-painting properly called grounding and dead colouring. as a local colour, black has the effect of connecting or amassing surrounding objects, and is the most retiring of all colours, a property which it communicates to other colours in mixture. it heightens the effect of warm as well as light colours, by a double contrast when opposed to them, and in like manner subdues that of cold and deep colours. in mixture or glazing, however, these effects are reversed, by reason of the predominance of cold colour in the constitution of black. having, therefore, the double office of colour and of shade, black is perhaps the most important of all colours to the artist, both as to its use and avoidance. it may be laid down as a rule that the black must be conspicuous. however small a point of black may be, it ought to catch the eye, otherwise the work is too heavy in the shadow. all the ordinary shadows should be of some _colour_--never black, nor approaching black, they should be evidently and always of a luminous nature, and the black should look strange among them; never occurring except in a black object, or in small points indicative of intense shade in the very centre of masses of shadow. shadows of absolutely negative grey, however, may be beautifully used with white, or with gold; but still though the black thus, in subdued strength, becomes spacious, it should always be conspicuous: the spectator should notice this grey neutrality with some wonder, and enjoy, all the more intensely on account of it, the gold colour and the white which it relieves. of all the great colourists, velasquez is the greatest master of the black chords: his black is more precious than other people's crimson. yet it is not simply black and white that must be made valuable, rare worth must be given to each colour employed; but the white and black ought to separate themselves quaintly from the rest, while the other colours should be continually passing one into the other, being all plainly companions in the same gay world; while the white, black, and neutral grey should stand monkishly aloof in the midst of them. crimson may be melted into purple, purple into blue, and blue into green, but none of them must be melted into black. all colours are comprehended in the synthesis of black, consequently the whole sedative power of colour is comprised in black. it is the same in the synthesis of white; and, with like relative consequence, white includes all the stimulating powers of colour in painting. it follows that a little white or black is equivalent to much colour, and hence their use as colours requires judgment and caution. by due attention to the synthesis of black, it may be rendered a harmonizing medium to all colours, to all which it lends brilliancy by its sedative effect on the eye, and its powers of contrast: nevertheless, we repeat, it must be introduced with caution when _hue_ is of greater importance than shade. even when employed as a shadow, without much judgment in its use, black is apt to appear as local colour rather than as privation of light; and black pigments obtained by charring have a tendency to rise and predominate over other hues, subduing the more delicate tints by their chemical bleaching power upon other colours, and their own disposition to turn brown or dusky. for these reasons deep and transparent colours, which have darkness in their constitution, are better adapted as a rule for producing the true natural and permanent effects of shade. many pictures of the early masters, and especially of the roman and florentine schools, evince the truth of our remarks; and it is to be feared the high reputation of these works has betrayed their admirers into this defective employment of black. black substances reflect a small quantity of white light, which receives the complementary of the colour contiguous to the black. by 'complementary' is meant that colour which is required with another colour to form white light; thus, green is the complementary of red, blue of orange, and yellow of violet, or vice versâ; because green and red, blue and orange, and yellow and violet, each make up the full complement of rays necessary to form white light. briefly digressing, we give the following mode of observing complementary colours:--place a sheet of white paper on a table opposite to one of two windows admitting diffused daylight[c] into a room; take a piece of coloured glass and so place it that the coloured light transmitted through it falls over the surface of the paper; then put an opaque object on the paper close to the coloured glass. the shadow of this object will not appear black or of the colour of the glass, as might be supposed, but of its complementary colour; thus if the glass is red, the colour of the shadow will be green, although the whole of the paper surrounding it appears red. similarly, if the glass is blue, the shadow will appear orange; if it is green, the shadow will appear red; and so with other colours. it is absolutely essential, however, to the success of this experiment, that the paper be also illuminated with the white light admitted from the other window. it has been said that black substances reflect a small quantity of white light, which receives the complementary of the colour contiguous to the black. if this colour is deep, it gives rise to a luminous complementary, such as orange, or yellow, and enfeebles the black; while the other complementaries, such as violet or green, strengthen and purify it. in colours associated with black, if green is juxtaposed therewith, its complementary red, added to the black, makes it seem rusty. those colours which best associate with black are orange, yellow, blue, and violet. it would be well to remember that black, being always deeper than the juxtaposed colour, entails contrast of tone, and tends to lower the tone of that colour. most of the black pigments in use are obtained by charring, and owe their colour to the carbon they contain. as the objects of vegetal and animal nature may be blackened through every degree of impurity by the action of fire, black substances more or less fitted for pigments abound. the following are the chief native and artificial black pigments, or colours available as such:-289. black lead, _plumbago_, or _graphite_, contains in spite of its name no lead, being simply a species of carbon or charcoal. in most specimens iron is present, varying in quantity from a mere trace up to five per cent, together with silica and alumina. sometimes manganese and titanic acid are likewise found. it is curious that carbon should occur in two distinct and very dissimilar forms--as diamond, and as graphite; one, white, hard, and transparent; the other, black, soft, and opaque: the artist, therefore, who uses a pigment of plumbago, paints with nothing more or less than a black diamond. the best graphite, the finest and most valuable for pencils, is yielded by the mine of borrowdale, at the west end of derwent lake, in cumberland, where it was first wrought during the reign of elizabeth. a kind of irregular vein traverses the ancient slate-beds of that district, furnishing the carbon of an iron-grey colour, metallic lustre, and soft and greasy to the touch. universally employed in the form of crayons, &c. in sketching, designing, and drawing, until of late years it was not acknowledged as a pigment: yet its powers in this respect claim a place for it. as a water-colour, levigated in gum in the usual manner, it may be effectively used with rapidity and freedom in the shading and finishing of pencil drawings, or as a substitute therein for indian ink. even in oil it may be employed occasionally, as it possesses remarkably the property of covering, forms very pure grey, dries quickly, injures no colour chemically, and endures for ever. these qualities render it the most eligible black for adding to white in minute quantity to preserve the neutrality of its tint. although plumbago has usurped the name of black lead, there is another substance more properly entitled to this appellation, and which may be used in the same way, and with like effects as a pigment. this substance is the sulphide of lead, found native in the beautiful lead ore, or galena, of derbyshire. an artificial sulphide can be prepared by dry and wet processes, which is subject to gradual oxidation on exposure to the air, and consequent conversion into grey or white. neither variety can be compared to graphite for permanence, although the native is preferable to the artificial. plumbago, or the so-called black lead, is often adulterated to an enormous extent with lamp black. 290. blue black, _charcoal_, _liege_, or _vine black_, is a well-burnt and levigated charcoal prepared from vine twigs, of weaker body than ivory or lamp black, and consequently better suited to the grays and general mixed tints of landscape painting, in which it is not so likely to look black and sooty as the others may do. of a cool neutral tint, it has, in common with all carbonaceous blacks, a preserving influence on white when duly mixed therewith; which it owes, chemically, to the bleaching power of carbon, and, chromatically, to the neutralizing and contrasting power of black with white. compounded slightly with blue black, and washed over with zinc white, white lead may be exposed to any ordinary impure atmosphere with comparative impunity. it would be well for art if carbon had a like power upon the colour of oils, but of this it is deficient; and although chlorine destroys their colour temporarily, they re-acquire it at no very distant period. alone, blue black is useful as a cool shade for white draperies; and compounded with cobalt, affords a good gray for louring clouds. 291. british ink is a compound black, preferred by some artists to indian ink, on account of its not being liable to wash streaky, as the latter does: at the same time it is not so perfectly fixed on the paper as indian ink. 292. indian ink, sometimes called _china_ or _chinese ink_, is chiefly brought from china in oblong cakes, of a musky scent, ready prepared for painting in water. varying considerably in body and colour, the best has a shining black fracture, is finely compact, and homogeneous when rubbed with water, in which, when largely diluted, it yields no precipitate. without the least appearance of particles, its dry surface is covered with a pellicle of a metallic appearance. when dry on the paper, it resists the action of water, yet it will give way at once to that action, when it has been used and dried on marble or ivory, a fact which proves that the alummed paper forms a strong combination with the ink; possibly a compound of the latter on an aluminous base, might even be employed in oil. different accounts are given of the mode of making this ink, the principal substance or colouring matter of which is a smoke black, having all the properties of our lamp black; the variety of its hues and texture seeming wholly to depend on the degree of burning and levigating it receives. from certain chinese documents, we learn that the ink of nan-king is the most esteemed; and among the many sorts imported into this country, we find those of the best quality are prepared with lamp black of the oil of sesame; with which are combined camphor, and the juice of a plant named _houng hoa_ to give it brightness of tone. according to an analysis by m. proust, the better kinds contain about two per cent. of camphor. by some, the pigment known as sepia has been supposed to enter into their composition. _liquid indian ink_ is a solution for architects, surveyors, &c. 293. ivory black is ivory charred to blackness by strong heat in closed vessels. differing chiefly through want of care or skill in preparing, when well made it is the richest and most transparent of all the blacks, a fine neutral colour perfectly durable and eligible both in water and oil. when insufficiently burnt, however, it is brown, and dries badly; or if too much burnt, it becomes cineritious, opaque, and faint in hue. with a slight tendency to brown in its pale washes, this full, silky black is serviceable where the sooty density of lamp black would be out of place. it is occasionally adulterated with bone black, a cheaper and inferior product. being nothing more nor less than animal charcoal, ivory or bone black had best not be compounded with organic pigments, in water at least. it is well known that this charcoal possesses the singular property of completely absorbing the colour of almost any vegetal or animal solution, and of rendering quite limpid and colourless the water charged with it. if a solution of indigo in concentrated sulphuric acid be diluted with water, and animal charcoal added in sufficient quantity, the solution will soon be deprived of colour. the more perfect the ivory or bone black, the more powerful is its action likely to be: either over or under calcined, animal charcoal is less energetic; in the former case, because it is less porous; in the latter, because the animal matter, not being wholly consumed, makes a kind of varnish in the charcoal which interferes with its acting. to a greater or less extent, gums, oils, and varnishes serve similarly as preventives, thereby decreasing the danger of employing these blacks in admixture; but, in the compounding of colours, nothing is gained by needless risk. to mix with organic pigments, therefore, blue or lamp blacks should be substituted for those of ivory or bone; that is, vegetal charcoal should be used instead of animal. it is a question whether even with inorganic pigments the adoption of the former in admixture would not be advisable. it was once the general opinion that the action of animal charcoal was limited to bodies of organic origin, but it has since been found that inorganic matters are likewise influenced. "through its agency," says graham, "even the iodine is separated from iodide of potassium;" whence probably pigments containing iodine would suffer by contact. the investigation of weppen appears to prove that the action of the charcoal extends to all metallic salts; with the following, no doubt remains of this being so, to wit:--the sulphates of copper, zinc, chromium, and protoxide of iron; the nitrates of lead, nickel, silver, cobalt, suboxide and oxide of mercury; the protochlorides of tin and mercury; the acetates of lead and sesquioxide of iron; and the tartrate of antimony. whether animal charcoal exercises any deleterious influence on pigments consisting of these metals, and, if so, how far and under what circumstances, can only be answered when our knowledge of the properties of pigments is greater than it now is. at present, perhaps, it is safer to choose vegetal charcoal for mixed tints, inasmuch as, although it shares the property of bleaching in a certain degree, it does not possess the same energy. 294. lamp black, or _lamblack_, is a smoke black, being the soot procured by the burning of resins or resinous woods. it is a pure vegetal charcoal of fine texture, not quite so intense nor so transparent as the black made from ivory, but less brown in its pale tones. it has a very strong body that covers readily every underlay of colour, works well, but dries badly in oil. on emergency, it may be prepared extemporaneously for water-painting by holding a plate over the flame of a lamp or candle, and adding gum to the colour: the nearer the plate is held to the wick of the lamp, the more abundant and warm will be the hue of the black obtained; at a greater distance it will be more effectually charred, and blacker. mixed with french blue or cobalt, lamp black gives good cloudy grays, which are useful for the shadows of heavy storm clouds. with french blue and this black alone various beautiful stormy skies may be represented; the contrast of the blue causing the black to assume, if desired, a warm tone in shadows. for like purposes, the black with ultramarine ash affords a very soft hue, and with light red and cobalt in different proportions yields silvery tones most serviceable. to the dark marking of murky and dirty clouds, a compound of lamp black and light red is particularly suited; while a mixture of the black with cobalt and purple madder is adapted for slate-coloured sunset and sunrise clouds. french blue softened with a little lamp black is fitted for mountains or hills, very remote; and the same blue and black with rose madder meet their tints if nearer. in seas the black is useful with raw sienna and other colours; while, whether in storm or calm, vessels and boats may be painted with tints of lamp black, madder brown, and burnt sienna, varying in degrees of strength according to the distances. lamp black alone, or with french blue, cobalt and purple madder, emerald green, or rose madder, is good for rocks; and for dark foreground objects when mixed with madder lake and burnt sienna. with aureolin the black furnishes a sober olive for foliage, and with rose madder a fine colour for the stems and branches of trees. compounded with light red, it is suited to the first general tones of the ground for banks and roads; and with yellow ochre or madder red, to parts of buildings and cattle. a very eminent miniature painter recommends for hair tints, lamp black, indian red, and burnt sienna. being a dense solid colour, this black must be used sparingly to avoid heaviness. hitherto confined to painting and engraving, lamp black has lately refuted the assertion that there is nothing new under the sun by making its appearance in photography. by a method which combines the fidelity of that art with the permanence of prints, there is produced a species of photographic engraving, so to speak, having lamp black or carbon for its colouring matter. indeed, in this 'autotype' process, as it is called, any other durable pigment or pigments may be used, and a photographic picture thus obtained. in copying the works of artists, especially, the mode promises to be of value, inasmuch as by its agency the same pigments may be made the colouring matter of the reproduction as are employed in the original. if this be in sepia or bistre, the copy can be autotyped in those colours; or if a red chalk drawing be required to be multiplied, the proofs may be in red chalk, the copy when produced to the same scale being scarcely distinguishable from the original. in like manner, any single colour of the artist's palette is applicable without restriction or limitation, so that not only are every line and touch rendered absolutely, but the very pigment used in the original is found in the copy. moreover, as the pigments are quite unchanged by the action of the other agents employed, the resulting colour of the print is determined once for all, just as the artist mixes those pigments on his palette for his picture. as extending the use of lamp black and permanent pigments in general, this brief digression on autotypography may be pardoned in a treatise on colours. 295. mixed black. black is to be considered as a synthesis of the three primary colours, the three secondaries, or the three tertiaries, or of all these together; and, consequently, also of the three semi-neutrals, and may thus be composed of due proportions of either tribe or triad. all antagonistic colours, or contrasts, likewise afford the neutral black by composition; but in all the modes of producing black by compounding colours, blue is to be regarded as its archeus or predominating colour, and yellow as subordinate to red, in the proportions, when their hues are true, of eight blue, five red, and three yellow. it is owing to this predominance of blue in the constitution of black, that it contributes by mixture to the pureness of hue in white colours, which usually incline to warmth, and that it produces the cool effect of blueness in glazing and tints, or however otherwise diluted or dilated. it accords with the principle here inculcated that in glass-founding the oxide of manganese, which gives the _red_ hue, and that of cobalt, which furnishes the _blue_, are added to brown or _yellow_ frit, to obtain a velvety black glass. similarly the dyer proceeds to dye black upon a deep blue basis of indigo, with the ruddy colour of madder and the yellow of quercitron, &c. some of the best blacks and neutrals of the painter are those formed with colours of sufficient power and transparency upon the palette. prussian blue and burnt lake afford a powerful though not very durable black; and compound blacks in which transparent pigments are employed will generally go deeper and harmonize better with other colours than any original black pigment alone. hence lakes and deep blues, added to the common blacks, greatly increase their clearness and intensity: in mixture and glazing of the fine blacks of some old pictures, ultramarine has evidently been used. in this view, black altogether compounded of blue with red and yellow, each deep and transparent, and duly subordinated according to its powers, will give the most powerful and transparent blacks; although, like most other blacks, they dry badly in oil. of course, as with all compound colours, it depends entirely on the pigments employed whether these mixed blacks are permanent or not: a compound black can very well pass through the stages of black to grey, gray, or dirty white, if each link in the chain of combination be not as strong as its fellows. * * * * * 296. _black chalk_ is an indurated clay, of the texture of white chalk, and chiefly used for cutting into crayons. fine specimens have been found near bantry in ireland, and in wales, but the italian has the most reputation. crayons for sketching and drawing are also artificially prepared, which are deeper in colour and free from grit. wood charcoal is likewise cut into crayons, that of soft woods, such as lime, poplar, &c., being best adapted for the purpose. 297. _black ochre_, earth black, or prussian black, is a native earth, combined with iron and alluvial clay. it is found in most countries, and should be washed and exposed to the atmosphere before being employed. sea-coal, and other black mineral substances, have been and may be used as substitutes for the more perfect blacks, when the latter are not procurable, which now seldom or never happens. 298. _bone black_, obtained by charring, is similar to that of ivory, except that it is a little warmer in tone, having a reddish or orange tinge, and is a worse drier in oil. like ivory black, it is very transparent. immense quantities of bone black are consumed with sulphuric acid in the manufacture of shoe blacking. 299. _coffee black_, though little known and not on sale, has been strongly recommended by bouvier as one of the best blacks that can be used. soft without being greasy, light, almost impalpable, even before being ground, it gives tints of a very bluish gray when mixed with white, a quality precious for making the blues of the sketch, and dull greens. it is said to dry better than blue or vine black, and to combine admirably with other colours. de montabert prefers calling it coffee brown, giving it as an exemplification of a bluish-brown, but probably this brown hue is owing to want of skill in its manufacture. we have not had personal experience of the colour, but there is no theoretical reason why a carbonaceous black should not be produced from coffee. the mode of proceeding is to calcine the berry in a covered vessel, and well wash the resulting charcoal with boiling water by decantation. in order to prevent the powder, which is of great lightness, from floating, it is made into paste with a few drops of alcohol before adding the water. 300. _frankfort black_ is said to be made of the lees of wine from which the tartar has been washed, by burning, in the manner of ivory black; although the inferior sort is merely the levigated charcoal of woods, of which the hardest, such as box and ebony, yield the best. fine frankfort black, though almost confined to copper-plate printing, is one of the best black pigments extant, being of a neutral colour, next in intensity to lamp black, and more powerful than that of ivory. strong light has the effect of deepening its colour. it is probable that this was the black used by some of the flemish painters, and that the pureness of the greys formed therewith is due to the property of charred substances of preventing discolourment. 301. _manganese black_, the common black oxide of that metal, is the best of all blacks for drying in oil without addition. it is also a colour of vast body and tingeing power. as a siccative, it might be advantageously employed with ivory black. 302. _mineral black_ is a native impure carbon of soft texture, found in devonshire. blacker than plumbago, and free from its metallic lustre, it is of a neutral colour, greyer and more opaque than ivory black, and forms pure neutral tints. being perfectly durable, and drying well in oil, it is of value in dead colouring on account of its solid body, as a preparation for black and deep colours before glazing. it would likewise be the most permanent and best possible black for frescoes. 303. _paper black_, a pigment unknown to the modern palette, like most of our numbered italicised colours, is of the nature of blue or vine black. very soft and of a fine bluish-gray, it is fitted for flesh, or for mixing with whites or yellows in landscapes. 304. _peach black_, or almond black, made by burning the stones of fruits, the shell of the cocoa-nut, &c., is a violet-black, once much used by parisian artists. bouvier believes it to be a good black, but at the same time sensibly asks, of what use is it to have a black of this cast, which can always be given by lake, without diminishing but rather increasing the intensity of the black it may be mixed with. 305. _prussian black._ the same prussian blue which gives a brown when burnt in the open air, yields a black when calcined in a close crucible. very intense, very soft and velvety, and very agreeable to work, this bluish-black dries much more promptly than most other blacks, and scarcely requires grinding. on account of its extreme division, however, it would probably be found more energetic as a decolourising agent in admixture with organic pigments than most carbonaceous blacks. another prussian black, containing copper, and made by a wet process, is obtained when a dilute solution of cupric sulphate and ferrous sulphate, in proper proportions, is mixed with a quantity of ferrocyanide of potassium not in excess. a very bulky deep black precipitate is formed, which is difficult to wash, and is deep black when dry. it is insoluble in water, and appears to be a compound analogous to prussian blue. as a pigment, this black is inferior to the preceding. 306. _purple black_ is, or rather was, a preparation of madder, of a deep purple hue approaching black. powerful and very transparent, it glazed and dried well in oil, and was a durable and eligible pigment. its tints with white lead were of a purple cast. 307. _spanish black_, or cork black, is a soft black, obtained by charring cork, and differs not essentially from frankfort black, except in being of a lighter and softer texture. "some of my friends," says bouvier, "call it _beggars' ultramarine_, because it produces, by combinations, tints almost as fine as ultramarine." a blue but not a velvet black, where intensity is required some other is to be preferred. for mixtures, however, it is stated to be admirable, and especially for linen, skies, distances, and the various broken tints of carnations, &c. * * * * * besides those blacks which have been mentioned, there are others furnished by several of the metals and by many organic substances employed as dyes; but as the blacks in common use are all permanent, and have been found sufficient for every purpose, it is scarce needful to swell the list. nor is it more needful, the editor considers, to swell the book; lest his aim be defeated of reflecting in a _moderate_-sized mirror the palette as it is and might be at the present day. arrived at age, as it were, in its twenty-first chapter, this treatise may fitly conclude with black, the last of the series of colours. let us hope the maxim of sir joshua reynolds, that success in some degree was never denied to earnest work may apply here. still, by way of finale, we would offer a few remarks. in no branch of the science, perhaps, is it more hazardous to commit oneself to a positive dictum than in the chemistry of colours, so liable are theory and practice to clash, and so often does the experience of one person or one time differ from that of another. he who has turned his attention to pigments, finds nearly every assertion must be qualified, for to nearly every rule there is some exception, and learns that theory alone may mislead. for example, a colour known to be fugacious may last, in certain cases, a surprisingly long time; while, on the contrary, a pigment permanent when used alone, may be rendered fugitive by improper compounding. again, what holds good of a colour produced by one process, or employed in one vehicle or by one artist, may not be true of the same colour made by a different mode, or used in another vehicle or by another artist. it is because, then, colours are of every degree of durability, from the perfectly stable to the utterly fugitive, and because each one is liable to influence by every condition of time, place, and circumstance, that the chemist's theory is opposed as often to the painter's practice as the experience of artists themselves varies. this may explain the charges of inconsistency and contradiction which have been brought against writers on pigments, faults that lie rather with the nature of the subject than with the authors. even at the risk of being tiresome, we have throughout insisted on the choice of permanent pigments, not simply for use alone but for mixed tints. to quote cennini, "i give you this advice, that you endeavour always to use ... good colours.... and if you say that a poor person cannot afford the expense, i answer, that if you work well (and give sufficient time to your works), and paint with good colours, you will acquire so much fame that from a poor person you will become a rich one; and your name will stand so high for using good colours, that if some masters receive a ducat for painting one figure, you will certainly be offered two, and your wishes will be fulfilled, according to the old proverb, 'good work, good pay.'" of a truth, if man cannot dip his brush in the rainbow and paint with the aerial colours of the skies, he can at least select the best pigments that earth and the sea afford him; preferring, where he cannot get brilliancy and permanence combined, sobriety and permanence to brilliancy and fugacity. it must be the wish of every real artist to leave behind him a lasting record of his skill, a permanent panorama of those hues of nature which in life he loved so well. to effect this, genius alone is powerless: there must be first a proper choice of materials, and next a proper use of them. the painter's pigments are the bricks wherewith the mortar of his mind must be mixed, either to erect an edifice that shall endure for ages, or one which will quickly topple over like a house of cards. now in nothing more than in painting is prevention better than cure--indeed cure may be said to be here out of the question: for good or for evil a picture once painted is painted for ever. without a strong constitution there is no hope for it; no chemistry can strengthen the sickly frame, restore the faded colour, stop the ravages of consumption: science stands helpless before dying art. and yet, she sighs to think, it might have been otherwise. if durable pigments had been employed, if her counsel had been sought, this need not have been. in the history of modern art the use and abuse of colours would furnish a sad chapter, telling of gross ignorance, and a grosser indifference. happily there is promise of a healthier state of things. when this comes, art will be less shy to consult her sister: in the interests of both there should be closer union. without waiting till the picture is finished--for then it will be too late--let her, if in doubt, frankly display the contents of her palette and ask advice. now, not knowing what pigments are chosen or how they are used, never standing by and watching the progress of the work, how can science lend her aid? she would willingly, for she herself needs help: at present her knowledge is limited, not so much of the chemistry of colours as of the properties of pigments. she seeks to mix her pound of theory with an ounce of practice, and craves a warmer welcome to the studio. for any approximation to the truth to be arrived at, facts must be noted with the conditions under which they occur, not by one sister alone nor by the other alone, but by both. in future, art and science should go hand in hand, mutually dependent on each other, mutually trustful of each other, working with and for each other, earnestly and patiently. footnotes: [c] light is either direct or diffused--direct, when the sun's rays fall upon any object; diffused, when ordinary daylight illumines objects with white light, causing them to appear of their peculiar colours. addendum. with the present rapid progress of applied chemistry, an addendum in a work of this kind is quite excusable. even while the book is being printed some fact may be announced which the author or editor would wish to insert. in our case this has happened. very recently there has been introduced in france as a pigment 308. tungsten white, or _tungstate of baryta_. "at the request of a landscape painter," says m. sacc in a letter to m. dumas, "i was induced to examine in succession all our insoluble white compounds, with regard to their adaptability to painting purposes. tungstate of baryta answers perfectly, covers as well as white lead, and is as unalterable as zinc white. it has been employed by this artist for three months, and was found equally successful in oil or water colours, chromolithography, and even in making white impressions on a black ground. this harmless substitute for the injurious white lead is prepared on a large scale in paris by m. e. rousseau." we have not met with a sample of that gentleman's manufacture, but judging from our own specimens, made both by wet and dry processes, and carefully tried in water and oil, it would seem that a perfect white pigment has yet to be discovered. with us, at least, tungstate of baryta is far from having the body of white lead, and indeed is inferior in opacity to good zinc white. unaffected by foul air, the tungstate appears to possess the common fault of all whites when compared with white lead--want of body, moreover it is a bad dryer. however, m. rousseau's preparation may not be open to these objections, and we therefore reserve our final opinion of tungsten white. it is intended to publish from time to time a fresh edition of field's chromatography, and we hope in the next issue to give a more detailed and favourable account of the new pigment. index. a. acacia catechu, 354. academy, royal, at burlington house, 365. acetate of lead, as a siccative, 51. " improper use of, 52. adulteration, 70. " of anotta, 256. " artificial ultramarine, 214. " black lead, 394. " cadmium yellow, 88. " carmine, 134. " chrome yellow, 94. " cochineal, 132. " genuine ultramarine, 214. " indigo, 202. " ivory black, 397. " madder, 140. " madder carmine, 142. " mars yellow, 102. " prussian blue, 203. " red lead, 152. " smalt, 198. " verdigris, 276. " vermilion, 156. " veronese green, 268. " white lead, 70, 74, 75. " yellow and orange orpiment, 113, 259. " zinc white, 77. advancing and retiring colours, 186-188. advice, cennini's, 411. aerial perspective, 22. african cochineal, 170. " green, 271. air and light, action of, on pigments, 39. air effect, want of, 378. albumen, 50. alchemy, 259. alexander the great, 296. " veronese, 284. alkanet, 302. almagra, 147. almond black, 407. american artist, an, 347. analysis of brown, 377. " citrine, 329. " gray, 377. " marrone, 377. " olive, 330. " russet, 330. anchusa tinctoria, 302. ancients, colouring of the, 3. " colours of the, 5, 6, 218. aniline, 162. " colours, 162. " " cakes of, 163. " " in oil, 247. animal æthiops, 348. " charcoal, 397-399. " jelly, 50. anotta, 255. antimony, golden sulphur of, 256. " orange, 256. " red, 159. " white, 79. " yellow, 105. antipathies of pigments, 193. antwerp blue, 207. " brown, 339. apelles, 7, 293. archil, 303. " purple, 303. arethas, 217. armenian blue, 5, 217, 228. " bole, 147. " stone, 228. arsenical pigments, 273. arsenic green, substitutes for, 288, 290. " white, 79. " yellow, 116. art and science, 238, 412. artificial ultramarine, 209-216. " acid pigments with, 214. " adulteration of, 215. " green in, 211. " gum with, 214. artificial ultramarine, in siliceous painting, 212. " origin of, 209. " prize for, 209. " test for, 212. artists and painters, 182. arts, society of, 130. ash, ultramarine, 379. ashes, blue, 228. asphaltic lake, the, 337. asphaltum and asphalt, 337. " liquid, 339. association of science, british, 357. assyrians, colouring and colours of, 6. augustus cæsar, 295. aureolin, 42, 47, 83-87. " chemical news on, 84. " in admixture, 86. " mr. aaron penley on, 85. " the purest yellow, 84, 384. aurine, 162. autotype process, the, 401. avignon, berries of, 312. axiom, a wholesome, 201. axioms for compounding, 250. azuline, 162. azure, 192, 196, 217. b. barff, mr., 212. barium and bismuth chrome greens, 280. barthe and laurent, mm., 235. bartholomew, mr., 143. baryta, ferrate of, 165. " silicate of, 290. barytic white, 65. beauty in pigments, 46. beeswax, 50. berries, french, persian, and turkey, 212. berzelius, 169. bice, green, 187. bignonia chica, 367. bismuth purple, 304. bixa orellana, 255. bixine, 256. black, 27. " ancient, 5. " as a colour, 387, 391. " as a pigment, 389. " colours with, 392. " on the neutral, 387. black pigments:- almond black, 407. beggars' ultramarine, 409. black chalk, 404. black lead, 382, 393. black ochre, 404. blue black, 394. bone black, 405. british ink, 395. charcoal black, 394. chinese ink, 395. coffee black, 405. copper prussian black, 408. cork black, 409. earth black, 404. frankfort black, 406. galena, 394. graphite, 393. indian ink, 395. ivory black, 397. lamp black, 399. liege black, 394. manganese black, 406. mineral black, 407. mixed black, 402. paper black, 407. peach black, 407. plumbago, 393. prussian black, 404, 408. purple black, 408. spanish black, 409. vine black, 394. bladder green, 282. blanc d'argent, 71. blending of pigments, 37. blood, dragon's, 137. bloodstone, 147. blue, 28. " ancient, 5, 217. " armenian, 5, 217. " as a colour, 183. " contrast of, 185, 188. " discordant, 185. " on the primary, 183. blue pigments:- antwerp blue, 207. artificial ultramarines, 209-216. azure, 192, 217. basic prussian blue, 207. berlin blue, 203, 207. bice, 228. bleu de garance, 209. blue ashes, 228. blue bice, 228. blue carmine, 228. blue ochre, 226, 380. blue sand, 196. blue verditer, 228. brilliant ultramarine, 215. cerulian blue, or coeruleum, 190. cobalt blue, 192. cobalt blues, 189-199. cobalt prussian blue, 227. cobalt ultramarine, 192. coëlin, 190. copper blues, 227-230. cotton seed blue, 230. cyanine, 198. dumont's blue, 196. dutch ultramarine, 189. enamel blue, 189. egyptian blue, 229. factitious ultramarine, 215. ferricyanide of iron, 208. ferrocyanide of iron, 203. french blue, 215. french ultramarine, 215. genuine ultramarine, 216-225. gmelin's german ultramarine, 209. gold blue, 231. guimet's ultramarine, 209. haerlem blue, 207. hungary blue, 189. indian blue, 199. indicum, 199. indigo, 199. intense blue, 202. iodine blue, 231. iridium blue, 232. iris, 228. lazuline, 217. lazulite blue, 217. lazurstein, 217. leitch's blue, 199. leithner's blue, 189. manganese blue, 232. mineral blue, 207. mountain blue, 228. native prussian blue, 207. native ultramarine, 216. natural ultramarine, 216. new blue, 216. outremer, 217. outremer de guimet, 209. paris blue, 192, 203. permanent blue, 216. platinum blue, 233. powder blue, 196. prussian blue, 203. prussiate of iron, 203. pure ultramarine, 217. real ultramarine, 216. reboulleau's blue, 230. royal blue, 196. saunders' blue, 230. saxon blue, 189. schweinfurt blue, 230. smalt, 195-198. terre bleu, 228. thénard's blue, 192. true ultramarine, 216. tungsten blue, 233. turnbull's blue, 208. ultramarines, 209-225. verditer, 228. vienna blue, 192. wood-tar blue, 233. zaffre, 189. zinc-cobalt blue, 235. body white, 72. bole, armenian, 147. borrowdale, 393. bouvier, 153, 345, 347, 355, 405, 407, 409. box, the painter's, 60. bradley, mr., 246. british school, 9. broken colours, 16. bronze, 279. brown, 28. " analysis of, 377. " as a colour, 335. " citrine, 317. " contrast of, 337. " liquid, prout's, 345. " madder, 305. " mars, 313. " on the semi-neutral, 334. brown pigments:- animal æthiops, 348. antwerp brown, 339. asphaltum or asphalt, 337. bistre, 340. bitumen, 339. bitumen of judea, 337. bone brown, 340. burnt umber, 341. cadmium brown, 353. caledonian brown, 341. campania brown, 352. cappah brown, 342. cassel earth, 343. castle earth, 343. catechu browns, 374. chalon's brown, 344. chestnut brown, 357. chrome browns, 355. cologne earth, 344. copper brown, 355. cory's madder or yellow madder, 353. cullen's earth, 344. egyptian brown, 347. euchrome, 342. french prussian brown, 355. gambogiate of iron, 357. hypocastanum, 357. iron browns, 357. ivory brown, 340. jew's pitch, 337. leitch's brown, 346. manganese brown, 358. mineral brown, 342. mineral pitch, 337. mixed brown, 346. mummy, 347. mummy brown, 347. nickel brown, 358. ochre browns, 358. prussian brown, 348. purple brown, 359. roman sepia, 351. rubens' brown, 359. sepia, 348. terre de cassel, 343. uranium brown, 360. vandyke brown, 351. verona brown, 353. warm sepia, 350. yellow madder, 353. zinc brown, 360. brown pink, 312. " red, 147. " spanish, 146. " stil de grain, 312. browns, abundance of, 336, 361. brun de mars, 313. brunswick green, 271, 279. brushes, soap and alkali in, 52. burlington house, royal academy at, 365. burnt carmine, 298. " lake, 298. " madder, 305. " orpiment, 259. " roman ochre, 255. " sienna, 243. " terra di sienna, 243. " verdigris, 331. c. cadmium brown, 353. " orange, 36, 42, 244. " red, 42, 130. " white, 78. " yellow, 87, 92. " " adulteration of, 88. " " manufacture of, 92. " " when fugacious, 92. " " with white lead, 89. caledonian brown, 341. campania brown, 352. camphor, 396. cappah or cappagh brown, 342. carajuru, 367. carbolic acid, 162. carbon, 393. carmichael, mr., 348. carmine, 133, 135. " adulteration of, 134. " blue, 225. " burnt, 298. " field's, 142. carmine, madder, 142. " manufacture of, 134. " vermilion, 156. " violet, 302. " with indian yellow, 98. " " white lead, 134. carnac, ruins at, 4. carnagione, 149. carthamus, 174. cartoons at hampton court, 10. cassel earth, 343. " green, 288. " terre de, 343. " yellow, 121. cassius, purple of, 306. cassius's purple precipitate, 306. castle earth, 343. catechu browns, 354. celandine, 96. cendres bleues, 230. cennini, advice of, 411. cerulian blue or coeruleum, 190. ceruse, 74. chalk, black, 404. " green, 173. " red, 172. " white, 79. chalon's brown, 344. chaptal, count, 105, 229. charcoal, animal, 397, 399. " black, 394. " vegetal, 398, 406. charles i., 220. charred blacks, 390, 395, 406. cheese, anotta in, 256. chemical news, extract from, 84. chestnut brown, 357. chevreul, m., 173, 191, 205, 364. chiaroscuro, 15. chica d'andiguez, 160. " marrone, 367. " red, 159. china, mandarins of, 219. " white, 80. chinese ink, 395. " lake, 137. " orange, 246. " rouge, 174. " vermilion, 156. " white, 75. " yellow, 111. chinoline, 162. chocolate lead, 368. chromate of mercury, 256. chromates of lead, organic pigments with, 248, 280. chrome arseniate, 284. " browns, 355. " green, true, 267. " greens, 279-281. " ochre, 267. chrome orange, 248. " oxide, 267. " oxides, 266-271. " red, 151. " scarlet, 151. " yellows, 93-95. " " adulteration of, 94. chromium, green oxide of, 267. " opaque oxide of, 267. " oxide of, 267. " transparent oxide of, 268. church, professor, 165. cicero, 296. cinnabar, 153. " green, 280. citrine, 28. " analysis of, 329. " as a colour, 310. " contrast of, 311. " on the tertiary, 310. citrine pigments:- brown pink, 312. brown stil de grain, 312. brun de mars, 313. cassia fistula, 316. citrine brown, 317. citrine lake, 312. mars brown, 313. mixed citrine, 314. quercitron lake, 312. raw umber, 315. umber, 315. citron yellow, 95. classes of colours, on, 27-30. classified pigments:- black, 409. blue, 236. brown, 361. citrine, 319. gray, 380. green, 291. grey, 386. marrone, 371. olive, 333. orange, 261. purple, 308. red, 181. russet, 324. white, 80. yellow, 125. claude, 345. cleanliness in painting, 53. coal-tar colours, 160-164, 247. " cakes of, 163. " in oil, 247. cobalt blue, 192. chalkiness in, 195. manufacture of, 192. " blues, 189-199. " green, 285. " marrone, 368. " prussian blue, 227. " " green, 282. " purples, 305. " ultramarine, 192. coccus (abies nigra), 168. " cacti, 131. " ficus, 138. " ilicis, 153, 167. cochineal, 132. " adulteration of, 132. " dr. warren de la rue on, 132. " lake, with vermilion, 136. " lakes, 131-137. coëlin, 190. coeruleum, 190, 198, 217, 229. coffee black, 405. " brown, 405. cohesion and colour, 197, 208. " durability, 197, 208. cologne earth, 344. " yellow, 94. colour and neutrality, 375. " latent, 58. " of extreme light objects, 21. " of shadow, 21. " on the relations and harmony of, 13. coloured rays, mixture of, 384. colouring, ancient, 3-7. " false, 20. " importance of, 10-12. " on, 3. " vicious, 11-21. colours, ancient, 5, 6, 218. " and pigments individually, on, 57. " broken, 16. " classes of:- " " neutral, 27. " " primary, 28. " " secondary, 28. " " semi-neutral, 29. " " tertiary, 28. " complementary, 391. " discordant, 17, 185. " entire, 28. " extreme, 28. " fugacity of ancient, 6. " held in check, 106. " hot and cold, 20. " imaginary, 115. " individual beauty of, 57. " light and dark, 30. " material, mixture of, 384. " mixture and compounding of, 17-19. " not obtainable, 114. " not pigments, 305. " perspective of, 22. colours, retiring or advancing, 186-188. " superfluous, 124. " unfitted for pigments, 115, 180. " vitrified, 33, 197. " with black, 27, 392. " " colours, 27. " " grey, 382. " " white, 27, 63. common pigments, 359. compounding colours, on, 242-252, 277. compound pigments, 36. constable, 265. constantinople, 7. constant white, 65. " free acid in, 66. contrast of colour and neutrality, 15. " gradations and extremes, 19. " hues, 13-15. " shades, 15. " warmth and coolness, 15. copper blues, 227-230. " borate, 285. " brown, 355. " chrome, 286. " greens, 271-276. " prussian black, 408. " prussiate of, 323. " reds, 164. " smalt, 220. " stannate, 286. " yellow, 116. cork black, 409. correggio, 8, 335. cory's madder or yellow madder, 119, 353. cotton seed blue, 230. cremnitz or crems white, 72. crimson lake, 135. crookes, mr., 260. crowding of pictures, 364. cudbear, 303. cullen's earth, 344. cuttle fish, 348. cuyp, 136. cyanine, 198. cyanus, 198, 217. d. damonico, 257. darkening of mineral colours, 284. davy, sir h., 229. dead sea, the, 337. deep cadmium, 87. " chrome, 93. " vermilion, 154. " deoxidation of pigments, 38. detractors of modern pigments, 43-45. dewint's green, 330. diagram, 89. diesbach, m. 203. dilution of colour, 34. di palito, 109. direct and diffused light, 391. discord of colours, 17, 185. disinfectants of the palette, 359. distance, law about, 188. distilled verdigris, 276. distinction of colours, 318, 320. dominichino, 8. dragon's blood, 137. " with white lead, 138. drop gum, 96. drying of pigments, 50. " oils, lead in, 121. duffield, mrs., 144. dumas, m., 234, 414. dumont's blue, 196. durability of pigments, 31-45, 46. dussance, professor h., 175. dutch pink, 100. " schools, 8. " the, 156, 200. " ultramarine, 189. " white, 74. dyeing, brown for, 318. " orange for, 257. dyes and pigments, 169. e. earth black, 404. " burnt sienna, 243. " cassel, or castle, 343. " cologne, 344. " cullen's, 344. " green, 283. " raw sienna, 113. egg-shells, white of, 80. egypt, catacombs of, 347. " temples of upper, 5, 217. egyptian blue, 229. " brown, 347. egyptians, the, colouring and colours of, 3-5. elizabeth, queen, 393. eisner's green, 286. emerald green, 271. emeraldine, 162. enamel blue, 189. " colours, 33, 197. england, climate and females of, 9. english green, 280. " pink, 100. " red, 149. " vermilion, 146. entire colours, 28. equations, 329, 330, 377. euchrome, 342. exhibition, international, of 1862, 244, 354. experiment, 213. exposure of pigments, 38. extract of gamboge, 97. " vermilion, 157. extreme colours, 28. f. factitious indigo, proposed, 202. " ultramarine, 215. falsalo, 341. fast and fugitive, pigments both, 38. ferrate of baryta, 165. ferricyanide of iron, 208. ferrocyanide " 203. field's carmine, 142. " lakes, 139-145. " orange vermilion, 158. " purple, 301. " russet, 321. fineness of texture in pigments, 50. fire, action of, on pigments, 371. " pigments affected by, 40. fistula, cassia, 316. flake white, 72. flemish painters, 406. " schools, 8, 37. " white, 72. florentine lake, 137. " painters and painting, 7, 8, 10, 391. flower pieces, background tint for, 279. foul air, ochres with, 359. frankfort black, 406. french berries, 312. " blue, 215. " green, 271. " prussian brown, 355. " purple, solid, 304. " ultramarine, 215. " veronese green, 268. " white, 71. fresco, prussian blue in, 206, 281. fruit pieces of w. hunt, 315. fugacity of pigments, 31-45. fugitive colours, 34. g. gainsborough, 20. galena, 394. galleries, picture, 363-365. gallstone, 95. gamboge, 96. " as a glaze, 97. " extract of, 97. gamboge orange, 257. gambogiate of iron, 357. garance, bleu de, 209. gas, effect of, on colours, 191. gelbin's yellow, 117. general qualities of pigments, on the, 46. genuine ultramarine, 216-225. " adulteration of, 224. " colouring matter of, 224. " defects in, 222. " manufacture of, 220. " price of, 220. " properties of, 221. " tests for, 224. giallolino, 103. gilpin, 351. giovanni bellini, 7. giulio romano, 11. glazing of colours, 18. gloucestershire, 109. gmelin, m., 178, 210, 218, 227. gmelin's german ultramarine, 209. gold blue, 231. " purple, 306. " reds, 166. " size, japanner's, 51. golden sulphur of antimony, 256. " yellow, 256. gradation in art, 328. " nature, 326. graham, mr., 398. graphite, 393. gray, 29, 372. " analysis of, 277. " and grey, 29, 372, 381. " as a colour, 372, 374. " as a pigment, 377. " contrast of, 373. " on the semi-neutral, 372. gray pigments:- mineral gray, 375. mixed gray, 377. neutral tint, 377. payne's gray, 378. ultramarine ash, 379. greeks, colouring of the, 7, 8. " the, 153, 167, 296. green, 28. " as a colour, 263, 265. " contrast of, 263. " dewint's, 330. " discordant, 265. " olive, 330. " on the secondary, 263. green pigments:- african green, 271. barium chrome green, 280. bismuth chrome green, 280. bladder green, 282. bronze, 279. brunswick green, 271, 279. chrome arseniate, 284. chrome greens, 279-281. chrome oxide, 267. chrome oxides, 266-271. cobalt green, 285. cobalt prussian green, 282. copper borate, 285. copper chrome, 286. copper greens, 271-276, 285-287, 288. copper stannate, 286. distilled verdigris, 276. elsner's green, 286. emerald green, 271, 283. english green, 280. french green, 271. french veronese green, 268. german mineral green, 288. green bice, 287. green cinnabar, 280. green earth, 283. green lake, 288. green ochre, 287. green oxide of chromium, 267. green ultramarine, 287. green verditer, 287. holy green, 283. hooker's green, 281. hungary green, 274. imperial green, 271. iris green, 282. malachite green, 274. manganese green, 288. marine green, 271. mineral green, 288. mitis green, 271. mixed green, 277. molybdenum green, 289. mountain green, 274. native green, 267. olympian green, 271. opaque oxide of chromium, 267. oxide of chromium, 267. patent green, 271. persian green, 271. pickle green, 276. prussian greens, 281. quinine green, 289. rinman's green, 285. roman green, 290. sap green, 282. saxon green, 271. sheele's green, 272. schweinfurt green, 271. silicate of baryta, 290. swedish green, 272. terre verte, 283. titanium green, 290. transparent oxide of chromium, 268. true chrome green, 267. true prussian green, 281. uranium green, 291. vanadium green, 291. venetian green, 283. verde vessie, 282. verdetto, 283. verdigris, 276. verona green, 283. veronese green, 268. vert de zinc, 285. vienna green, 271. viride æris, 276. viridian, 269. zinc green, 285. green, pure, to obtain, 277. greens, ancient, 5. grey, 28-30, 372. " and gray, 29, 381. " as a colour, 381. " as a pigment, 382. " colours with, 382, 383. " on the neutral, 381. grey pigments:- black lead, 382. mixed grey, 384-386. grinding of pigments, 37. guido, 8. guimet, m., 210, 215. " outremer de, 209. guimet's ultramarine, 209. gum, drop, 96 " tragacanth, 66. gyges, 7. h. haerlem blue, 207. hamburgh lake, 137. " white, 74. hampton court, cartoons at, 10. harding's tint, 380. harmony of colour, 13-24. hatching of colours, 18. haydon, 293. hercules tyrius, 296. holy green, 283. hooker's green, 281. houng hoa, 396. hues, 27, 30. hungary blue, 189. " green, 274. hunt, w., 315. hypocastanum, 357. i. illumination, cadmium orange in, 246. " coal-tar colours in, 163, 247. " manual of, 246. " viridian in, 270. imperial green, 271. indian blue, 199. " ink, 349, 395. " lake, 138. " ochre, 146. " purple, 298. " red, 148. " yellow, 98. indicum, 199. indigo, 199. " adulteration of, 202. " possible substitute for, 235. " proposed factitious, 202. indigofera, 200. indium yellow, 117. individually, on colours and pigments, 57. ink, blue, 207. " british, 395. " chinese, 395. " green, 276. " indelible brown, 345. " indian, 395. " liquid indian, 397. " red, 145. inkfish, the, 348. innoxious pigments, 53. intense blue, 202. " " manufacture of, 202. international exhibition of 1862, 244, 354. invisible green, 329. iodine, 118. " blue, 231. " pink, 166. " scarlet, 150. " yellow, 118. iridium blue, 232. iris, 228. " green, 282. iron browns, 357. " ferricyanide of, 208. " ferrocyanide of, 203. " gambogiate of, 357. " pigments affected by, 39, 90, 145, 147, 149, 150, 249. " prussiate of, 203. " smalt, 218. " yellow, 102, 118. italian greens, 276, 277. " pink, 100. italics, numbered colours in, 114, 407. italy, colouring in modern, 8. ivory black, 397. " " with manganese black, 407. ivory brown, 340. j. japanner's gold size, 51. jaune de cologne, 94. " " fer, 102. " " mars, 102. " minérale, 94. jew's pitch, 337. judea, bitumen of, 337. k. kermes, 153. " lake, 167. " mineral, 159. key of colouring, 40. khair tree, the, 354. king's yellow, 111. knowledge of pigments, 43, 44. kremnitz or krems white, 72. kremser white, 75. l. lac, 138, 167. " lake, 138. lake, asphaltic, the, 337. " burnt, 198. " chinese, 137. " citrine, 312. " crimson, 135. " drop, 131. " florentine, 137. " green, 288. " hamburgh, 137. " indian, 138. " kermes, 167. " liquid madder, 145. " madder, 144. " marrone, 369. " olive, 331. " orange, 258. " purple, 137. " quercitron, 100, 312. " roman, 137. " scarlet, 136. " venetian, 137. " yellow, 100. lakes, cochineal, 131-137. " field's, 139-145. " madder, 139-145. " rubric, 139-145. " yellow, 99, 100. lamblack, 399. lamp black, 399. lapis lazuli, 209, 217, 219. laque de garance, 142. " minérale, 258. latent colour, 58. lawson, professor, 168. lawson's red, 168. layard, mr., 6, 218. lazuline, 217. lazulite blue, 217. lazur, persian and tartarian, 228. lazurium, 217. lazurstein, 217. lead, acetate or sugar of, 50-52. " black, 382, 393. " carbonate of, 68. " chocolate, 368. " dicarbonate of, 69. " hydrated oxide of, 68. " in drying oils, 121. " orange, 258 " oxychloride of, 73. " pigments affected by, 39, 67, 97, 99, 112, 120, 134, 138, 139, 152, 201, 206, 248, 280, 312, 341. " pigments, avoidance of, 67. " red, 151. " sulphate of, 72. " white, 67-70. " whites, 67-75. leitch's blue, 199. " brown, 346. leithner's blue, 189. lemon cadmium, 91. " yellow, 101. leonardo da vinci, 8. leyden, cassius of, 306. lichens, 304. liege black, 394. light and air, pigments affected by, 91, 92, 95, 97, 98, 99, 112, 124, 134, 135, 136, 139, 151, 163, 199, 201, 205, 208, 247, 276, 282, 298, 303, 313, 330, 340, 343. light, direct and diffused, 391. " electric, the, 191. " magnesium, the, 191. " red, 149. likes and dislikes of pigments, 194. lime, pigments affected by, 40, 97, 98, 206, 275, 281. " with prussian blue, 206, 281. linear perspective, 22. linseed oil with white lead, 69. liquid asphaltum, 339. " indian ink, 397. " madder lake, 145. " prout's brown, 345. " rubiate, 145. lists of permanent pigments:- " blue, 278, 300. " green, 315, 329. " orange, 315, 323. " purple, 323, 329. " red, 253, 300. " yellow, 252, 278. litharge, 51, 120. litmus, 303. local colour, 24. lombard school, 8. london white, 73. m. macpherson's tint, 380. madder, 139. " adulteration of, 140. " brown, 365. " burnt, 305. " carmine, 142. " " adulteration of, 142. " colouring matters of, 140. " cory's or cory's yellow, 119, 353. " dr. schunck on, 140. " lake, 144. " lakes, 139-145. " " manufacture of, 141. " liquid lake, 145. " orange, 258, 353. " pink, 144. " purple, 301. " reds in oil, 144. " rose, 143. " rubens', 321. " yellow, 118, 353. magenta, 162. majolica, 146. malachite green, 274. manganese as a siccative, 51, 77, 406. " black, 406. " blue, 232. " brown, 358. " green, 288. " red, 168. manufacture of cadmium yellow, 92. " carmine, 134. " cobalt blue, 192. " intense blue, 202. " vermilion, 92, 153. marine green, 271. marrone, 28. " analysis of, 377. " as a colour, 362. " contrasts of, 362. " for walls of picture galleries, 363. " on the semi-neutral, 362. marrone pigments:- brown madder, 365. chica marrone, 367. chocolate lead, 368. cobalt marrone, 368. madder marrone, 369. marrone lake, 369. marrone red, 368. mars marrone, 369. mixed marrone, 367. purple black, 369. mars brown, 313. " brun de, 313. " colours named after, 102, 146. " orange, 248. " red, 145. " rouge de, 145. " violet, 290. " violet de, 290. " yellow, 102. massicot, 120. mastic varnish, 50. mauve, 163. mercury, chromate of, 256. " marrone, 371. " white, 79. mérimée, 121, 142, 229, 284, 316, 343. metallic whites, 79. metals, rare, 172. michael angelo, 8. mineral black, 407. " blue, 207. " brown, 342. " colours, darkening of, 284. " gray, 375. " green, 288. " green, german, 288. " kermes, 159. " orange, 258. " pitch, 337. " purple, 290. " turbith, 123. " yellow, 106, 116, 121. minérale, jaune, 94. " laque, 258. miniature painter, a, 401. minium, 151, 153. mitis green, 271. mixed colours:- " black, 402. " brown, 346. " citrine, 314. " gray, 377. " green, 277. " grey, 384. " marrone, 367. " olive, 328. " orange, 249. " purple, 290. " russet, 322. mixed tints, on, 249-252, 262. mixture, a, 199. " of bitumen and mummy, 348. " of coloured rays, 384. " of material colours, 384. " unnecessary, 35. modan or morat white, 80. modern pigments, 41-45. " detractors of, 43-45. " inferior, 41. " superior, 42. molybdenum green, 289. monicon, 257. montabert, de, 405. montbeillard, roman pavement at, 218. montpellier yellow, 121. mountain blue, 228. " green, 274. mountains, 254. mummy, 347. " brown, 347. " and bitumen, mixed, 348. murexide, 169. musée minéralogique, of paris, 219. mutrie, miss, 143. " yellow, 92. n. naphthaline, 162. naples yellow, modern, 104. " old, 103. napoleon, emperor, 176. native bitumen, 338. " green, 267. " prussian blue, 207, 226. " ultramarine, 216. natural ultramarine, 216. nature, colour in, 311. " gradation in, 326. " palette of, 185. " study of, 24. negative colours, 28. nepos cornelius, 295. neutral colours, 27. " orange, penley's, 253. " tint, 377. neutrality and colour, 375, 376. neutrals, colour as applied to the, 62. new blue, 216. " pigments, 41-45. nickel brown, 358. nineveh, 6, 218. nottingham white, 73. o. objectionable pigments, substitutes for, 96, 104, 114. ochre, black, 404 " blue, 226. " brown, 108. " browns, 358. " burnt roman, 255. " chrome, 267. " green, 287. " indian, 148. " orange, 255. " oxford, 109. " purple, 290. " red, 147. " roman, 107. " scarlet, 149. " spanish, 255. " spruce, 108. " stone, 109. " transparent gold, 108. " yellow, 106. ochres and foul air, 359. " red, 146-150. " yellow, 105-109. ocre de ru, 108 oil, coal-tar colours in, 247. " water-colour cakes in, 50. oils, 33, 152, 194. olive, 28. " analysis of, 330. " as a colour, 325. " contrast of, 325. " on the tertiary, 325. olive pigments:- burnt verdigris, 331. dewint's green, 330. mixed olive, 328. olive green, 330. olive lake, 331. olive oxide of chromium, 331. olive rinman's green, 332. olive scheele's green, 332. olive schweinfurt green, 332. olive terre verte, 333. olive purples, 301. olympian green, 271. o'neill, mr., 159. opacity of pigments, 48. orange, 28, " as a colour, 239. " as an archeus, 240. " contrast of, 240. " discordant, 240. " on the secondary, 239. orange pigments:- anotta, 255. antimony orange, 256. bixine, 256. burnt roman ochre, 255. burnt sienna, 243. burnt terra di sienna, 243. cadmium orange, 36, 244. chinese orange, 246. chromate of mercury, 256. chrome orange, 248. damonico, 257. gamboge orange, 257. golden sulphur of antimony, 256. golden yellow, 256. laque minérale, 258. madder orange, 258, 353. mars orange, 248. mineral orange, 248. mixed orange, 249. monicon, 257. neutral orange, 253. orange chrome, 248. orange chromate of lead, 248. orange de mars, 248. orange lake, 258. orange lead, 258. orange ochre, 255. orange orpiment, 258. penley's neutral orange, 253. realgar, 258. red orpiment, 258. rocou, 255. spanish ochre, 255. terra orellana, 255. thallium orange, 259. uranium orange, 260. zinc orange, 261. orange russet, 321. " vermilion, 157. " " field's, 158. order of colours:- white, 62-80, 414. yellow, 81-126. red, 127-182. blue, 183-238. orange, 239-262. green, 263-293. purple, 294-309. citrine, 310-319. russet, 320-324. olive, 325-333. brown, 334-361. marrone, 362-371. gray, 372-380. grey, 381-386. black, 387-413. organic pigments with lead chromates, 248. orient yellow, 42, 110. original pigments, 35. " importance of, 240-242. orpiment yellow, 111-113. outremer, 217. outremer de guimet, 209. oxford ochre, 109. oxidation of pigments, 38. oxide, chrome, 267. " of chromium, green, 267. " " opaque, 267. " " transparent, 268. oxychloride of lead, 73. oxygenated water, 69. oyster-shell, white of, 80. p. paille de mil, 170. painting, siliceous, 212. pale cadmium, 90. " chrome, 93. " vermilion, 154. " washes of a pigment, 91. palette, disinfectants of the, 359. " motto for the, 156. " setting the, 23. palette-knife, avoidance of a steel, 39, 50, 90, 103. palladium, 122. paper black, 407. " smalt and ultramarine in, 196. " to give a tone to, 253. paris blue, 192, 203. paris, musée minéralogique at, 219. " société d'encouragement of, 210. particular colour, predilection for a, 58, 59. patent green, 271. " yellow, 121. pattison's white, 73. paul veronese, 229, 335. payne's gray, 378. peach black, 407. pearl white, 78. peganum harmala, 171. penley, mr. aaron, 85-87, 158, 268, 270. penley's neutral orange, 253. perfect pigment, a, 46. perkin, mr. w., 162. permanent blue, 216. " pigments, 252, 278, 300, 315, 323, 329. " white, 65. peroxidized pigments, 38. persian berries, 312. " green, 271. " lazur, 228. " red, 148. perspective, aerial, 22, 23. " linear, 22. " of colours, 22, 23. persulphomolybdates, 171. philocles, 7. phosphine, 162. photography, lamp black in, 401. " pigments generally in, 401. pickle green, 276. picric acid, 162. picture galleries, 363-365. pictures and pigments, 292. pigment and colour, 31. pigments, action of fire and time on 31. " adulteration of, 70. " apt to vary, 126, 181. " beauty in, 46. " blending of, 37. " common, 359. " compound, 36. " drying of, 50. " fineness of texture in, 50. " grinding of, 37. " individual beauty of, 58. " innoxious, 53. " on the durability and fugacity of, 31. " on the general qualities of, 46. " opacity and transparency of, 48. " past and present, 293. " rays from, 384. " truth of hue in, 47. " vehicles with, 48-53. " working well, 49. pink, brown, 313. " dutch, 100. " english, 100. " italian, 100. " madder, 144. " rose, 173. " saucers, 174. pitch, jew's, 337. " mineral, 337. pittacal, 234. platinum blue, 233. " yellow, 121. playfair, dr. lyon, 355. pliny, 7, 153, 198, 218, 295, 338. plumbago, 393. polygnotus, 9. pompeii, 105, 229. porcelain, blue for, 235. " green for, 267. poussin, 11, 316. powder blue, 196. power of pigments, individual, 59. powers of colours, 82. practice of sir j. reynolds, 37. precipitate, red, 173. prevention and cure, 412. price, dr. d. s., 69. primary colours, 28. principles of practice, 35. process, autotype, 401. protoxide, pigments in the state of, 37. proust, m., 396. prout, samuel, 346. prout's brown, liquid, 345. prussian black, 404, 408. " copper, 408. prussian blue, 203. " adulteration of, 203. " character of, 237, 278, 301. " cobalt, 227. " manufacture of, 203. " native, 207, 226. " want of a permanent, 189. " with alkalies, 206. prussian brown, 348. " " french, 255. " greens, 281, 282. " red, 149. prussiate of copper, 323. " iron, 203. pure scarlet, 150. " ultramarine, 216. purple, 28. " as a colour, 295. " as a pigment, 297. " black, 369, 408. " brown, 359. " contrast of, 294, 297. " lake, 137. " on the secondary, 294. purple pigments:- archil purple, 303. bismuth purple, 304. burnt carmine, 298. burnt lake, 298. burnt madder, 305. cassius's purple precipitate, 306. cobalt purples, 305. field's purple, 301. gold purple, 306. indian purple, 298. mars violet, 290. mauve, 163. mineral purple, 290. mixed purple, 290. prussian purple, 307. purple madder, 301. purple ochre, 290. purple of cassius, 306. purple rubiate, 301. sandal wood purple, 307. solid french purple, 304. tin violet, 308. violet carmine, 302. violet de mars, 290. purple, pure, 300. " tyrian, 295, 296. purpurates, 170. purree, 98. q. qualities of pigments, on the general, 46. queen's yellow, 123. quercitron lake, 100, 312. " yellow, 100. quinine green, 289. r. ramnus infectorius, 315. raphael, 8, 9. rare metals, 172. raw sienna, 113. " umber, 315. rays from pigments, 384. real ultramarine, 216. realgar, 258. reboulleau's blue, 230. red, 28. " as a colour, 128. " contrasts of, 128, 129. " discordant, 129. " marrone, 368. " on the primary, 127. " orpiment, 258. red pigments:- almagra, 147. antimony red, 159. armenian bole, 147. bloodstone, 147. brown red, 147. cadmium red, 130. carmine, 133-135. carmine vermilion, 156. carnagione, 149. chica red, 159. chinese lake, 137. chinese rouge, 174. chinese vermilion, 156. coal-tar colours, 160. cobalt reds, 164. cochineal lakes, 131-137. copper reds, 164. crimson lake, 135. deep vermilion, 154. dragon's blood, 137. english red, 149. english vermilion, 146. extract of vermilion, 157. ferrate of baryta, 165. field's carmine, 142. field's lakes, 139-145. field's orange vermilion, 158. florentine lake, 137. red pigments:- gold reds, 166. hamburgh lake, 137. indian lake, 138. indian ochre, 146. indian red, 148. iodine pink, 166. iodine scarlet, 150. kermes lake, 167. lac lake, 138. lawson's red, 168. light red, 149. liquid madder lake, 145. liquid rubiate, 145. madder carmine, 142. madder lake, 144. madder lakes, 139-145. magenta, 160. majolica, 146. manganese red, 168. mars red, 145. mineral kermes, 159. minium, 151. murexide, 169. ochres, 146-150. orange vermilion, 157. paille de mil, 170. pale vermilion, 154. peganum harmala, 171. persian red, 148. persulphomolybdates, 171. pink madder, 144. pink saucers, 174. prussian red, 149. pure scarlet, 150. purple lake, 137. red chalk, 172. red chrome, 151. red lead, 151. red ochre, 147. red precipitate, 173. redding, 146. roman lake, 137. rose madder, 143. rose pink, 173. rose rubiate, 145. rouge, 173. rouge de mars, 145. rubric lakes, 139-145. rufigallic red, 174. sandal red, 175. saturnine red, 151. scarlet chrome, 151. scarlet lake, 136. scarlet ochre, 149. scarlet vermilion, 156. sil atticum, 147. silver red, 176. sinoper, 151. sorgho red, 176. spanish brown, 146. spanish red, 150. terra puzzoli, 149. terra sinopica, 147. thallium red, 177. tin pink, 177. ultramarine red, 178. uranium red, 179. venetian lake, 137. venetian red, 149. vermilion, 154. vermilions, 153-158. wongshy red, 180. reds, ancient, 5. relations of colour, 13-24. relative durability of colour, 32. rembrandt, 11, 345. revelation, book of, 217. reynolds, sir joshua, 10, 35, 37, 158, 374, 410. rinman's green, 285. " olive, 332. rocou, 255. roman green, 290. " lake, 137. " ochre, 107. " " burnt, 255. " painters and painting, 7, 8, 10, 391. " sepia, 351. " white, 74. romans, the, 153, 295. romulus, 295. rosaniline, 162. rose, the, 327. rousseau, m. e., 414. rowbotham, messrs., 144. royal academy at burlington house, 365. " blue, 196. rubens, 11, 37, 64, 157, 283, 334, 374. " brown, 359. " madder, 321. rubia tinctorum, 139. rubiate, purple, 301. rue, dr. warren de la, 132. ruskin, mr., 13. russet, 28. " analysis of, 330. " as a colour, 320. " contrast of, 321. " on the tertiary, 320. russet pigments:- field's russet, 321. mixed russet, 322. orange russet, 321. prussiate of copper, 323. rubens' madder, 321. russet rubiate, 321. s. sacc, m., 414. safflower, 174. samuel prout, 346. sandal red, 175. " wood purple, 307. sandarac, 259. sap green, 282. satin white, 80. saturnine red, 151. saucers, pink, 174. saunders blue, 230. saxon blue, 189. " green, 271. " smalts, 215. scarlet chrome, 151. " iodine, 150. " lake, 136. " ochre, 149. " pure, 150. " transparent, a, reward for, 130. " " substitute for, 130. " vermilion, 156. scheele's green, 272. " olive, 332. schools of painting, 8-10, 37. schunck, dr., 140. schweinfurt blue, 230. " green, 271. " " olive, 332. scoffern, dr., 357. sea, the dead, 337. " transparency of the, 269. secondary colours, 28. " pigments, 242. semi-neutral colours, 29. " the term, 334. semi-stability, on, 308. semi-stable pigments, 298, 313. sepia, 348, 397. " liquid, 348. " roman, 350. " warm, 351. shades, 21. shadow, colour of, 27, 30. siccatives, 51-53. sienna, burnt, 243. " raw, 113. " terra di, 113. sil atticum, 147. silicate of baryta, 290. siliceous painting, ultramarine in, 212. silver red, 176. " white, 71. sinoper, 151. slate clays, 380. " powdered, 380. smalt, 195-198. " adulteration of, 198. " copper, 229. smalt, grinding of, 197. " in mural decoration, 198. " in paper, 196. " iron, 218. soap and alkali in brushes, 52. société d'encouragement of paris, 210. society of arts, 130. soda flame, 191. solid french purple, 304. sorgho red, 176. sources of pigments, 60. south america, chica from, 368. spanish black, 409. " brown, 146. " ochre, 255. " red, 150. " schools, 8. " white, 80. spence, mr., 68. spruce ochre, 108. st. petersburg, palace at, 219. starch, 66. stil de grain, brown, 312. stippling, 315. stone, armenian, 228. " lapis lazuli, 217, 219. " malachite, 274. " ochre, 109. strontian yellow, 113. sulphate of lead, 72. " zinc, 51. sulphide of cadmium, thallium in, 260. sulphur and ochres, 359. sulphuretted hydrogen, pigments affected by, 39, 67, 69, 73, 78, 79, 93, 103, 120, 151, 152, 229, 248, 275, 276. susa, 296. swedish green, 272. synonyms, value of, 145. t. talent of money, 296. teniers, 360. terra di sienna, 113. " " " burnt, 243. " orellana, 255. " puzzoli, 149. " sinopica, 147. terre bleu, 228. " verte, 283. " " olive, 333. terrene whites, 66, 80. tertiary colours, 28. " on, 311. thallium, in sulphide of cadmium, 260. " orange, 259. " red, 177. " yellow, 122. thebes, mausoleum at, 3. thénard, m., 69, 192. thénard's blue, 192. theophrastus, 198. theory and practice, 410. thwaites' yellow, 122. time, pigments affected by, 40. tin pink, 177. " violet, 308. " white, 79. tin-copper green, 286. tint, harding's, 380. " macpherson's, 380. " neutral, 377. tintoret, 8. tints, 27. titanium green, 290. titian, 7, 8, 9, 11, 37, 150, 157, 293, 334. transparency of pigments, 48. " to obtain, 245. transparent gold ochre, 108. " oxide of chromium, 268. " pigments, use of, 237. troy white, 80. true chrome green, 267. " prussian green, 281. " ultramarine, 216. truth of hue in pigments, 47. tullus hostilius, 295. tungsten blue, 233. " white, 414. turacine, 165. turbith mineral, 123. turkey berries, 312. turnbull's blue, 208. turner, 309, 328. turner's yellow, 121. tyrian purple, 295, 296. u. ultramarine, artificial, 209-216. " acid pigments with, 214. " adulteration of, 215. " experiment with, 213. " green in, 211. " gum with, 214. " in siliceous painting, 212. " test for, 212. ultramarine ash, 379. " beggars', 409. " brilliant, 215. " cobalt, 192. " dutch, 189. " factitious, 215. " french, 215. ultramarine, genuine, 216-225. " adulteration of, 224. " colouring matter of, 224. " defects in, 222, 223. " manufacture of, 220. " price of, 220. " properties of, 221. " tests for, 224. ultramarine, gmelin's german, 209. " green, 287. " guimet's, 209-211. " native, 216. " natural, 216. " pure, 217. " real, 216. " red, 178. " true, 216. umber, 315. " burnt, 341. " grounds primed with, 316. " raw, 315. unnecessary mixture, 35. uranium brown, 360, " green, 291. " orange, 260. " red, 179. " yellow, 123. ure, dr., 73. v. vanadium green, 291. vandyke, 11, 150, 220, 351. " brown, 351. van eyck, 167. varnishes, 33, 152. vegetal charcoal, 398. vehicles with pigments, 48-53. velasquez, 389. venetian green, 283. " lake, 137. " painters, painting, and pigments, 7, 8, 34, 37, 139, 167. " red, 149. " white, 75. verde vessie, 282. verdetto, 283. verdigris, 51, 276. " burnt, 331. " distilled, 276. verditer, blue, 228. " green, 287. vermilion, 153-158. " adulteration of, 156. " carmine, 156. " chinese, and english, 156, 146. " deep, 154. " european and chinese, 154. " extract of, 157. " field's orange, 158. " manufacture of, 154. " orange, 157. vermilion pale, 154. " scarlet, 156. " with cochineal lake, 136. " with iodide of mercury, 155. verona brown, 353. " green, 283. veronese green, 268. " french, 268. vert de zinc, 285. vicious extremes in colouring, 59. vienna blue, 192. " green, 271. " white, 72. vine black, 394. violet, carmine, 302. " de mars, 290. " mars, 290. " tin, 308. viride æris, 276. viridian, 42, 269. vision, derangement of, 59. vitrification and permanence, 197. vitrified colours, 33, 103, 197. vitruvius, 229. w. wall colour for picture galleries, 363. " space in " " 364. walpole, mrs., 220. warm sepia, 350. water-colour cakes in oil, 50. watts, mr., 165. weppen, 398. white, 27. " as a colour, 62. " as a pigment, 64. " chalk, 79. " colour as applied to, 62. whitelac varnish, 50. white lead, 67-70. " adulteration of, 70. " colour restored in, 69. " hydrated oxide in, 68. " loss of opacity in, 68. " use of, 70. " with blue black, 395. " " bone brown, 341. " " brown pink, 312. " " cadmium yellow, 89. " " carmine, 134. " " dragon's blood, 138. " " gamboge, 97. " " indian lake, 139. " " indigo, 201. " " massicot, 120. " " orpiment, 112. " " prussian blue, 206. " " red lead, 152. " " yellow lakes, 99. white, on the neutral, 62. " perfect, 62, 64. white pigments:- antimony white, 79. arsenic white, 79. barytic white, 65. blanc d'argent, 71. body white, 72. cadmium white, 78. ceruse, 74. china white, 80. chinese white, 75. constant white, 65. cremnitz or kremnitz white, 72. crems or krems white, 72. dutch white, 74. flake white, 72. flemish white, 72. french white, 71. hamburgh white, 74. kremser white, 75. london white, 73. mercury white, 79. modan or morat white, 80. nottingham white, 73. oxychloride of lead, 73. pattison's white, 73. pearl white, 78. permanent white, 65. roman white, 74. rouen white, 80. satin white, 80. silver white, 71. spanish white, 80. sulphate of lead, 72. tin white, 79. tungsten white, 414. troy white, 80. venetian white, 75. vienna white, 72. white lead, 67-70. zinc white, 76. zinc whites, 75-78. white, properties of, 62-64. " use of, 64. whites, classified, 80. " in old pictures, 65. williamson, professor, 205. wilson, 336. winter scene, a water-colour, 352. wongshy red, 180. wood-tar blue, 233. working well in pigments, 49. y. yellow, 28. " as a colour, 82. " contrasts of, 82, 83. yellow, discordant, 83. " golden, 256. " madder, cory's, 353. " on the primary, 81. yellow pigments:- antimony yellow, 105. arsenic yellow, 116. aureolin, 83-87. bismuth yellow, 116. brown ochre, 108. cadmium yellows, 87-92. cassel yellow, 121. chinese yellow, 111. chrome yellows, 93-95. citron yellow, 95. cologne yellow, 94. copper yellow, 116. deep cadmium, 87. deep chrome, 93. di palito, 109. drop gum, 96. dutch pink, 100. english pink, 100. extract of gamboge, 97. gallstone, 95. gamboge, 96. gelbin's yellow, 117. giallolino, 103. indian yellow, 98. indium yellow, 117. iodine yellow, 118. iron yellow, 102, 118. italian pink, 100. jaune de cologne, 94. jaune de fer, 102. jaune de mars, 102. jaune minérale, 94. king's yellow, 111. lakes, 99, 100. lemon cadmium, 91. lemon yellow, 101. litharge, 120. madder yellow, 118, 353. mars yellow, 102. massicot, 120. mineral yellow, 106, 116, 121. montpellier yellow, 121. mutrie yellow, 92. naples yellow, 103. ochres, 105-109. ocre de ru, 108. orient yellow, 110. orpiment or yellow orpiment, 111. oxford ochre, 109. pale cadmium, 90. pale chrome, 93. patent yellow, 121. platinum yellow, 121. purree, 98. queen's yellow, 123. quercitron lake, or yellow, 100. raw sienna, 113. roman ochre, 107. spruce ochre, 108. stone ochre, 109. strontian yellow, 113. terra di sienna, 113. thallium yellow, 122. thwaites' yellow, 122. transparent gold ochre, 108. turbith yellow, 123. turner's yellow, 121. uranium yellow, 123. yellow carmine, 123. yellow lake, 100. yellow ochre, 106. yellows, ancient, 5. " classified, 125. " former paucity of, 83. " various, 124. z. zaffre, 189. zeuxis and apelles, 7. zinc brown, 360. " cobalt blue, 235. " green, 285. " orange, 261, " siccatives, 51, 77. " vert de, 285. " white, 76. " " adulteration of, 77. " " over white lead, 76. " whites, 75-78. errata. page 16 _for_ inharmonious _read_ harmonious " 35 _for_ there prevails _read_ there prevail " 48 _for_ as whiteness, or light do, _read_ as whiteness or light does " 166 _for_ purple of cassius _read_ purple of cassius " 182 _for_ which manufactures _read_ which manufactures pictures " 258 _for_ _laque minéral_ _read_ _laque minérale_ " 342 _for_ rivals _read_ rivels " 378 _for_ predominate _read_ predominates the end. london: printed by a. schulze, 13, poland street. +------------------------------------------------------+ |transcriber's note: | | | |the errata above and the following have been corrected| |in the text: | | | |page vi semi-neutral changed to semi-neutral | | 10 life less changed to lifeless | | 17 sun-rise changed to sunrise | | 20 in the the changed to in the | | 22 perpective changed to perspective | | 29 marone changed to marrone | | 69 di-carbonate changed to dicarbonate | | 73 hydrogren changed to hydrogen | | 77 imimical changed to inimical | | 81 feuillemorte changed to feuillemort | | 91 item numbering has been left consistent | | with the omission of item no. 23 | | 129 extemes changed to extremes | | 169 muroxide changed to murexide | | 188 dullness changed to dulness | | 192 gaslight changed to gas-light | | 200 durablity changed to durability | | 206 and 293 developement changed to development | | 212 decolorized changed to decolourised | | 235 indentical changed to identical | | 241 re-acting changed to reacting | | 250 exibition changed to exhibition | | 273 childrens' changed to children's | | 336 toneing changed to toning | | 352 fine tooth-comb changed to fine-tooth comb | | 408 analagous changed to analogous | | 414 announceed changed to announced | | 421 abies changed to abies | | | |inconsistencies in the use of analyse/analyze, | |harmonise/harmonize and neutralise/neutralize have | |been retained as in the original text, as have the | |use of aërial and aerial. | +------------------------------------------------------+ proofreading team experiments and considerations touching colours. first occasionally written, among some other _essays_, to a friend; and now suffer'd to come abroad as the beginning of an experimental history of colours. by the honourable robert boyle, fellow of the royal society. _non fingendum, aut excogitandum, sed inveniendum, quid natura faciat, aut ferat._ bacon. _london._ printed for _henry herringman_ at the _anchor_ on the lower walk of the _new exchange._ mdclxiv. * * * * * the preface. having in convenient places of the following treatise, mention'd the motives, that induc'd me to write it, and the scope i propos'd to my self in it; i think it superfluous to entertain the reader now, with what he will meet with hereafter. and i should judge it needless, to trouble others, or my self, with any thing of preface: were it not that i can scarce doubt, but this book will fall into the hands of some readers, who being unacquainted with the difficulty of attempts of this nature, will think itn strange that i should publish any thing about colours, without a particular theory of them. but i dare expect that intelligent and equitable readers will consider on my behalf: that the professed design of this treatise is to deliver things rather _historical_ than _dogmatical_, and consequently if i have added divers new _speculative_ considerations and hints, which perhaps may afford no despicable assistance, towards the framing of a solid and comprehensive hypothesis, i have done at least as much as i promis'd, or as the nature of my undertaking exacted. but another thing there is, which if it should be objected, i fear i should not be able so easily to answer it, and that is; that in the following treatise (especially in the third part of it) the experiments might have been better marshall'd, and some of them deliver'd in fewer words. for i must confess that this essay was written to a private friend, and that too, by snatches, at several times, and places, and (after my manner) in loose sheets, of which i oftentimes had not all by me that i had already written, when i was writing more, so that it needs be no wonder if all the experiments be not rang'd to the best advantage, and if some connections and consecutions of them might easily have been mended. especially since having carelessly laid by the loose papers, for several years after they were written, when i came to put them together to dispatch them to the press, i found some of those i reckon'd upon, to be very unseasonably wanting. and to make any great change in the order of the rest, was more than the printers importunity, and that, of my own avocations (and perhaps also considerabler solicitations) would permit. but though some few preambles of the particular experiments might have (perchance) been spar'd, or shorten'd, if i had had all my papers under my view at once; yet in the most of those introductory passages, the reader will (i hope) find hints, or advertisements, as well as transitions. if i sometimes seem to insist long upon the circumstances of a tryall, i hope i shall be easily excused by those that both know, how nice divers experiments of colours are, and consider that i was not barely to _relate_ them, but so as to teach a young gentleman to make them. and if i was not sollicitous, to make a nicer division of the whole treatise, than into three parts, whereof the one contains some considerations about colours in general. the other exhibits a specimen of an account of particular colours, exemplifi'd in whiteness and blackness. and the third promiscuous experiments about the remaining colours (especially red) in order to a theory of them. if, i say, i contented my self with this easie division of my discourse, it was perhaps because i did not think it so necessary to be curious about the method or contrivance of a treatise, wherein i do not pretend to present my reader with a compleat fabrick, or so much as modell; but only to bring in materials proper for the building; and if i did not well know how ingenious the curiosity and civility of friends makes them, to perswade men by specious allegations, to gratifie their desires; i should have been made to believe by persons very well qualify'd to judge of matters of this nature, that the following experiments will not need the addition of accurate method and speculative notions to procure acceptance for the treatise that contains them: for it hath been represented, that in most of them, as the novelty will make them surprizing, and the quickness of performance, keep them from being tedious; so the sensible changes, that are effected by them, are so manifest, so great, and so sudden, that scarce any will be displeased to see them, and those that are any thing curious will scarce be able to see them, without finding themselves excited, to make reflexions upon them. but though with me, who love to measure physical things by their _use_, not their _strangeness_, or _prettiness_, the partiality of others prevails not to make me over value these, or look upon them in themselves as other than trifles: yet i confess, that ever since i did divers years ago shew some of them to a learned company of _virtuosi_: so many persons of differing conditions, and ev'n sexes, have been curious to see them, and pleas'd not to dislike them, that i cannot despair, but that by complying with those that urge the publication of them, i may both gratifie and excite the curious, and lay perhaps a foundation whereon either others or my self may in time superstruct a substantial theory of colours. and if _aristotle_, after his master _plato_, have rightly observ'd admiration to be the _parent of philosophy_, the wonder, some of these trifles have been wont to produce in all sorts of beholders, and the access they have sometimes gain'd ev'n to the closets of ladies, seem to promise, that since the subject is so pleasing, that the speculation appears as delightful! as difficult, such easie and recreative experiments, which require but little time, or charge, or trouble in the making, and when made are sensible and surprizing enough, may contribute more than others, (far more important but as much more difficult) to recommend those parts of learning (chymistry and corpuscular philosophy) by which they have been produc'd, and to which they give testimony ev'n to such kind of persons, as value a pretty trick more than a true notion, and would scarce admit philosophy, if it approach'd them in another dress: without the strangeness or endearments of pleasantness to recommend it. i know that i do but ill consult my own advantage in the consenting to the publication of the following treatise: for those things, which, whilst men knew not how they were perform'd, appear'd so strange, will, when the way of making them, and the grounds on which i devis'd them, shall be publick, quickly lose all that their being _rarityes_, and their _being thought mysteries_, contributed to recommend them. but 'tis fitter for mountebancks than naturalis to desire to have their discoverys rather admir'd than understood, and for my part i had much rather deserve the thanks of the ingenious, than enjoy the applause of the ignorant. and if i can so farr contribute to the discovery of the nature of colours, as to help the curious to it, i shall have reach'd my end, and sav'd my self some labour which else i may chance be tempted to undergo in prosecuting that subect, and adding to this treatise, which i therefore call a _history_, because it chiefly contains matters of fact, and which history the title declares me to look upon but as _begun_: because though that above a hundred, not to say a hundred and fifty experiments, (some loose, and others interwoven amongst the discourses themselves) may suffice to give a _beginning_ to a history not hitherto, that i know, begun, by any; yet the subject is so fruitfull, and so worthy, that those that are curious of these matters will be farr more wanting to themselves than i can suspect, if what i now publish prove any more than a _beginning_. for, as i hope my endeavours may afford them some assistance towards this work, so those endeavours are much too vnfinish'd to give them any discouragement, as if there were little left for others to do towards the history of colours. for (first) i have been willing to leave unmention'd the _most part_ of those phænomena of colours, that nature presents us of her own accord, (that is, without being guided or over-ruld by man) such as the different colours that several sorts of fruites pass through before they are perfectly ripe, and those that appear upon the fading of flowers and leaves, and the putrifaction (and its several degrees) of fruits, &c. together with a thousand other obvious instances of the changes of colours. nor have i _much_ medled with those familiar phænomena wherein man is not an idle spectator; such as the greenness produc'd by salt in beef much powder'd, and the redness produc'd in the shells of lobsters upon the boyling of those fishes; for i was willing to leave the _gathering_ of _observations_ to those that have not the opportunity to _make experiments_. and for the same reasons, among others, i did purposly omit the lucriferous practise of trades-men about colours; as the ways of making pigments, of bleanching wax, of dying scarlet, &c. though to divers of them i be not a stranger, and of some i have myself made tryall. next; i did purposely pass by divers experiments of other writers that i had made tryall of (and that not without registring some of their events) unless i could some way or other improve them, because i wanted leasure to insert them, and had thoughts of prosecuting the work once begun of laying together those i had examin'd by themselves in case of my not being prevented by others diligence. so that there remains not a little, among the things that are already published, to imploy those that have a mind to exercise themselves in repeating and examining them. and i will not undertake, that _none_ of the things deliver'd, ev'n in this treatise, though never so faithfully set down, may not prove to be thus farr of this sort, as to afford the curious somewhat to add about them. for i remember that i have somewhere in the book it self acknowledged, that having written it by snatches, partly in the counntrey, and partly at unseasonable times of the year, when the want of fit instruments, and of a competent variety of flowers, salts, pigments, and other materials made me leave some of the following experiments, (especialy those about emphatical colours) far more unfinish'd than they should have been, if it had been as easie for me to _supply_ what was wanting to compleat them, as to _discern_. thirdly to avoyd discouraging the young gentleman i call pyrophilus, whom the less familiar, and more laborious operations of chymistry would probably have frighted, i purposely declin'd in what i writ to him, the setting down any number of such chymicall experiments, as, by being very elaborate or tedious, would either require much skill, or exercise his patience. and yet that this sort of experiments is exceedingly numerous, and might more than a little inrich the history of colours, those that are vers'd in chymical processes, will, i presume, easily allow me. and (lastly) for as much as i have occasion more than once in my several writings to treat either porposely or incidentally of matters relating to colours; i did not, perhaps, conceive my self oblig'd, to deliver in one treatise _all_ that i would say concerning that subject. but to conclude, by summing up what i would say concerning what i _have_ and what i _have not_ done, in the following papers; i shall not (_on the one side_) deny, that considering that i pretended not to write an accurate treatise of colours, but an occasional essay to acquaint a private friend with what then occurrd to me of the things i had thought or try'd concerning them; i might presume i did enough for once, if i did clearly and faithfully set down, though not _all_ the experiments i could, yet at least such a variety of them, that an attentive reader that shall consider the grounds on which they have been made, and the hints that are purposely (though dispersedly) couched in them, may easily _compound_ them, and otherwise _vary_ them, so as very much to increase their number. and yet (_on the other side_) i am so sensible both of how much i have, either out of necessity or choice, left undone, and of the fruitfullness of the subject i have begun to handle; that though i had performed far more then 'tis like many readers will judge i have, i should yet be very free to let them apply to my attempts that of _seneca_, where having spoken of the study of natures mysteries, and particularly of the cause of earth-quakes, he subjoins.[1] _nulla res consummata est dum incipit. nec in hac tantum re omnium maxima ac involutissimá, in quâ etiam cum multum actum erit, omnis ætas, quod agat inveniet; sed in omni alio negotio, longè semper à perfecto fuere principia._ [1] l. annæ senecæ natur. quest. l. 6. c. 5. * * * * * _the publisher to the_ reader. _friendly reader,_ here is presented to thy view one of the abstrusest as well as the gentilest subjects of natural philosophy, the _experimentall history of colours_; which though the noble author be pleased to think but _begun_, yet i must take leave to say, that i think it so well begun, that the work is more than half dispatcht. concerning which i cannot but give this advertisement to the reader, that i have heard the author express himself, that it would not surprise him, if it should happen to be objected, that some of these experiments have been already published, partly by chymists, and partly by two or three very fresh writers upon other subjects. and though the number of these experiments be but very small, and though they be none of the considerablest, yet it may on this occasion be further represented, that it is easie for our author to name several men, (of whose number i can truly name my self) who remember either their having seen him make, or their having read, his accounts of the experiments delivered in the following tract several years since, and long before the publication of the books, wherein they are mentioned. nay in divers passages (where he could do it without any great inconvenience) he hath struck out experiments, which he had tryed many years ago, because he since found them divulged by persons from whom he had not the least hint of them; which yet is not touched, with design to reflect upon any ingenious man, as if he were a plagiary: for, though our generous author were not reserved enough in showing his experiments to those that expressed a curiosity to see them (amongst whom a very learned man hath been pleased publickly to acknowledge it several years ago[2]; yet the same thing may be well enough lighted on by persons that know nothing of one another. and especially chymical laboratories may many times afford the same _phænomenon_ about colours to several persons at the same or differing times. and as for the few _phænomena_ mentioned in the same chymical writers, as well as in the following treatise, our author hath given an account, why he did not decline rejecting them, in the anotations upon the 47th experiment of the third part. not here to mention, what he elsewhere saith, to shew what use may be justifiably made of experiments not of his own devising by a writer of natural history, if, what he employes of others mens, be well examined or verified by himself. [2] he that desires more instances of this kind and matter, that according to this doctrine may much help the theory of colours, and particularly the force both of sulphureous and volatile, is likewise of alcalizate and acid salts, and in what particulars, colours likely depend not in the causation from any salt at all, may beg his information from m. boyle who hath some while since honoured me with the sight of his papers concerning this subject, containing many excellent experiments, made by him for the elucidation of this doctrine, &c dr. r. sharrock in his ingenious and usefull history of the propagation and improvement of vegetables, published in the yeare 1660. in the mean time, this treatise is such, that there needs no other invitation to peruse it, but that tis composed by one of the deepest & most indefatigable searchers of nature, which, i think the world, as far as i know it, affords. for mine own part, i feel a secret joy within me, to see such beginings upon such _themes_, it being demonstratively true, _mota facilius moveri_, which causeth me to entertain strong hopes, that this illustrious _virtuoso_ and restless inquirer into nature's secrets will not stop here, but go on and prosper in the disquisition or the other principal colours, _green, red_, and _yellow_. the reasoning faculty set once afloat, will be carried on, and that with ease, especially, when the productions thereof meet, as they do here, with so greedy an entertainment at home and abroad. i am confident, that the royal society, lately constituted by his most excellent majesty _for improving natural knowledge_, will judge it their interest to exhort our author to the prosecution of this argument, considering, how much it is their design and business to accumulate a good stock of such accurate observations and experiments, as may afford them and their offpring genuine matter to raise a masculine philosophy upon, whereby the mind of man may be enobled with the knowledge of solid truths, and the life of man benefited with ampler accommodations, than it hath been hitherto. our great author, one of the pillars of that illustrious corporation, is constantly furnishing large _symbola_'s to this work, and is now falln, as you see, upon so comprehensive and important a theme, as will, if insisted on and compleated, prove one of the considerablest peeces of that structure. to which, if he shall please to add his treatise of _heat_ and _flame_, as he is ready to publish his experimental accounts of _cold_, i esteem, the world will be obliged to him for having shewed them both the _right_ and _left hand_ of nature, and the operations thereof. the considering reader will by this very treatise see abundant cause to sollicit the author for more; sure i am, that of whatever of the productions of his ingeny comes into _forein parts_ (where i am happy in the acquaintance of many intelligent friends) is highly valued; and to my knowledge, there are those among the french, that have lately begun to learn english, on purpose to enable themselves to read his books, being impatient of their traduction into latin. if i durst say all, i know of the elogies received by me from abroad concerning him, i should perhaps make this preamble too prolix, and certainly offend the modesty of our author. wherefore i shall leave this, and conclude with desiring the reader, that if he meet with other faults besides those, that the errata take notice of (as i believe he may) he will please to consider both the weakness of the authors eyes, for not reviewing, and the manifold avocations of the publisher for not doing his part; who taketh his leave with inviting those, that have also considered this nice subject experimentally, to follow the example of our noble author, and impart such and the like performances to the now very inquisitive world. _farewell._ _h. o._ * * * * * the contents. * * * * * chap. i. _the author shews the reason, first of his writing on this subject_ (1.) _next of his present manner of handling it, and why he partly declines a methodical way_ (2.) _and why he has partly made use of it in the history of_ whiteness _and_ blackness. (3.) chap. 2. _some general considerations are premis'd, first of the insignificancy of the observasion of colours in many bodies_ (4, 5.) _and the importance of it in others_ (5.) _as particularly in the tempering of steel_ (6, 7, 8.) _the reason why other particular instances are in that place omitted_ (9) _a necessary distinction about colour premis'd_ (10, 11.) _that colour is not inherent in the object_ (11.) _prov'd first by the phantasms of colours to_ dreaming _men, and_ lunaticks; _secondly by the sensation or apparition of light upon a blow given the eye or the distemper of the brain from internal vapours_ (12.) _the author recites a particular instance in himself; another that hapn'd to an excellent person related to him_ (13.) _and a third told him by an ingenious physician_ (14, 15.) _thirdly, from the change of colours made by the sensory disaffected_ (15, 16.) _some instances of this are related by the author, observ'd in himself_ (16, 17.) _others told him by a lady of known veracity_ (18.) _and others told him by a very eminent man_ (19.) _but the strange instances afforded by such as are bit by the_ tarantula _are omitted, as more properly deliver'd in another place_. (20.) chap. 3. _that the colour of bodies depends chiefly on the disposition of the superficial parts, and partly upon the variety of the texture of the object_ (21.) _the former of these are confirm'd by several persons_ (22.) _and two instances, the first of the steel mention'd before, the second of melted lead_ (23, 24.) _of which last several observables are noted_ (25.) _a third instance is added of the porousness of the appearing smooth surface of cork_ (26, 27.) _and that the same kind of porousness may be also in the other colour'd bodies; and of what kind of figures, the superficial reflecting particles of them may be_ (28.) _and of what bulks, and closeness of position_ (29.) _how much these may conduce to the generation of colour instanc'd in the whiteness of froth, and in the mixtures of dry colour'd powders_ (30.) _a further explication of the variety that may be in the superficial parts of colour'd bodies, that may cause that effect, by an example drawn from the surface of the earth_ (31.) _an apology for that gross comparison_ (32.) _that the appearances of the superficial asperities may be varied from the position of the eye, and several instances given of such appearances_ (33, 34, 35.) _that the appearance of the superficial particles may be varied also by their motion, confirm'd by an instance of the smoaking liquor_ (35.) _especially if the superficial parts be of such a nature as to appear divers in several postures, explain'd by the variety of colours exhibited by the shaken leaves of some plants_ (36.) _and by changeable taffities_ (37, 38, 39.) _the authors wish that the variety of colours in mother of pearl were examin'd with a_ microscope (40.) _and his conjectures, that possibly good_ microscopes _might discover those superficial inequalities to be real, which we now only imagine with his reasons drawn partly from the discoveries of the_ telescope, _and_ microscope (41.) _and partly also from the prodigiously strange example of a blind man that could feel colours_ (42.) _whose history is related_ (43, 44, 45.) _the authors conjecture and thoughts of it_ (46, 47, 48, 49.) _and several conclusions and corollaries drawn from it about the nature of blackness and black bodies_ (50, 51, 52.) _and about the asperities of several other colour'd bodies_ (53.) _and from these, and some premis'd considerations, are propos'd some conjectures; that the reason of the several phænomena of colours, afterwards to be met with, depends upon the disposition of the seen parts of the object_ (54.) _that liquors may alter the colours of each other, and of other bodies, first by their insinuating themselves into the pores, and filling them, whence the asperity of the surface of a body becomes alter'd, explicated with some instances_ (55, 56.) _next by removing those bodies, which before hindred the appearance of the genuine colour, confirm'd by several examples_ (57) _thirdly, by making a fissure or separation either in the contiguous or continued particles of a body_ (58.) _fourthly, by a union or conjunction of the formerly separated particles; illustrated with divers instances of precipitated bodies_ (59.) _fifthly, by dislocating the parts, and putting them both into other orders and postures, which is illustrated with instances_ (60, 61.) _sixthly, by motion, which is explain'd_ (62.) _and lastly, and chiefly, by the union of the saline bodies, with the superficial parts of another body, whereby both their bigness and shape must necessarily be alter'd_ (63, 64.) _explain'd by experiments_ (65, 66.) _that the colour of bodies may be chang'd by the concurrence of two or more of these ways_ (67.) _and besides all these, eight reflective causes of colours, there may be in transparent bodies several refractive_ (68, 69) _why the author thinks the nature of colours deserves yet a further inquiry_ (69.) _first for that the little motes of dust exhibited very lovely colours in a darkned room, whilst in a convenient posture to the eye, which in other postures and lights they did not_ (70.) _and that though the smaller parts of some colour'd bodies are transparent, yet of others they are not, so that the first doubt's, whether the superficial parts create those colours, and the second, whether there be any refraction at all in the later_ (71, 72, 73.) _a famous controversie among philosophers, about the nature of colour decided_. (74. 75.) chap. 4. _the controversie stated about real and emphatical colours_ (75, 76.) _that the great disparity between them seems to be, partly their duration in the same state, and partly, that genuine colours are produc'd in opacous bodies by reflection, and emphatical in transparent by refraction_ (78.) _but that this is not to be taken in too large a sense, the cautionary instance of froth is alleged and insisted on_ (78, 79.) _that the duration is not a sufficient characteristick, exemplify'd by the duration of froth, and other emphatical colours, and the suddain fading of flowers, and other bodies of real ones_ (80.) _that the position of the eye is not necessary to the discerning emphatical colours, shew'd by the seeing white froth, or an iris cast on the wall by a prism, in what place of the room soever the eye be_ (81.) _which proceeds from the specular reflection of the wall_ (82.) _that emphatical colours may be compounded, and that the present discourse is not much concern'd, whether there be, or be not made a distinction between real and emphatical colours_. (83.) chap. 5. _six hypotheses about colour recited_ (84, 85) _why the author cannot more fully speak of any of these_ (86.) _nor acquiesce in them_ (87, 88.) _what_ pyrophilus _is to expect in this treatise_ (88, 89.) _what hypothesis of light and colour the author most inclines too_ (90.) _why he thinks neither that nor any other sufficient; and what his difficulties are, that make him decline all hypotheses, and to think it very difficult to stick to any._ (91, 92.) * * * * * part the second. _of the nature of whiteness and blackness,_ chap. i. _the reason why the author chose the explication of whiteness and blackness_ (93.) _wherein_ democritus _thought amiss of these_ (94.) gassendus _his opinion about them_ (95.) _what the author approves, and a more full explication of white, makinig it a multiplicity of light or reflections_ (96, 97.) _confirm'd first by the whiteness of the_ meridian _sun, observ'd in water_ (98.) _and of a piece of iron glowing hot_ (99.) _secondly, by the offensiveness of snow to the travellers eyes, confirm'd by an example of a person that has travell'd much in russia_ (100.) _and by an observation out of_ olaus magnus (100.) _and that the snow does inlighten and clear the air in the night, confirm'd by the mosco physician, and captain_ james (101.) _but that snow has no inherent light, prov'd by experience_ (102.) _thirdly, by the great store of reflections, from white bodies observ'd in a darkned room, and by their unaptness to be kindled by a burning-glass_ (103.) _fourthly, the specularness of white bodies is confirm'd by the reflections in a dark room from other bodies_ (104.) _and by the appearance of a river, which both to the eye and in a darkned room appear'd white_ (105, 106.) _fifthly, by the whiteness of distill'd_ mercury, _and that of the_ galaxie (107, 108.) _and by the whiteness of froth, rais'd from whites of eggs beaten; that this whiteness comes not from the air, shew'd by experiments_ (109, 110.) _where occasionally the whiteness of distill'd oyls, hot water, &c. are shew'd_ (111.) _that it seems not necessary the reflecting surfaces should be sphærical, confirm'd by experiments_ (112, 113.) _sixthly, by the whiteness of the powders of transparent bodies_ (114.) _seventhly, by the experiment of whitening and burnishing silver._ (115, 116.) chap. 2. _a recital of some opinions about blackness, and which the author inclines to_ (117.) _which he further insists on and explicates_ (118, 119.) _and shews for what reasons he imbrac'd that hypothesis_ (120.) _first, from the contrary nature of whiteness and blackness, white reflecting most beams outwards, black should reflect most inward_ (120.) _next, from the black appearance of all bodies, when shadow'd; and the manner how this paucity of reflection outwards is caus'd, is further explicated, by shewing that the superficial parts may be conical and pyramical_ (121.) _this and other considerations formerly deliver'd, illustrated by experiments with black and white marble_ (122, 123.) _thirdly, from the black appearance of holes in white linnen, and from the appearance of velvet stroak'd several ways, and from an observation of carrots_ (124, 125.) _fourthly, from the small reflection from black in a darkned room_ (125, 126.) _fifthly, from the experiment of a checker'd tile expos'd to the sun-beams_ (127.) _which is to be preferr'd before a similar experiment try'd in_ italy, _with black and white marble_ (128.) _some other congruous observations_ (129.) _sixthly, from the roasting black'd eggs in the sun_ (130.) _seventhly, by the observation of the blind man lately mention'd, and of another mention'd by_ bartholine (130.) _that notwithstanding all these reasons, the author is not absolutely positive, but remains yet a seeker after the true nature of whiteness and blackness._ (131, 132.) experiments _in consort, touching_ whiteness _and_ blackness. _the first_ experiment, _with a solution of sublimate, made white with spirit of urine_, &c. (133, 134.) _the second_ experiment, _with an infusion of galls, made black with vitriol_, &c. (135, 136.) _further discours'd of_ (137.) _the third_ experiment, _of the blacking of hartshorn, and ivory, and tartar, and by a further calcination making them white_ (138, 139.) _the fourth_ experiment, _limiting the_ chymist's _principle_, adusta nigra sed perusta alba, _by several instances of calcin'd alabaster, lead, antimony, vitriol, and by the testimony of_ bellonius, _about the white charcoles of_ oxy-cædar, _and by that of_ camphire. (140, 141, 142.) _that which follows about inks was misplac'd by an errour of the printer, for it belongs to what has been formerly said of galls_ (142, 143.) _the fifth_ experiment, _of the black smoak of camphire_ (144.) _the sixth_ experiment, _of a black_ caput mortuum, _of oyl of vitriol, with oyl of worm-word, and also with oyl of winter-savory_ (145.) _the seventh_ experiment, _of whitening wax_ (146.) _the eighth_ experiment, _with tin-glass, and sublimate_ (147, 148.) _the ninth_ experiment, _of a black powder of gold in the bottom of_ aqua-fortis, _and of the blacking of refin'd gold and silver_ (148, 149.) _the tenth_ experiment, _of the staining hair, skin, ivory_, &c. _black, with crystals of silver_ (150, 151.) _the eleventh_ experiment, _about the blackness of the skin, and hair of_ negroes, _and inhabitants of hot climates. several objections are made, and the whole matter more fully discours'd and stated from several notable histories and observations_ (from the 151 to the 167.) _the twelfth_ experiment, _of the white powders, afforded by precipitating several bodies, as crabs eyes, minium, coral, silver, lead, tin, quick-silver, tin-glass, antimony, benzoin, and resinous gumms out of spirit of wine_, &c. _but this is not universal, since other bodies, as gold, antimony, quick-silver_, &c. _may be precipitated of other colours_ (168, 169, 170.) _the thirteenth_ experiment, _of changing the blackness of some bodies into other colours_ (171, 172.) _and of whitening what would be minium, and copper, with tin, and of copper with arsnick, which with coppilling again vanishes; of covering the colour of that of_ 1/3 _of gold with_ 2/3 _of silver melted in a mass together_ (173, 174) _the fourteenth_ experiment, _of turning the black body of horn into a white immediately with scraping, without changing the substantial form, or without the intervention of salt, sulphur, or mercury_ (176.) _the fifteenth_ experiment, _contains several instances against the opinion of the_ chymists _that sulphur_ adust _is the cause of blackness, and the whole matter is fully discuss'd and stated_ (from 176 to 184) part the third. _concerning promiscuous experiments about colours_. experiment the first. _in confirmation of a former conjecture about the generation of colours from diversity of reflections are set down several observations made in a darkned room_ (186, 187.) experiment _the second, that white linnen seem'd ting'd with the red of silk plac'd near it in a light room_ (188,189.) experiment _the third, of the trajection of light through colour'd papers_ (189, 190.) experiment _the fourth, observations of a prism in a dark room_ (191, 192.) experiment _the fifth, of the refracting and reflecting prismatical colours in a light room_ (193.) experiment _the sixth, on the vanishing of the_ iris _of the prism, upon the access of a greater adventitious light_ (194.) experiment _the seventh, of the appearances of the same colour'd papers by candle-light_ (195, 196). experiment _the eighth, of the yellowness of the flame of a candle_ (197). experiment _the ninth, of the greenish blew transparency of leaf gold_ (198). experiment _the tenth, of the curious tinctures afforded by_ lignum nephriticum (from 199 to 203). _several trials for the investigation of the nature of it_ (from 204 to 206.) kircher's _relation of this wood set down, and examin'd_ (from 206 to 212). _a corollary on this tenth_ experiment, _shewing how it may be applicable for the discovering, whether any salt be of an acid, or a sulphureous, and alcalizate nature_ (from 213 to 216). _the eleventh_ experiment, _of certain pieces of glass that afforded this variety of colours; and of the way of so tinging any plate of glass with silver_ (from 216 to 219). _the twelfth_ experiment, _of the mixing and tempering of painters pigments_ (219, 220, 221). _the thirteenth_ experiment, _of compounding several colours by trajecting the sun-beams through ting'd glasses_ (from 221 to 224). _the fourteenth_ experiment, _of the compounding of real and phantastical colours, and the results_ (224, 225, 226.) _as also the same of phantastical colours_ (226, 227.) _the fifteenth_ experiment, _of varying the trajected_ iris _by a colour'd prism_ (228, 229.) _the sixteenth_ experiment, _of the red fumes of spirit of_ nitre, _and, the resembling redness of the horizontal sun-beams_ (230, 231.) _the seventeenth_ experiment, _of making a green by nine kinds of compositions_ (from 231 to 236.) _and some deductions from them against the necessity of recurring to substantial forms and hypostatical principles for the production of colours_ (from 237 to 240.) _the eighteenth_ experiment, _of several compositions of blew and yellow which produce not a green, and of the production of a green by other colours_ (241, 242.) _the nineteenth_ experiment, _contains several instances of producing colours, without the alteration of any hypostatical principle, by the prism, bubbles, and feathers_ ( from 242 to 245.) _the twentieth_ experiment _of turning the blew of violets into a red by acid salts, and to a green by alcalizate (245, 246.) and the use of it for investigating the nature of salts_ (247, 248.) _the one and twentieth_ experiment, _of the same changes effected by the same means on the blew tinctures of corn-flowers_ (249, 250.) _and some restrictions to shew it not to be so general a propriety as one might imagine_ (251.) _the twenty second_ experiment, _of turning a solution of verdigrease into a blew, with alcalizate and urinous salts_ (252, 253, 254.) _the twenty third_ experiment, _of taking away the colour of roses with the steams of sulphur, and heightning them with the steams condens'd into oyl of sulphur_ per campanam (254, 255.) _the twenty fourth_ experiment, _of tinging a great quantity of liquor with a very little ting'd substance, instanced in_ cochineel (from 255 to 257.) _the twenty fifth_ experiment, _of the more general use of alcalizate and sulphureous salts in the tinctures of vegetables, further instanced in the tincture of privet berries, and of the flowers of mesereon and pease_ (from 257 to 259.) _an_ annotation, _shewing that of the three hypostatical principles, salt according to_ paracelsus _is the most active about colours_ (from 259 to 261.) _some things precursory premis'd to three several instances next following, against the fore-mention'd operations of salts_ (261, 262.) _the twenty sixth_ experiment, _containing trials with acid and sulphureous salts on the red tinctures of clove-july-flowers, buckthorn berries, red-roses, brasil_, &c. (262, 263.) _the twenty seventh_ experiment, _of the changes of the colour of jasmin flowers, and snow drops, by alcalizate and sulphureous salts_ (263, 264.) _the twenty eighth_ experiment, _of other differing effects on mary-golds, prim-roses, and fresh madder_ (265.) _with an admonition, that these salts may have differing effects in the changing of the tinctures of divers other vegetables_ (266, 267.) _the twenty ninth_ experiment, _of the differing effects of these salts on ripe and unripe juices, instanced in black-berries, and the juices of roses_ (from 267 to 270.) _two reasons, why the author added this twenty ninth_ experiment, _the last of which is confirm'd by an instance of mr._ parkinson, _consonant to the confession of the makers of such colours_ (272.) _the thirtieth_ experiment, _of several changes in colours by digestion, exemplify'd by an_ amalgam _of_ gold _and_ mercury _and by spirit of harts-horn. and (to such as believe it) by the changes of the_ elixir. _the thirty first_ experiment, _shewing that most tinctures drawn by digestion incline to a red, instanc'd in_ jalap, guaicum, _amber, benzoin, sulphur, antimony_, &c. (276, 277.) _the thirty second_ experiment, _that some reds with diluting turn yellow, others not, exemplify'd by the tincture of_ cochineel, _and by balsam of_ sulphur, _tinctures of_ amber, &c. (277, 278, 279.) _the thirty third_ experiment, _of a red tincture of_ saccarum saturni _and oyl of_ turpentine _made by digestion_ (279.) _the thirty fourth_ experiment, _of drawing a volatile red tincture of mercury_, _whose steams were white, but it would tinge the skin black_ (279, 280.) _the thirty fifth_ experiment, _of a suddain way of making a blood red colour with oyl of_ vitriol, _and oyl of_ anniseeds, _two transparent liquors_ (280, 281.) _the thirty sixth_ experiment, _of the degenerating of several colours exemplify'd in the last mention'd blood red, and by mr._ parkinsons _relation of_ turnsol, _by some trials with the juice of buck-thorn berries, and other vegetables, to which several notable considerations and advertisements back'd with_ experiments _are adjoyn'd_ (from 281 to 288.) _the thirty seventh_ experiment, _of varying the colour of the tinctures of_ cochineel, _red-cherries, and brasil, with acid and sulphureous salts, and divers considerations thereon_ (from 288 to 290.) _the thirty eighth_ experiment, _about the red fumes of some, and white of other distill'd bodies, and of their coalition for the most part into a transparent liquor_ (290, 291.) _and of the various colours of dry sublimations, exemplify'd with several_ experiments (292, 293, 294.) _the thirty ninth_ experiment, _of varying the decoction of_ balaustiums _with acid and urinous salts_ (294, 295.) _some_ annotations _wherein two_ experiments _of_ gassendus _are related, examined, and improv'd_ (from 295 to 302.) _the fortieth_ experiment, _of the no less strange than pleasant changes made with a solution of sublimate_ (from 301 to 306.) _the difference between a chymical axd philosophical solution of a_ phænomenon (307, 308.) _the authors chymical explication of the_ phænomena, _confirm d by several_ experiments _made on_ mercury, _with several saline liquors_ (from 308 to 310.) _an improvement of the fortieth_ experiment, _by a fresh decoction of_ antimony _in a_ lixivium (311, 312, 313.) _reflections on the tenth, twentieth, and fortieth_ experiments, _compar'd together, shewing a way with this tincture of sublimate to distinguish whether any saline body to be examin'd be of a urinous or alcalizate nature_ (from 314 to 317.) _the examination of spirit of_ sal-armoniack, _and spirit of_ oak _by these principles_ (from 316 to 319.) _that the author knows ways of making highly operative saline bodies, that produce none of the before mention'd effects_ (319, 320.) _some notable_ experiments _about solutions and precipitations of gold and silver_ (320, 321.) _the one and fortieth_ experiment, _of depriving a deep blew solution of copper of its colour_ (322.) _to which is adjoyn'd the discolouring or making transparent a solution of verdigrease, &c. and another of restoring or increasing it_ (322, 323.) _the forty second_ experiment, _of changing a milk white precipitate of_ mercury _into a yellow, by affusion of fair water, with several considerations thereon_ (from 323 to 326.) _the forty third_ experiment, _of extracting a green solution with fair water out of imperfectly calcin'd vitriol_ (327.) _the forty fourth_ experiment, _of the deepning and diluting of several tinctures, by the affusions of liquors, and by conical glasses that contain'd them, exemplify'd in the tinctures of_ cochineel, brasil, verdigrease, glass, litmus, _of which last on this occasion several pleasant_ phænomena _are related_ (from 328 to 335.) _to which are adjoyn'd certain cautional corollaries_ (335, 336.) _the waterdrinker and some of his legerdemain tricks related._(337.) _the forty fifth_ experiment, _of the turning rhenish and white wine into a lovely green, with a preparation of steel _(338, 339.) _some further trial made about these tinctures, and a similar_ experiment _of_ olaus wormius (340.) _the forty sixth_ experiment, _of the internal colour of metalls exhibited by calcination_ (341, 342, 343.) annotation _the first, that several degrees of fire may disclose a differing colour_ (343.) annotation _the second, that the glasses of metalls may exhibit also other kinds of colours_ (344.) annotation _the third, that minerals by several degrees of fire may disclose several colours_(345). experiment _the forty seventh, of the internal colours of metalls disclos'd by their dissolutions in several_ menstruums (from 345 to 350.) annotation _the first, the authors apology for recording some already known_ experiments, _without mentioning their authors_ (from 350 to 352.) annotation _the second, that some minerals also by dissolutions in_ menstruums _may exhibit divers colours_. annotation _the third, that metalls disclose other colours by precipitations, instanc'd in_ mercury (from 353 to 355.) _the forty eighth_ experiment, _of tinging glass blew with leaf silver, and with calcin'd copper, and white with putty_ (from 355 to 358.) annotation _the first, that this white glass is the basis of ammels_ (358.) annotion _the second, that colour'd glasses may be compounded like colour'd liquors in dying fats_ (359.) annotation _the third, of tinging glass with minerel substances, and of trying what metalls they contain by this means_ (from 360 to 362.) annotation _the fourth, that metalls may be ting'd by mineralls_ (362, 363.) annotation _the fifth, of making several kinds of amauses or counterfeit stones_ (from 363 to 365.) annotation _the sixth, of the scarlet dye, of the stains of dissolv'd gold and silver_ (366, 367) _of the greenness of salt beef, and redness of neats tongues from salts; of gilding silver with bathe water_ (368, 369.) _and tinging the nails and skin with_ alcanna (369) _the forty ninth_ experiment, _of making lakes_ (369.) _a particular example in turmerick_ (370, 371.) annotation _the first, that in precipitations wherein allum is a coefficient, a great part of them may consist of the stony particles of that compound body_ (from 372 to 375.) annotation _the second, that lakes may be made of other substances, as madder, rue,_ &c. _but that alcalizate salts do not always extract the same colour of which the vegetable appears_ (from 376 to 378.) annotation _the third, that the_ experiments _related may hint divers others_ (378) annotation _the fourth, that alum is usefull for the preparing other than vegetable pigments_ (379.) _the fiftieth_ experiment, _of the similar effects of_ saccarum saturni _and_ alkalies, _of precipitating with oyl of_ vitriol _out of_ aqua-fortis, _and spirit of_ vinegar; _and of divers varyings of the colours, with these compounded_ (from 380 to 384.) _another very pretty_ experiment, _with a solution of_ minium (384, 385.) _that these_ experiments _skilfully digested may hint divers matters about colours_ (386.) _the authors apologetick conclusion, in which is cursorily hinted the bow or scarlet dye_ (387.) _the authors letter to sir_ robert moray, _concerning his observations on the shining diamond_ (391. &c.) _and the observations themselves_. * * * * * errata. pag. 142. l. 20. these words, _and to manifest_, with the rest of what is by a mistake further printed in this fourth experiment, belongeth, and is to be referred to the end of the second eperiment, p.137. pag. 145. l. 1. leg. _matter_. 146. l. 4. leg. _bolts-head_. pag 161. in the marginal note l. 2. dele _de_ ib. l. 3. lege lib 1. p 163. l. ult. insert _where_ between the words _places_ and _the_. p. 164 l. 1. dele _that_. ibid, l. 8. leg _epidermis_. ibid. l. 19 leg. 300. for 200. p. 169. l. 22. leg. _into it_. p. 170. l. 23. & 24. leg. _some solutions hereafter to be mentioned_, for _the solutions of potashes_, and other _lixiviate salts_. p. 171. l. 6. insert _part of_ between the words _most_ and _dissolved_ p. 176. l. ult. insert the participle _it_ between the words _judged_ and _not_ p. 234. l. 4. leg. _woud-wax_ or _wood-wax_. p. 320 l. 29. leg. _urine_ for _urne_. * * * * * _the_ _experimental history_ _of colours begun._ the first part. chap. i. 1 i have seen you so passionately addicted, _pyrophilus_ to the delightful art of limning and painting, that i cannot but think my self obliged to acquaint you with some of those things that have occurred to mee concerning the changes of colours. and i may expect that i shall as well serve the _virtuosi_ in general, as gratifie you in particular, by furnishing a person, who, i hope, will both improve my communications, and communicate his improvements, with such experiments and observations as may both invite you to enquire seriously into the nature of colours, and assist you in the investigation of it. this being the principal scope of the following tract, i should do that which might prevent my own design, if i should here attempt to deliver you an accurate and particular theory of colours; for that were to present you with what i desire to receive from you; and, as farr as in mee lay, to make that study needless, to which i would engage you. 2 wherefore my present work shall be but to divert and recreate, as well as excite you by the delivery of matters of fact, such as you may for the most part try with much _ease_, and possibly not without some _delight_: and lest you should expect any thing of elaborate or methodical in what you will meet with here, i must confess to you before-hand, that the seasons i was wont to chuse to devise and try experiments about colours, were those daies, wherein having taken physick, and finding my self as unfit to speculate, as unwilling to be altogether idle, i chose this diversion, as a kind of mean betwixt the one and the other. and i have the less scrupled to set down the following experiments, as some of them came to my mind, and as the notes wherein i had set down the rest, occurr'd to my hands, that by declining a methodical way of delivering them, i might leave you and my self the greater liberty and convenience to add to them, and transpose them as shall appear expedient. 3 yea, that you may not think mee too reserv'd, or look upon an enquiry made up of meer narratives, as somewhat jejune, am content to _premise_ a few considerations, that now offer themselves to my thoughts, which relate in a more general way, either to the nature of colours, or to the study of it. and i shall _insert_ an _essay_, as well speculative as historical, of the nature of whiteness and blackness, that you may have a _specimen_ of the history of colours, i have sometimes had thoughts of; and if you dislike not the method i have made use of, i hope, you, and some of the _virtuosi_, your friends, may be thereby invited to go thorow with _red, blew, yellow_, and the rest of the particular colours, as i have done with _white_ and _black_, but with farr more sagacity and success. and if i can invite ingenious men to undertake such tasks, i doubt not but the curious will quickly obtain a better account of colours, than as yet we have, since in our method the theorical part of the enquiry being attended, and as it were interwoven with the historical, whatever becomes of the disputable conjectures, the philosophy of colours will be promoted by the indisputable experiments. * * * * * chap. ii. 1 to come then in the first place to our more general considerations, i shall begin with saying something as to the importance of examining the colours of bodies. for there are some, especially _chymists_, who think, that a considerable diversity of colours does constantly argue an equal diversity of nature, in the bodies wherein it is conspicuous; but i confess i am not altogether of their mind; for not to mention changeable taffaties, the blew and golden necks of pidgeons, and divers water-fowl, rainbows natural and artificial, and other bodies, whose colours the philosophers have been pleased to call not real, but apparent and phantastical; not to insist on these, i say, (for fear of needlesly engaging in a controversie) we see in parrots, goldfinches, and divers other birds, not only that the contiguous feathers which are probably as near in properties as place, are some of them red, and others white, some of them blew, & others yellow, _&c._ but that in the several parts of the self-same feather there may often be seen the greatest disparity of colours; and so in the leaves of tulips, july-flowers, and some other vegetables the several leaves, and even the several parts of the same leaf, although no difference have been observed in their other properties, are frequently found painted with very different colours. and such a variety we have much more admired in that lovely plant which is commonly, and not unjustly call'd the _marvayl of peru_; for of divers scores of fine flowers, which in its season that gaudy plant does almost daily produce, i have scarce taken notice of any two that were dyed perfectly alike. but though _pyro_: such things as these, among others, keep mee from daring to affirm, that the diversity and change of colours does _alwaies_ argue any great difference or alteration, betwixt, or in, the bodies, wherein it is to be discerned, yet that _oftentimes_ the alteration of colours does signifie considerable alterations in the disposition of parts of bodies, may appear in the extraction of tinctures, and divers other chymical operations, wherein the change of colours is the chief, and sometimes the only thing, by which the artist regulates his proceeding, and is taught to know when 'tis seasonable for him to leave off. instances of this sort are more obvious in divers sorts of fruits, as cherries, plums, &c. wherein, according as the vegetable sap is sweetned, or otherwise ripened, by passing from one degree to another of maturation, the external part of the fruit passes likewise from one to another colour. but one of the noblest instances i have met with of this kind, is not so obvious; and that is the way of tempering steel to make gravers, drills, springs, and other mechanical instruments, which we have divers times both made artificers practise in our presence, and tryed our selves, after the following manner, first, the slender steel to be tempered is to be hardened by heating as much of it as is requisite among glowing coals, till it be glowing hot, but it must not be quenched assoon as it is taken from the fire (for that would make it too brittle, and spoil it) but must be held over a bason of water, till it descend from a white heat to a red one, which assoon as ever you perceive, you must immediately quench as much as you desire to harden in the cold water. the steel thus hardened, will, if it be good, look somewhat white and must be made bright at the end, that its change of colours may be there conspicuous; and then holding it so in the flame of a candle, that the bright end may be, for about half an inch, or more, out of the flame, that the smoak do not stain or sully the brightness of it, you shall after a while see that clean end, which is almost contiguous to the flame, pass very nimbly from one colour to another, as from a brighter yellow, to a deeper and reddish yellow, which artificers call a _sanguine_, and from that to a fainter first, and then a a deeper blew. and to bring home this experiment to our present purpose, it is found by daily experience, that each of these succeeding colours argue such a change made in the texture of the steel, that if it be taken from the flame, and immediately quenched in the tallow (whereby it is setled in whatever temper it had before) when it is yellow, it is of such a hardness as makes it fit for gravers drills, and such like tools; but if it be kept a few minutes longer in the flame till it grow blew, it becomes much softer, and unfit to make gravers for metalls, but fit to make springs for watches, and such like instruments, which are therefore commonly of that colour; and if the steel be kept in the flame, after that this deep blew hath disclosed it self, it will grow so soft, as to need to be new hardened again, before it can be brought to a temper, fit for drills or penknives. and i confess _pyro._ i have taken much pleasure to see the colours run along from the parts of the steel contiguous to the flame, to the end of the instrument, and succeed one another so fast, that if a man be not vigilant, to thrust the steel into the tallow at the very nick of time, at which it has attain'd its due colour, he shall miss of giving his tool the right temper. but because the flame of a candle is offensive to my weak eyes, and because it is apt to either black or sully the contiguous part of the steel which is held in it, and thereby hinder the change of colours from being so long and clearly discern'd, i have sometimes made this experiment by laying the steel to be tempered upon a heated bar of iron, which we finde also to be employ'd by some artificers in the tempering of such great instruments, as are too big to be soon heated sufficiently by the flame of a candle. and you may easily satisfie your self _pyro_: of the differing hardness and toughness, which is ascribed to steel temper'd at different colours, if you break but some slender wires of steel so temper'd, and observe how they differ in brittleness, and if with a file you also make tryal of their various degrees of hardness. 2 but _pyrophilus_, i must not at present any further prosecute the consideration of the importance of experiments about colours, not only because you will in the following papers finde some instances, that would here be presented you out of their due place, of the use that may be made of such experiments, in discovering in divers bodies, what kind the salt is, that is predominant in them; but also because a speculative naturalist might justly enough allege, that as light is so pleasing an object, as to be well worth our looking on, though it discover'd to us nothing but its self; so modifi'd light called colour, were worth our contemplation, though by understanding its nature we should be taught nothing else. and however, i need not make either you or my self excuses for entertaining you on the subject i am now about to treat of, since the pleasure _pyro_: takes in mixing and laying on of colours, will i presume keep him, and will (i am sure) keep mee from thinking it troublesome to set down, especially after the tedious processes (about other matters) wherewith i fear i may have tyr'd him, some easie, and not unpleasant experiments relating to that subject. 3 but, before we descend to the more particular considerations, we are to present you concerning colours, i presume it will be seasonable to propose at the very entrance a distinction; the ignorance or neglect of which, seems to mee to have frequently enough occasioned either mistakes or confusion in the writings of divers modern philosophers; for colour may be considered, either as it is a quality residing in the body that is said to be coloured, or to modifie the light after such or such a manner; or else as the light it self, which so modifi'd, strikes upon the organ of sight, and so causes that sensation which we call colour; and that this latter may be look'd upon as the more proper, though not the usual acception of the word colour, will be made probable by divers passages in the insuing part of our discourse; and indeed it is the light it self, which after a certain manner, either mingled with shades, or some other waies troubled, strikes our eyes, that does more immediately produce that motion in the organ, upon whose account men say they see such or such a colour in the object; yet, because there is in the body that is said to be coloured, a certain disposition of the superficial particles, whereby it sends the light reflected, or refracted, to our eyes thus and thus alter'd, and not otherwise, it may also in some sense be said, that colour depends upon the visible body; and therefore we shall not be against that way of speaking of colours that is most used among the modern naturalists, provided we be allowed to have recourse when occasion shall require to the premis'd distinction, and to take the more immediate cause of colour to be the modifi'd light it self, as it affects the sensory; though the disposition also of the colour'd body, as that modifies the light, may be call'd by that name metonimically (to borrow a school term) or efficiently, that is in regard of its turning the light, that rebounds from it, or passes thorow it, into this or that particular colour. 4 i know not whether i may not on this occasion add, that colour is so far from being an inherent quality of the object in the sense that is wont to be declar'd by the schools, or even in the sense of some modern atomists, that, if we consider the matter more attentively, we shall see cause to suspect, if not to conclude, that though light do more immediately affect the organ of sight, than do the bodies that send it thither, yet light it self produces the sensation of a colour, but as it produces such a determinate kind of local motion in some part of the brain; which, though it happen most commonly from the motion whereinto the slender strings of the _retina_ are put, by the appulse of light, yet if the like motion happen to be produc'd by any other cause, wherein the light concurrs not at all, a man shall think he sees the same colour. for proof of this, i might put you in mind, that 'tis usual for dreaming men to think they see the images that appear to them in their sleep, adorn'd some with this, and some with that lively colour, whilst yet, both the curtains of their bed, and those of their eyes are close drawn. and i might add the confidence with which distracted persons do oftentimes, when they are awake, think, they see black fiends in places, where there is no black object in sight without them. but i will rather observe, that not only when a man receives a great stroak upon his eye, or a very great one upon some other part of his head, he is wont to see, as it were, flashes of lightning, and little vivid, but vanishing flames, though perhaps his eyes be shut: but the like apparitions may happen, when the motion proceeds not from something without, but from something within the body, provided the unwonted fumes that wander up and down in the head, or the propagated concussion of any internal part in the body, do cause about the inward extremities of the optick nerve, such a motion as is wont to be there produc'd, when the stroak of the light upon the _retina_ makes us conclude, that we see either light, or such and such a colour: this the most ingenious _des cartes_ hath very well observ'd, but because he seems not to have exemplifi'd it by any unobvious or peculiar observation, i shall indeavour to illustrate this doctrine by a few instances. 5 and first, i remember, that having, through gods goodness, been free for several years, from troublesome coughs, being afterwards, by an accident, suddenly cast into a violent one, i did often, when i was awaked in the night by my distempers, observe, that upon coughing strongly, it would seem to mee, that i saw very vivid, but immediately disappearing flames, which i took particular notice of, because of the conjecture i am now mentioning. 6 an excellent and very discreet person, very near ally'd both to you and mee, was relating to mee, that some time since, whilst she was talking with some other ladies, upon a sudden, all the objects, she looked upon, appeared to her dyed with unusual colours, some of one kind, and some of another, but all so bright and vivid, that she should have been as much delighted, as surpriz'd with them, but that finding the apparition to continue, she fear'd it portended some very great alteration as to her health: as indeed the day after she was assaulted with such violence by hysterical and hypocondrical distempers, as both made her rave for some daies, and gave her, during that time, a bastard palsey. 7 being a while since in a town, where the plague had made great havock, and inquiring of an ingenious man, that was so bold, as without much scruple to visit those that were sick of it, about the odd symptomes of a disease that had swept away so many there; he told mee, among other things, that he was able to tell divers patients, to whom he was called, before they took their beds, or had any evident symptomes of the plague, that they were indeed infected upon peculiar observations, that being asked, they would tell him that the neighbouring objects, and particularly his cloths, appear'd to them beautifi'd with most glorious colours, like those of the rainbow, oftentimes succeeding one another; and this he affirm'd to be one of the most usual, as well as the most early symptomes, by which this odd pestilence disclos'd it self: and when i asked how long the patients were wont to be thus affected, he answered, that it was most commonly for about a day; and when i further inquired whether or no vomits, which in that pestilence were usually given, did not remove this symptome (for some used the taking of a vomit, when they came ashore, to cure themselves of the obstinate and troublesome giddiness caus'd by the motion of the ship) reply'd, that generally, upon the evacuation made by the vomit, that strange apparition of colours ceased, though the other symptomes were not so soon abated, yet he added (to take notice of that upon the by, because the observation may perchance do good) that an excellent physician, in whose company he was wont to visit the sick, did give to almost all those to whom he was called, in the beginning before nature was much weakened, a pretty odd vomit consisting of eight or ten dramms of infusion of _crocus metallorum_, and about half a dramm, or much more, of white vitriol, with such success, that scarce one of ten to whom it was seasonably administred, miscarried. 8 but to return to the consideration of colours: as an apparition of them may be produced by motions from within, without the assistance of an outward object, so i have observed, that 'tis sometimes possible that the colour that would otherwise be produced by an outward object, may be chang'd by some motion, or new texture already produced in the sensory, as long as that unusual motion, or new disposition lasts; for i have divers times try'd, that after i have through a telescope look'd upon the sun, though thorow a thick, red, or blew glass, to make its splendor supportable to the eye, the impression upon the _retina_, would be not only so vivid, but so permanent, that if afterwards i turned my eye towards a flame, it would appear to mee of a colour very differing from its usual one. and if i did divers times successively shut and open the same eye, i should see the adventitious colour, (if i may so call it) changed or impair'd by degrees, till at length (for this unusual motion of the eye would not presently cease) the flame would appear to mee, of the same hew that it did to other beholders; a not unlike effect i found by looking upon the moon, when she was near full, thorow an excellent telescope, without colour'd glass to screen my eye with; but that which i desire may be taken notice of, because we may elsewhere have occasion to reflect upon it, and because it seems not agreeable to what anatomists and optical writers deliver, touching the relation of the two eyes to each other, is this circumstance, that though my right eye, with which i looked thorow the telescope, were thus affected by the over-strong impression of the light, yet when the flame of a candle, or some other bright object appear'd to me of a very unusual colour, whilst look'd upon with the discompos'd eye, or (though not so notably) with both eyes at once; yet if i shut that eye, and looked upon the same object with the other, it would appear with no other than its usual colour, though if i again opened, and made use of the dazled eye, the vivid adventitious colour would again appear. and on this occasion i must not pretermit an observation which may perswade us, that an over-vehement stroak upon the sensory, especially if it be naturally of a weak constitution, may make a more lasting impression than one would imagine, which impression may in some cases, as it were, mingle with, and vitiate the action of vivid objects for a long time after. for i know a lady of unquestionable veracity, who having lately, by a desperate fall, receiv'd several hurts, and particularly a considerable one upon a part of her face near her eye, had her sight so troubl'd and disorder'd, that, as she hath more than once related to me, not only when the next morning one of her servants came to her bed side, to ask how she did, his cloaths appear'd adorn'd with such variety of dazling colours, that she was fain presently to command him to withdraw, but the images in her hangings, did, for many daies after, appear to her, if the room were not extraordinarily darken'd, embellish'd with several offensively vivid colours, which no body else could see in them; and when i enquir'd whether or no white objects did not appear to her adorn'd with more luminous colours than others, and whether she saw not some which she could not now well describe to any, whose eyes had never been distemper'd, she answer'd mee, that sometimes she thought she saw colours so new and glorious, that they were of a peculiar kind, and such as she could not describe by their likeness to any she had beheld either before or since, and that white objects did so much disorder her sight, that if several daies after her fall, she look'd upon the inside of a book, she fanci'd she saw there colours like those of the rain-bow, and even when she thought her self pretty well recover'd, and made bold to leave her chamber, the coming into a place where the walls and ceeling were whited over, made those objects appear to her cloath'd with such glorious and dazling colours, as much offended her sight, and made her repent her venturousness, and she added, that this distemper of her eyes lasted no less than five or six weeks, though, since that, she hath been able to read and write much without finding the least inconvenience in doing so. i would gladly have known, whether if she had shut the injur'd eye, the _phænomena_ would have been the same, when she employ'd only the other, but i heard not of this accident early enough to satisfie that enquiry. 9 wherefore, i shall now add, that some years before, a person exceedingly eminent for his profound skil in almost all kinds of philological learning, coming to advise with mee about a distemper in his eyes, told me, among other circumstances of it, that, having upon a time looked too fixedly upon the sun, thorow a telescope, without any coloured glass, to take off from the dazling splendour of the object, the excess of light did so strongly affect his eye, that ever since, when he turns it towards a window, or any white object, he fancies, he seeth a globe of light, of about the bigness the sun then appeared of to him, to pass before his eyes: and having inquir'd of him, how long he had been troubled with this indisposition, he reply'd, that it was already nine or ten years, since the accident, that occasioned it, first befel him. i could here subjoyn, _pyrophilus_, some memorable relations that i have met with in the account given us by the experienc'd _epiphanius ferdinandus_, of the symptomes he observ'd to be incident to those that are bitten with the tarantula, by which (relations) i could probably shew, that without any change in the object, a change in the instruments of vision may for a great while make some colours appear charming, and make others provoking, and both to a high degree, though neither of them produc'd any such effects before. these things, i say, i could here subjoyn in confirmation of what i have been saying, to shew, that the disposition of the organ is of great importance in the dijudications we make of colours, were it not that these strange stories belonging more properly to another discourse, i had rather, (contenting my self to have given you an intimation of them here) that you should meet with them fully deliver'd there. * * * * * chap. iii. but, _pyrophilus_, i would not by all that i have hitherto discours'd, be thought to have forgotten the distinction (of colour) that i mentioned to you about the beginning of the third section of the former chapter; and therefore, after all i have said of colour, as it is modifi'd light, and immediately affects the sensory, i shall now re-mind you, that i did not deny, but that colour might in some sense be consider'd as a quality residing in the body that is said to be colour'd, and indeed the greatest part of the following experiments referr to colour principally under that notion, for there is in the bodyes we call colour'd, and chiefly in their superficial parts, a certain disposition, whereby they do so trouble the light that comes from them to our eye, as that it there makes that distinct impression, upon whose account we say, that the seen body is either white or black, or red or yellow, or of any one determinate colour. but because we shall (god permiting) by the experiments that are to follow some pages hence, more fully and particularly shew, that the changes, and consequently in divers places the production and the appearance of colours depends upon the continuing or alter'd texture of the object, we shall in this place intimate (and that too but as by the way) two or three things about this matter. 2. and first it is not without some reason, that i ascribe colour (in the sense formerly explan'd) _chiefly_ to the superficial parts of bodies, for not to question how much opacous corpuscles may abound even in those bodies we call diaphanous, it seems plain that of opacous bodies we do indeed see little else than the superficies, for if we found the beams of light that rebound from the object to the eye, to peirce deep into the colour'd body, we should not judge it opacous, but either translucid, or at least semi-diaphanous, and though the schools seem to teach us that colour is a penetrative quality, that reaches to the innermost parts of the object, as if a piece of sealing-wax be broken into never so many pieces, the internal fragments will be as red as the external surface did appear, yet that is but a particular example that will not overthrow the reason lately offer'd, especially since i can alleage other examples of a contrary import, and two or three negative instances are sufficient to overthrow the generality of a positive rule, especially if that be built but upon one or a few examples. not (then) to mention cherries, plums, and i know not how many other bodies, wherein the skin is of one colour, and what it hides of another, i shall name a couple of instances drawn from the colours of durable bodies that are thought far more homogeneous, and have not parts that are either organical, or of a nature approaching thereunto. 3 to give you the first instance, i shall need but to remind you of what i told you a little after the beginning of this essay, touching the blew and red and yellow, that may be produc'd upon a piece of temper'd steel, for these colours though they be very vivid, yet if you break the steel they adorn, they will appear to be but superficial; not only the innermost parts of the metall, but those that are within a hairs breadth of the superficies, having not any of these colours, but retaining that of the steel it self. besides that, we may as well confirm this observation, as some other particulars we elsewhere deliver concerning colours, by the following experiment which we purposely made. 4 we took a good quantity of clean lead, and melted it with a strong fire, and then immediately pouring it out into a clean vessel of a convenient shape and matter, (we us'd one of iron, that the great and sudden heat might not injure it) and then carefully and nimbly taking off the scum that floated on the top, we perceiv'd, as we expected, the smooth and glossie surface of the melted matter, to be adorn'd with a very glorious colour, which being as transitory as delightfull, did almost immediately give place to another vivid colour, and that was as quickly succeeded by a third, and this as it were chas'd away by a fourth, and so these wonderfully vivid colours successively appear'd and vanish'd, (yet the same now and then appearing the second time) till the metall ceasing to be hot enough to afford any longer this pleasing spectacle, the colours that chanc'd to adorn the surface, when the lead thus began to cool, remain'd upon it; but were so superficial, that how little soever we scrap'd off the surface of the lead, we did in such places scrape off all the colour, and discover only that which is natural to the metall it self, which receiving its adventitious colours, only when the heat was very intense, and in that part which was expos'd to the comparatively very cold air, (which by other experiments seems to abound with subtil saline parts, perhaps not uncapable of working upon lead so dispos'd:) these things i say, together with my observing that whatever parts of the so strongly melted lead were expos'd a while to the air, turn'd into a kind of scum or litharge, how bright and clean soever they appear'd before, suggested to me some thoughts or ravings, which i have not now time to acquaint you with. one that did not know me, _pyrophilus_, would perchance think i endeavour'd to impose upon you by relating this experiment, which i have several times try'd, but the reason why the _phænomena_ mention'd have not been taken notice of, may be, that unless lead be brought to a much higher degree of fusion or fluidity than is usual, or than is indeed requisite to make it melt, the _phænomena_ i mention'd will scarce at all disclose themselves; and we have also observ'd that this successive appearing and vanishing of vivid colours, was wont to be impair'd or determin'd whilst the metal expos'd to the air remain'd yet hotter than one would readily suspect. and one thing i must further note, of which i leave you to search after the reason, namely, that the same colours did not always and regularly succeed one another, as is usually in steel, but in the diversify'd order mention'd in this following note, which i was scarce able to write down, the succession of the colours was so very quick, whether that proceeded from the differing degrees of heat in the lead expos'd to the cool air, or from some other reason, i leave you to examine. [_blew, yellow, purple, blew; green, purple, blew, yellow, red; purple, blew, yellow and blew, yellow, blew, purple, green mixt, yellow, red, blew, green, yellow, red, purple, green_.] 5. the _atomists_ of old, and some learned men of late, have attempted to explicate the variety of colours in opacous bodies from the various figures of their superficial parts; the attempt is ingenious, and the doctrine seems partly true, but i confess i think there are divers other things that must be taken in as concurrent to produce those differing forms of asperity, whereon the colours of opacous bodies seem to depend. to declare this a little, we must assume, that the surfaces of all such bodies how smooth or polite soever they may appear to our dull sight and touch, are exactly smooth only in a popular, or at most in a physical sense, but not in a strict and rigid sense. 6. this, excellent _microscopes_ shew us in many bodies, that seem smooth to our naked eyes; and this not only as to the little hillocks or protuberancies that swell above that which may be conceiv'd to be the plain or level of the consider'd surface, for it is obvious enough to those that are any thing conversant with such glasses, but as to numerous depressions beneath that level, of which sort of cavities by the help of a _microscope_, which the greatest artificer that makes them, judges to be the greatest magnifying glass in _europe_, except one that equals it, we have on the surface of a thin piece of cork that appear'd smooth to the eye, observ'd about sixty in a row, within the length of less then an 31 and 32 part of an inch, (for the glass takes in no longer a space at one view) and these cavities (which made that little piece of cork look almost like an empty honey-comb) were not only very distinct, and figur'd like one another, but of a considerable bigness, and a scarce credible depth; insomuch that their distinct shadows as well as sides were plainly discern'd and easiy to be reckon'd, and might have been well distinguish'd, though they had been ten times lesser than they were; which i thought it not amiss to mention to you _pyrophilus_ upon the by, that you may thence make some estimate, what a strange inequality, and what a multitude of little shades, there may really be, in a scarce sensible part of the physical superficies, though the naked eye sees no such matter. and as excellent _microscopes_ shew us this ruggedness in many bodies that pass for smooth, so there are divers experiments, though we must not now stay to urge them, which seem to perswade us of the same thing as to the rest of such bodies as we are now treating off; so, that there is no sensible part of an opacous body, that may not be conceiv'd to be made up of a multitude of singly insensible corpuscles, but in the giving these surfaces that disposition, which makes them alter the light that reflects thence to the eye after the manner requisite to make the object appear green, blew, &c. the figures of these particles have _a great_, but not _the only_ stroak. 'tis true indeed that the protuberant particles may be of very great variety of figures, sphærical, elliptical, conical, cylindrical, polyedrical, and some very irregular, and that according to the nature of these, and the situation of the lucid body, the light must be variously affected, after one manner from surfaces (i now speak of physical surfaces) consisting of sphaerical, and in another from those that are made up of conical or cylindrical corpuscles; some being fitted to reflect more of the incident beams of light, others less, and some towards one part, others towards another. but besides this difference of shape, there may be divers other things that may eminently concurr to vary the forms of asperity that colours so much depend on. for, willingly allowing the figure of the particles in the first place, i consider secondly, that the superficial corpuscles, if i may so call them, may be bigger in one body, and less in another, and consequently fitted to allay the light falling on them with greater shades. next, the protuberant particles may be set more or less close together, that is, there may be a greater or a smaller number of them within the compass of one, than within the compass of another small part of the surface of the same extent, and how much these qualities may serve to produce colour may be somewhat guess'd at, by that which happens in the agitation of water; for if the bubbles that are thereby made be great, and but few, the water will scarce acquire a sensible colour, but if it be reduc'd to a froth, consisting of bubbles, which being very minute and contiguous to each other, are a multitude of them crowded into a narrow room, the water (turned to froth) does then exhibit a very manifest white colour,[3] (to which these last nam'd conditions of the bubbles do as well as their convex figure contribute) and that for reasons to be mention'd anon. besides, it is not necessary that the superficial particles that exhibit one colour, should be all of them round, or all conical, or all of any one shape, but corpuscles of differing figures may be mingled on the surface of the opacous body, as when the corpuscles that make a blew colour, and those that make a yellow, come to be accurately and skilfully mix'd, they make up a green, which though it seem one simple colour, yet in this case appears to be made by corpuscles of very differing kinds, duely commix'd. moreover the figure and bigness of the little depressions, cavities, furrows or pores intercepted betwixt these protuberant corpuscles, are as well to be consider'd as the sizes and shapes of the corpuscles themselves: for we may conceive the physical superficies of a body, where (as we said) its colour does as it were reside, to be cut transversly by a mathematical plain, which you know is conceiv'd to be without any depth or thickness at all, and then as some parts of the physical superficies will be protuberant; or swell above this last plain, so others may be depress'd beneath it; as (to explane my self by a gross comparison) in divers places of the surface of the earth, there are not only neighbouring hills, trees, &c. that are rais'd above the horizontal level of the valley, but rivers, wells, pits and other cavities that are depress'd beneath it, and that such protuberant and concave parts of a surface may remit the light so differingly, as much to vary a colour, some examples and other things, that we shall hereafter have occasion to take notice off in this tract, will sufficiently declare, till when, it may suffice to put you in mind, that of two flat-sides of the same piece of, for example, red marble, the one being diligently polished, and the other left to its former roughness, the differing degrees or sorts of asperity, for the side that is smooth to the touch wants not its roughness, will so diversifie the light reflected from the several plains to the eye, that a painter would employ two differing colours to represent them. [3] _see the discourse of the nature of whiteness and blackness._ 7. and i hope, _pyrophilus_, you will not think it strange or impertinent, that i employ in divers passages of these papers, examples drawn from bodies and shadows far more gross, than those minute protuberances and shady pores on which in most cases the colour of a body as 'tis an inherent quality or disposition of its surface, seems to depend. for sometimes i employ such examples, rather to declare my meaning, than prove my conjecture; things, whom their smallness makes insensible, being better represented to the imagination by such familiar objects, as being like them enough in other respects, are of a visible bulk. and next, though the beams of light are such subtil bodies, that in respect of them, even surfaces that are sensibly smooth, are not exactly so, but have their own degree of roughness, consisting of little protuberances and depressions; and though consequently such inequalities may suffice to give bodies differing colours, as we see in marble that appears white or black, or red or blew, even when the most carefully polish'd, yet 'tis plain by the late instance of red marble, and many others, that even bigger protuberances and greater shades may likewise so diversifie the roughness of a bodies superficies, as manifestly to concurr to the varying of its colour, whereby such examples appear to be proper enough to be employ'd in such a subject as we have now in hand. and having hinted thus much on this occasion, i now proceed. 8. the situation also of the superficial particles is considerable, which i distinguish into the posture of the single corpuscles, in respect of the light, and of the eye, and the order of them in reference also to one another; for a body may otherwise reflect the light, when its superficial particles are more erected upon the plain that may be conceiv'd to pass along their basis, and when the points or extremes of such particles are obverted to the eye, than when those particles are so inclin'd, that their sides are in great part discernable, as the colour of plush or velvet will appear vary'd to you, if you carefully stroak part of it one way, and part of it another, the posture of the particular thrids, in reference to the light, or the eye, becoming thereby different. and you may observe in a field of ripe corn blown upon by the wind, that there will appear as it were waves of a colour (at least gradually) differing from that of the rest of the field, the wind by depressing some of the ears, and not at the same time others, making the one reflect more from the lateral and strawy parts, than do the rest. and so, when doggs are so angry, as to erect the hairs upon their necks, and upon some other parts of their bodies, those parts seem to acquire a colour vary'd from that which the same hairs made, when in their usual posture they did farr more stoop. and that the order wherein the superficial corpuscles are rang'd is not to be neglected, we may guess by turning of water into froth, the beating of glass, and the scraping of horns, in which cases the corpuscles that were before so marshall'd as to be perspicuous, do by the troubling of that order become dispos'd to terminate and reflect more light, and thereby to appear whitish. and there are other ways in which the order of the protuberant parts, in reference to the eye, may much contribute to the appearing of a particular colour, for i have often observ'd, that when pease are planted, or set in parallel lines, and are shot up about half a foot above the surface of the ground, by looking on the field or plot of ground from that part towards which the parallel lines tended, the greater part of the ground by farr would appear of its own dirty colour, but if i look'd upon it transversly, the plot would appear very green, the upper parts of the pease hindering the intercepted parts of the ground, which as i said retain'd their wonted colour, from being discover'd by the eye. and i know not, _pyrophilus_, whether i might not add, that even the motion of the small parts of a visible object may in some cases contribute, though it be not so easie to say how, to the producing or the varying of a colour; for i have several times made a liquor, which when it has well settled in a close vial, is transparent and colourless, but as soon as the glass is unstopp'd, begins to fly away very plentifully in a white and opacous fume; and there are other bodies, whose fumes, when they fill a receiver, would make one suspect it contains milk, and yet when these fumes settle into a liquor, that liquor is not white, but transparent; and such white fumes i have seen afforded by unstopping a liquor i know, which yet is it self diaphanous and red; nor are these the only instances of this kind, that our tryals can supply us with. and if the superficial corpuscles be of the grosser sort, and be so framed, that their differing sides or faces may exhibit differing colours, then the motion or rest of those corpuscles may be considerable, as to the colour of the superficies they compose, upon this account, that sometimes more, sometimes fewer of the sides dispos'd to exhibit such a colour may by this means become or continue more obverted to the eye than the rest, and compose a physical surface, that will be more or less sensibly interrupted; as, to explane my meaning, by proposing a gross example, i remember, that in some sorts of leavy plants thick set by one another, the two sides of whose leaves were of somewhat differing colours, there would be a notable disparity as to colour, if you look'd upon them both when the leaves being at rest had their upper and commonly expos'd sides obverted to the eye, and when a breath of wind passing thorow them, made great numbers of the usually hidden sides of the leaves become conspicuous. and though the little bodies, we were lately speaking of, may singly and apart seem almost colourless, yet when many of them are plac'd by one another, so near, that the eye does not easily discern an interruption, within a sensible space, they may exhibit a colour; as we see, that though a slenderest thrid of dy'd silk do's, whilst look'd on single, seem almost quite devoyd of redness, (for instance) yet when numbers of these thrids are brought together into one skein, their colour becomes notorious. 9. but the same occasion that invited me to say what i have mention'd concerning the leaves of trees, invites me also to give you some account of what happens in changeable taffities, where we see differing colours, as it were, emerge and vanish upon the ruffling of the same piece of silk: as i have divers times with pleasure observ'd, by the help of such a _microscope_, as, though it do not very much magnifie the object, has in recompence this great conveniency, that you may easily, as fast as you please, remove it from one part to another of a large object, of which the glass taking a great part at once, you may thereby presently survey the whole. now by the help of such a _microscope_ i could easily (as i began to say) discern, that in a piece of changeable taffity, (that appear'd, for instance, sometimes red, and sometimes green) the stuff was compos'd of red thrids and green, passing under and over each other, and crossing one another in almost innumerable points; and if i look'd through the glass upon any considerable portion of the stuff, that (for example sake) to the naked eye appear'd to be red, i could plainly see, that in that position, the red thrids were conspicuous, and reflected a vivid light; and though i could also perceive, that there were green ones, yet by reason of their disadvantagious position in the _physical surface_ of the taffity, they were in part hid by the more protuberant thrids of the other colour; and for the same cause, the reflection from as much of the green as was discover'd, was comparatively but dim and faint. and if, on the contrary, i look'd through the _microscope_ upon any part that appear'd green, i could plainly see that the red thrids were less fully expos'd to the eye, and obscur'd by the green ones, which therefore made up the predominant colour. and by observing the texture of the silken stuff, i could easisy so expose the thrids either of the one colour or of the other to my eye, as at pleasure to exhibit an apparition of red or green, or make those colours succeed one another: so that, when i observ'd their succession by the help of the glass, i could mark how the predominant colour did as it were start out, when the thrids that exhibited it came to be advanagiously plac'd; and by making little folds in the stuff after a certain manner, the sides that met and terminated in those folds, would appear to the naked eye, one of them red, and the other green. when thrids of more than two differing colours chance to be interwoven, the resulting changeableness of the taffity may be also somewhat different. but i choose to give an instance in the stuff i have been speaking off, because the mixture being more simple, the way whereby the changeableness is produc'd, may be the more easily apprehended: and though reason alone might readily enough lead a considering man to guess at the explication, in case he knew how changeable taffities are made: yet i thought it not impertinent to mention it, because both scholars and gentlemen are wont to look upon the inquiry into manufactures, as a _mechanick_ imployment, and consequently below them; and because also with such a _microscope_ as i have been mentioning, the discovery is as well pleasant as satisfactory, and may afford hints of the solution of other _phænomena_ of colours. and it were not amiss, that some diligent inquiry were made, whether the _microscope_ would give us an account of the variableness of colour, that is so conspicuous and so delightfull in mother of pearl, in opalls, and some other resembling bodies: for though i remember i did formerly attempt something of that kind (fruitlesly enough) upon mother of pearl, yet not having then the advantage of my best _microscope_, nor some conveniences that might have been wish'd, i leave it to you, who have better eyes, to try what you can do further; since 'twill be _some_ discovery to find, that, in this case, the best eyes and _microscopes_ themselves can make _none_. 10. i confess, _pyrophilus_, that a great part of what i have deliver'd, (or propos'd rather) concerning the differing forms of asperity in bodies, by which differences the incident light either comes to be reflected with more or less of shade, and with that shade more or less interrupted, or else happens to be also otherwise modify'd or troubl'd, is but conjectural. but i am not sure, that if it were not for the dullness of our senses, either these or some other notions of kin to them, might be better countenanc'd; for i am apt to suspect, that if we were sharp sighted enough, or had such perfect _microscopes_, as i fear are more to be wish'd than hop'd for, our promoted sense might discern in the physical surfaces of bodies, both a great many latent ruggidnesses, and the particular sizes, shapes, and situations of the extremely little bodies that cause them, and perhaps might perceive among other varieties that we now can but imagine, how those little protuberances and cavities do interrupt and dilate the light, by mingling with it a multitude of little and singly undiscernable shades, though some of them more, and some of them less minute, some less, and some more numerous; according to the nature and degree of the particular colour we attribute to the visible object; as we see, that in the moon we can with excellent _telescopes_ discern many hills and vallies, and as it were pits and other parts, whereof some are more, and some less vividly illustrated, and others have a fainter, others a deeper shade, though the naked eye can discern no such matter in that planet. and with an excellent _microscope_, where the _naked_ eye did see but a green powder, the _assisted_ eye as we noted above, could discern particular granules, some of them of a blew, and some of them of a yellow colour, which corpuscles we had beforehand caus'd to be exquisitly mix'd to compound the green. 11. and, _pyrophilus_, that you may not think me altogether extravagant in what i have said of the possibility, (for i speak of no more) of discerning the differing forms of asperity in the surfaces of bodies of several colours, i'l here set down a memorable particular that chanc'd to come to my knowledge, since i writ a good part of this _essay_; and it is this. meeting casually the other day with the deservedly famous[4] dr. _j. finch_, extraordinary _anatomist_ to that great patron of the _virtuosi_, the now great duke of _toscany_, and enquiring of this ingenious person, what might be the chief rarity he had seen in his late return out of _italy_ into _england_, he told me, it was a man at _maestricht_ in the low-countrys, who at certain times can discern and _distinguish colours by the touch_ with his fingers. you'l easily conclude, that this is farr more strange, than what i propos'd but as _not impossible_; since the sense of the _retina_ seeming to be much more tender and quick than that of those grosser filaments, nerves or membranes of our fingers, wherewith we use to handle gross and hard bodies, it seems scarce credible, that any accustomance, or diet, or peculiarity of constitution, should enable a man to distinguish with such gross and unsuitable organs, such nice and subtile differences as those of the forms of asperity, that belong to differing colours, to receive whose languid and delicate impressions by the intervention of light, nature seems to have appointed and contexed into the _retina_ the tender and delicate pith of the optick nerve. wherefore i confess, i propos'd divers scruples, and particularly whether the doctor had taken care to bind a napkin or hankerchief over his eyes so carefully, as to be sure he could make no use of his sight, though he had but counterfeited the want of it, to which i added divers other questions, to satisfie my self, whether there were any likelihood of collusion or other tricks. but i found that the judicious doctor having gone farr out of his way, purposely to satisfie himself and his learned prince about this wonder, had been very watchfull and circumspect to keep _himself_ from being impos'd upon. and that he might not through any mistake in point of memory mis-inform _me_, he did me the favour at my request, to look out the notes he had written for his own and his princes information, the summ of which memorials, as far as we shall mention them here, was this, that the doctor having been inform'd at _utrecht_, that there lived one at some miles distance from _maestricht_, who could distinguish colours by the touch, when he came to the last nam'd town, he sent a messenger for him, and having examin'd him, was told upon enquiry these particulars: [4] since for his eminent qualities and loyalty grac'd, by his majesty, with the honour of knighthood. that the man's name was _john vermaasen_, at that time about 33 years of age; that when he was but two years old, he had the small pox, which rendred him absolutely blind: that at this present he is an _organist_, and serves that office in a publick quire. that the doctor discoursing with him over night, the blind man affirm'd, that he could distinguish colours by the touch, but that he could not do it, unless he were fasting; any quantity of drink taking from him that exquisitness of touch, which is requisite to so nice a sensation. that hereupon the doctor provided against the next morning seven pieces of ribbon, of these seven colours, black, white, red, blew, green, yellow, and gray, but as for _mingled_ colours, this _vermaasen_ would not undertake to discern them, though if offer'd, he would tell that they were _mix'd_. that to discern the colour of the ribbon, he places it betwixt the thumb and the fore-finger, but his most exquisite perception was in his thumb, and much better in the right thumb than in the left. that after the blind man had four or five times told the doctor the several colours, (though blinded with a napkin for fear he might have some sight) the doctor found he was twice mistaken, for he call'd the white black, and the red blew, but still, he, before his errour, would lay them by in pairs, saying, that though he could easily distinguish them from all others, yet those two pairs were not easily distinguish'd amongst themselves, whereupon the doctor desir'd to be told by him what kind of discrimination he had of colours by his touch, to which he gave a reply, for whose sake chiefly i insert all this narrative in this place, namely, that all the difference was more or less asperity, for says he, (i give you the doctor's own words) black feels as if you were feeling needles points, or some harsh sand, and red feels very smooth. that the doctor having desir'd him to tell in order the difference of colours to his touch, he did as follows; black and white are the most asperous or unequal of all colours, and so like, that 'tis very hard to distinguish them, but black is the most rough of the two, green is next in asperity, gray next to green in asperity, yellow is the fifth in degree of asperity, red and blew are so like, that they are as hard to distinguish as black and white, but red is somewhat more asperous than blew, so that red has the sixth place, and blew the seventh in asperity. 12. to these informations the obliging doctor was pleas'd to add the welcome present of three of those very pieces of ribbon, whose colours in his presence the blind man had distinguished, pronouncing the one gray, the other red, and the third green, which i keep by me as rarities, and the rather, because he fear'd the rest were miscarry'd. 13. before i saw the notes that afforded me the precedent narrative, i confess i suspected this man might have thus discriminated colours, rather by the smell than by the touch; for some of the ingredients imployed by dyers to colour things, have sents, that are not so languid, nor so near of kin, but that i thought it not impossible that a very critical nose might distinguish them, and this i the rather suspected, because he requir'd, that the ribbons, whose colours he was to name, should be offer'd him fasting in the morning; for i have observ'd in setting doggs, that the feeding of them (especially with some sorts of aliments) does very much impair the exquisite sent of their noses. and though some of the foregoing particulars would have prevented that conjecture, yet i confess to you (_pyrophilus_) that i would gladly have had the opportunity of examining this man my self, and of questioning him about divers particulars which i do not find to have been yet thought upon. and though it be not incredible to me, that since the liquors that dyers imploy to tinge, are qualifi'd to do so by multitudes of little corpuscles of the pigment or dying stuff, which are dissolved and extracted by the liquor, and swim to and fro in it, those corpuscles of colour (as the _atomists_ call them) insinuating themselves into, and filling all the pores of the body to be dyed, may asperate its superficies more or less according to the bigness and texture of the corpuscles of the pigment; yet i can scarce believe, that our blind man could distinguish all the colours he did, meerly by the ribbons having more or less of asperity, so that i cannot but think, notwithstanding this history, that the blind man distinguish'd colours not only by the _degrees_ of asperity in the bodies offer'd to him, but by _forms_ of it, though this (latter) would perhaps have been very difficult for him to make an intelligible mention of, because those minute disparities having not been taken notice of by men for want of touch as exquisite as our blind mans, are things he could not have intelligibly express'd, which will easily seem probable, if you consider, that under the name of sharp, and sweet, and sour, there are abundance of, as it were, immediate peculiar relishes or tasts in differing sorts of wine, which though critical and experienc'd palats can easily discern themselves cannot make them be understood by others, such minute differences not having hitherto any distinct names assign'd them. and it seems that there was somthing in the forms of asperity that was requisite to the distinction of colours, besides the degree of it, since he found it so difficult to distingush black and white from one another, though not from other colours. for i might urge, that he seems not consonant to himself about the _red_, which as you have seen in one place, he represents as somewhat more asperous than the _blew_; and in another, very smooth: but because he speaks of this smoothness in that place, where he mentions the roughness of _black_, we may favourably presume that he might mean but a _comparative smoothness_; and therefore i shall not insist on this, but rather countenance my conjecture by this, that he found it so difficult, not only, to discriminate red and blew, (though the first of our promiscuous experiments will inform you, that the red reflects by great odds more light than the other) but also to distinguish black and white from one another, though not from other colours. and indeed, though in the ribbonds that were offer'd him, they might be almost equally rough, yet in such slender corpuscles as those of colour, there may easily enough be conceiv'd, not only a greater closeness of parts, or else paucity of protuberant corpuscles, and the little extant particles may be otherwise figur'd, and rang'd in the white than in the black, but the cavities may be much deeper in the one than the other. 14. and perhaps, (_pyrophilus_) it may prove some _illustration of what i mean_, and help you to conceive how _this may_ be, if i represent, that where the particles are so exceeding slender, we may allow the parts expos'd to the sight and touch to be a little convex in comparison of the erected particle of black bodies, as if there were wyres i know not how many times slenderer than a hair: whether you suppose them to be figur'd like needles, or cylindrically, like the hairs of a brush, with hemisphærical (or at least convex) tops, they will be so very slender, and consequently the points both of the one sort and the other so very sharp, that even an exquisite touch will be able to distinguish no greater difference between them, than that which our blind man allow'd, when comparing black and white bodies, he said, that the latter was the less rough of the two. nor is every kind of roughness, though sensible enough, inconsistent with whiteness, there being cases, wherein the physical superficies of a body is made by the same operation both _rough_ and _white_, as when the level surface of clear water being by agitation asperated with a multitude of unequal bubbles, do's thereby acquire a whiteness; and as a smooth piece of glass, by being scratch'd with a diamond, do's in the asperated part of its surface disclose the same colour. but more (perchance) of this elsewhere. 15. and therefore, we shall here pass by the question, whether any thing might be consider'd about the opacity of the corpuscles of black pigments, and the _comparative_ diaphaneity of those of many white bodies, apply'd to our present case; and proceed, to represent, that the newly mention'd exiguity and shape of the extant particles being suppos'd, it will then be considerable what we lately but hinted, (and therefore must now somewhat explane) that the depth of the little cavities, intercepted between the extant particles, without being so much greater in black bodies than in white ones, as to be perceptibly so to the gross organs of touch, may be very much greater in reference to their disposition of reflecting the imaginary subtile beams of light. for in black bodies, those little intercepted cavities, and other depressions, may be so figur'd, so narrow and so deep, that the incident beams of light, which the more extant parts of the physical superficies are dispos'd to reflect inwards, may be detain'd there, and prove unable to emerge; whilst in a white body, the slender particles may not only by their figure be fitted to reflect the light copiously outwards, but the intercepted cavities being not deep, nor perhaps very narrow, the bottoms of them may be so constituted, as to be fit to reflect outwards much of the light that falls even upon them; as you may possibly better apprehend, when we shall come to treat of whiteness and blackness. in the mean time it may suffice, that you take notice with me, that the blind mans relations import no necessity of concluding, that, though, because, according to the judgment of his touch, black was the roughest, as it is the darkest of colours, therefore white, which (according to us) is the lightest, should be also the smoothest: since i observe, that he makes yellow to be two degrees more asperous than blew, and as much less asperous than green; whereas indeed, yellow do's not only appear to the eye a lighter colour than blew, but (by our first experiment hereafter to be mention'd) it will appear, that yellow reflected much more light than blew, and manifestly more than green, (which we need not much wonder at, since in this colour and the two others (blew and yellow) 'tis not _only_ the _reflected light_ that is to be considered, since to produce both these, _refraction_ seems to intervene, which by its varieties may much alter the case:) which both seems to strengthen the conjecture i was formerly proposing, that there was something else in the _kinds_ of asperity, as well as in the _degrees_ of it, which enabled our blind man to discriminate colours, and do's at least show, that we cannot in all cases from the bare difference in the degrees of asperity betwixt colours, safely conclude, that the rougher of any two always reflects the least light. 16. but this notwithstanding, (_pyrophilus_) and what ever curiosity i may have had to move some questions to our sagacious blind man, yet thus much i think you will admit us to have gain'd by his testimony, that since many colours may be felt with the circumstances above related, the surfaces of such coloured bodies must certainly have differing _degrees_, and in all probability have differing _forms_ or kinds of asperity belonging to them, which is all the use that my present attempt obliges me to make of the history above deliver'd, that being sufficient to prove, _that_ colour do's much depend upon the disposition of the superficial parts of bodies, and to shew in general, _wherein_ 'tis probable that such a disposition do's (principally at least) consist. 17. but to return to what i was saying before i began to make mention of our blind _organist_, what we have deliver'd touching the causes of the several forms or asperity that may diversifie the surfaces of colour'd bodies, may perchance somewhat assist us to make some conjectures in the general, at several of the ways whereby 'tis possible for the experiments hereafter to be mention'd, to produce the suddain changes of colours that are wont to be consequent upon them; for most of these _phænomena_ being produc'd by the intervention of liquors, and these for the most part abounding with very minute, active, and variously figur'd saline corpuscles, liquors so qualify'd may well enough very nimbly after the texture of the body they are imploy'd to work upon, and so may change the form of asperity, and thereby make them remit to the eye the light that falls on them, after another manner than they did before, and by that means vary the colour, so farr forth as it depends upon the texture or disposition of the seen parts of the object, which i say, _pyrophilus_, that you may not think i would absolutely exclude all other ways of modifying the beams of light between their parting from the lucid body, and their reception into the common sensory. 18. now there seem to me divers ways, by which we may conceive that liquors may nimbly alter the colour of one another, and of other bodies, upon which they act, but my present haste will allow me to mention but some of them, without insisting so much as upon those i shall name. 19. and first, the minute corpuscles that compose a liquor may early insinuate themselves into those pores of bodies, whereto their size and figure makes them congruous, and these pores they may either exactly fill, or but inadequately, and in this latter case they will for the most part alter the number and figure, and always the bigness of the former pores. and in what capacity soever these corpuscles of a liquor come to be lodg'd or harbour'd in the pores that admit them, the surface of the body will for the most part have its asperity alter'd, and the incident light that meets with a grosser liquor in the little cavities that before contain'd nothing but air, or some yet subtiler fluid, will have its beams either refracted, or imbib'd, or else reflected more or less interruptedly, than they would be, if the body had been unmoistned, as we see, that even fair water falling on white paper, or linnen, and divers other bodies apt to soak it in, will for some such reasons as those newly mention'd, immediately alter the colour of them, and for the most part make it sadder than that of the unwetted parts of the same bodies. and so you may see, that when in the summer the high-ways are dry and dusty, if there falls store of rain, they will quickly appear of a much darker colour than they did before, and if a drop of oyl be let fall upon a sheet of white paper, that part of it, which by the imbibition of the liquor acquires a greater continuity, and some transparency, will appear much darker than the rest, many of the incident beams of light being now transmitted, that otherwise would be reflected towards the beholders eyes. 20. secondly, a liquor may alter the colour of a body by freeing it from those things that hindred it from appearing in its genuine colour; and though this may be said to be rather a restauration of a body to its own colour, or a retection of its native colour, than a change, yet still there intervenes in it a change of the colour which the body appear'd to be of before this operation. and such a change a liquor may work, either by dissolving, or corroding, or by some such way of carrying off that matter, which either veil'd or disguis'd the colour that afterwards appears. thus we restore old pieces of dirty gold to a clean and nitid yellow, by putting them into the fire, and into _aqua-fortis_, which take off the adventitious filth that made that pure metall look of a dirty colour. and there is also an easie way to restore silver coyns to their due lustre, by fetching off that which discolour'd them. and i know a _chymical_ liquor, which i employ'd to restore pieces of cloath spotted with grease to their proper colour, by imbibing the spotted part with this liquor, which incorporating with the grease, and yet being of a very volatile nature, does easily carry it away with it self. and i have sometimes try'd, that by rubbing upon a good touch-stone a certain _metalline_ mixture so compounded, that the impression it left upon the stone appear'd of a very differing colour from that of gold, yet a little of _aqua-fortis_ would in a trice make the golden colour disclose it self, by dissolving the other _metalline_ corpuscles that conceal'd those of the gold, which you know that _menstruum_ will leave untouch'd. 21. thirdly, a liquor may alter the colour of a body by making a comminution of its parts, and that principally two ways, the first by disjoyning and dissipating those clusters of particles, if i may so call them, which stuck more loosely together, being fastned only by some more easily dissoluble ciment, which seems to be the case of some of the following experiments, where you'l find the colour of many corpuscles brought to cohere by having been precipitated together, destroy'd by the affusion of very peircing and incisive liquors. the other of the two ways i was speaking of, is, by dividing the grosser and more solid particles into minute ones, which will be always lesser, and for the most part otherwise shap'd than the entire corpuscle so divided, as it will happen in a piece of wood reduc'd into splinters or chips, or as when a piece of chrystal heated red hot and quench'd in cold water is crack'd into a multitude of little fragments, which though they fall not asunder, alter the disposition of the body of the chrystal, as to its manner of reflecting the light, as we shall have occasion to shew hereafter. 22. there is a fourth way contrary to the third, whereby a liquor may change the colour of another body, especially of another fluid, and that is, by procuring the coalition of several particles that before lay too scatter'd and dispers'd to exhibit the colour that afterwards appears. thus sometimes when i have had a solution of gold so dilated, that i doubted whether the liquor had really imbib'd any true gold or no, by pouring in a little _mercury_, i have been quickly able to satisfie my self, that the liquor contain'd gold, that mettall after a little while cloathing the surface of the _quick-silver_, with a thin film of its own livery. and chiefly, though not only by this way of bringing the minute parts of bodies together in such numbers as to make them become notorious to the eye, many of these colours seem to be generated which are produc'd by precipitations, especially by such as are wont to be made with fair water, as when resinous gumms dissolv'd in spirit of wine, are let fall again, if the spirit be copiously diluted with that weakning liquor. and so out of the rectify'd and transparent butter of _antimony_, by the bare mixture of fair water, there will be plentifully precipitated that milk-white substance, which by having its looser salts well wash'd off, is turn'd into that medicine, which vulgar _chymists_ are pleas'd to call _mercurius vitæ._ 23. a fifth way, by which a liquor may change the colour of a body, is, by dislocating the parts, and putting them out of their former order into another, and perhaps also altering the posture of the single corpuscles as well as their order or situation in respect of one another. what certain kinds of commotion or dislocation of the parts of a body may do towards the changing its colour, is not only evident in the mutations of colour observable in _quick-silver_, and some other concretes long kept by _chymists_ in a convenient heat, though in close vessels, but in the obvious degenerations of colour, which every body may take notice of in bruis'd cherries, and other fruit, by comparing after a while the colour of the injur'd with that of the sound part of the same fruit. and that also such liquors, as we have been speaking of, may greatly discompose the textures of many bodies, and thereby alter the disposition of their superficial parts, the great commotion made in metalls, and several other bodies by _aqua-fortis_, oyl of _vitriol_, and other saline _menstruums_, may easily perswade us, and what such vary'd situations of parts may do towards the diversifying of the manner of their reflecting the light, may be guess'd in some measure by the beating of transparent glass into a white powder, but farr better by the experiments lately pointed at, and hereafter deliver'd, as the producing and destroying colours by the means of subtil saline liquors, by whose affusion the parts of other liquors are manifestly both agitated, and likewise dispos'd after another manner than they were before such affusion. and in some _chymical_ oyls, as particularly that of lemmon pills, by barely shaking the glass, that holds it, into bubbles, that transposition of the parts which is consequent to the shaking, will shew you on the surfaces of the bubbles exceeding orient and lively colours, which when the bubbles relapse into the rest of the oyl, do immediately vanish. 24. i know not, _pyrophilus_, whether i should mention as a distinct way, because it is of a somewhat more general nature, that power, whereby a liquor may alter the colour of another body, by putting the parts of it into motion; for though possibly the motion so produc'd, does, as such, seldome suddenly change the colour of the body whose parts are agitated, yet this seems to be one of the most general, however not immediate causes of the quick change of colours in bodies. for the parts being put into motion by the adventitious liquor, divers of them that were before united, may become thereby disjoyn'd, and when that motion ceases or decays others of them may stick together, and that in a new order, by which means the motion may sometimes produce permanent changes of colours, as in the experiment you will meet with hereafter, of presently turning a snowy white body into a yellow, by the bare affusion of fair water, which probably so dissolves the saline corpuscles that remain'd in the _calx_, and sets them at liberty to act upon one another, and the metall, far more powerfully than the water without the assistance of such saline corpuscles could do. and though you rubb blew _vitriol_, how venereal and unsophisticated soever it be, upon the whetted blade of a knife, it will not impart to the iron its latent colour, but if you moisten the _vitriol_ with your spittle, or common water, the particles of the liquor disjoyning those of the _vitriol_, and thereby giving them the various agitation requisite to fluid bodies, the metalline corpuscles of the thus dissolv'd _vitriol_ will lodge themselves in throngs in the small and congruous pores of the iron they are rubb'd on, and so give the surface of it the genuine colour of the copper. 25. there remains yet a way, _pyrophilus_ to be mention'd, by which a liquor may alter the colour of another body, and this seems the most important of all, because though it be nam'd but as one, yet it may indeed comprehend many, and that is, by associating the saline corpuscles, or any other sort of the more rigid ones of the liquor, with the particles of the body that it is employ'd to work upon. for these adventitious corpuscles associating themselves with the protuberant particles of the surface of a colour'd body, must necessarily alter their bigness, and will most commonly alter their shape. and how much the colours of bodies depend upon the bulk and figure of their superficial particles, you may guess by this, that eminent antient _philosophers_ and divers _moderns_, have thought that all colours might in a general way be made out by these two; whose being diversify'd, will in our case be attended with these two circumstances, the one, that the protuberant particles being increas'd in bulk, they will oftentimes be vary'd as to the closness or laxity of their order, fewer of them being contain'd within the same sensible (though minute) space than before; or else by approaching to one another, they must straighten the pores, and it may be too, they will by their manner of associating themselves with the protuberant particles, intercept new pores. and this invites me to consider farther, that the adventitious corpuscles, i have been speaking of, may likewise produce a great change as well in the little cavities or pores as in the protuberances of a colour'd body; for besides what we have just now taken notice of, they may by lodging themselves in those little cavities, fill them up, and it may well happen, that they may not only fill the pores they insinuate themselves into, but likewise have their upper parts extant above them; and partly by these new protuberances, partly by increasing the bulk of the former, these extraneous corpuscles may much alter the number and bigness of the surfaces pores, changing the old and intercepting new ones. and then 'tis odds, but the order of the little extancies, and consequently that of the little depressions in point of situation will be alter'd likewise: as if you dissolve _quick-silver_ in some kind of _aqua-fortis_, the saline particles of the _menstruum_ associating themselves with the mercurial corpuscles, will make a green solution, which afterwards easily enough degenerates. and red lead or _minium_ being dissolv'd in spirit of vinegar, yields not a red, but a clear solution, the redness of the lead being by the liquor destroy'd. but a better instance may be taken from copper, for i have try'd, that if upon a copper-plate you let some drops of weak _aqua-fortis_ rest for a while, the corpuscles of the _menstruum_, joyning with those of the metall, will produce a very sensible asperity upon the surface of the plate, and will concoagulate that way into very minute grains of a pale blew _vitriol_; whereas if upon another part of the same plate you suffer a little strong spirit of urine to rest a competent time, you shall find the asperated surface adorn'd with a deeper and richer blew. and the same _aqua-fortis_, that will quickly change the redness of red lead into a darker colour, will, being put upon crude lead, produce a whitish substance, as with copper it did a blewish. and as with iron it will produce a reddish, and on white quills a yellowish, so much may the coalition of the parts of the same liquor, with the differingly figur'd particles of stable bodies, divers ways asperate the differingly dispos'd surfaces, and to diversifie the colour of those bodies. and you'l easily believe, that in many changes of colour, that happen upon the dissolutions of metalls, and precipitations made with oyl of _tartar_, and the like fix'd salts, there may intervene a coalition of saline corpuscles with the particles of the body dissolv'd or precipitated, if you examine how much the _vitriol_ of a metall may be heavier than the metalline part of it alone, upon the score of the saline parts concoagulated therewith, and, that in several precipitations the weight of the _calx_ does for the same reason much exceed that of the metall, when it was first put in to be dissolv'd. 26. but, _pyrophilus_, to consider these matters more particularly would be to forget that i declar'd against adventuring, at least for this time, at particular theories of colours, and that accordingly you may justly expect from me rather experiments than speculations, and therefore i shall dismiss this subject of the forms of superficial asperity in colour'd bodies, as soon as i shall but have nam'd to you by way of supplement to what we have hitherto discours'd in this section, a couple of particulars, (which you'l easily grant me) the one, that there are divers other ways for the speedy production even of true and permanent colours in bodies, besides those practicable by the help of liquors; for proof of which advertisement, though several examples might be alleged, yet i shall need but re-mind you of what i mention'd to you above, touching the change of colours suddenly made on temper'd steel, and on lead, by the operation of heat, without the intervention of a liquor. but the other particular i am to observe to you is of more importance to our present subject and it is, that though nature and art may in some cases so change the asperity of the superficial parts of a body, as to change its colour by either of the ways i have propos'd single or unassisted, yet for the most part 'tis by two or three, or perhaps by more of the fore-mention'd ways associated together, that the effect is produc'd, and if you consider how variously those several ways and some others ally'd unto them, which i have left unmention'd, may be compounded and apply'd, you will not much wonder that such fruitfull, whether principles (or manners of diversification) should be fitted to change or generate no small store of differing colours. 27. hitherto, _pyrophilus_, we have in discoursing of the asperity of bodies consider'd the little protuberances of other superficial particles which make up that roughness, as if we took it for granted, that they must be perfectly opacous and impenetrable by the beams of light, and so, must contribute to the variety of colours as they terminate more or less light, and reflect it to the eye mix'd with more or less of thus or thus mingl'd shades. but to deal ingenuously with you, _pyrophilus_, before i proceed any further, i must not conceal from you, that i have often thought it worth a serious enquiry, whether or no particles of matter, each of them sing'y insensible, and therefore small enough to be capable of being such minute particles as the _atomists_ both of old and of late have (not absurdly) called _corpuscula coloris_, may not yet consist each of them of divers yet minuter particles, betwixt which we may conceive little commissures where they adhere to one another, and, however, may not be porous enough to be, at least in some degree, pervious to the unimaginably subtile corpuscles that make up the beams of light, and consequently to be in such a degree diaphanous. for, _pyrophilus_, that the proposed enquiry may be of moment to him that searches after the nature of colour, you'l easily grant, if you consider, that whereas perfectly opacous bodies can but reflect the incident beams of light, those that are diaphanous are qualified to refract them too, and that refraction has such a stroak in the production of colours, as you cannot but have taken notice of, and perhaps admir'd in the colours generated by the trajection of light through drops of water that exhibit a rain-bow, through prismatical glasses, and through divers other transparent bodies. but 'tis like, _pyrophilus_, you'l more easily allow that about this matter 'tis rather important to have a certainty, than that 'tis rational to entertain a doubt; wherefore i must mention to you some of the reasons that make me think it may need a further enquiry, for i find that in a darkned room, where the light is permitted to enter but at one hole, the little wandering particles of dust, that are commonly called motes, and, unless in the sunbeams, are not taken notice of by the unassisted sight, i have, i say, often observ'd, that these roving corpuscles being look'd on by an eye plac'd on one side of the beams that enter'd the little hole, and by the darkness having its pupill much enlarg'd, i could discern that these motes as soon as they came within the compass of the luminous, whether cylinder or inverted cone, if i may so call it, that was made up by the unclouded beams of the sun, did in certain positions appear adorn'd with very vivid colours, like those of the rain-bow, or rather like those of very minute, but sparkling fragments of diamonds; and as soon as the continuance of their motion had brought them to an inconvenient position in reference to the light and the eye, they were only visible without darting any lively colours as before, which seems to argue that these little motes, or minute fragments, of several sorts of bodies reputed opacous, and only crumbled as to their exteriour and looser parts into dust, did not barely reflect the beams that fell upon them, but remit them to the eye refracted too. we may also observe, that several bodies, (as well some of a vegetable, as others of an animal nature) which are wont to pass for opacous, appear in great part transparent, when they are reduc'd into thin parts, and held against a powerful light. this i have not only taken notice of in pieces of ivory reduc'd but into thick leaves, as also in divers considerable thick shells of fishes, and in shaving of wood, but i have also found that a piece of deal, far thicker than one would easily imagine, being purposly interposed betwixt my eye plac'd in a room, and the clear daylight, was not only somewhat transparent, but (perhaps by reason of its gummous nature) appear'd quite through of a lovely red. and in the darkned room above mention'd, bodies held against the hole at which the light enter'd, appear'd far less opacous then they would elsewhere have done, insomuch that i could easily and plainly see through the whole thickness of my hand, the motions of a body plac'd (at a very near distance indeed, but yet) beyond it. and even in minerals, the opacity is not always so great as many think, if the body be made thin, for white marble though of a pretty thickness, being within a due distance plac'd betwixt the eye and a convenient light, will suffer the motions of ones finger to be well discern'd through it, and so will pieces, thick enough, of many common flints. but above all, that instance is remarkable, that is afforded us by _muscovie_ glass, (which some call _selenites_, others _lapis specularis_) for though plates of this mineral, though but of a moderate thickness, do often appear opacous, yet if one of these be dextrously split into the thinnest leaves 'tis made up of, it will yield such a number of them, as scarce any thing but experience could have perswaded me, and these leaves will afford the most transparent sort of consistent bodies, that, for ought i have observ'd, are yet known; and a single leaf or plate will be so far from being opacous, that 'twill scarce be so much as visible. and multitudes of bodies there are, whose fragments seem opacous to the naked eye, which yet, when i have included them in good _microscopes_, appear'd transparent; but, _pyrophilus_, on the other side i am not yet sure that there are no bodies, whose minute particles even in such a _microscope_ as that of mine, which i was lately mentioning, will not appear diaphanous. for having consider'd _mercury_ precipitated _per se_, the little granules that made up the powder, look'd like little fragments of coral beheld by the naked eye at a distance (for very near at hand coral will sometimes, especially if it be good, shew some transparency.) filings likewise of steel and copper, though in an excellent _microscope_, and a fair day, they show'd like pretty big fragments of those metalls, and had considerable brightness on some of their surfaces, yet i was not satisfi'd, that i perceiv'd any reflection from the inner parts of any of the filings. nay, having look'd in my best _microscope_ upon the red _calx_ of lead, (commonly call'd _minium_) neither i, nor any i shew'd it to, could discern it to be other than opacous, though the day were clear, and the object strongly enlightned. and the deeply red colour of _vitriol_ appear'd in the same _microscope_ (notwithstanding the great comminution effected by the fire) but like grossy beaten brick. so that, _pyrophilus_, i shall willingly resign you the care of making some further enquiries into the subject we have now been considering; for i confess, as i told you before, that i think that the matter may need a further scrutiny, nor would i be forward to determine how far or in what cases the transparency or semi-diaphaniety of the superficial corpuscles of bigger bodies, may have an interest in the production of their colours, especially because that even in divers white bodies, as beaten glass, snow and froth, where it seems manifest that the superficial parts are singly diaphanous, (being either water, or air, or glass) we see not that such variety of colours are produc'd as usually are by the refraction of light, even in those bodies, when by their bigness, shape, &c. they are conveniently qualify'd to exhibit such various and lively colours as those of the rain-bow, and of prismatical glasses. 28. by what has been hitherto discours'd, _pyrophilus_, we may be assisted to judge of that famous controversie which was of old disputed betwixt the _epicureans_ and other _atomists_ on the one side, and most other _philosophers_ on the other side. the former denying bodies to be colour'd in the dark, and the latter making colour to be an inherent quality, as well as figure, hardness; weight, or the like. for though this controversie be reviv'd, and hotly agitated among the _moderns_, yet i doubt whether it be not in great part a nominal dispute, and therefore let us, according to the doctrine formerly deliver'd, distinguish the acceptions of the word colour, and say, that if it be taken in the stricter sense, the _epicureans_ seem to be in the right, for if colour be indeed, though not according to them, but light modify'd, how can we conceive that it can subsist in the dark, that is, where it must be suppos'd there is no light; but on the other side, if colour be consider'd as a certain constant disposition of the superficial parts of the object to trouble the light they reflect after such and such a determinate manner, this constant, and, if i may so speak, modifying disposition persevering in the object, whether it be shin'd upon or no, there seems no just reason to deny, but that in this sense, bodies retain their colour as well in the night as day; or, to speak a little otherwise, it may be said, that bodies are potentially colour'd in the dark, and actually in the light. but of this matter discoursing more fully elsewhere, as 'tis a difficulty that concerns qualities in general, i shall forbear to insist on it here. * * * * * chap. iv 1. of greater moment in the investigation of the nature of colours is the controversie, whether those of the rain-bow, and those that are often seen in clouds, before the rising, or after the setting of the sun; and in a word, whether those other colours, that are wont to be call'd emphatical, ought or ought not to be accounted true colours. i need not tell you that the negative is the common opinion, especially in the schools, as may appear by that vulgar distinction of colours, whereby these under consideration are term'd apparent, by way of opposition to those that in the other member of the distinction are call'd true or genuine. this question i say seems to me of importance, upon this account, that it being commonly granted, (or however, easie enough to be prov'd) that emphatical colours are light it self modify'd by refractions chiefly, with a concurrence sometimes of reflections, and perhaps some other accidents depending on these two; if these emphatical colours be resolv'd to be genuine, it will seem consequent, that colours, or at least divers of them, are but diversify'd light, and not such real and inherent qualities as they are commonly thought to be. 2. now since we are wont to esteem the echoes and other sounds of bodies, to be true sounds, all their odours to be true odours, and (to be short) since we judge other sensible qualities to be true ones, because they are the proper objects of some or other of our senses, i see not why emphatical colours, being the proper and peculiar objects of the organ of sight, and capable to affect it as truly and as powerfully as other colours, should be reputed but imaginary ones. and if we have (which perchance you'l allow) formerly evinc'd colour, (when the word is taken in its more proper sense) to be but modify'd light, there will be small reason to deny these to be true colours, which more manifestly than others disclose themselves to be produc'd by diversifications of the light. 3. there is indeed taken notice of a difference betwixt these apparent colours, and those that are wont to be esteem'd genuine, as to the duration, which has induc'd some learned men to call the former rather evanid than fantastical. but as the ingenious _gassendus_ does somewhere judiciously observe, if this way of arguing were good, the greeness of a leaf ought to pass for apparent, because, soon fading into a yellow, it scarce lasts at all, in comparison of the greeness of an emerauld. i shall add, that if the sun-beams be in a convenient manner trajected through a glass-prism, and thrown upon some well-shaded object within a room, the rain-bow thereby painted on the surface of the body that terminates the beams, may oftentimes last longer than some colours i have produc'd in certain bodies, which would justly, and without scruple be accounted genuine colours, and yet suddenly degenerate, and lose their nature. 4. a greater disparity betwixt emphatical colours, and others, may perhaps be taken from this, that genuine colours seem to be produc'd in opacous bodies by reflection, but apparent ones in diaphanous bodies, and principally by refraction, i say principally rather than solely, because in some cases reflection also may concurr, but still this seems not to conclude these latter colours not to be true ones. nor must what has been newly said of the differences of true and apparent colours, be interpreted in too unlimited a sense, and therefore it may perhaps somewhat assist you, both to reflect upon the two fore-going objections, and to judge of some other passages which you'l meet with in this tract, if i take this occasion to observe to you, that if water be agitated into froth, it exhibits you know a white colour, which soon after it loses upon the resolution of the bubbles into air and water, now in this case either the whiteness of the froth is a true colour or not, if it be, then true colours, supposing the water pure and free from mixtures of any thing tenacious, may be as short-liv'd as those of the rain-bow; also the matter, wherein the whiteness did reside, may in a few moments perfectly lose all foot-steps or remains of it. and besides, even diaphanous bodies may be capable of exhibiting true colours by reflection, for that whiteness is so produc'd, we shall anon make it probable. but if on the other side it be said, that the whiteness of froth is an emphatical colour, then it must no longer be said, that fantastical colours require a certain position of the luminary and the eye, and must be vary'd or destroy'd by the change thereof, since froth appears white, whether the sun be rising or setting, or in the meridian, or any where between it and the horizon, and from what (neighbouring) place soever the beholders eye looks upon it. and since by making a liquor tenacious enough, yet without destroying its transparency, or staining it with any colour, you may give the little films, whereof the bubbles consist, such a texture, as may make the froth last very many hours, if not some days, or even weeks, it will render it somewhat improper to assign duration for the distinguishing character to discriminate genuine from fantastical colours. for such froth may much outlast the undoubtedly true colours of some of nature's productions, as in that gaudy plant not undeservedly call'd the mervail of _peru_, the flowers do often fade, the same day they are blown; and i have often seen a _virginian_ flower, which usually withers within the compass of a day; and i am credibly inform'd, that not far from hence a curious herborist has a plant, whose flowers perish in about an hour. but if the whiteness of water turn'd into froth must therefore be reputed emphatical, because it appears not that the nature of the body is alter'd, but only that the disposition of its parts in reference to the incident light is chang'd, why may not the whiteness be accounted emphatical too, which i shall shew anon to be producible, barely by such another change in black horn? and yet this so easily acquir'd whiteness seems to be as truly its colour as the blackness was before, and at least is more permanent than the greenness of leaves, the redness of roses, and, in short, than the genuine colours of the most part of nature's productions. it may indeed be further objected, that according as the sun or other luminous body changes place, these emphatical colours alter or vanish. but not to repeat what i have just now said, i shall add, that if a piece of cloath in a drapers shop (in such the light being seldome primary) be variously folded, it will appear of differing colours, as the parts happen to be more illuminated or more shaded, and if you stretch it flat, it will commonly exhibit some one uniform colour, and yet these are not wont to be reputed emphatical, so that the difference seems to be chiefly this, that in the case of the rain-bow, and the like, the position of the luminary varies the colour, and in the cloath i have been mentioning, the position of the object does it. nor am i forward to allow that in all cases the apparition of emphatical colours requires a determinate position of the eye, for if men will have the whiteness of froth emphatical, you know what we have already inferr'd from thence. besides, the sun-beams trajected through a triangular glass, after the manner lately mention'd, will, upon the body that terminates them, paint a rain-bow, that may be seen whether the eye be plac'd on the right hand of it or the left, or above or beneath it, or before or behind it; and though there may appear some little variation in the colours of the rain-bow, beheld from differing parts of the room, yet such a diversity may be also observ'd by an attentive eye in real colours, look'd upon under the like circumstances, nor will it follow, that because there remains no footsteps of the colour upon the object, when the prism is remov'd, that therefore the colour was not real, since the light was truly modify'd by the refraction and reflection it suffer'd in its trajection through the prism; and the object in our case serv'd for a specular body, to reflect that colour to the eye. and that you may not be startled, _pyrophilus_, that i should venture to say, that a rough and coiour'd object may serve for a _speculum_ to reflect the artificial rain-bow i have been mentioning, consider what usually happens in darkned rooms, where a wall, or other body conveniently situated within, may so reflect the colours of bodies, without the room, that they may very clearly be discern'd and distinguish'd, and yet 'tis taken for granted, that the colours seen in a darkned room, though they leave no traces of themselves upon the wall or body that receives them, are the true colours of the external objects, together with which the colours of the images are mov'd or do rest. and the errour is not in the eye, whose office is only to perceive the appearances of things, and which does truly so, but in the judging or estimative faculty, which mistakingly concludes that colour to belong to the wall, which does indeed belong to the object, because the wall is that from whence the beams of light that carry the visible _species_, do come in straight lines directly to the eye, as for the same reason we are wont at a certain distance from concave sphærical glasses, to perswade our selves that we see the image come forth to meet us, and hang in the air betwixt the glass and us, because the reflected beams that compose the image cross in that place, where the image seems to be, and thence, and not from the glass, do in direct lines take their course to the eye, and upon the like cause it is, that divers deceptions in sounds and other sensible objects do depend, as we elsewhere declare. 5. i know not, whether i need add, that i have purposely try'd, (as you'l find some pages hence, and will perhaps think somewhat strange) that colours that are call'd emphatical, because not inherent in, the bodies in which they appear, may be compounded with one another, as those that are confessedly genuine may. but when all this is said, _pyrophilus_, i must advertise you, that it is but problematically spoken, and that though i think the opinion i have endeavour'd to fortifie probable, yet a great part of our discourse concerning colours may be true, whether that opinion be so or not. * * * * * chap. v. 1. there are you know, _pyrophilus_, besides those obsolete opinions about colours which have been long since rejected, very various theories that have each of them, even at this day, eminent men for its abetters; for the peripatetick schools, though they dispute amongst themselves divers particulars concerning colours, yet in this they seem unanimously enough to agree, that colours are inherent and real qualities, which the light doth but disclose, and not concurr to produce. besides there are _moderns_, who with a slight variation adopt the opinion of _plato_, and as he would have colour to be nothing but a kind of flame consisting of minute corpuscles as it were darted by the object against the eye, to whose pores their littleness and figure made them congruous, so these would have colour to be an internal light of the more lucid parts of the object, darkned and consequently alter'd by the various mixtures of the less luminous parts. there are also others, who in imitation of some of the ancient _atomists_, make colour not to be lucid steam, but yet a corporeal _effluvium_ issuing out of the colour'd body, but the knowingst of these have of late reform'd their hypothesis, by acknowledging and adding that some external light is necessary to excite, and as _they_ speak, sollicit these corpuscles of colour as _they_ call them, and bring them to the eye. another and more principal opinion of the _modern_ philosophers, to which this last nam'd may by a favourable explication be reconcil'd, is that which derives colours from the mixture of light and darkness, or rather light and shadows. and as for the _chymists_ 'tis known, that the generality of them ascribes the origine of colours to the sulphureous principle in bodies, though i find, as i elsewhere largely shew, that some of the chiefest of them derive colours rather from salt than sulphur, and others, from the third hypostatical principle, _mercury_. and as for the _cartesians_ i need not tell you, that they, supposing the sensation of light to bee produc'd by the impulse made upon the organs of sight, by certain extremely minute and solid globules, to which the pores of the air and other diaphanous bodies are pervious, endeavour to derive the varieties of colours from the various proportion of the direct progress or motion of these globules to their circumvolution or motion about their own centre, by which varying proportion they are by this hypothesis suppos'd qualify'd to strike the optick nerve after several distinct manners, so to produce the perception of differing colours. 2. besides these six principal hypotheses, _pyrophilus_, there may be some others, which though less known, may perhaps as well as thesc deserve to be taken into consideration by you; but that i should copiously debate any of them at present, i presume you will not expect, if you consider the scope of these papers, and the brevity i have design'd in them, and therefore i shall at this time only take notice to you in the general of two or three things that do more peculiarly concern the treatise you have now in your hands. 3. and first, though the embracers of the several hypotheses i have been naming to you, by undertaking each sect of them to explicate colours indefinitely, by the particular hypotheses they maintain, seem to hold it forth as the only needful theory about that subject, yet for my part i doubt whether any one of all these hypotheses have a right to be admitted exclusively to all others, for i think it probable, that whiteness and blackness may be explicated by reflection alone without refraction, as you'l find endeavour'd in the discourse you'l meet with e're long of the origine of whiteness and blackness, and on the other side, since i have not found that by any mixture of white and true black, (for there is a blewish black which many mistake for a genuine) there can be a blew, a yellow, or a red, to name no other colours, produced, and since we do find that these colours may be produc'd in the glass-prism and other transparent bodies, by the help of refractions, it seems that refraction is to be taken in into the explication of some colours, to whose generation they seem to concurr, either by making a further or other commixture of shades with the refracted light, or by some other way not now to be discours'd. and as it seems not improbable, that in case the pores of the air, and other diaphanous bodies be every where almost fill'd with such _globuli_ as the _cartesians_ suppose, the various kind of motion of these _globuli_, may in many cases have no small stroak in varying our perception of colour, so without the supposition of these _globuli_, which 'tis not so easie to evince, i think we may probably enough conceive in general, that the eye may be variously affected, not only by the entire beams of light that fall upon it as they are such, but by the order, and by the degree of swiftness, and in a word by the manner according to which the particles that compose each particular beam arrive at the sensory, so that whatever be the figure of the little corpuscles, of which the beams of light consist, not only the celerity or slowness of their revolution or rotation in reference to their progressive motion, but their more absolute celerity, their direct or undulating motion, and other accidents, which may attend their appulse to the eye, may fit them to make differing impressions on it. 4. secondly, for these and the like considerations, _pyrophilus_, i must desire that you would look upon this little treatise, not as a discourse written principally to maintain any of the fore-mention'd theories, exclusively to all others, or substitute a new one of my own, but as the beginning of a history of colours, upon which, when you and your ingenious friends shall have enrich'd it, a solid theory may be safely built. but yet because this history is not meant barely for a register of the things recorded in it, but for an _apparatus_ to a sound and comprehensitive hypothesis, i thought fit, so to temper the whole discourse, as to make it as conducible, as conveniently i can to that end, and therefore i have not scrupled to let you see that i was willing, as to save you the labour of cultivating some theories that i thought would never enable you to reach the ends you aim at, so to contract your enquiries into a narrow compass, for both which purposes i thought it requisite to do these two things, the _one_, to set down some experiments which by the help of the reflections and insinuations that attend them, may assist you to discover the infirmness and insufficiency both of the common peripatetick doctrine, and of the now more applauded theory of the _chymists_ about colour, because those two doctrines having possess'd themselves, the one of the most part of the schools, and the other of the esteem of the generality ef physicians and other learned men, whose professions and ways of study do not exact that they should scrupulously examine the very first and simplest principles of nature, i fear'd it would be to little purpose, without doing something to discover the insufficiency of these hypotheses, that i should, (which was the _other_ thing i thought requisite for me to do) set down among my other experiments those in the greatest number, that may let you see, that, till i shall be better inform'd, i encline to take colour to be a modification of light, and would invite you chiefly to cultivate that hypothesis, and improve it to the making out of the generation of particular colours, as i have endeavour'd to apply it to the explication of whiteness and blackness. 5. thirdly. but, _pyrophilus_, though this be at present the hypothesis i preferr, yet i propose it but in a general sense, teaching only that the beams of light, modify'd by the bodies whence they are sent (reflected or refracted) to the eye, produce there that kind of sensation, men commonly call colour; but whether i think this modification of the light to be perform'd by mixing it with shades, or by varying the proportion of the progress and rotation of the _cartesian globuli cælestes_, or by some other way which i am not now to mention, i pretend not here to declare. much less do i pretend to determine, or scarce so much as to hope to know all that were requisite to be known, to give you, or even my self, a perfect account of the theory of vision and colours, for in order to such an undertaking i would first know what light is, and if it be a body (as a body or the motion of a body it seems to be) what kind of corpuscles for size and shape it consists of, with what swiftness they move forwards, and whirl about their own centres. then i would know the nature of refraction, which i take to be one of the abstrusest things (not to explicate plausibly, but to explicate satisfactorily) that i have met with in physicks; i would further know what kind and what degree of commixture of darkness or shades is made by refractions or reflections, or both, in the superficial particles of those bodies, that being shin'd upon, constantly exhibit the one, for instance, a blew, the other a yellow, the third a red colour; i would further know why this contemperation of light and shade, that is made, for example, by the skin of a ripe cherry, should exhibit a red, and not a green, and the leaf of the same tree should exhibit a green rather than a red; and indeed, lastly, why since the light that is modify'd into these colours consists but of corpuscles moved against the _retina_ or pith of the optick nerve, it should there not barely give a stroak, but produce a colour, whereas a needle wounding likewise the eye, would not produce colour but pain. these, and perhaps other things i should think requisite to be known, before i should judge my self to have fully comprehended the true and whole nature of colours; and therefore, though by making the experiments and reflections deliver'd in this paper, i have endeavour'd somewhat to lessen my ignorance in this matter, and think it far more desireable to discover a little, than to discover nothing, yet i pretend but to make it probable by the experiments i mention, that some colours may be plausibly enough explicated in the general by the doctrine here propos'd; for whensoever i would descend to the minute and accurate explication of particulars, i find my self very sensible of the great obscurity of things, without excepting those which we never see but when they are enlightned, and confess with _scaliger_[5], _latet natura hæc_, (says he, speaking of that of colour) _& sicut aliarum rerum species in profundissima caligine inscitiæ humanæ._ [5] exercitat. 325 parag. 4 * * * * * _the_ _experimental history_ _of colours._ * * * * * part. ii. _of the nature of whiteness and_ _blackness._ chap. i. 1. though after what i have acknowledged, _pyrophilus_, of the abstruse nature of colours in _particular_, you will easily believe, that i pretend not to give you a satisfactory account of whiteness and blackness; yet not wholly to frustrate your expectation of my offering something by way of specimen towards the explication of some colours in particular, i shall make choice of these as the most simple ones, (and by reason of their mutual opposition the least hardly explicable) about which to present you my thoughts, upon condition you will take them at most to be my conjectures, not my opinions. 2. when i apply'd my self to consider, how the cause of whiteness might be explan'd by intelligible and mechanical principles, i remembred not to have met with any thing among the antient _corpuscularian_ philosophers, touching the quality we call whiteness, save that _democritus_ is by _aristotle_ said to have ascrib'd the whiteness of bodies to their smoothness, and on the contrary their blackness to their asperity.[6] but though about the latter of those qualities his opinion be allowable, as we shall see anon, yet that he heeds a favourable interpretation in what is deliver'd concerning the first, (at least if his doctrine be not mis-represented in this point, as it has been in many others) we shall quickly have occasion to manifest. but amongst the _moderns_, the most learned _gassendus_ in his ingenious epistle publish'd in the year 1642. _de apparente magnitudine solis humilis & sublimis_, reviving the _atomical_ philosophy, has, though but incidentally, deliver'd something towards the explication of whiteness upon mechanical principles: and because no man that i know of, has done so before him, i shall, to be sure to do him right, give you his sense in his own words:[7] _cogites velim_ (says he) _lucem quidem in diaphano nullius coloris videri, sed in opaco tamen terminante candicare, ac tantò magis, quantò densior seu collectior fuerit. deinde aquam non esse quidem coloris ex se candidi & radium tamen ex eâ reflexum versus oculum candicare. rursus cum plana aquæ superficies non nisi ex una parte eam reflexionem faciat: si contigerit tamen illam in aliquot bullas intumescere, bullam unamquamque reflectionem facere, & candoris speciem creare certa superficiei parte. ad hæc spumam ex aqua pura non alia ratione videri candescere & albescerere quam quod sit congeries confertissima minutissimarum bullarum, quarum unaquæque suum radium reflectit, unde continens candor alborve apparet. denique nivem nihil aliud videri quam speciem purissimæ spumæ ex bullulis quam minutissimis & confertissimis cohærentis. sed ridiculam me exhibeam, si tales meas nugas uberius proponem._ [6] _album quippe & agrum, hoc quidem asperum esse dicit, hoc vero læve. de sensu & sensib. 3. 3._ [7] epist. 2. pag. 45. 3. but though in this passage, that very ingenous person has anticipated part of what i should say; yet i presume you will for all that expect, that i should give you a fuller account of that notion of whiteness, which i have the least exceptions to, and of the particulars whence i deduce it, which to do, i must mention to you the following experiments and observations. whiteness then consider'd as a quality in the object, seems chiefly to depend upon this, that the superficies of the body that is call'd white, is asperated by almost innumerable small surfaces, which being of an almost specular nature, are also so plac'd, that some looking this way, and some that way, they yet reflect the rays of light that fall on them, not towards one another, but outwards towards the spectators eye. in this rude and general account of whiteness, it seems that besides those qualities, which are common to bodies of other colours, as for instance the minuteness and number of the superficial parts, the two chief things attributed to bodies as white are made to be, first, that its little protuberances and superficial parts be of somewhat a specular nature, that they may as little looking-glasses each of them reflect the beams it receives, (or the little picture of the sun made on it) without otherwise considerably altering them; whereas in most other colours, they are wont to be much chang'd, by being also refracted, or by being return'd to the eye, mixt with shades or otherwise. and next, that its superficial parts be so situated, that they retain not the incident rays of light by reflecting them inwards, but send them almost all back, so that the outermost corpuscles of a white body, having their various little surfaces of a specular nature, a man can from no place behold the body, but that there will be among those innumerable _superficieculæ_, that look some one way, and some another, enough of them obverted to his eye, to afford like a broken looking-glass, a confused idæa, or representation of light, and make such an impression on the organ, as that for which men are wont to call a body white. but this notion will perhaps be best explan'd by the same experiments and observations, on which it is built, and therefore i shall now advance to _them_. 4. and in the first place i consider, that the sun and other powerfully lucid bodies, are not only wont to offend, which we call to dazle our eyes, but that if any colour be to be ascrib'd to them as they are lucid, it seems it should be whiteness: for the sun at noon-day, and in clear weather, and when his face is less troubled, and as it were stained by the steams of sublunary bodies, and when his beams have much less of the atmosphere to traject in their passage to our eyes, appears of a colour more approaching to white, than when nearer the horizon, the interposition of certain sorts of fumes and vapours make him oftentimes appear either red, or at least more yellow. and when the sun shines upon that natural looking-glass, a smooth water, that part of it, which appears to this or that particular beholder, the most shin'd on, does to his eye seem far whiter than the rest. and here i shall add, that i have sometimes had the opportunity to observe a thing, that may make to my present purpose, namely, that when the sun was veil'd over as it were, with a thin white cloud, and yet was too bright to be look'd upon directly without dazling, by casting my eyes upon a smooth water, as we sometimes do to observe eclipses without prejudice to our eyes, the sun then not far from the meridian, appear'd to me not red, but so white, that 'twas not without some wonder, that i made the observation. besides, though we in _english_ are wont to say, a thing is red hot, as an expression of its being superlatively _ignitum_, (if i may so speak for want of a proper _english_ word) yet in the forges of smiths, and the furnaces of other artificers, by that which they call a white heat, they mean a further degree of _ignition_, than by that which both they and we call a red heat. 5. secondly, i consider, that common experience informs us, that as much light over-powers the eye, so when the ground is covered with snow, (a body extremely white) those that have weak eyes are wont to complain of too much light: and even those that have not, are generally sensible of an extraordinary measure of light in the air; and if they are fain to look very long upon the snow, find their sight offended by it. on which occasion we may call to mind what _xenophon_ relates, that his _cyrus_ marching his army for divers days through mountains covered with snow, the dazling splendor of its whiteness prejudic'd the sight of very many of his souldiers, and blinded some of them; and other stories of that nature be met with in writers of good note. and the like has been affirm'd to me by credible persons of my own acquaintance, and especially by one who though skill'd in physick and not ancient confess'd to me when i purposely ask'd him, that not only during his stay in _muscovy_, he found his eyes much impair'd, by being reduc'd frequently to travel in the snow, but that the weakness of his eyes did not leave him when he left that country, but has follow'd him into these parts, and yet continues to trouble him. and to this doth agree what i as well as others have observ'd, namely, that when i travell'd by night, when the ground was all cover'd with snow, though the night otherwise would not have been lightsome, yet i could very well see to choose my way. but much more remarkable to my present purpose is that, which i have met with in _olaus magnus_,[8] concerning the way of travelling in winter in the _northern_ regions, where the days of that season are so very short; for after other things not needfull to be here transcribed: _iter_, says he, _diurnum duo scilicet montana milliaria (quæ 12 italica sunt) consiciunt. nocte verò sub splendissima luna, duplatum iter consumunt aut triplatum. neque id incommodè fit, cum nivium reverberatione lunaris splendoris sublimes & declives campos illustret, ac etiam montium præcipitia ac noxias feras à lorgè prospiciant evitandas_. which testimony i the less scruple to allege, because that it agrees very well with what has been affirm'd to me by a physician of _mosco_, whom the notion i have been treating of concerning whiteness invited me to ask whether he could not see much farther when he travell'd by night in _russia_ than he could do in _england_, or elsewhere, when there was no snow upon the ground; for this ingenious person inform'd me, that he could see things at a farr greater distance, and with more clearness, when he travell'd by night on the _russian_ snow, though without the assistance of moon-shine, than we in these parts would easily be perswaded. though it seems not unlikely to me, that the intenseness of the cold may contribute something to the considerableness of the effect, by much clearing the air of darkish steams, which in these more temperate climates are wont to thicken it in snowy weather: for having purposely inquir'd of this doctor, and consulted that ingenious navigator captain _james_'s voyage hereafter to be further mention'd, i find both their relations agree in this, that in dark frosty nights they could discover more stars, and see the rest clearer than we in _england_ are wont to do. [8] gent. septen. histor. lib. 4 cap. 13. 6. i know indeed that divers learned men think, that snow so strongly affects our eye, not by a borrow'd, but a native light; but i venture to give it as a proof, that white bodies reflect more light than others, because having once purposely plac'd a parcel of snow in a room carefully darkned, that no celestial light might come to fall upon it; neither i, nor an ingenous person, (skill'd in opticks) whom i desir'd for a witness, could find, that it had any other light than what it receiv'd. and however, 'tis usual among those that travel in dark nights, that the guides wear something of white to be discern'd by, there being scarce any night so dark, but that in the free air there remains some light, though broken and debilitated perhaps by a thousand reflections from the opacous corpuscles that swim in the air, and lend it to one another before it comes to arrive at the eye. 7. thirdly, and the better to shew that white bodies reflect store of light, in comparson of those that are otherwise colour'd, i did in the darkn'd room, formerly mention'd, hold not far from the hole, at which the light was admitted, a sheet only of white paper, from whence casting the sun-beams upon a white wall, whereunto it was obverted, it manifestly appear'd both to me, and to the person i took for a witness of the experiment, that it reflected a far greater light, than any of the other colours formerly mention'd, the light so thrown upon one wall notably enlightning it, and by it a good part of the room. and yet further to show you, that white bodies reflect the beams from them, and not towards themselves, let me add, that ordinary burning-glasses, such as are wont to be employ'd to light tobacco, will not in a great while burn, or so much as discolour a sheet of white paper. insomuch that even when i was a boy, and lov'd to make tryals with burning-glasses, i could not but wonder at this odd _phænomenon_, which set me very early upon guessing at the nature of whiteness, especially because i took notice, that the image of the sun upon a white paper was not so well defin'd (the light seeming too diffus'd) as upon black, and because i try'd, that blacking over the paper with ink, not only the ink would be quickly dry'd up, but the paper that i could not burn before, would be quickly set on fire. i have also try'd, that by exposing my hand with a thin black glove over it to the warm sun, it was thereby very quickly and considerably more heated, than if i took off the glove, and held my hand naked, or put on it another glove of thin but white leather. and having thus shewn you, _pyrophilus_, that white bodies reflect the most light of any, let us now proceed, to consider what is further to be taken notice of in them, in order to our present enquiry. 8. and fourthly, whereas among the dispositions we attributed to white bodies, we also intimated this, that such bodies are apt, like _speculums_, though but imperfect ones, to reflect the light that falls on them untroubled or unstain'd, we shall besides other particulars to be met with in these papers, offer you this in favour of the conjecture; that in the darkned room several times mention'd in this treatse, we try'd that the sun-beams being cast from a coloured body upon a neighbouring white wall, the determinate colour of the body was from the wall reflected to the eye; whereas we could in divers cases manifestly alter the colour arriving at the eye, by substituting at a convenient distance, a (conveniently) colour'd (and glossy) body instead of the white wall. as by throwing the beams from a yellow body upon a blew, there would be exhibited a kind of green, as in the experiments about colours is more fully declar'd. 9. i know not whether i should on this occasion take notice, that when, as when looking upon the calm and smooth surface of a river betwixt my eye and the sun, it appear'd to be a natural _speculum_, wherein that part which reflected to my eye the entire and defin'd image of the sun, and the beams less remote from those which exhibited that image, appear'd indeed of a great and whitish brightness, but the rest comparatively dark enough: if afterwards the superficies chanc'd to be a little, but not much troubled, by a gentle breath of wind, and thereby reduc'd into a multitude of small and smooth _speculums_, the surface of the river would suitably to the doctrine lately deliver'd, at a distance appear very much of kin to white, though it would lose that brightness or whiteness upon the return of the surface to calmness and an uniform level. and i have sometimes for tryals sake brought in by a lenticular glass, the image of a river, shin'd upon by the sun, into an upper room darkn'd, and distant about a quarter of a mile from the river, by which means the numerous declining surfaces of the water appear'd so contracted, that upon the body that receiv'd the images, the whole river appear'd a very white object at two or three paces distance. but if we drew near it, this whiteness appear'd to proceed from an innumerable company of lucid reflections, from the several gently wav'd superficies of the water, which look'd near at hand like a multitude of very little, but shining scales of fish, of which many did every moment disappear, and as many were by the sun, wind and river generated anew. but though this observation seem'd sufficiently to discover, how the appearing whiteness in that case was produc'd, yet in some other cases water may have the same, though not so vivid a colour upon other accounts; for oftentimes it happens that the smooth surface of the water does appear bright or whitish, by reason of the reflection not immediatly of the images of the sun, but of the brightness of the sky; and in such cases a convenient wind may where it passes along make the surface look black, by causing many such furrows and cavities, as may make the inflected superficies of the water reflect the brightness of the sky rather inward than outward. and again if the wind increase into a storm, the water may appear white, especially near the shore and the ship, namely because the rude agitation breaks it into fome or froth. so much do whiteness and blackness depend upon the disposition of the superficial parts of a body to reflect the beams of light inward or outward. but that as white bodies reflect the most light of any, so there superficial particles are, in the sense newly deliver'd, of a specular nature, i shall now further endeavour to shew both by the making of specular bodies white, and the making of a white body specular. 10. in the fifth place then, i will inform you, that (not to repeat what _gassendus_ observes concerning water) i have for curiosity sake distill'd quicksilver in a cucurbit, fitted with a capacious glass-head, and observ'd that when the operation was perform'd by the degrees of fire requisite for my purpose, there would stick to the inside of the alembick a multitude of little round drops of _mercury_. and as you know that _mercury_ is a specular body, so each of these little drops was a small round looking-glass, and a multitude of them lying thick and near one another, they did both in my judgment, and that of those i invited to see it, make the glass they were fastened to, appear manifestly a white body. and yet as i said, this whiteness depended upon the minuteness and nearness of the little mercurial _globuli_, the convexity of whose surfaces fitted them to represent in a narrow compass a multitude of little lucid images to differingly situated beholders. and here let me observe a thing that seems much to countenance the notion i have been recommending: namely, that whereas divers parts of the sky, and especially the milky-way, do to the naked eye appear white, (as the name it self imports) yet the galaxie look'd upon through the telescope, does not shew white, but appears to be made up of a vast multitude of little starrs; so that a multitude of lucid bodies, if they be so small that they cannot singly or apart be discern'd by the eye, and if they be sufficiently thick set by one another, may by their confus'd beams appear to the eye one white body. and why it is not possible, that the like may be done, when a multitude of bright and little corpuscles being crowded together, are made to send together vivid beams to the eye, though they shine but as the planets by a borrow'd light? 11. but to return to our experiments. we may take notice, that the white of an egg, though in part transparent, yet by its power of reflecting some incident rays of light, is in some measure a natural _speculum_, being long agitated with a whisk or spoon, loses its transparency, and becomes very white, by being turn'd into froth, that is into an aggregate of numerous small bubbles, whose convex superficies fits them to reflect the light every way outwards. and 'tis worth noting, that when water, for instance, is agitated into froth, if the bubbles be great and few, the whiteness will be but faint, because the number of _specula_ within a narrow compass is but small, and they are not thick set enough to reflect so many little images or beams of the lucid body, as are requisite to produce a vigorous sensation of whiteness: and partly least it should be said, that the whiteness of such globulous particles proceeds from the air included in the froth; (which to make good, it should be prov'd that the air it self is white) and partly to illustrate the better the notion we have propos'd of whiteness, i shall add, that i purposely made this experiment, i took a quantity fair water, & put to it in a clear glass phial, a convenient quantity of oyl or spirit of turpentine, because that liquor will not incorporate with water, and yet is almost as clear and colourless as it; these being gently shaken together, the agitation breaks the oyl (which as i said, is indispos'd to mix like wine or milk _per minima_ with the water) into a multitude of little globes, which each of them reflecting outwards a lucid image, make the imperfect mixture of the two liquors appear whitish; but if by vehemently shaking the glass for a competent time you make a further comminution of the oyl into far more numerous and smaller _globuli_, and thereby confound it also better with the water, the mixture will appear of a much greater whiteness, and almost like milk; whereas if the glass be a while let alone, the colour will by degrees impair, as the oyly globes grow fewer and bigger, and at length will quite vanish, leaving both the liquors distinct and diaphanous as before. and such a tryal hath not ill succeeded, when insteed of the colourless oyl of turpentine i took a yellow mixture made of a good proportion of crude turpentine dissolv'd in that liquor; and (if i mis-remember not) it also succeeded better than one would expect, when i employ'd an oyl brought by filings of copper infused in it, to a deep green. and this (by the way) may be the reason, why often times when the oyls of some spices and of anniseeds &c. are distilled in a limbec with water, the water (as i have several times observ'd) comes over whitish, and will perhaps continue so for a good while, because if the fire be made too strong, the subtile chymical oyl is thereby much agitated and broken, and blended with the water in such numerous and minute globules, as cannot easily in a short time emerge to the top of the water, and whilst they remain in it, make it, for the reason newly intimated, look whitish; and perhaps upon the same ground a cause may be rendred, why hot water is observ'd to be usually more opacous and whitish, than the same water cold, the agitation turning the more spirituous or otherwise conveniently dispos'd particles of the water into vapours, thereby producing in the body of the liquor a multitude of small bubbles, which interrupt the free passage, that the beams of light would else have every way, and from the innermost parts of the water reflect many of them outwards. these and the like examples, _pyrophilus_, have induc'd me to suspect, that the superficial particles of white bodies, may for the most part be as well convex as smooth; i content my self to say _suspect_ and _for the most part_, because it seems not easie to prove, that when diaphanous bodies, as we shall see by and by, are reduc'd into white powders, each corpuscle must needs be of a convex superficies, since perhaps it may suffice that specular surfaces look severally ways. for (as we have seen) when a diaphanous body comes to be reduc'd to very minute parts, it thereby requires a multitude of little surfaces within a narrow compass. and though each of these should not be of a figure convenient to reflect a round image of the sun, yet even from such an inconveniently figur'd body, there may be reflected some (either streight or crooked) physical line of light, which line i call physical, because it has some breadth in it, and in which line in many cases some refraction of the light falling upon the body it depends on, may contribute to the brightness, as if a slender wire, or solid cylinder of glass be expos'd to the light, you shall see in some part of it a vivid line of light, and if we were able to draw out and lay together a multitude of these little wires or thrids of glass, so slender, that the eye could not discern a distance betwixt the luminous lines, there is little doubt (as far as i can guess by a tryal purposely made with very slender, but far less slender thrids of glass, whose aggregate was look'd upon one way white) but the whole physical superficies compos'd of them, would to the eye appear white, and if so, it will not be always necessary that the figure of those corpuscles, that make a body appear white, should be _globulous_. and as for snow it self, though the learned _gassendus_ (as we have seen above) makes it to seem nothing else but a pure frozen froth, consisting of exceedingly minute and thickset bubbles; yet i see no necessity of admitting that, since not only by the variously and curiously figur'd snow, that i have divers times had the opportunity with pleasure to observe, but also by the common snow, it rather doth appear both to the naked eye, and in a _microscope_, often, if not most commonly, to consist principally of little slender icicles of several shapes, which afford such numerous lines of light, as we have been newly speaking of. 12. sixthly, if you take a diaphanous body, as for instance a piece of glass, and reduce it to powder, the same body, which when it was entire, freely transmitted the beams of light, acquiring by contusion a multitude of minute surfaces, each of which is as it were a little, but imperfect _speculum_, is qualify'd to reflect in a confus'd manner, so many either beams, or little and singly unobservable images of the lucid body, that from a diaphanous it degenerates into a white body. and i remember, i have for trials sake taken lumps of rock crystal, and heating them red hot in a crucible, i found according to my expectation, that being quench'd in fair water, even those that remain'd in seemingly entire lumps exchang'd their translucency for whiteness, the ignition and extinction having as it were crack'd each lump into a multitude of minute bodies, and thereby given it a great multitude of new surfaces. and ev'n with diaphanous bodies, that are colour'd, there may be this way a greater degree of whiteness produced, than one would lightly think; as i remember, i have by contusion obtain'd whitish powders of _granates_, glass of _antimony_, and _emeralds_ finely beaten, and you may more easily make the experiment, by taking good venereal _vitriol_ of a deep blew, and comparing with some of the entire crystalls purposely reserv'd, some of the subtile powder of the same salt, which will comparatively exhibit a very considerable degree of whitishness. 13. seventhly, and as by a change of position in the parts, a body that is not white, may be made white, so by a slight change of the texture of its surface, a white body may be depriv'd of its whiteness. for if, (as i have try'd in gold-smiths shops) you take a piece of silver that has been freshly boyl'd, as the artificers call it, (which is done by, first brushing, and then decocting it with salt and tartar, and perhaps some other ingredients) you shall find it to be of a lovely white. but if you take a piece of smooth steel, and therewith burnish a part of it, which may be presently done, you shall find that part will lose its whiteness, and turn a _speculum_, looking almost every where dark, as other looking-glasses do, which may not a little confirm our doctrine. for by this we may guess, what it is chiefly that made the body white before, by considering that all that was done to deprive it of that whiteness, was only to depress the little protuberances that were before on the surface of the silver into one continu'd superficies, and thereby effect this, that now the image of the lucid body, and consequently a kind of whiteness shall appear to your eye, but in some place of the greater silver looking-glass (whence the beams reflected at an angle equal to that wherewith they fall on it, may reach your eye) whilst the asperity remain'd undestroy'd, the light falling on innumerable little _specula_ obverted some one way, and some another, did from all sensibly distinguishable parts of the superficies reflect confus'd beams or representations of light to the beholders eye, from whence soever he chance to look upon it. and among the experiments annex'd to this discourse, you will find one, wherein by the change of texture in bodies, whiteness is in a trice both generated and destroy'd. * * * * * chap. ii. 1. what we have discours'd of whiteness, may somewhat assist us to form a notion of blackness, those two qualities being contrary enough to illustrate each other. yet among the antient _philosophers_ i find less assistance to form a notion of blackness than of whiteness, only _democritus_ in the passage above recited out of _aristotle_ has given a general hint of the cause of this colour, by referring the blackness of bodies to their asperity. but this i call but a general hint, because those bodies that are green, and purple, and blew, seem to be so as well as black ones, upon the account of their superficial asperity. but among the _moderns_, the formerly mention'd _gassendus_, perhaps invited by this hint of _democritus_, has incidentally in another epistle given us, though a very short, yet a somewhat clearer account of the nature of blackness in these words: _existimare par est corpora suâpte naturâ nigra constare ex particulis, quarum superficieculæ scabræ sint, nec facilè lucem extrorsum reflectant._ i wish this ingenious man had enlarg'd himself upon this subject; for indeed it seems, that as that which makes a body white, is chiefly such a disposition of its parts, that it reflects (i mean without much interruption) more of the light that falls on it, than bodies of any other colour do, so that which makes a body black is principally a peculiar kind of texture, chiefly of its superficial particle, whereby it does as it were dead the light that falls on it, so that very little is reflected outwards to the eye. 2. and this texture may be explicated two, and perhaps more than two several ways, whereof the first is by supposing in the superficies of the black body a particular kind of asperity, whereby the superficial particles reflect but few of the incident beams outwards, and the rest inwards towards the body it self. as if for instance, we should conceive the surface of a black body to be asperated by an almost numberless throng of little cylinders, pyramids, cones, and other such corpuscles, which by their being thick set and _erected_, reflect the beams of light from one to another inwards, and send them too and fro so often, that at length they are lost before they can come to rebound out again to the eye. and this is the first of the two mention'd ways of explicating blackness. the other way is by supposing the texture of black bodies to be such, that either by their yielding to the beams of light, or upon some other account, they do as it were dead the beams of light, and keep them from being reflected in any plenty, or with any considerable vigour of motion, outwards. according to this notion it may be said, that the corpuscles that make up the beams of light, whether they be solary _effluviums_, or minute particles of some ætherial substance, thrusting on one another from the lucid body, do, falling on black bodies, meet with such a texture, that such bodies receive into themselves, and retain almost all the motion communicated to them by the corpuscles that make up the beams of light, and consequently reflect but few of them, or those but languidly, towards the eye, it happening here almost in like manner as to a ball, which thrown against a stone or floor, would rebound a great way upwards, but rebounds very little or not at all, when it is thrown against water, or mud, or a loose net, because the parts yield, and receive into themselves the motion, on whose account the ball should be reflected outwards. but this last way of explicating blackness, i shall content my self to have propos'd, without either adopting it, or absolutely rejecting it. for the hardness of touchstones, black marble and other bodies, that being black are solid, seem to make it somewhat improbable, that such bodies should be of so yielding a texture, unless we should say, that some bodies may be more dispos'd to yield to the impulses of the corpuscles of light by reason of a peculiar texture, than other bodies, that in other tryals appear to be softer than they. but though the former of these two explications of blackness be that, by which we shall endeavour to give an account of it, yet as we said, we shall not absolutely reject this latter, partly because they both agree in this, that black bodies reflect but little of the light that falls on them, and partly because it is not impossible, that in some cases both the disposition of the superficial particles, as to figure and position, and the yielding of the body, or some of its parts, may joyntly, though not in an equal measure concurr to the rendring of a body black. the considerations that induc'd me to propose this notion of blackness, as i explan'd it, are principally these: 3. first, that as i lately said, whiteness and blackness being generally reputed to be contrary qualities, whiteness depending as i said upon the disposition of the parts of a body to reflect much light, it seems likely, that blackness may depend upon a contrary disposition of the black bodies surface; but upon this i shall not insist. 4. next then we see, that if a body of one and the same colour be plac'd, part in the sun-beams, and part in the shade, that part which is not shin'd on will appear more of kin to blackness than the other, from which more light rebounds to the eye; and dark colours seem the blacker, the less light they are look'd upon in, and we think all things black in the dark, when they send no beams to make impressions on our organs of sight, so that shadows and darkness are near of kin, and shaddow we know is but a privation of light; and accordingly blackness seems to proceed from the paucity of beams reflected from the black body to the eye, i say the paucity of beams, because those bodies that we call black, as marble, jeat, &c. are short of being perfectly so, else we should not see them at all. but though the beams that fall on the sides of those erected particles that we have been mentioning, do few of them return outwards, yet those that fall upon the points of those cylinders, cones, or pyramids, may thence rebound to the eye, though they make there but a faint impression, because they arrive not there, but mingl'd with a great proportion of little shades. this may be confirm'd by my having procur'd a large piece of black marble well polish'd, and brought to the form of a large sphærical and concave _speculum_; for on the inside this marble being well polish'd, was a kind of dark looking-glass, wherein i could plainly see a little image of the sun, when that shin'd upon it. but this image was very far from offending and dazling my eyes, as it would have done from another _speculum_; nor, though the _speculum_ were large, could i in a long time, or in a hot sun set a piece of wood on fire, though a far less _speculum_ of the same form, and of a more reflecting matter, would have made it flame in a trice. 5. and on this occasion we may as well in reference to something formerly deliver'd concerning whiteness, as in reference to what has been newly said, subjoyn what we further observ'd touching the differing reflections of light from white and black marble, namely, that having taking a pretty large mortar of white marble, new and polish'd in the inside, and expos'd it to the sun, we found that it reflected a great deal of glaring light, but so dispers'd, that we could not make the reflected beams concurr in any such conspicuous _focus_, as that newly taken notice of in the black marble, though perhaps there may enough of them be made to meet near the bottom, to make some kind of _focus_, especially since by holding in the night-time a candle at a convenient distance, we were able to procure a concourse of some, though not many of the reflected beams, at about two inches distant from the bottom of the mortar: but we found the heat even of the sunbeams so dispersedly reflected to be very languid, even in comparison of the black marbles _focus_. and the little picture of the sun, that appear'd upon the white marble as a _speculum_, was but very faint and exceeding ill defin'd. secondly, that taking two pieces of plain and polish'd surfaces, and casting on them successively the beams of the same candle, in such manner, as that the neighbouring superficies being shaded by an opacous and perforated body, the incident beams were permitted to pass but through a round hole of about half an inch diameter, the circle of light that appear'd on the white marble was in comparison very bright, but very ill defin'd; whereas that on the black marble was far less luminous, but much more precisely defin'd. 6. thirdly, when you look upon a piece of linnen that has small holes in it, those holes appear very black, and men are often deceiv'd in taking holes for spots of ink; and painters to represent holes, make use of black, the reason of which seems to be, that the beams that fall on those holes, fall into them so deep, that none of them is reflected back to the eye. and in narrow wells part of the mouth seems black, because the incident beams are reflected downwards from one side to another, till they can no more rebound to the eye. we may consider too, that if differing parts of the same piece of black velvet be stroak'd opposite ways, the piece of velvet will appear of two distinct kinds of blackness, the one far darker than the other, of which disparity the reason seems to be, that in the less obscure part of the velvet, the little silken piles whereof 'tis made up, being inclin'd, there is a greater part of each of them obverted to the eye, whereas in the other part the piles of silk being more erected, there are far fewer beams reflected outwards from the lateral parts of each pile, so that most of those that rebound to the eye, come from the tops of the piles, which make but a small part of the whole superficies, that may be cover'd by the piece of velvet. which explication i propose, not that i think the blackness of the velvet proceeds from the cause assign'd, since each single pile of silk is black by reason of its texture, in what position soever you look upon it; but that the greater blackness of one of these tuffts seems to proceed from the greater paucity of beams reflected from it, and that from the fewness of those parts of a surface that reflect beams, and the multitude of those shaded parts that reflect none. and i remember, that i have oftentimes observ'd, that the position of particular bodies far greater than piles of silk in reference to the eye, may notwithstanding their having each of them a colour of its own, make one part of their aggregate appear far darker than the other; for i have near great towns often taken notice, that a cart-load of carrots pack'd up, appear'd of a much darker colour when look'd upon, where the points of the carrots were obverted to the eye, than where the sides of them were so. 7. fourthly, in a darkned room, i purposely observ'd, that if the sun-beams, which came in at the hole were receiv'd upon white or any other colour, and directed to a convenient place of the room, they would manifestly, though not all equally, encrease the light of that part; whereas if we substituted, either a piece of black cloth or black velvet, it would so dead the incident beams, that the place (newly mention'd) whereto i obverted the black body, would be less enlightned than it was before, when it received its light but from the weak and oblique reflections of the floor and walls of a pretty large room, through which the beams that came in at the hole were confusedly and brokenly dispers'd. 8. fifthly, and to shew that the beams that fall on black bodies, as they do not rebound outwards to the eye, so they are reflected towards the body it self, as the nature of those erected particles to which we have imputed blackness, requires, we will add an experiment that will also confirm our doctrine touching whiteness; namely, that we took a broad and large tile, and having whitened over one half of the superficies of it, and black'd the other, we expos'd it to the summer sun; and having let it lye there a convenient time (for the difference is more apparent, if it have not lain there too long) we found, as we expected, that whilst the whited part of the tile remained cool enough, the black'd part of the same tile was grown not only sensible, but very hot, (sometimes to a strong degree.) and to satisfie some of our friends the more, we have sometimes left upon the surface of the tile, besides the white and black parts thereof, a part that retain'd the native red of the tile it self, and exposing them to the sun, we observ'd this last mention'd to have contracted a heat in comparison of the white, but a heat inferiour to that of the black, of which the reason seems to be, that the superficial particles of black bodies, being, as we said, more erected, than those of white or red ones, the corpuscles of light falling on their sides, being for the most part reflected inwards from one particle to another, and thereby engag'd as it were and kept from rebounding upwards, they communicate their brisk motion, wherewith they were impell'd against the black body, (upon whose account had they fallen upon a white body, they would have been reflected outwards) to the small parts of the black body, and thereby produce in those small parts such an agitation, as (when we feel it) we are wont to call heat. i have been lately inform'd, that an observation near of kin to ours, has been made by some learned men in _france_ and _italy_, by long exposing to a very hot sun, two pieces of marble, the one white, the other black; but though the observation be worthy of them, and may confirm the same truth with our experiment, yet besides that our tryal needs not the summer, nor any great heat to succeed, it seems to have this advantage above the other, that whereas bodies more solid, and of a closer texture, though they use to be more slowly heated, are wont to receive a greater degree of heat from the sun or fire, than (_cæteris paribus_) bodies of a slightest texture; i have found by the information of stone-cutters, and by other ways of enquiry, that black marble is much solider and harder than white, so that possibly the difference betwixt the degrees of heat they receive from the sunbeams will by many be ascrib'd to the difference of their texture, rather than to that of their colour, though i think our experiment will make it probable enough that the greater part of that difference may well be ascrib'd to that disposition of parts, which makes the one reflect the sunbeams inward; and the other outwards. and with this doctrine accords very well, that rooms hung with black, are not only darker than else they would be, but are wont to be warmer too; insomuch that i have known a great lady, whose constitution was somewhat tender, complain that she was wont to catch cold, when she went out into the air, after having made any long visits to persons, whose rooms were hung with black. and this is not the only lady i have heard complain of the warmth of such rooms, which though perhaps it may be partly imputed to the _effluvia_ of those materials wherewith the hangings were dy'd, yet probably the warmth of such rooms depends chiefly upon the same cause that the darkness does; as (not to repeat what i formerly noted touching my gloves,) to satisfie some curious persons of that sex, i have convinc'd them, by tryall, that of two pieces of silken stuff given me by themselves, and expos'd in their presence, to the same window, shin'd on by that sun, the white was _considerably_ heated, when the black was not so much as _sensibly_ so. 9. sixthly, i remember, that acquainting one day a _virtuoso_ of unsuspected credit, that had visited hot countries, with part of what i have here deliver'd concerning blackness, he related to me by way of confirmation of it, a very notable experiment, which he had both others make, and made himself in a warm climate, namely, that having carefully black'd over eggs, and expos'd them to the hot sun, they were thereby in no very long time well roasted, to which effect i conceive the heat of the climate must have concurr'd with the disposition of the black surface to reflect the sunbeams inward, for i remember, that having made that among other tryals in _england_, though in summer-time, the eggs i expos'd, acquir'd indeed a considerable degree of heat, but yet not so intense a one, as prov'd sufficient to roast them. 10. seventhly, and lastly, our conjectures at the nature of blackness may be somewhat confirm'd by the (formerly mention'd) observation of the blind _dutch-man_, that discerns colours with his fingers; for he says, that he feels a greater roughness upon the surfaces of black bodies, than upon those of red, or yellow, or green. and i remember, that the diligent _bartholinus_ says,[9] that a blind earl of _mansfield_ could distinguish white from black only by the touch, which would sufficiently argue a great disparity in the asperities, or other superficial textures of bodies of those two colours, if the learn'd relator had affirm'd the matter upon his own knowledge. [9] hist. anatom. cent. 3. hist. 44. ii. these, _pyrophilus_, are the chief things that occurr to me at present, about the nature of whiteness and blackness, which it they have rendred it so much as probable, that in _most_; or at least _many_ cases, the causes of these qualities may be such as i have adventur'd to deliver, it is as much as i pretend to; for till i have opportunity to examine the matter by some further tryals, i am not sure, but that in some white and black bodies, there may concurr to the colour some peculiar texture or disposition of the body, whereby the motion of the small corpuscles that make up the incident beams of light, may be differingly modify'd, before they reach the eye, especially in this, that white bodies do not only copiously reflect those incident corpuscles outwards, but reflect them briskly, and do not otherwise alter them in the manner of their motion. nor shall i now stay to enquire, whether some of those other ways, (as a disposition to alter the velocity, the rotation, or the order and manner of appulse so the eye of the reflected corpuscles that compos'd the incident beams of light) which we mention'd when we consider'd the production of colours in general, may not in some cases be applicable to those of white and black bodies: for i am yet so much a _seeker_ in this matter, and so little wedded to the opinions i have propos'd, that what i am to add shall be but the beginning of a collection of experiments and observation towards the history of whiteness and blackness, without at present interposing my explications of them, that so, i may assist your enquires without much fore-stalling or biassing your judgment. * * * * * experiment in consort, touching whiteness & blackness. * * * * * experiment i. having promis'd in the 114, and 115. pages of the foregoing discourse of whiteness and blackness, to shew, that those two colours may by a change of texture in bodies, each of them apart diaphanous and colourless, be at pleasure and in a trice as well generated as destroy'd, we shall begin with experiments that may acquit us of that promise. take then what quantity you please of fair water, and having heated it, put into it as much good common sublimate, as it is able to dissolve, and (to be sure of having it well glutted:) continue putting in the sublimate, till some of it lye untouch'd in the bottom of the liquor, filter this solution through cap-paper, to have it cleer and limpid, and into a spoonfull or two thereof, (put into a clean glass vessel,) shake about four or five drops (according as you took more or less of this solution) of good limpid spirits of urine, and immediately the whole mixture will appear white like milk, to which mixture if you presently add a convenient proportion of rectifi'd _aqua fortis_ (for the number of drops is hard to determine, because of the differing strength of the liquor, but easily found by tryal) the whiteness will presently disappear, and the whole mixture become transparent, which you may, if you please, again reduce to a good degree of whiteness (though inferiour to the first) onely by a more copious affusion of fresh spirit of urine. _n_. first, that it is not so necessary to employ either _aqua fortis_ or spirit of urine about this experiment, but that we have made it with other liquors instead of these, of which perhaps more elsewhere. secondly, that this experiment, though not made with the same _menstruums_, nor producing the same colour is yet much of kin to that other to be mentioned in this tract among our other experiments of colours, about turning a solution of præcipitate into an orange-colour, and the chymical reason being much alike in both, the annexing it to one of them may suffice for both. _experiment ii._ make a strong infusion of broken galls in fair water, and having filtred it into a clean vial, add more of the same liquor to it, till you have made it somewhat transparent, and sufficiently diluted the colour, for the credit of the experiment, lest otherwise the darkness of the liquor might make it be objected, that 'twas already almost ink; into this infusion shake a convenient quantity of a cleer, but very strong solution of vitriol, and you shall immediately see the mixture turn black almost like ink, and such a way of producing blackness is vulgar enough; but if presently after you doe upon this mixture drop a small quantity of good oyl of vitriol, and, by shaking the vial disperse it nimbly through the two other liquors, you shall (if you perform your part well, and have employ'd oyl of vitriol cleer and strong enough) see the darkness of the liquor presently begin to be discuss'd, and grow pretty cleer and transparent, losing its inky blackness, which you may again restore to it by the affusion of a small quantity of a very strong solution of salt of tartar. and though neither of these atramentous liquors will seem other than very pale ink, if you write with a clean pen dipt in them, yet that is common to them with some sorts of ink that prove very good when dry, as i have also found, that when i made these carefully, what i wrote with either of them, especially with the former, would when throughly dry grow black enough not to appear bad ink. this experiment of taking away and restoring blackness from and to the liquors, we have likewise tryed in common ink; but there it succeeds not so well, and but very slowly, by reason that the gum wont to be employed in the making it, does by its tenacity oppose the operations of the above mention'd saline liquors. but to consider gum no more, what some kind of præcipitation may have to do in the producing and destroying of inks without it, i have elsewhere given you some occasion and assistance to enquire; but i must not now stay to do so my self, only i shall take notice to you, that though it be taken for granted that bodies will not be præcipitated by alcalizat salts, that have not first been dissolved in some acid _menstruums_, yet i have found upon tryals, which my conjectures lead me to make on purpose, that divers vegetables _barely infus'd_, or, _but slightly decocted in common water_, would, upon the affusion of a strong and cleer _lixivium_ of potashes, and much more of some other præcipitating liquors that i sometimes employ, afford good store of a crudled matter, such as i have had in the præcipitations of vegetable substances, by the intervention of acid things, and that this matter was easily separable from the rest of the liquor, being left behind by it in the filtre; and in making the first ink mention'd in this experiment, i found that i could by filtration separate pretty store of a very black pulverable substance, that remain'd in the filtre, and when the ink was made cleer again by the oyl of vitriol, the affusion of dissolv'd _sal tartari_ seem'd but to præcipitate, and thereby to unite and render conspicuous the particles of the black mixture that had before been dispers'd into very minute and singly invisible particles by the incisive and resolving power of the highly corrosive oyl of vitriol. and to manifest, _pyrophilus_, that galls are not so requisite as many suppose to the making atramentous liquors, we have sometimes made the following experiment, we took dryed rose leaves and decocted them for a while in fair water, into two or three spoonfulls of this decoction we shook a few drops of a strong and well filtrated solution of vitriol (which perhaps had it been green would have done as well) and immediately the mixture did turn black, and when into this mixture presently after it was made, we shook a just proportion of _aqua fortis_, we turn'd it from a black ink to a deep red one, which by the affusion of a little spirit of urine may be reduc'd immediately to an opacous and blackish colour. and in regard, _pyrophilus_, that in the former experiments, both the infusion of galls, and the decoction of roses, and the solution of copperis employ'd about them, are endow'd each of them with its own colour, there may be a more noble experiment of the sudden production of blackness made by the way mention'd in the second section of the second part of our essays, for though upon the confusion of the two liquors there mention'd, there do immediately emerge a very black mixture, yet both the infusion of _orpiment_ and the solution of _minium_ were before their being joyn'd together, limpid and colourless. _experiment iii._ if pieces of white harts-horn be with a competent degree of fire distill'd in a glass-retort, they will, after the avolation of the flegm, spirit, volatile salt, and the looser and lighter parts of the oleagenous substance, remain behind of a cole-black colour. and even ivory it self being skilfully burnt (how i am wont to do it, i have elsewhere set down) affords painters one of the best and deepest blacks they have, and yet in the instance of distill'd harts-horn, the operation being made in glass-vessels carefully clos'd, it appears there is no extraneous black substance that insinuates it self into white harts-horn, and thereby makes it turn black; but that the whiteness is destroy'd, and the blackness generated, only by a change of texture, made in the burnt body, by the recess of some parts and the transposition of others. and though i remember not that in many distillations of harts-horn i ever sound the _cap. mort_. to pass from black to a true whiteness, whilst it continu'd in clos'd vessels, yet having taken out the cole-black fragments, and calcin'd them in open vessels, i could in few hours quite destroy that blackness, & without sensibly changing their bulk or figure, reduce them to great whiteness. so much do these two colours depend upon the disposition of the little parts, that the bodies wherein they are to be met with do consist of. and we find, that if whitewine tartar, or even the white crystalls of such tartar be burnt without being truly calcin'd, the _cap. mortuum_ (as the chymists call the more fixt part) will be black. but if you further continue the calcination till you have perfectly incinerated the tartar, & kept it long enough in a strong fire, the remaining _calx_ will be white. and so we see that not only other vegetable substances, but even white woods, as the hazel, will yield a black charcoal, and afterwards whitish ashes; and so animal substances naturally white, as bones and eggshels, will grow black upon the being burnt, and white again when they are perfectly calcin'd. _experiment iv._ but yet i much question whether that rule delivered by divers, as well philosophers as chymists, _adusta nigra, sed perusta alba_, will hold as universally as is presum'd, since i have several examples to allege against it: for i have found that by burning alablaster, so as both to make it appear to boyl almost like milk, and to reduce it to a very fine powder, it would not at all grow black, but retain its pure and native whiteness, and though by keeping it longer than is usual in the fire, i produced but a faint yellow, even in that part of the powder that lay nearest the top of the crucible, yet having purposely enquired of an experienced stone-cutter, who is curious enough in tryng conclusions in his own trade, he told me he had found that if alabaster or plaster of paris be very long kept in a strong fire, the whole heap of burnt powder would exchange its whiteness for a much deeper colour than the yellow i observ'd. lead being calcin'd with a strong fire turns (after having purhaps run thorough divers other colour) into _minium_, whose colour we know is a deep red; and if you urge this _minium_, as i have purposely done with a strong fire, you may much easier find a glassie and brittle body darker than _minium_, than any white _calx_ or glass. 'tis known among chymists, that the white _calx_ of antimony, by the further and more vehement operation of the fire, may be melted into glass, which we have obtain'd of a red colour, which is far deeper than that of the _calx_ of burnt antimony, and though common glafs of antimony being usually adulterated with _borax_, have its colour thereby diluted, oftentimes to a very pale yellow; yet not onely ours made more sincerily, was, as we said, of a colour less remote from black, than was the _calx_; but we observ'd, that by melting it once or twice more, and so exposing it to the further operation of the fire, we had, as we expected, the colour heightned. to which we shall add but this one instance, (which is worth the taking notice of in reference to colours:) that, if you take blew, but unsophisticated, vitriol, and burn it very slowly, and with a gentle degree of heat, you may observe, that when it has burnt but a little, and yet so far as that you may rub it to powder betwixt your fingers, it will be of a white or whitish colour; but if you prosecute the calcination, this body which by a light adustion was made white, will pass through other colours, as gray, yellowish, and red; and if you further burn it with a long and vehement fire, by that time it comes to be _perustum_, it will be of a dark purple, nearer to black, not only than the first _calx_, but than the vitriol before it at all felt the fire. i might add that _crocus_ _martis_ (_per se_ as they call it) made by the lasting violence of the reverberated flames is not so near a kin to white, as the iron or steel that afforded it was before its calcinations; but that i suppose, these instances may suffice to satisfie you, that minerals are to be excepted out of the forementioned rule, which perhaps, though it seldome fail in substances belonging to the vegetable or animal kingdome, may yet be question'd even in some of these, if that be true, which the judicious traveller _bellonius_ affirms, that charcoales made out of the wood of _oxycæder_ are white; and i could not find that though in retorts hartshorn and other white bodies will be denigrated by heat, yet camphire would not at all lose its whiteness, though i have purposely kept it in such a heat, as made it melt and boyl. _experiment v._ and now i speak of camphire, it puts me in mind of adding this experiment, that, though as i said in clos'd glasses, i could not denigrate it by heat, but it would sublime to the sides and top of the glass, as it was before, yet not only it will, being set on fire in the free air, send forth a copious smoak, but having purposely upon some of it that was flaming, clapt a large glass, almost in the form of a hive, (but more slender only) with a hole at the top, (which i caus'd to be made to trye experiments of fire and flame in) it continued so long burning that it lin'd all the inside of the glass with a soot as black as ink, and so copious, that the closeness of the vessel consider'd, almost all that part of the white camphire that did take fire, seem'd to have been chang'd into that deep black substance. _experiment vi_ and this also brings into my mind another experiment that i made about the production of blackness, whereof, for reasons too long to be here deduced, i expected and found a good success, an it was this: i took rectifi'd oyl of vitriol (that i might have the liquor clean as well as strong) and by degrees mixt with it a convenient proportion of the essential oyl, as chymists call it, of wormwood, drawn over with store of water in a limbec, and warily distilling the mixture in a retort, there remain'd a scarce credible quantity of dry matter, black as a coal. and because the oyl of wormwood, though a chymical oyl drawn by a _virtuoso_, seem'd to have somewhat in it of the colour of the plant, i substituted in its room, the pure and subtile essential oyl of winter-savory, and mixing little by little this liquor, with (if i mis-remember not) an equal weight of the formerly mention'd rectifi'd oyl of vitriol, and distilling them as before in a retort, besides what there pass'd over into the receiver, even these two clear liquors left me a considerable proportion, (though not so great as the two former) of a substance black as pitch, which i yet keep by me as a rarity. _experiment vii._ a way of whiting wax cheaply and in great quantity may be a thing of good oeconomical use, and we have elsewhere set down the practice of trades-men that blanch it; but here treating of whiteness only in order to the philosophy of colours, i shall not examine which of the slow wayes may be best employ'd, to free wax from the yellow melleous parts, but shall rather set down a quick way of making it white, though but in very small quantities. take then a little yellow wax, scraped or thinly sliced, and putting it into a bolts-head or some other convenient glass, pour to it a pretty deal of spirit of wine, and placing the vessel in warm sand, encrease the heat by degrees, till the spirit of wine begin to simper or to boyl a little; and continuing that degree of fire, if you have put liquor enough, you will quickly have the wax dissolv'd, then taking it off the fire, you may either suffer it to cool as hastily as with safety to the glass you can, or pour it whilst 'tis yet hot into a filtre of paper, and either in the glass where it cools, or in the filtre, you will soon find the wax and _menstruum_ together reduc'd into a white substance, almost like butter, which by letting the spirit exhale will shrink into a much lesser bulk, but still retaining its whiteness. and that which is pretty in the working of this magistery of wax, is, that the yellowness vanishes, neither appearing in the spirit of wine that passes limpid through the filtre, nor in the butter of wax, if i may so call it, that, as i said, is white. _experiment viii._ there is an experiment, _pyrophilus_, which though i do not so exactly remember, and though it be somewhat nice to make, yet i am willing to acquaint you with, because the thing produc'd, though it be but a curiosity, is wont not a little to please the beholders, and it is a way of turning by the help of a dry substance, an almost golden-colour'd concrete, into a white one, the several tryals are not at present so fresh in my memory to enable me to tell you certainly, whether an equal onely or a double weight of common sublimate must be taken in reference to the tinglass, but if i mistake not, there was in the experiment that succeeded best, two parts of the former taken to one of the latter. these ingredients being finely powdred and exactly mix'd, we sublim'd together by degrees of fire (the due gradation of which is in this experiment a thing of main importance) there ascended a matter of a very peculiar texture, for it was for the most part made up of very thin, smooth, soft and slippery plates, almost like the finest sort of the scales of fishes, but of so lovely a white inclining to pearl-colour, and of so curious and shining a gloss, that they appear'd in some respect little inferiour to orient pearls, and in other regards, they seem'd to surpass them, and were applauded for a sort of the prettiest trifles that we had ever prepar'd to amuse the eye. i will not undertake that though you'l hardly miss changing the colour of your shining tinglass, yet you will the first or perhaps the second time hit right upon the way of making the glistring sublimate i have been mentioning. _experiment ix._ when we dissolve in _aqua fortis_ a mixture of gold and silver melted into one lump, it usually happens that the powder of gold that falls to the bottom, as not being dissoluble by that _menstruum_, will not have its own yellow, but appear of a black colour, though neither the gold, nor the silver, nor the _aqua fortis_ did before manifest any blackness. and divers alchymists, when they make solutions of minerals they would examine, are very glad, if they see a black powder præcipitated to the bottom, taking it for a hopefull sign, that those particles are of a golden nature, which appear in a colour so ordinary to gold parted from other metalls by _aqua fortis_, that it is a trouble to the refiner to reduce the præcipitated _calx_ to its native colour. for though, (as we have try'd,) that may be quickly enough done by fire, which will make this gold look very gloriously (as indeed 'tis at least one of the best wayes that is practis'd for the refining of gold,) yet it requires both watchfulness and skill, to give it such a degree of fire as will serve to restore it to its lustre, without giving it such a one, as may bring it to fusion, to which the minuteness of the _corpuseles_ it consists of makes the powder very apt. and this brings into my mind, that having taken a flat and bright piece of gold, that was refin'd by a curious and skilfull person on purpose to trye to what height of purity gold could be brought by art, i found that this very piece, as glorious as it look'd, being rubb'd a little upon a piece of fine clean linnen, did sully it with a kind of black; and the like i have observ'd in refin'd silver, which i therefore mention, because i formerly suspected that the impurity of the metall might have been the only cause of what i have divers times obferv'd in wearing silver-hilted swords, namely, that where they rubb'd upon my clothes, if they were of a light-colour'd cloath, the affriction would quickly black them; and congruously hereunto i have found pens blackt almost all over, when i had a while carri'd them about me in a silver ink-case. to which i shall only add, that whereas in these several instances of denigration, the metalls are worn off, or otherwise reduc'd into very minute parts, that circumstance may prove not unworthy your notice. _experiment x._ that a solution of silver does dye hair of a black colour, is a known experiment, which some persons more curious than dextrous, have so unluckily made upon themselves as to make their friends very merry. and i remember that the other day, i made my self some sport by an improvement of this observation, for having dissolv'd some pure silver in _aqua fortis_, and evaporated the _menstruum ad siccitatem_, as they speak, i caus'd a quantity of fair water to be pour'd upon the _calx_ two or three several times, and to be at each evaporated, till the _calx_ was very drye, and all the greenish blewness that is wont to appear in common crystals of silver, was quite carry'd away. then i made those i meant to deceive, moisten some part of their skin with their own spittle, and slightly rub the moistned parts with a little of this prepar'd silver, whereupon they admir'd to see, that a snow-white body laid upon the white skin should presently produce a deep blackness, as if the stains had been made with ink, especially considering that this blackness could not, like that produc'd by ordinary ink, be readily wash'd off, but requir'd many hours, and part of it some dayes to its obliteration. and with the same white _calx_ and a little fair water we likewise stain'd the white hafts of knives, with a lasting black in those parts where the _calx_ was plentifully enough laid on, for where it was laid on but very thinly, the stain was not quite of so deep a colour. _experiment xi_ the cause of the blackness of those many nations, which by one common name we are wont to call _negroes_, has been long since disputed of by learned men, who possibly had not done amiss, if they had also taken into consideration, why some whole races of other animals besides men, as foxes and hares, are distinguish'd by a blackness not familiar to the generality of animals of the same species; the general opinion (to be mention'd a little lower) has been rejected even by some of the antient geographers, and among our moderns _ortelius_ and divers other learned men have question'd it. but this is no place to mention what thoughts i have had to and fro about these matters: only as i shall freely acknowledge, that to me the inquiry seems more abstruse than it does to many others, and that because consulting with authors, and with books of voyages, and with travellers, to satisfie my self in matters of fact, i have met with some things among them, which seem not to agree very well with the notions of the most classick authors concerning these things; for it being my present work to deliver rather matters historical than theorys, i shall annex some few of my collections, instead of a solemn disputation. it is commonly presum'd that the heat of the climate wherein they live, is the reason, why so many inhabitants of the scorching regions of _africa_ are black; and there is this familiar observation to countenance this conjecture, that we plainly see that mowers, reapers, and other countrey-people, who spend the most part of the hot summer dayes expos'd to the sun, have the skin of their hands and faces, which are the parts immediately expos'd to the sun and air, made of a darker colour than before, and consequently tending to blackness; and contrarywise we observe that the _danes_ and some other people that inhabit cold climates, and even the _english_ who feel not so rigorous a cold, have usually whiter faces than the _spaniards_, _portugalls_ and other european inhabitants of hotter climates. but this argument i take to be far more specious than convincing; for though the heat of the sun may darken the colour of the skin, by that operation, which we in _english_ call sun-burning, yet experience doth not evince, that i remember, that that heat alone can produce a discolouring that shall amount to a true blackness, like that of _negroes_, and we shall see by and by that even the children of some _negroes_ not yet 10. dayes old (perhaps not so much by three quarters of that time) will notwithstanding their infancy be of the same hue with their parents. besides, there is this strong argument to be alleg'd against the vulgar opinion, that in divers places in _asia_ under the same parallel, or even of the same degree of latitude with the _african_ regions inhabited by blacks, the people are at most but tawny;[10] and in _africa_ it self divers nations in the empire of _ethiopia_ are not _negroes_, though situated in the torrid zone, and as neer the æquinoctial, as other nations that are so (as the black inhabitants of _zeylan_ and _malabar_ are not in our globes plac'd so near the line as _amara_ the famousest place in _ethiopia_.) moreover, (that which is of no small moment in our present disquisition) i find not by the best navigators and travellers to the _west-indies_, whose books or themselves i have consulted on this subject, that excepting perhaps one place or two of small extent, there are any blacks originally natives of any part of _america_ (for the blacks now there have been by the _europeans_ long transplanted thither) though the new world contain in it so great a variety of climates, and particularly reach quite cross the torri'd zone from one tropick to another. and enough it be true that the _danes_ be a whiter people than the _spaniards_, yet that may proceed rather from other causes (not here to be enquired into) than from the coldness of the climate, since not onely the _swedes_ and other inhabitants of those cold countreys, are not usually so white as the _danes_, nor whiter than other nations in proportion to their vicinity to the pole. [and since the writing of the former part of this essay, having an opportunity on a solemn occasion to take notice of the numerous train of some extraordinary embassadours sent from the _russian_ emperour to a great monarch, observ'd, that (though it were then winter) the colour of their hair and skin was far less whitish than the _danes_ who inhabit a milder region is wont to be, but rather for the most part of a darkish brown; and the physician to the embassadour with whom those _russes_ came, being ask'd by me whether in _muscovy_ it self the generality of the people were more inclin'd to have dark-colour'd hair than flaxen, he answer'd affirmatively; but seem'd to suspect that the true and antient _russians_, a sept of whom he told me he had met with in one of the provinces of that vast empire, were rather white like the _danes_, than any thing near so brown as the present _muscovites_ whom he guesses to be descended of the _tartars_, and to have inherited their colour from them.] but to prosecute our former discourse, i shall add for further proof of the conjecture i was countenancing that good authors inform us that there are _negroes_ in _africa_ not far from the _cape of good hope_, and consequently beyond the southern tropick, and without the torrid zone, much about the same northern latitude (or very little more) wherein there are divers _american_ nations that are not _negroes_, and wherein the inhabitants of _candia_, some parts of _sicily_, and even of _spain_ are not so much as tawny-mores. but (which is a fresh and strong argument against the common opinion,) i find by our recent relations of _greenland_ (our accounts whereof we owe to the curiosity of that royal _virtuoso_ the present king of _denmark_,) that the inhabitants are olive-colour'd, or rather of a darker hiew. but if the case were the same with men, and those other kinds of animals i formerly nam'd, i should offer something as a considerable proof, that, cold may do much towards the making men white or black, and however i shall let down the observation as i have met with it, as worthy to come into the history of whiteness and blackness, and it is, that in some parts of _russia_ and of _livonia_ it is affirm'd by _olaus magnus_ and others, that hares and foxes (some add partridges) which before were black, or red, or gray, do in the depth of winter become white by reason of the great cold; (for that it should be, as some conceive, by looking upon the snow, seems improbable upon divers accounts) and i remember that having purposely enquir'd of a _virtuoso_ who lately travell'd through _livonia_ to _mosco_ concerning the truth of this tradition, he both told me, he believ'd it, and added, that he saw divers of those lately nam'd animals either in _russia_ or _livonia_, (for i do not very well remember whether of the two) which, though white when he saw them in winter, they assur'd him had been black, or of other colours before the winter began, and would be so again when it was over. but for further satisfaction, i also consulted one that had for some years been an eminent physician in _russia_, who though he rejected some other traditions that are generally enough believ'd concerning that countrey, told me nevertheless, that he saw no cause to doubt of this tradition of _olaus magnus_ as to foxes and hares, not onely because 'tis the common and uncontroul'd assertion of the natives, but also because he himself in the winter could never that he remember'd see foxes and hares of any other colour than white; and i my self having seen a small white fox brought out of _russia_ into _england_ towards the latter end of winter, foretold those that shew'd him me, that he would change colour in summer, and accordingly coming to look upon him again in _july_, i found that the back and sides, together with the upper part of the head and tayl were already grown of a dark colour, the lower part of the head and belly containing as yet a whiteness. let me add, that were it not for some scruple i have, i should think more than what _olaus_ relates, confirm'd by the judicious _olearius_, who was twice employ'd into those parts as a publick minister, who in his account of _moscovy_ has this passage: _the hares there are gray; but in some provinces they grow white in the winter_. and within some few lines after: _it is not very difficult to find the cause of this change, which certainly proceeds only from the outward cold, since i know that even in summer, hares will change colour, if they be kept a competent time in a cellar_; i say, were it not for some scruple, because i take notice, that in the same page the author affirms, that the like change of colour that happens to hares in some provinces of _muscovy_, happens to them also in _livonia_, and yet immediately subjoyns, that in _curland_ the hares vary not their colour in winter, though these two last named countries be contiguous, (that is) sever'd only by the river of _dugna_; for it is scarce conceivable how cold alone should have, in countries so near, so strangely differing an operation, though no less strange a thing is confess'd by many, that ascribe the complexion of _negroes_ to the heat of the sun, when they would have the river of _cenega_ so to bound the _moors_, that though on the north-side they are but tawny, on the other side they are black. [10] olearius voyage de mosco. et de perse _liv_. 3. there is another opinion concerning the complexion of _negroes_, that is not only embrac'd by many of the more vulgar writers, but likewise by that ingenious traveller mr. _sandys_, and by a late most learned critick, besides other men of note, and these would have the blackness of _negroes_ an effect of _noah's_ curse ratify'd by god's, upon _cham_; but though i think that even a naturalist may without disparagement believe all the miracles attested by the holy scriptures, yet in this case to flye to a supernatural cause, will, i fear, look like shifting off the difficulty, instead of resolving it; for we enquire not the first and universal, but the proper, immediate, and physical cause of the jetty colour of _negroes_; and not only we do not find expressed in the scripture, that the curse meant by _noah_ to _cham_, was the blackness of his posterity, but we do find plainly enough there that the curse was quite another thing, namely that he should be a servant of servants, that is by an ebraism, a very abject servant to his brethren, which accordingly did in part come to pass, when the _israelites_ of the posterity of _sem_, subdued the _canaanites_, that descended from _cham_, and kept them in great subjection. nor is it evident that blackness is a curse, for navigators tell us of black nations, who think so much otherwise of their own condition, that they paint the devil white. nor is blackness inconsistent with beauty, which even to our european eyes consists not so much in colour, as an advantageous stature, a comely symmetry of the parts of the body, and good features in the face. so that i see not why blackness should be thought such a curse to the _negroes_, unless perhaps it be, that being wont to go naked in those hot climates, the colour of their skin does probably, according to the doctrine above deliver'd, make the sun-beams more scorching to them, than they would prove to a people of a white complexion. greater probability there is, that the principal cause (for i would not exclude all concurrent ones) of the blackness of _negroes_ is some peculiar and seminal impression, for not onely we see that _blackmore_ boyes brought over into these colder climates lose not their colour; but good authors inform us, that the off-spring of _negroes_ transplanted out of _africa_, above a hundred years ago, retain still the complexion of their progenitors, though possibly in tract of time it will decay; as on the other side, the white people removing into very hot climates, have their skins by the heat of the sun scorch'd into dark colours; yet neither they, nor their children have been observ'd, even in the countreys of _negroes_, to descend to a colour amounting to that of the natives; whereas i remember i have read in _pisos_[11] excellent account of _brasile_, that betwixt the _americans_ and _negroes_ are generated a distinct sort of men, which they call _cabocles_, and betwixt _portugalls_ and _æthiopian_ women, he tells us, he has sometimes seen twins, whereof one had a white skin, the other a black; not to mention here some other instances, he gives, that the productions of the mixtures of differing people, that is (indeed,) the effects of seminal impressions which they consequently argue to have been their causes; and we shall not much scruple at this, if we consider, that even organical parts may receive great differences from such peculiar impressions, upon what account soever they came to be setled in the first individual persons, from whom they are propogated to posterity, as we see in the blobber-lips and flat-noses of most nations of _negroes_. and if we may credit what learned men deliver concerning the little feet of the _chinesses_, the _macrocephali_ taken notice of by _hippocrates_, will not be the only instance we might apply to our present purpose. and on this occasion it will not perchance be impertinent to add something of what i have observ'd in other animals, as that there is a sort of hens that want rumps; and that (not to mention that in several places there is a sort of crows or daws that are not cole-black as ours, but partly of a whitish colour) in spight of _porphyries_ examples of inseparable accidents, i have seen a perfectly white raven, as to bill as well as feathers, which i attentively considered, for fear of being impos'd upon. and this recalls into my memory, what a very ingenious physician has divers times related to me of a young lady, to whom being call'd, he found that though she much complain'd of want of health, yet there appear'd so little cause either in her body, or her condition to guess that she did any more than fancy her self sick, that scrupling to give her physick, he perswaded her friends rather to divert her mind by little journeys of pleasure, in one of which going to visit st. _winifrids_ well, this lady, who was a _catholick_, and devout in her religion, and a pretty while in the water to perform some devotions, and had occasion to fix her eyes very attentively upon the red pipple-stones, which in a scatter'd order made up a good part of those that appear'd through the water, and a while after growing bigg, she was deliver'd of a child, whose white skin was copiously speckl'd with spots of the colour and bignesss of those stones, and though now this child have already liv'd several years, yet she still retains them. i have but two things to add concerning the blackness of _negroes_, the one is, that the seat of that colour seems to be but the thin _epidermes_, or outward skin, for i knew a young _negroe_, who having been lightly sick of the small pox or measles, (for it was doubted which of the two was his disease) i found by enquiry of a person that was concern'd for him, that in those places where the little tumors had broke their passage through the skin, when they were gone, they left within specks behind them; and the lately commended _piso_ assures us, that having the opportunity in _brasil_ to dissect many _negroes_, he cleerly found that their blackness went no deeper than the very outward skin, which _cuticula_ or _epidermis_ being remov'd, the undermost skin or _cutis_ appear'd just as white as that of _europæan_ bodyes. and the like has been affirmed to me by a physician of our own, whom, hearing he had dissectcd a _negroe_ here in _england_, i consulted about this particular. the other thing to be here taken notice of concerning _negroes_ is, that having enquir'd of an intelligent acquaintance of mine (who keeps in the _indies_ about 300. of them as well women as men to work in his plantations,) whether their children come black into the world; he answer'd, that they did not, but were brought forth of almost the like reddish colour with our _european_ children; and having further enquir'd, how long it was before these infants appear'd black, be reply'd, that 'twas not wont to be many daies. and agreeable to this account i find that, given us in a freshly publish'd french book written by a _jesuit_, that had good opportunity of knowing the truth of what he delivers, for being one of the missionaries of his order into the southern _america_ upon the laudable design of converting infidels to christianity, he baptiz'd several infants, which when newly born, were much of the same colour with _european_ babes, but within about a week began to appear of the hue of their parents. but more pregnant is the testimony of our countrey-man _andrew battel_, who being sent prisoner by the _portugalls_ to _angola_, liv'd there, and in the adjoyning regions, partly as a prisoner, partly as a pilot, and partly as a souldier, near 18. years, and he mentioning the _african_ kingdom of _longo_, peopl'd with blacks, has this passage:[12] _the children in this countrey are born white, and change their colour in two dayes to a perfect black_. as for example, _the_ portugalls _which dwell in the kingdome of_ longo _have sometimes children by the_ negroe_-women, and many times the fathers are deceived, thinking, when the child is born, that it is theirs, and within two dayes it proves the son or daughter of a_ negroe,_ which the_ portugalls _greatly grieve at_; and the same person has elsewhere a relation, which, if he have made no use at all of the liberty of a traveller, is very well worth our notice, since this, together with that we have formerly mention'd of seminal impressions, shews a possibility, that a race of _negroes_ might be begun, though none of the sons of _adam_, for many precedent generations were of that complexion. for i see not why it should not be at least as possible, that white parents may sometimes have black children, as that _african negroes_ should sometimes have lastingly white ones, especially since concurrent causes may easily more befriend the productions of the former kind, than under the scorching heat of _africa_ those of the latter. and i remember on the occasion of what he delivers, that of the white raven formerly mention'd, the possessor affirm'd to me, that in the nest out of which he was taken white, they found with him but one other young one, and that he was of as jetty a black as any common raven. but let us hear our author himself[13]; _here are_ (sayes he, speaking of the formerly mention'd regions) _born in this countrey white children, which is very rare among them, for their parents are_ negroes; _and when any of them are born, they are presented to the king, and are call'd_ dondos; _these are as white as any white men. these are the kings witches, and are brought up in witchcraft, and alwayes wait on the king: there is no man that dare meddle with these_ dondos, _if they go to the market they may take what they lift, for all men stand in awe of them. the king of_ longo _hath four of them_. and yet this countrey in our globes is plac'd almost in the midst of the torrid zone (four or five degrees southward of the line.) and our author elsewhere tells us of the inhabitants, that they are so fond of their blackness, that they will not suffer any that is not of that colour (as the _portugalls_ that come to trade thither) to be so much as buri'd in their land, of which he annexes a particular example,[14] that may be seen in his voyage preserv'd by our industrious countreyman mr. _purchas_. but it is high time for me to dismiss observations, and go on with experiments. [11] _piso_ nat. & med. hist. _brasil. lib_ 1. in fine. [12] _purchas_ pilgrim. second part, seventh book 3. chap. sect 5. [13] _purchas_. ibid. [14] _purchas_ ibid. in fin _experiment xii._ the way, _pyrophilus,_ of producing whiteness by chymical præcipitations is very well worth our observing, for thereby bodyes of very differing colours as well as natures, though dissolv'd in several liquors, are all brought into _calces_ or powders that are white. thus we find that not only crabs-eyes, that are of themselves white, and pearls that are almost so, but _coral_ and _minium_ that are red, being dissolv'd in spirit of vinegar, may be uniformly præcipitated by oyl of _tartar_ into white powders. thus silver and tin separately dissolv'd in _aqua fortis_, will the one præcipitate it self, and the other be præcipitated by common salt-water into a white _calx_, and so will crude lead and quicksilver first dissolv'd likewise in _aqua fortis_. the like _calx_ will be afforded as i have try'd by a solution of that shining mineral tinglass dissolv'd in _aqua fortis_, and præcipitated out of it; and divers of these _calces_ may be made at least as fair and white, if not better colour'd, if instead of oyl of _tartar_ they were præcipitated with oyl of _vitriol_, or with another liquor i could name. nay, that black mineral _antimony_ it self, being reduc'd by and with the salts that concurr to the composition of common sublimate, into that cleer though unctuous liquor that chymists commonly call rectifi'd butter of _antimony_, will by the bare affusion of store of fair water be struck down into that snow-white powder, which when the adhering saltness is well wash'd off, chymists are pleas'd to call _mercurius vitæ_, though the like powder may be made of _antimony_, without the addition of any _mercury_ at all. and this lactescence if i may so call it, does also commonly ensue when spirit of wine, being impregnated with those parts of gums or other vegetable concretions, that are suppos'd to abound with sulphureous corpuscles, fair water is suddenly pour'd upon the tincture or solution. and i remember that very lately i did, for tryal sake, on a tincture of _benjamin_ drawn with spirit of wine, and brought to be as red as blood, pour some fair water, which presently mingling with the liquor, immediately turn'd the whole mixture white. but if such seeming milks be suffer'd to stand unstirr'd for a convenient while, they are wont to let fall to the bottome a resinous substance, which the spirit of wine diluted and weakned by the water pour'd into it was unable to support any longer. and something of kin to this change of colour in vegetables is that, which chymists are wont to observe upon the pouring of acid spirits upon the red solution of _sulphur_, dissolv'd in an infusion of pot-ashes, or in some other sharp _lixivium_, the præcipitated _sulphur_ before it subsides, immediately turning the red liquor into a white one. and other examples might be added of this way of producing whiteness in bodyes by præcipitating them out of the liquors wherein they have been dissolv'd; but i think it may be more usefull to admonish you, _pyrophilus_, that this observation admits of restrictions, and is not so universal, as by this time perhaps you have begun to think it; for though most præcipitated bodyes are white, yet i know some that are not; for gold dissolv'd in _aqua regis_, whether you præcipitate it with oyl of _tartar_, or with spirit of _sal armoniack_, will not afford a white but a yellow _calx_. _mercury_ also though reduc'd into sublimate, and præcipitated with liquors abounding with volatile salts, as the spirits drawn from urine, harts-horn, and other animal substances, yet will afford, as we noted in our first experiment about whiteness and blackness, a white præcipitate, yet with some solutions hereafter to be mentioned, it will let fall an orange-tawny powder. and so will crude _antimony_, if, being dissolv'd in a strong lye, you pour (as farr as i remember) any acid liquor upon the solution newly filtrated, whilst it is yet warm. and if upon the filtrated solution of _vitriol_, you pour a solution of one of these fix'd salts, there will subside a copious substance, very farr from having any whiteness, which the chymists are pleas'd to call, how properly i have elsewhere examin'd, the _sulphur of vitriol_. so that most part of dissolv'd bodyes being by præcipitation brought to white powders, and yet some affording præcipitates of other colours, the reason of both the phænomena may deserve to be enquir'd into. _experiment xiii._ some learned modern writers[15] are of opinion, that the account upon which whiteness and blackness ought to be call'd, as they commonly are, the two extreme colours, is, that blackness (by which i presume is meant the bodyes endow'd with it) receives no other colours; but whiteness very easily receives them all; whence some of them compare whiteness to the _aristotelian materia prima_, that being capable of any sort of forms, as they suppose white bodyes to be of every kind of colour. but not to dispute about names or expressions, the thing it self that is affirm'd as matter of fact, seems to be true enough in most cases, not in all, or so, as to hold universally. for though it be a common observation among dyers, that clothes, which have once been throughly imbu'd with black, cannot so well afterwards be dy'd into lighter colours, the præexistent dark colour infecting the ingredients, that carry the lighter colour to be introduc'd, and making it degenerate into some more sad one; yet the experiments lately mention'd may shew us, that where the change of colour in black bodies is attempted, not by mingling bodyes of lighter colours with them, but by addition of such things as are proper to alter the texture of those corpuscles that contain the black colour, 'tis no such difficult matter, as the lately mention'd learned men imagine, to alter the colour of black bodyes. for we saw that inks of several kinds might in a trice be depriv'd of all their blackness; and those made with logwood and red-roses might also be chang'd, the one into a red, the other into a reddish liquor; and with oyl of _vitriol_ i have sometimes turn'd black pieces of silk into a kind of yellow, and though the taffaty were thereby made rotten, yet the spoyling of that does no way prejudice the experiment, the change of black silk into yellow, being never the less true, because the yellow silk is the less good. and as for whiteness, i think the general affirmation of its being so easily destroy'd or transmuted by any other colour, ought not to be receiv'd without some cautions and restrictions. for whereas, according to what i formerly noted, lead is by calcination turned into that red powder we call _minium_; and tin by calcination reduc'd to a white _calx_, the common putty that is sold and us'd so much in shops, instead of being, as it is pretended and ought to be, only the _calx_ of tin, is, by the artificers that make it, to save the charge of tin, made, (as some, of themselves have confess'd, and as i long suspected by the cheap rate it may be bought for) but of half tin and half lead, if not far more lead than tin, and yet the putty in spight of so much lead is a very white powder, without disclosing any mixture of _minium_. and so if you take two parts of copper, which is a high-colour'd metall, to but one of tin, you may by fusion bring them into one mass, wherein the whiteness of the tin is much more conspicuous and predominant than the reddishness of the copper. and on this occasion it may not be impertinent to mention an experiment, which i relate upon the credit of a very honest man, whom i purposely enquir'd of about it, being my self not very fond of making tryals with _arsenick_, the experiment is this, that if you colliquate _arsenick_ and copper in a due proportion, the _arsenick_ will blanch the copper both within and without, which is an experiment well enough known; but when i enquir'd, whether or no this white mixture being skilfully kept a while upon the cupel would not let go its _arsenick_, which made whiteness its prædominant colour, and return to the reddishness of copper, i was assur'd of the affirmative; so that among mineral bodyes, some of those that are white, may be far more capable, than those i am reasoning with seem to have known, of eclipsing others, and of making their colour prædominant in mixtures. in further confirmation of which may be added, that i remember that i also took a lump of silver and gold melted together, wherein by the æstimate of a very experienced refiner, there might be about a fourth or third part of gold, and yet the yellow colour of the gold was so hid by the white of the silver, that the whole mass appear'd to be but silver, and when it was rubb'd upon the touchstone, an ordinary beholder could scarce have distinguish'd it from the touch of common silver; though if i put a little _aqua fortis_ upon any part of the white surface it had given the touchstone, the silver in the moistned part being immediately taken up and conceal'd by the liquor, the golden particles would presently disclose that native yellow, and look rather as if gold, than if the above mention'd mixture, had been rubb'd upon the stone. [15] see _scaliger_ exercit. 325. sect. 9. _experiment xiv._ i took a piece of black-horn, (polish'd as being part of a comb) this with a piece of broken glass i scrap'd into many thin and curdled flakes, some shorter and some longer, and having laid a pretty quantity of these scrapings together, i found, as i look'd for, that the heap they compos'd was white, and though, if i laid it upon a clean piece of white paper, its colour seem'd somewhat eclips'd by the greater whiteness of the body it was compar'd with, looking somewhat like linnen that had been sulli'd by a little wearing, yet if i laid it upon a very black body, as upon a beaver hatt, it then appear'd to be of a good white, which experiment, that you may in a trice make when you please, seems very much to disfavour both their doctrine that would have colours to flow from the substantial forms of bodyes, and that of the chymists also, who ascribe them to one or other of their three hypostatical principles; for though in our case there was so great a change made, that the same body without being substantially either increas'd or lessened, passes immediately from one extreme colour to another (and that too from black to white) yet this so great and sudden change is effected by a slight mechanical transposition of parts, there being no salt or _sulphur_ or _mercury_ that can be pretended to be added or taken away, nor yet any substantial form that can reasonably be suppos'd to be generated and destroy'd, the effect proceeding only from a local motion of the parts which so vary'd their position as to multiply their distinct surfaces, and to qualifie them to reflect far more light to the eye, than they could before they were scrap'd off from the entire piece of black horn. _experiment xv._ and now, _pyrophilus_, it will not be improper for us to take some notice of an opinion touching the cause of blackness, which i judged it not so seasonable to question, till i i had set down some of the experiments, that might justifie my dissent from it. you know that of late divers learned men, having adopted the three hypostatical principles, besides other notions of the chymists, are very inclinable to reduce all qualities of bodies to one or other of those three principles, and particularly assign for the cause of blackness the sootie steam of _adust_ or _torrifi'd sulphur_. but i hope that what we have deliver'd above to countenance the opinion we have propos'd about the cause of blackness, will so easily supply you with several particulars that may be made use of against this opinion, that i shall now represent to you but two things concerning it. and first it seems that the favourers of the chymicall theories might have pitcht upon some more proper term, to express the efficient of blackness than _sulphur adust_; for we know that _common sulphur_, not only when melted, but even when sublim'd, does not grow black by suffering the action of the fire, but continues and ascends yellow, and rather more than less white, than it was before its being expos'd to the fire. and if it be set on fire, as when we make that acid liquor, that chymists call _oleum sulphuris per campanam_, it affords very little soot, and indeed the flame yeelds so little, that it will scarce in any degree black a sheet of white paper, held a pretty while over the flame and smoak of it, which is observed rather to whiten than infect linnen, and which does plainly make red roses grow very pale, but not at all black, as far as the smoak is permitted to reach the leaves. and i can shew you of a sort of fixt sulphur made by an industrious laborant of your acquaintance, who assur'd me that he was wont to keep it for divers weeks together night and day in a naked and violent fire, almost like that of the glass-house, and when, to satisfie my curiosity, i made him take out a lump of it, though it were glowing hot (and yet not melted,) it did not, when i had suffered it to cool, appear black, the true colour of it being a true red. i know it may be said, that _chymists_ in the opinion above recited mean the _principle of sulphur_, and not _common sulphur_ which receives its name, not from its being _all_ perfectly of a sulphureous nature, but for that _plenty_ and _predominancy_ of the sulphureous principle in it. but allowing this, 'tis easie to reply, that still according to this very reason, torrifi'd sulphur should afford more blackness, than most other concretes, wherein that principle is confess'd to be far less copious. also when i have expos'd camphire to the fire in close vessels, as inflamable, and consequenly (according to the chymists) as sulphureous a body as it is, i could not by such a degree of heat, as brought it to fusion, and made it boyl in the glass, impress any thing of blackness, or of any other colour, than its own pure white, upon this vegetable concrete. but what shall we say to spirit of wine, which being made by a chymical analysis of the liquor that affords it, and being totally inflamable, seems to have a full right to the title they give it of _sulphur vegetabile_, & yet this fluid sulphur not only contracts not any degree of blackness by being often so heated, as to be made to boyl, but when it burns away with an actual flame, i have not found that it would discolour a piece of white paper held over it, with any discernable soot. tin also, that wants not, according to the chymists, a _sulphur joviale_, when throughly burned by the fire into a _calx_, is not black, but eminently white. and i lately noted to you out of _bellonius_, that the charcoals of oxy-cedar are not of the former of these two colours, but of the latter. and the smoak of our tinby coals here in _england_, has been usually observ'd, rather to blanch linnen then to black it. to all which, other particulars of the like nature might be added, but i rather choose to put you in mind of the third experiment, about making black liquors, or inks, of bodies that were non of them black before. for how can it be said, that when those liquors are put together actually cold, and continue so after their mixture, there intervenes any new _adustion of sulphur_ to produce the emergent blackness? (and the same question will be appliable to the blackness produc'd upon the blade of a knife, that has cut lemmons and some kind of sowr apples, if the juyce (though both actually and potentially cold) be not quickly wip'd of) and when by the instilling either of a few drops of oyl of vitriol as in the second experiment, or of a little of the liquor mention'd in the passage pointed at in the fourth experiment, (where i teach at once to destroy one black ink, and make another) the blackness produc'd by those experiments is presently destroy'd; if the colour proceeded only from the plenty of sulphurous parts, torrify'd in the black bodies, i demand, what becomes of them, when the colour so suddenly dissappears? for it cannot reasonably be said, that all those that suffic'd to make so great a quantity of black matter, should resort to so very small a proportion of the clarifying liquor, (if i may so call it) as to be deluted by it, with out at all denigrating it. and if it be said that the instill'd liquor dispers'd those black corpuscles, i demand, how that dispersion comes to destroy their blackness, but by making such a local motion of their parts, as destroys their former texture? which may be a matter of such moment in cases like ours, that i remember that i have in few houres, without addition, from soot it self, attain'd pretty store of crystalline salt, and good store of transparent liquor, and (which i have on another occasion noted as remarkable) this so black substance had its colour so alter'd, by the change of texture it receiv'd from the fire, wherewith it was distill'd, that it did for a great while afford such plenty of very white exhalations, that the receiver, though large, seem'd to be almost fill'd with milk. secondly, but were it granted, as it is in some cases not improbable, that divers bodies may receive a blackness from a sootie exhalation, occasion'd by the adustion of their sulphur, which (for the reasons lately mention'd i should rather call their oyly parts;) yet still this account is applicable but to some particular bodies, and will afford us no general theory of blackness. for if, for example, white harts-horn, being, in vessels well luted to each other, expos'd to the fire, be said to turn black by the infection of its own smoak, i think i may justly demand, what it is that makes the smoak or soot it self black, since no such colour, but its contrary, appear'd before in the harts-horn? and with the same reason, when we are told, that torrify'd sulphur makes bodies black, i desire to be told also, why torrefaction makes sulphur it self black? nor will there be any satisfactory reason assign'd of these quæries, without taking in those fertile as well as intelligible mechanical principles of the position and texture of the minute parts of the body in reference to the light and the eye; and these applicable principles may serve the turn in many cases, where the adustion of sulphur cannot be pretended; as in the appearing blackness of an open window, lookt upon at a somewhat remote distance from the house, as also in the blackness men think they see in the holes that happen to be in white linnen, or paper of the like colour; and in the increasing blackness immediatly produc'd barely by so rubbing velvet, whose piles were inclin'd before, as to reduce them to a more erected posture, in which and in many other cases formerly alleg'd, there appears nothing requisite to the production of _the_ blackness, but the hindering of the incident beams of light from rebounding plentifully enough to the eye. to be short, those i reason with, do concerning blackness, what the chymists are wont also to do concerning other qualities, namely to content themselves to tell us, in what ingredient of a mixt body, the quality enquir'd after, does reside, instead of explicating the nature of it, which (to borrow a comparison from their own laboratories) is much as if in an enquiry after the cause of salivation, they should think it enough to tell us, that the several kinds of præcipitates of gold and _mercury_) as likewise of quick-silver and silver (for i know that make and use of such precipitates also) do salivate upon the account of the _mercury_, which though disguis'd abounds in them, whereas the difficulty is as much to know upon what account _mercury_ it self, rather than other bodies, has that power of working by salivation. which i say not, as though it were not _something_ (and too often the most we can arrive at) to discover in which of the ingredients of a compounded body, the quality, whose nature is sought, resides, but because, though this discovery it self may pass for _something_, and is oftentimes more than what is taught us about the same subjects in the schools, yet we ought not to think it _enough_, when more clear and particular accounts are to be had. * * * * * the experimental history of colours begun. * * * * * the third part. * * * * * containing promiscuous experiments about colours. * * * * * experiment i. because that, according to the conjectures i have above propos'd, one of the most general causes of the diversity of colours in opacous bodyes, is, that some reflect the light mingl'd with more, others with less of shade (either as to quantity, or as to interruption) i hold it not unfit to mention in the first place, the experiments that i thought upon to examine this conjecture. and though coming to transcribe them out of some physiological _adversaria_ i had written in loose papers, i cannot find one of the chief records i had of my tryals of this nature, yet the papers that scap'd miscarrying, will, i presume, suffice to manifest the main thing for which i now allege them; i find then among my _adversaria_, the following narrative. _october_ the 11. about ten in the morning in sun-shiny weather, (but not without fleeting clouds) we took several sorts of paper stain'd, some of one colour, and some of another; and in a darken'd room whose window look'd southward, we cast the beams that came in at a hole about three inches and a half in diameter, upon a white wall that was plac'd on one side, about five foot distance from them. the white gave much the brightest reflection. the green, red, and blew being compar'd together, the red gave much the strongest reflection, and manifestly enough also threw its _colour_ upon the wall; the green and blew were scarce discernable by their colours, and seem'd to reflect an almost equal light. the yellow compar'd with the two last nam'd, reflected somewhat more light. the red and purple being compar'd together, the former manifestly reflected a good deal more light. the blew and purple compar'd together, the former seem'd to reflect a little more light, though the purple colour were more manifestly seen. a sheet of very well fleck'd marbl'd paper being apply'd as the others, did not cast any or its distinct colours upon the wall; nor throw its light upon it with an equal diffusion, but threw the beams unstain'd and bright to this and that part of the wall, as if it's polish had given it the nature of a specular body. but comparing it with a sheet of white paper, we found the reflection of the latter to be much stronger, it diffusing almost as much light to a _good extent_ as the marble paper did to _one part_ of the wall. the green and purple left us somewhat in suspence which reflected the most light; only the purple seem'd to have some little advantage over the green, which was dark in its kind. thus much i find in our above mention'd _collections_, among which there are also some notes concerning the production of _compounded colours_, _by reflection_ from bodyes differingly colour'd. and these notes we intended should supply us with what we should mention as our second experiment: but having lost the paper that contain'd the particulars, and remembring onely in general, that if the objects which reflected the light were not strongly colour'd and somewhat glossy, the reflected beams would not manifestly make a compounded colour upon the wall, and even then but very faintly, we shall now say no more of that matter, only reserving our selves to mention hereafter the composition of a green, which we still retain in memory. _experiment ii._ we may add, _pyrophilus_, on this occasion, that though a darken'd room be generally thought requisite to make the colour of a body appear by reflection from another body, that is not one of those that are commonly agreed upon to be specular (as polish'd metall, quick silver, glass, water, &c.) yet i have often observ'd that when i wore doublets lin'd with some silken stuff that was very glossy and vividly colour'd, especially red, i could in an inlightned room plainly enough discern the colour, upon the pure white linnen that came out at my sleeve and reach'd to my cufs; as if that fine white body were more specular, than colour'd and unpolish'd bodyes are thought capable of being. _experiment iii._ whilst we were making the newly mention'd experiments, we thought fit to try also what composition of colours might be made by altering the light in its passage to the eye by the interposition not of perfectly diaphanous bodies, (that having been already try'd by others as well as by us (as we shall soon have occasion to take notice) but of semi-opacous bodyes, and those such as look'd upon in an ordinary light, and not held betwixt it and the eye, are not wont to be discriminated from the rest of opacous bodyes; of this tryal, our mention'd _adversaria_ present us the following account. holding these sheets, sometimes one sometimes the other of them, before the hole betwixt the sun and the eye, with the colour'd sides obverted to the sun; we found them _single_ to be somewhat transparent, and appear of the same colour as before, onely a little alter'd by the great light they were plac'd in; but laying _two_ of them one over another and applying them so to the hole, the colours were compounded as follows. the blew and yellow scarce exhibited any thing but a darker yellow, which we ascrib'd to the coarseness of the blew papers, and its darkness in its kind. for applying the blew parts of the marbl'd paper with the yellow paper after the same manner, they exhibited a good green. the yellow and red look'd upon together gave us but a dark red, somewhat (and but a little,) inclining to an orange colour. the purple and red look'd on together appear'd more scarlet. the purple and yellow made an orange. the green and red made a dark orange tawny. the green and purple made the purple appear more dirty. the blew and purple made the purple more lovely, and far more deep. the red parts of the marbl'd paper look'd upon with the yellow appear'd of a red far more like scarlet than without it. [page 191] but the fineness or coarseness of the papers, their being carefully or slightly colour'd, and divers other circumstances, may so vary the events of such experiments as these, that if, _pyrophilus_, you would build much on them, you must carefully repeat them. _experiment iv._ the triangular prismatical glass being the instrument upon whose effects we may the most commodiously speculate the nature of emphatical colours, (and perhaps that of others too;) we thought it might be usefull to observe the several reflections and refractions which the incident beams of light suffer in rebounding from it, and passing through it. and this we thought might be best done, not (as is usual,) in an ordinary inlightn'd room, where (by reason of the difficulty of doing otherwise) ev'n the curious have left particulars unheeded, which may in a convenient place be easily taken notice of; but in a darken'd room, where by placing the glass in a convenient posture, the various reflections and refractions may be distinctly observ'd; and where it may appear _what_ beams are unting'd; and _which_ they are, that upon the bodyes that terminate them, do paint either the primary or secondary iris. in pursuance of this we did in the above mention'd darken'd room, make observation of no less than four reflections, and three refractions that were afforded us by the same prism, and thought that notwithstanding what was taught us by the rules of catoptricks and dioptricks, it would not be amiss to find also, by hiding sometimes one part of the prism, and sometimes another, and observing where the light or colour vanish'd thereupon, by which reflection and by which refraction each of the several places whereon the light rebounding from, or passing through, the prism appear'd either sincere or tincted, was produc'd. but because it would be tedious and not so intelligible to deliver this in words, i have thought fit to referr you to the annexed scheme where the newly mention'd particulars may be at one view taken notice of. _experiment v._ [illustration: _the explication of the scheme._] _ppp_. an aequilaterotriangular crystalline prism, one of whose edges _p_. is placed directly towards the sun. _a b_ & [alpha] [beta] two rays from the sun falling on the prism at _b_ [beta]. and thence partly reflected towards _c_ & [gamma]. and partly refracted towards _d_ & [delta]. _b c_ & [beta] [gamma]. those reflected rays. _b d_ & [beta] [delta]. those refracted rays which are partly refracted towards _e_ & [epsilon]. and there paint an iris 1 2 3 4 5. denoting the five consecutions of colours red, yellow, green, blew, and purple; and are partly reflected towards _f_ & [zeta]. _d f_ & [delta] [zeta]. those reflected rays which are partly refracted towards _g_ & [eta]. colourless, and partly reflected, towards _h_ & [theta]. _f h_ & [zeta] [theta]. those reflected rays which are refracted towards _i_ & [iota]. and there paint an other fainter iris, the colours of which are contrary to the former 5 4 3 2 1. signifying purple, blew, green, yellow, red, so that the prism in this posture exhibits four rainbows. i know not whether you will think it inconsiderable to annex to this experiment, that we observ'd in a room not darken'd, that the prismatical iris (if i may so call it) might be reflected without losing any of its several _colours_ (for we now consider not their _order_) not onely from a plain looking-glass and from the calm surface of fair water, but also from a concave looking-glass; and that refraction did as little destroy those colours as reflection. for by the help of a large (double convex) burning-glass through which we refracted the suns beams, we found that one part of the iris might be made to appear either beyond, or on this side of the other parts of the same iris; but yet the same vivid colours would appear in the displac'd part (if i may so term it) as in the other. to which i shall add, that having, by hiding the side of the prism, obverted to the sun with an opacous body, wherein only one small hole was left for the light to pass through, reduc'd the prismatical iris (cast upon white paper) into a very narrow compass, and look'd upon it througn a microscope; the colours appear'd the same as to kind that they did to the naked eye. _experiment vi._ it may afford matter of speculation to the inquisitive, such as you, _prophilus_, that as the colours of outward objects brought into a darken'd room, do so much depend for their visibility upon the dimness of the light they are there beheld by; that the ordinary light of the day being freely let in upon them, they immediately disappear: so our tryals have inform'd us, that as to the prismatical iris painted on the floor by the beams of the sun trajected through a triangular-glass; though the colours of it appear very vivid ev'n at noon-day, and in sun shiny weather, yet by a more powerfull light they may be made to disappear. for having sometimes, (in prosecution of some conjectures of mine not now to be insisted on,) taken a large metalline concave _speculum_, and with it cast the converging beams of the sun upon a prismatical iris which i had caus'd to be projected upon the floor, i found that the over-powerfull light made the colours of the iris disappear. and if i so reflected the light as that it cross'd but the middle of the iris, in that part only the colours vanish'd or were made invisible; those parts of the iris that were on the right and left hand of the reflected light (which seem'd to divide them, and cut the iris asunder) continuing to exhibit the same colours as before. but upon this we must not now stay to speculate. _experiment vii._ i have sometimes thought it worth while to take notice, whether or no the colours of opacous bodies might not appear to the eye somewhat diversify'd, not only by the disposition of the superficial parts of the bodyes themselves and by the position of the eye in reference to the object and the light, (for these things are notorious enough;) but according also to the nature of the lucid body that shines upon them. and i remember that in prosecution of this curiosity, i observ'd a manifest difference in some kinds of colour'd bodyes look'd on by day-light, and afterwards by the light of the moon; either directly falling on them or reflected upon them from a concave looking-glass. but not finding at present in my collections about colours any thing set down of this kind, i shall, till i have opportunity to repeat them, content my self to add what i find register'd concerning colours look'd on by candle-light, in regard that not only the experiment is more easie to be repeated, but the objects being the same sorts of colour'd paper lastly mention'd, the collation of the two experiments may help to make the conjectures they will suggest somewhat the less uncertain. within a few dayes of the time above mention'd, divers sheets of colour'd paper that had been look'd upon before in the sunshine were look'd upon at night by the light of a pretty big candle, (snuff'd) and the changes that were observ'd were these. the yellow seem'd much fainter than in the day, and inclinable to a pale straw colour. the red seem'd little chang'd; but seem'd to reflect light more strongly than any other colour (for white was none of them.) a fair deep green look'd upon by it self seem'd to be a dark blew: but being look'd upon together with a dark blew, appear'd greenish; and beheld together with a yellow appear'd more blew than at first. the blew look'd more like a deep purple or murray than it had done in the daylight. the purple seem'd very little alter'd. the red look'd upon with the yellow made the yellow look almost like brown cap-paper. _n_. the caution subjoyned to the third experiments is also applicable to this. _experiment viii._ but here i must not omit to subjoyn, that to satisfie our selves, whether or no the light of a candle were not made unsincere, and as it were ting'd with a yellow colour by the admixtion of the corpuscles it assumes from its fuel; we did not content our selves with what appears to the naked eye, but taking a pretty thick rod or cylinder (for thin peeces would not serve the turn) of deep blew glass, and looking upon the candles flame at a convenient distance througn it, we perceiv'd as we expected, the flame to look green; which as we often note, is the colour wont to emerge from the composition of opacous bodies, which were apart one of them blew, and the other yellow. and this perchance may be the main reason of that which some observe, that a sheet of very white paper being look'd upon by candle light, 'tis not easie at first to discern it from a light yellow or lemon colour; white bodyes (as we have elsewhere observ'd) having more than those that are otherwise colour'd, of a specular nature; in regard that though they exhibit not, (unless they be polish'd,) the shape of the luminary that shines on them, yet they reflect its light more sincere and untroubl'd, by either shades or refractions, than bodyes of other colours (as blew, or green, or yellow or the like.) _experiment ix._ we took a leaf of such foliated gold as apothecaries are wont to gild their pills with; and with the edge of a knife, (lightly moysten'd by drawing it over the surface of the tongue, and afterwards) laid upon the edge of the gold leaf; we so fasten'd it to the knife, that being held against the light, it conctinu'd extended like a little flagg. this leaf being held very near the eye, and obverted to the light, appear'd so full of pores, that it seem'd to have such a kind of transparency as that of a sive, or a piece of cyprus, or a love-hood; but the light that pass'd by these pores was in its passages so temper'd with shadow, and modify'd, that the eye discern'd no more a golden colour, but a greenish blew. and for other's satisfaction, we did in the night look upon a candle through such a leaf of gold; and by trying the effect of several proportions of distance betwixt the leaf, the eye and the light, we quickly hit upon such a position for the leaf of gold, as that the flame, look'd on through it, appear'd of a greenish blew, as we have seen in the day time. the like experiment try'd with a leaf of silver succeeded not well. * * * * * _experiment x._ we have sometimes found in the shops of our druggists, a certain wood, which is there called _lignum nephriticum_, because the inhabitants of the country where it grows, are wont to use the infusion of it made in fair water against the stone of the kidneys, and indeed an eminent physician of our acquaintance, who has very particularly enquir'd into that disease, assures me, that he has found such an infusion one of the most effectual remedyes, which he has ever tried against that formidable disease. the ancientest account i have met with of this simple, is given us by the experienc'd _monardes_ in these words. _nobis,_ says he,[16] _nova hispania mittit quoddam ligni genus crassum & enode, cujus usus jam diu receptus fuit in his regionibus ad renum vitia & urinæ difficultates ac arenulas pellendas. fit autem hac ratione, lignum assulatim & minutim concisum in limpidissima aqua fontana maceratur, inque ea relinquitur, donec aqua à bibentibus absumpta sit, dimidia hora post injectum lignum aqua cæruleum colorem contrabit, qui sensim intenditur pro temporis diuturnitate, tametsi lignum candidum fit_. this wood, _pyrophilus_, may afford us an experiment, which besides the singularity of it, may give no small assistance to an attentive considerer towards the detection of the nature of colours. the experiment as we made it is this. take _lignum nephriticum_, and with a knife cut it into thin slices, put about a handfull of these slices into two three or four pound of the purest spring-water, let them infuse there a night, but if you be in hast, a much shorter time may suffice; _decant_ this impregnated water into a clear glass vial, and if you hold it directly between the light and your eye, you shall see it wholly tincted (excepting the very top of the liquor, wherein you will some times discern a sky-colour'd circle) with an almost golden colour, unless your infusion have been made too strong of the wood, for in that case it will against the light appear somewhat dark and reddish, and requires to be diluted by the addition of a convenient quantity of fair water. but if you hold this vial from the light, so that your eye be plac'd betwixt the window and the vial, the liquor will appear of a deep and lovely cæruleous colour, of which also the drops, if any be lying on the outside of the glass, will seem to be very perfectly; and thus far we have try'd the experiment, and found it to succeed even by the light of candles of the larger size. if you so hold the vial over against your eyes, that it may have a window on one side of it, and a dark part of the room both before it and on the other side, you shall see the liquor partly of a blewish and partly of a golden colour. if turning your back to the window, you powr out some of the liquor towards the light and towards your eyes, it will seem at the comming out of the glass to be perfectly cæruleous, but when it is fallen down a little way, the drops may seem particolour'd, according as the beams of light do more or less fully penetrate and illustrate them. if you take a bason about half full of water, and having plac'd it so in the sun-beams shining into a room, that one part of the water may be freely illustrated by the beams of light, and the other part of it darkned by the shadow of the brim of the bason, if then i say you drop of our tincture, made somewhat strong, both into the shaded and illuminated parts of the water, you may by looking upon it from several places, and by a little agitation of the water, observe divers pleasing phænomena which were tedious to particularize. if you powr a little of this tincture upon a sheet of white paper, so as the liquor may remain of some depth upon it, you may perceive the neighbouring drops to be partly of one colour, and partly of the other, according to the position of your eye in reference to the light when it looks upon them, but if you powr off all the liquor, the paper will seem dy'd of an almost yellow colour. and if a sheet of paper with some of this liquor in it be plac'd in a window where the sunbeams may shine freely on it, then if you turn your back to the sun and take a pen or some such slender body, and hold it over-thwart betwixt the sun and the liquor, you may perceive that the shadow projected by the pen upon the liquor, will not all of it be a vulgar and dark, but in part a curiously colour'd shadow, that edge of it, which is next the body that makes it, being almost of a lively golden colour, and the remoter verge of a cæruleous one. [16] _nicolaus monardes_ lib _simplic. ex india allatis_, cap. 27. these and other phænomena, which i have observ'd in this delightfull experiment, divers of my friends have look'd upon not without some wonder, and i remember an excellent oculist finding by accident in a friends chamber a fine vial full of this liquor, which i had given that friend, and having never heard any thing of the experiment, nor having any body near him that could tell him what this strange liquor might be, was a great while apprehensive, as he presently after told me, that some strange new distemper was invading his eyes. and i confess that the unusualness of the phænomena made me very sollicitous to find out the cause of this experiment, and though i am far from pretending to have found it, yet my enquiries have, i suppose, enabled me to give such hints, as may lead your greater sagacity to the discovery of the cause of this wonder. and first finding that this tincture, if it were too copious in the water, kept the colours from being so lively, and their change from being so discernable, and finding also that the impregnating virtue of this wood did by its being frequently infus'd in new water by degrees decay, i conjectur'd that the tincture afforded by the wood must proceed from some subtiler parts of it drawn forth by the water, which swimming too and fro in it did so modifie the light, as to exhibit such and such colours; and because these subtile parts were so easily soluble even in cold water, i concluded that they must abound with salts, and perhaps contain much of the essential salt, as the _chymists_ call it, of the wood. and to try whether these subtile parts were volatile enough to be distill'd, without the dissolution of their texture, i carefully distill'd some of the tincted liquor in very low vessels, and the gentle heat of a lamp furnace; but found all that came over to be as limpid and colourless as rock-water, and the liquor remaining in the vessel to be so deeply cæruleous, that it requir'd to be oppos'd to a very strong light to appear of any other colour. i took likewise a vial with spirit of wine, and a little salt of harts-horn, and found that there was a certain proportion to be met with betwixt the liquor and the salt, which made the mixture fit to exhibit some little variety of colours not observable in ordinary liquors, as it was variously directed in reference to the light and the eye, but this change of colour was very far short from that which we had admir'd in our tincture. but however, i suspected that the tinging particles did abound with such salts, whose texture, and the colour springing from it, would probably be alter'd by peircing acid salts, which would in likelihood either make some dissipation of their parts, or associate themselves to the like bodies, and either way alter the colour exhibited by them; whereupon pouring into a small vial full of impregnated water, a very little spirit of vinegar, i found that according to my expectation, the cæruleous colour immediately vanish'd, but was deceiv'd in the expectation i had, that the golden colour would do so too; for, which way soever i turned the vial, either to or from the light, i found the liquor to appear always of a yellowish colour and no other: upon this i imagin'd that the acid salts of the vinegar having been able to deprive the liquor of its cæruleous colour, a sulphureous salt being of a contrary nature, would be able to mortifie the saline particles of vinegar, and destroy their effects; and accordingly having plac'd my self betwixt the window, and the vial, and into the same liquor dropt a few drops of oyl of tartar _per deliquium_, (as _chymists_ call it) i observ'd with pleasure, that immediately upon the diffusion of this liquor, the impregnated water was restor'd to its former cæruleous colour; and this liquor of _tartar_ being very ponderous, and falling at first to the bottom of the vial, it was easie to observe that for a little while the lower part of the liquor appear'd deeply cæruleous; whilst all the upper part retain'd its former yellowness, which it immediately lost as soon as either agitation or time had made a competent diffusion of the liquor of _tartar_ through the body of the former tincture; and this restored liquor did, as it was look'd upon against or from the light, exhibit the same _phænomena_ as the tincted water did, before either of the adventitious liquors was pour'd into it. having made, _pyrophilus_, divers tryals upon this nephritick wood, we found mention made of it by the industrious jesuit _kircherus_, who having received a cup turned of it from the _mexican_ procurator of his society, has probably receiv'd also from him the information he gives us concerning that _exotick_ plant, and therefore partly for that reason, and partly because what he writes concerning it, does not perfectly agree with what we have deliver'd, we shall not scruple to acquaint you in his own words, with as much of what he writes concerning our wood, as is requisite to our present purpose. _hoc loco_ (says he)[17] _neutiquam omittendum duximus quoddam ligni candidi mexicani genus, quod indigenæ coalle & tlapazatli vocant, quod etsi experientia hucusque non nisi cæruleo aquam colore tingere docuerit, nos tamen continua experientia invenimus id aquam in omne colorum genus transformare, quod merito cuipiam paradoxum videri posset; ligni frutex grandis, ut aiunt, non rarò in molem arboris excrescit, truncus illius eft crassus, enodis, instar piri arboris, folia ciceris foliis, aut rutæ haud absimilia, flores exigui, oblongi, lutei & spicatim digesti; est frigida & humida planta, licet parum recedat à medio temperamento. hujus itaque descriptæ arboris lignum in poculum efformatum, aquam eidem infusam primo in aquam intense cæruleam, colore floris buglossæ; tingit, & quo diutius in eo steterit, tanto intensiorem colorem acquirit. hanc igitur aquam si vitreæ sphæræ infuderis, lucique exposueris, ne ullum quidem cærulei coloris vestigium apparebit, sed instar aquæ puræ putæ fontanæ limpidam claramque aspicientibus se præbebit. porro si hanc phialam vitream versus locum magis umbrosum direxeris, totus humor gratissimum virorem referet; si adhuc umbrosioribus locis, subrubrum, & sic pro rerum objectarum conditione, mirum dictu, colorem mutabit; in tenebris verò vel in vase opaco posita, cæruleum colorem suum resumet._ [17] kircher. art. mag. lucis & umbræ, _lib. 1. part. 3._ in this passage we may take notice of the following particulars. and first, he calls it a white _mexican_ wood, whereas (not to mention that _mornardes_ informs us that it is brought out of _nova hispania_) the wood that we have met with in several places, and employ'd as _lignum nephriticum_, was not white, but for the most part of a much darker colour, not unlike that of the sadder colour'd wood of juniper. 'tis true, that _monardes_ himself also says, that the wood is white; and it is affirm'd, that the wood which is of a sadder colour is adulterated by being imbu'd with the tincture of a vegetable, in whose decoction it is steep'd. but having purposely enquir'd of the eminentest of our _english_ druggists, he peremptorily deny'd it. and indeed, having consider'd some of the fairest round pieces of this wood that i could meet with in these parts, i had opportunity to take notice that in one or two of them it was the external part of the wood that was white, and the more inward part that was of the other colour, the contrary of which would probably have appear'd, if the wood had been adulterated after the afore-mention'd manner. and i have at present by me a piece of such wood, which for about an inch next the bark is white, and then as it were abruptly passes to the above-mention'd colour, and yet this wood by the tincture, it afforded us in water, appears to have its colour'd part genuine enough; for as for the white part, it appears upon tryal of both at once, much less enrich'd with the tingent property. next, whereas our author tells us, that the infusion of this wood expos'd in a vial to the light, looks like spring-water, in which he afterwards adds, that there is no tincture to be seen in it, our observation and his agree not, for the liquor, which opposed to the darker part of a room exhibits a sky-colour, did constantly, when held against the light, appear yellowish or reddish, according as its tincture was more dilute or deep; and then, whereas it has been already said, that the cæruleous colour was by acid salts abolished, this yellowish one surviv'd without any considerable alteration, so that unless our author's words be taken in a very limited sense, we must conclude, that either his memory mis-inform'd him, or that his white _nephritick_ wood, and the sadder colour'd one which we employ'd, were not altogether of the same nature: what he mentions of the cup made of _lignum nephriticum_, we have not had opportunity to try, not having been able to procure pieces of that wood great enough, and otherwise fit to be turned into cups; but as for what he says in the title of his experiment, that this wood tinges the water with all sorts of colours, that is much more than any of those pieces of nephritick wood that we have hitherto employ'd, was able to make good; the change of colours discernable in a vial full of water, impregnated by any of them, as it is directed towards a place more lightsome or obscure, being far from affording a variety answerable to so promising a title. and as for what he tells us, that in the dark the infusion of our wood will resume a cæruleous colour, i wish he had inform'd us how he try'd it. but this brings into my mind, that having sometimes for curiosity sake, brought a round vial with a long neck fill'd with the tincture of _lignum nephriticum_ into the darken'd room already often mention'd, and holding it sometimes in, sometimes near the sun-beams that enter'd at the hole, and sometimes partly in them, and partly out of them, the glass being held in several postures, and look'd upon from several neighbouring parts of the room, disclos'd a much greater variety of colours than in ordinary inlightn'd rooms it is wont to do; exhibiting, besides the usual colours, a red in some parts, and a green in others, besides intermediate colours produc'd by the differing degrees, and odd mixtures of light and shade. by all this you may see, _pyrophilus_, the reasonableness of what we elsewhere had occasion to mention, when we have divers times told you, that it is usefull to have new experiments try'd over again, though they were, at first, made by knowing and candid men, such reiterations of experiments commonly exhibiting some new phænomena, detecting some mistake or hinting some truth, in reference to them, that was not formerly taken notice of. and some of our friends have been pleas'd to think, that we have made no unusefull addition to this experiment, by shewing a way, how in a moment our liquor may be depriv'd of its blewness, and restor'd to it again by the affusion of a very few drops of liquors, which have neither of them any colour at all of their own. and that which deserves some particular wonder, is, that the cæruleous tincture of our wood is subject by the former method to be destroy'd or restor'd, the yellowish or reddish tincture continuing what it was. and that you may see, that salts are of a considerable use in the striking of colours, let me add to the many experiments which may be afforded us to this purpose by the dyers trade, this observation; that as far as we have hitherto try'd, those liquors in general that are strong of acid salts have the power of destroying the blewness of the infusion of our wood, and those liquors indiscriminatly that abound with sulphureous salts, (under which i comprehend the urinous and volatile salts of animal substances, and the alcalisate or fixed salts that are made by incineration) have the vertue of restoring it. _a corollary of the tenth experiment._ that this experiment, _pyrophilus_, may be as well usefull as delightfull to you, i must mind you, _pyrophilus_, that in the newly mention'd observation, i have hinted to you a new and easie way of discovering in many liquors (for i dare not say in all) whether it be an acid or sulphureous salt, that is predominant; and that such a discovery is oftentimes of great difficulty, and may frequently be of great use, he that is not a stranger to the various properties and effects of salts, and of how great moment it is to be able to distinguish their tribes, may readily conceive. but to proceed to the way of trying other liquors by an infusion of our wood, take it briefly thus. suppose i have a mind to try whether i conjecture aright, when i imagine that allom, though it be plainly a mixt body, does abound rather with acid than sulphureous salt. to satisfie my self herein, i turn my back to the light, and holding a small vial full of the tincture of _lignum nephriticum_, which look'd upon in that position, appears cæruleous, i drop into it a little of a strong solution of allom made in fair water, and finding upon the affusion and shaking of this new liquor, that the blewness formerly conspicuous in our tincture does presently vanish, i am thereby incited to suppose, that the salt prædominant in allom belongs to the family of sour salts; but if on the other side i have a mind to examine whether or no i rightly conceive that salt of urine, or of harts-horn is rather of a saline sulphureous (if i may so speak) than of an acid nature, i drop a little of the saline spirit of either into the nephritick tincture, and finding that the cæruleous colour is rather thereby deepned than destroy'd, i collect that the salts, which constitute these spirits, are rather sulphureous than acid. and to satisfie my self yet farther in this particular, i take a small vial of fresh tincture, and placing both it and my self in reference to the light as formerly, i drop into the infusion just as much distill'd vinegar, or other acid liquor as will serve to deprive it of its blewness (which a few drops, if the sour liquor be strong, and the vial small will suffice to do) then without changing my posture, i drop and shake into the same vial a small proportion of spirit of hartshorn or urine, and finding that upon this affusion, the tincture immediately recovers its cæruleous colour, i am thereby confirm'd firm'd in my former opinion, of the sulphureous nature of these salts. and so, whereas it is much doubted by some modern chymists to what sort of salt, that which is prædominant in quick-lime belongs, we have been perswaded to referr it rather to lixiviate than acid salts, by having observ'd, that though an evaporated infusion of it will scarce yield such a salt, as ashes and other alcalizate bodyes are wont to do, yet if we deprive our nephritick tincture of its blewness by just so much distill'd vinegar as is requisite to make that colour vanish, the _lixivium_ of quick-lime will immediately upon its affusion recall the banished colour; but not so powerfully as either of the sulphureous liquors formerly mention'd. and therefore i allow my self to guess at the _strength_ of the liquors examin'd by this experiment, by the _quantity_ of them which is sufficient to destroy or restore the cæruleous colour of our tincture. but whether concerning liquors, wherein neither acid nor alcalisate salts are eminently prædominant, our tincture will enable us to conjecture any thing more than that such salts are not prædominant in them, i take not upon me to determine here, but leave to further tryal; for i find not that spirit of wine, spirit of tartar freed from acidity, or chymical oyl of turpentine, (although liquors which must be conceiv'd very saline, if chymists have, which is here no place to dispute, rightly ascrib'd tasts to the saline principle of bodyes,) have any remarkable power either to deprive our tincture of its cæruleous colour, or restore it, when upon the affusion of spirit of vinegar it has disappear'd. _experiment xi._ and here i must not omit, _pyrophilus_, to inform you, that we can shew you even in a mineral body something that may seem very near of kin to the changeable quality of the tincture of _lignum nephriticum_, for we have several flat pieces of glass, of the thickness of ordinary panes for windows one of which being interposed betwixt the eye and a clear light, appears of a golden colour, not much unlike that of the moderate tincture of our wood, but being so look'd upon as that the beams of light are not so much trajected thorough it as reflected from it to the eye, that yellow seems to degenerate into a pale blew, somewhat like that of a turquoise. and what which may also appear strange, is this, that if in a certain posture you hold one of these plates perpendicular to the horizon, so that the sun-beams shine upon half of it, the other half being shaded, you may see that the part shin'd upon will be of a much diluter yellow than the shaded part which will appear much more richly colour'd; and if you alter the posture of the glass, so that it be not held perpendicular, but parallel in reference to the horizon, you may see, (which perhaps you will admire) the shaded part look of a golden colour, but the other that the sun shines freely on, will appear considerably blew, and as you remove any part of the glass thus held horizontally into the sun-beams or shade, it will in the twinkling of an eye seem to pass from one of the above mention'd colours to the other, the sun-beams trajected through it upon a sheet of white paper held near it, do colour it with a yellow, somewhat bordering upon a red, but yet the glass may be so oppos'd to the sun, that it may upon paper project a mix'd colour here and there more inclin'd to yellow, and here and there more to blew. the other phænomena of this odd glass, i fear it would be scarce worth while to record, and therefore i shall rather advertise you, _first_ that in the trying of these experiments with it, you must take notice that one of the sides has either alone, or at least principally its superficial parts dispos'd to the reflection of the blew colour above nam'd, and that therefore you must have a care to keep that side nearest to the eye. and next, that we have our selves made glasses not unfit to exhibit an experiment not unlike that i have been speaking of, by laying upon pieces of glass some very finely foliated silver, and giving it by degrees a much stronger fire than is requisite or usual for the tinging of glasses of other colours. and this experiment, not to mention that it was made without a furnace in which artificers that paint glass are wont to be very curious, is the more considerable, because, that though a skilfull painter could not deny to me that 'twas with silver he colour'd his glasses yellow; yet he told me, that when to burn them (as they speak) he layes on the plates of glass nothing but a _calx_ of silver calcin'd without corrosive liquors, and temper'd with fair water, the plates are ting'd of a fine yellow that looks of a golden colour, which part soever of it you turn to or from the light; whereas (whether it be what an artificer would call over-doing, or burning, or else the imploying the silver crude that makes the difference,) we have found more than once, that some pieces of glass prepar'd as we have related, though held against the light they appear'd of a transparent yellow, yet look'd on with ones back turn'd to the light they exhibited an untransparent blew. _experiment xii._ if you will allow me, _pyrophilus_, for the avoiding of ambiguity, to imploy the word pigments, to signifie such prepared materials (as cochinele, vermilion, orpiment,) as painters, dyers and other artificers make use of to impart or imitate particular colours, i shall be the better understood in divers passages of the following papers, and particularly when i tell you, that the mixing of pigments being no inconsiderable part of the painters art, it may seem an incroachment in me to meddle with it. but i think i may easily be excus'd (though i do not altogether pass it by) if i restrain my self to the making of a transient mention of some few of their practices about this matter; and that only so far forth, as may warrant me to observe to you, that there are but few simple and primary colours (if i may so call them) from whose various compositions all the rest do as it were result. for though painters can imitate the hues (though not always the splendor) of those almost numberless differing colours that are to be met with in the works of nature, and of art, i have not yet found, that to exhibit this strange variety they need imploy any more than _white_, and _black_, and _red_, and _blew_, and _yellow_; these _five_, variously _compounded_, and (if i may so speak) _decompounded_, being sufficient to exhibit a variety and number of colours, such, as those that are altogether strangers to the painters pallets, can hardly imagine. thus (for instance) black and white differingly mix'd, make a vast company of lighter and darker grays. blew and yellow make a huge variety of greens. red and yellow make orange tawny. red with a little white makes a carnation. red with an eye of blew, makes a purple; and by these simple compositions again compounded among themselves, the skilfull painter can produce what kind of colour he pleases, and a great many more than we have yet names for. but, as i intimated above, 'tis not my design to prosecute this subject, though i thought it not unfit to take some notice of it, because we may hereafter have occasion to make use of what has been now deliver'd, to illustrate the generation of intermediate colours; concerning which we must yet subjoyn this caution, that to make the rules about the emergency of colours, fit to be relied upon, the corpuscles whereof the pigments consist must be such as do not destroy one anothers texture, for in case they do, the produced colour may be very different from that which would result from the mixture of other harmless pigments of the same colours, as i shall have occasion to shew ere long. _experiment xiii._ it may also give much light to an enquirer into the nature of colours, to know that not only in green, but in many (if not all) other colours, the light of the sun passing through diaphanous bodies of differing hues may be tinged of the same compound colour, as if it came from some painters colours of the same denomination, though this later be exhibited by reflection, and be (as the former experiment declares) manifestly compounded of material pigments. wherefore to try the composition of colours by trajection, we provided several plates of tinged glass, which being laid two at a time one on the top of another, the object look'd upon through them both, appear'd of a compounded colour, which agrees well with what we have observ'd in the second experiment, of looking against the light through differingly colour'd papers. but we thought the experiment would be more satisfactory, if we procur'd the sun-beams to be so ting'd in their passage through plates of glass, as to exhibit the compounded colour upon a sheet of white paper. and though by reason of the thickness of the glasses, the effect was but faint, even when the sun was high and shin'd forth clear, yet, we easily remedied that by contracting the beams we cast on them by means of a convex burning-glass, which where it made the beams much converge increas'd the light enough to make the compounded colour very manifest upon the paper. by this means we observ'd, that the beams trajected through blew and yellow compos'd a green, that an intense and moderate red did with yellow make differing degrees of saffron, and orange tawny colours, that green and blew made a colour partaking of both, such as that which some latin writers call _pavonaceus_, that red and blew made a purple, to which we might add other colours, that we produc'd by the combinations of glasses differingly ting'd, but that i want proper words to express them in our language, and had not when we made the tryals, the opportunity of consulting with a painter, who perchance might have suppli'd me with some of the terms i wanted. i know not whether it will be requisite to subjoyn on this occasion, what i tried concerning reflections from colour'd glasses, and other transparent bodies, namely, that having expos'd four or five sorts of them to the sun, and cast the reflected beams upon white paper held near at hand, the light appear'd not manifestly ting'd, but as if it had been reflected from the impervious parts of a colourless glass, only that reflected from the yellow was here and there stain'd with the same colour, as if those beams were not all reflected from the superficial, but some from the internal parts of the glass; upon which occasion you may take notice, that a skilfull tradesman, who makes such colour'd glass told me, that where as the red pigment was but superficial, the yellow penetrated to the very midst of the plate. but for further satisfaction, not having the opportunity to foliate those plates, and so turn them into looking-glasses, we foliated a plate of _muscovy_ glass, and then laying on it a little transparent varnish of a gold colour, we expos'd it to the sun-beams, so as to cast them upon a body fit to receive them, on which the reflected light, appearing, as we expected, yellow, manifested that rebounding from the specular part of the _selenitis_, it was ting'd in its return with the colour of the transparent varnish through which it pass'd. _experiment xiv._ after what we have said of the composition of colours, it will now be seasonable to annex some experiments that we made in favour of those colours, that are taught in the schools not to be real, but only apparent and phantastical; for we found by tryals, that these colours might be compounded, both with true and stable colours, and with one another, as well as unquestionably genuine and lasting colours, and that the colours resulting from such compositions, would respectively deserve the same denominations. for first, having by the trajection of the sun-beams through a glass-prism thrown an iris on the floor, i found that by placing a blew glass at a convenient distance betwixt the prism and the iris, that part of the iris that was before yellow, might be made to appear green, though not of a grass green, but of one more dilute and yellowish. and it seems not improbable, that the narrow greenish list (if i may so call it) that is wont to be seen between the yellow and blew parts of the iris, is made by the confusion of those two bordering colours. next, i found, that though the want of a sufficient liveliness in either of the compounding colours, or a light error in the manner of making the following tryals, was enough to render some of them unsuccessfull, yet when all necessary circumstances were duely observ'd, the event was answerable to our expectation and desire. and (as i formerly noted) that red and blew compound a purple, so i could produce this last nam'd colour, by casting at some distance from the glass the blew part of the prismatical iris (as i think it may be call'd for distinction sake) upon a lively red, (for else the experiment succeeds not so well.) and i remember, that sometimes when i try'd this upon a piece of red cloath, _that_ part of the iris which would have been blew, (as i try'd by covering that part of the cloath with a piece of white paper) and compounded with the red, wherewith the cloath was imbued before, appear'd of a fair purple, did, when i came to view it near at hand, look very odly, as if there were some strange reflection or refraction or both made in the hairs of which that cloath was composed. calling likewise the prismatical iris upon a very vivid blew, i found that part of it, which would else have been the yellow, appear green. (another somewhat differing tryal, and yet fit to confirm this, you will find in the fifteenth experiment.) but it may seem somewhat more strange, that though the prismatical iris being made by the refraction of light through a body that has no colour at all, must according to the doctrine of the schools consist of as purely emphatical colours, as may be, yet even these may be compounded with one another, as well as real colours in the grossest pigments. for i took at once two triangular glasses, and one of them being kept fixt in the same posture, that the iris it projected on the floor might not waver, i cast on the same floor another iris with the other prism, and moving it too and fro to bring what part of the second iris i pleas'd, to fall upon what part of the first i thought fit, we did sometimes (for a small errour suffices to hinder the success) obtain by this means a green colour in that part of the more stable iris, that before was yellow, or blew, and frequently by casting those beams that in one of the iris's made the blew upon the red parts of the other iris, we were able to produce a lovely purple, which we can destroy or recompose at pleasure, by severing and reapproaching the edges of the two iris's. _experiment xv._ on this occasion, _pyrophilus_, i shall add, that finding the glass-prism to be the usefullest instrument men have yet imploy'd about the contemplation of colours, and considering that prisms hitherto in use are made of glass, transparent and colourless, i thought it would not be amiss to try, what change the superinduction of a colour, without the destruction of the diaphaneity, would produce in the colours exhibited by the prism. but being unable to procure one to be made of colour'd glass, and fearing also that if it were not carefully made, the thickness of it would render it too opacous, i endeavoured to substitute one made of clarify'd rosin, or of turpentine brought (as i elsewhere teach) to the consistence of a transparent gum. but though these endeavours were not wholly lost, yet we found it so difficult to give these materials their true shape, that we chose rather to varnish over an ordinary prism with some of these few pigments that are to be had transparent; as accordingly we did first with yellow, and then with red, or rather crimson, made with lake temper'd with a convenient oyl, and the event was, that for want of good transparent colours, (of which you know there are but very few) both the yellow and the red made the glass so opacous, (though the pigment were laid on but upon two sides of the glass, no more being absolutely necessary) that unless i look'd upon an inlightned window, or the flame of a candle, or some other luminous or very vivid object, i could scarce discern any colours at all, especially when the glass was cover'd with red. but when i did look on such objects, it appear'd (as i expected) that the colour of the pigment had vitiated or drown'd some of those which the prism would according to its wont have exhibited, and mingling with others, alter'd them: as i remember, that both to my eyes, and others to whom i show'd it, when the prism was cover'd with yellow, it made those parts of bright objects, where the blew would else have been conspicuous, appear of a light green. but, _pyrophilus_, both the nature of the colours, and the degree of transparency, or of darkness in the pigment, besides divers other circumstances, did so vary the _phænomena_ of these tryals, that till i can procure small colour'd prisms, or hollow ones that may be filled with tincted liquor, or obtain some better pigments than those i was reduc'd to imploy, i shall forbear to build any thing upon what has been delivered, and shall make no other use of it, than to invite you to prosecute the inquiry further. _experiment xvi._ and here, _pyrophilus_, since we are treating of emphatical colours, we shall add what we think not unworthy your observation, and not unfit to afford some exercise to the speculative. for there are some liquors, which though colourless themselves, when they come to be elevated, and dispers'd into exhalations, exhibit a conspicuous colour, which they lose again, when they come to be reconjoyn'd into a liquor, as good spirit of _nitre_; or upon its account strong _aqua-fortis_, though devoid of all appearance of redness whilst they continue in the form of a liquor, if a little heat chance to turn the minute parts of them into vapour, the steam will appear of a reddish or deep yellow colour, which will vanish when those exhalations come to resume the form of liquor. and not only if you look upon a glass half full of _aqua-fortis_, or spirit of _nitre_, and half full of _nitrous_ steams proceeding from it, you will see the upper part of the glass of the colour freshly mention'd, if through it you look upon the light. but which is much more considerable, i have tried, that putting _aqua-fortis_ in a long clear glass, and adding a little copper or some such open metall to it, to excite heat and fumes, the light trajected through those fumes, and cast upon a sheet of white paper, did upon that appear of the colour that the fumes did, when directly look'd upon, as if the light were as well ting'd in its passage through these fumes, as it would have been by passing through some glass or liquor in which the same colour was inherent. to which i shall further add, that having sometimes had the curiosity to observe whether the beams of the sun near the horizon trajected through a very red sky, would not (though such rednesses are taken to be but emphatical colours) exhibit the like colour, i found that the beams falling within a room upon a very white object, plac'd directly opposite to the sun, disclos'd a manifest redness, as if they had pass'd through a colour'd _medium_. _experiment xvii._ the emergency, _pyrophilus_, of colours upon the coalition of the particles of such bodies as were neither of them of the colour of that mixture whereof they are the ingredients, is very well worth our attentive observation, as being of good use both speculative and practical; for much of the mechanical use of colours among painters and dyers, doth depend upon the knowledge of what colours may be produc'd by the mixtures of pigments so and so colour'd. and (as we lately intimated) 'tis of advantage to the contemplative naturalist, to know how many and which colours are primitive (if i may so call them) and simple, because it both eases his labour by confining his most sollicitous enquiry to a small number of colours upon which the rest depend, and assists him to judge of the nature of particular compounded colours, by shewing him from the mixture of what more simple ones, and of what proportions of them to one another, the particular colour to be consider'd does result. but because to insist on the proportions, the manner and the effects of such mixtures would oblige me to consider a greater part of the painters art and dyers trade, than i am well acquainted with, i confin'd my self to make trial of _several ways to produce green_, by the composition of blew and yellow. and shall in this place both recapitulate most of the things i have dispersedly deliver'd already concerning that subject, and recruit them. and first, whereas painters (as i noted above) are wont to make green by tempering blew and yellow, both of them made into a soft consistence, with either water or oyl, or some liquor of kin to one of those two, according as the picture is to be drawn with those they call _water colours_, or those they term _oyl colours_, i found that by choosing fit ingredients, and mixing them in the form of dry powders, i could do, what i could not if the ingredients were temper'd up with a liquor; but the blew and yellow powders must not only be finely ground, but such as that the corpuscles of the one may not be too unequal to those of the other, lest by their disproportionate minuteness the smaller cover and hide the greater. we us'd with good success a slight mixture of the fine powder of bise, with that of orpiment, or that of good yellow oker, i say a _slight_ mixture, because we found that an _exquisite_ mixture did not do so well, but by lightly mingling the two pigments in several little parcels, those of them in which the proportion and manner of mixture was more lucky, afforded us a good green. 2. we also learn'd in the dye-houses, that cloth being dy'd blew with woad, is afterwards by the yellow decoction of _luteola_ or woud-wax or wood-wax dy'd into a green colour. 3. you may also remember what we above related, where we intimated, that having in a darkn'd room taken two bodies, a blew and a yellow, and cast the light reflected from the one upon the other, we likewise obtain'd a green. 4. and you may remember, that we observ'd a green to be produc'd, when in the same darkn'd room we look'd at the hole at which alone the light enter'd, through the green and yellow parts of a sheet of marbl'd paper laid over one another. 5. we found too, that the beams of the sun being trajected through two pieces of glass, the one blew and the other yellow, laid over one another, did upon a sheet of white paper on which they were made to fall, exhibit a lovely green. 6. i hope also, that you have not already forgot, what was so lately deliver'd, concerning the composition of a green, with a blew and yellow; of which most authors would call the one a _real_, and the other an _emphatical_. 7. and i presume, you may have yet fresh in your memory, what the fourteenth experiment informs you, concerning the exhibiting of a green, by the help of a blew and yellow, that were both of them emphatical. 8. wherefore we will proceed to take notice, that we also devis'd a way of trying whether or no metalline solutions though one of them at least had its colour adventitious, by the mixture of the _menstruum_ employ'd to dissolve it, might not be made to compound a green after the manner of other bodies. and though this seem'd not easie to be perform'd by reason of the difficulty of finding metalline solutions of the colour requisite, that would mix without præcipitating each other; yet after a while having consider'd the matter, the first tryal afforded me the following experiment. i took a high yellow solution of good gold in _aqua-regis_, (made of _aqua-fortis_, and as i remember half its weight of spirit of salt) to this i put a due proportion of a deep and lovely blew solution of crude copper, (which i have elsewhere taught to be readily dissoluble in strong spirit of urine) and these two liquors though at first they seem'd a little to curdle one another, yet being throughly mingl'd by shaking, they presently, as had been conjectur'd, united into a transparent green liquor, which continu'd so for divers days that i kept it in a small glass wherein 'twas made, only letting fall a little blackish powder to the bottom. the other _phænomena_ of this experiment belong not to this place, where it may suffice to take notice of the production of a green, and that the experiment was more than once repeated with success. 9. and lastly, to try whether this way of compounding colours would hold ev'n in ingredients actually melted by the violence of the fire, provided their texture were capable of safely induring fusion, we caus'd some blew and yellow ammel to be long and well wrought together in the flame of a lamp, which being strongly and incessantly blown on them kept them in some degree of fusion, and at length (for the experiment requires some patience as well as skil) we obtain'd the expected ammel of a green colour. i know not, _pyrophilus_, whether it be worth while to acquaint you with the ways that came into my thoughts, whereby in some measure to explicate the first of the mention'd ways of making a green; for i have sometimes conjectur'd, that the mixture of the bise and the orpiment produc'd a green by so altering the superficial asperity, which each of those ingredients had apart, that the light incident on the mixture was reflected with differing shades, as to quantity, or order, or both, from those of either of the ingredients, and such as the light is wont to be modify'd with, when it reflects from grass, or leaves, or some of those other bodies that we are wont to call green. and sometimes too i have doubted, whether the produced green might not be partly at least deriv'd from this, that the beams that rebound from the corpuscles of the orpiment, giving one kind of stroak upon the _retina_, whose perception we call yellow, and the beams reflected from the corpuscles of the bise, giving another stroak upon the same _retina_, like to objects that are blew, the contiguity and minuteness of these corpuscles may make the appulse of the reflected light fall upon the _retina_ within so narrow a compass, that the part they beat upon being but as it were a physical point, they may give a compounded stroak, which may consequently exhibit a compounded and new kind of sensation, as we see that two strings of a musical instrument being struck together, making two noises that arrive at the ear at the same time as to sense, yield a sound differing from either of them, and as it were compounded of both; insomuch that if they be discordantly ton'd, though each of them struck apart would yield a pleasing sound, yet being struck together they make but a harsh and troublesome noise. but this not being so fit a place to prosecute speculations, i shall not insist, neither upon these conjectures nor any others, which the experiment we have been mentioning may have suggested to me. and i shall leave it to you, _pyrophilus_, to derive what instruction you can from comparing together the various ways whereby a yellow and a blew can be made to compound a green. that which i now pretend to, being only to shew that the first of those mention'd ways, (not to take at present notice of the rest) does far better agree with our conjectures about colours, than either with the doctrine of the schools, or with that of the _chymists_, both which seem to be very much disfavour'd by it. for first, since in the mixture of the two mention'd powders i could by the help of a very excellent _microscope_ (for ordinary ones will scarce serve the turn) discover that which seem'd to the naked eye a green body, to be but a heap of distinct, though very small grains of yellow orpiment and blew bise confusedly enough blended together, it appears that the colour'd corpuscles of either kind did each retain its own nature and colour; by which it may be guess'd, what meer transposition and juxtaposition of minute and singly unchang'd particles of matter can do to produce a new colour; for that this local motion and new disposition of the small parts of the orpiment did intervene is much more manifest than it is easie to explicate how they should produce this new green otherwise than by the new manner of their being put together, and consequently by their new disposition to modifie the incident light by reflecting it otherwise than they did before they were mingl'd together. secondly, the green thus made being (if i may so speak) mechanically produc'd, there is no pretence to derive it from i know not what incomprehensible substantial form, from which yet many would have us believe that colours must flow; nor does this green, though a real and permanent, not a phantastical and vanid colour, seem to be such an inherent quality as they would have it, since not only each part of the mixture remains unalter'd in colour, and consequently of a differing colour from the heap they compose, but if the eye be assisted by a _microscope_ to discern things better and more distinctly than before it could, it sees not a green body, but a heap of blew and yellow corpuscles. and in the third place, i demand what either sulphur, or salt, or mercury has to do in the production of this green; for neither the bise nor the orpiment were indu'd with that colour before, and the bare juxtaposition of the corpuscles of the two powders that work not upon each other, but might if we had convenient instruments be separated, unalter'd, cannot with any probability be imagin'd either to increase or diminish any of the three hypostatical principles, (to which of them soever the _chymists_ are pleas'd to ascribe colours) nor does there here intervene so much as heat to afford them any colour to pretend, that at least there is made an extraversion (as the _helmontians_ speak) of the sulphur or of any of the two other supposed principles; but upon this experiment we have already reflected enough, if not more than enough for once. _experiment xviii._ but here, _pyrophilus_, i must advertise you, that 'tis not every yellow and every blew that being mingl'd will afford a green; for in case one of the ingredients do not act only as endow'd with such a colour, but as having a power to alter the texture of the corpuscles of the other, so as to indispose them to reflect the light, as corpuscles that exhibit a blew or a yellow are wont to reflect it, the emergent colour may be not green, but such as the change of texture in the corpuscles of one or both of the ingredients qualifies them to shew forth; as for instance, if you let fall a few drops of syrrup of violets upon a piece of white paper, though the syrrup being spread will appear blew, yet mingling with it two or three drops of the lately mention'd solution of gold, i obtain'd not a green but a reddish mixture, which i expected from the remaining power of the acid salts abounding in the solution, such salts or saline spirits being wont, as we shall see anon, though weakn'd, so to work upon that syrrup as to change it into a red or reddish colour. and to confirm that for which i allege the former experiment, i shall add this other, that having made a very strong and high-colour'd solution of filings of copper with spirit of urine, though the _menstruum_ seem'd glutted with the metall, because i put in so much filings that many of them remain'd for divers days undissolv'd at the bottom, yet having put three or four drops of syrrup of violets upon white paper, i found that the deep blew solution proportionably mingl'd with this other blew liquor did not make a blew mixture, but, as i expected, a fair green, upon the account of the urinous salt that was in the _menstruum_. _experiment xix._ to shew the _chymists_, that colours may be made to appear or vanish, where there intervenes no accession or change either of the sulphureous, or the saline, or the mercurial principle (as they speak) of bodies: i shall not make use of the iris afforded by the glass-prism, nor of the colours to be seen in a fair morning in those drops of dew that do in a convenient manner reflect and refract the beams of light to the eye; but i will rather mind them of what they may observe in their own laboratories, namely, that divers, if not all, chymical essential oyls, as also good spirit of wine, being shaken till they have good store of bubbles, those bubbles will (if attentively consider'd) appear adorn'd with various and lovely colours, which all immediately vanish, upon the relapsing of the liquor that affords those bubbles their skins, into the rest of the oyl, or spirit of wine, so that a colourless liquor may be made in a trice to exhibit variety of colours, and may lose them in a moment without the accession or diminution of any of its hypostatical principles. and, by the way, 'tis not unworthy our notice, that some bodies, as well colourless, as colour'd, by being brought to a great thinness of parts, acquire colours though they had none before, or colours differing from them they were before endued with: for, not to insist on the variety of colours, that water, made somewhat glutinous by sope, acquires, when 'tis blown into such sphærical bubbles as boys are wont to make and play with; turpentine (though it have a colour deep enough of its own) may (by being blown into after a certain manner) be brought to afford bubbles adorn'd with variety of orient colours, which though they vanish after some while upon the breaking of the bubbles, yet they would in likelihood always exhibit colours upon their _superfices_, (though not always the same in the same parts of them, but vary'd according to the incidence of the sight, and the position of the eye) if their texture were durable enough: for i have seen one that was skill'd at fashioning glasses by the help of a lamp, blowing some of them so strongly as to burst them, whereupon it was found, that the tenacity of the metall was such, that before it broke it suffer'd it self to be reduc'd into films so extremely thin, that being kept clean they constantly shew'd on their surfaces (but after the manner newly mention'd) the varying colours of the rain-bow, which were exceedingly vivid, as i had often opportunity to observe in some, that i caus'd purposely to be made, to keep by me. but lest it should be objected, that the above mentioned instances are drawn from transparent liquors, it may possibly appear, not impertinent to add, what i have sometimes thought upon, and several times tried, when i was considering the opinions of the _chymists_ about colours, i took then a feather of a convenient bigness and shape, and holding it at a fit distance betwixt my eye and the sun when he was near the horizon, me thought there appear'd to me a variety of little rain-bows, with differing and very vivid colours, of which none was constantly to be seen in the feather; the like _phænomenon_ i have at other times (though not with altogether so good success) produc'd, by interposing at a due distance a piece of black ribband betwixt the almost setting sun and my eye, not to mention the trials i have made to the same purpose, with other bodies. _experiment xx._ take good syrrup of violets, imprægnated with the tincture of the flowers, drop a little of it upon a white paper (for by that means the change of colour will be more conspicuous, and the experiment may be practis'd in smaller quantities) and on this liquor let fall two or three drops of spirit either of salt or vinegar, or almost any other eminently acid liquor, and upon the mixture of these you shall find the syrrup immediatly turn'd red, and the way of effecting such a change has not been unknown to divers persons who have produc'd the like, by spirit of vitriol, or juice of limmons, but have groundlessly ascrib'd the effect to some peculiar quality of those two liquors, whereas, (as we have already intimated) almost any acid salt will turn syrrup of violets red. but to improve the experiment, let me add what has not (that i know of) been hitherto observ'd, and has, when we first shew'd it them, appear'd something strange, even to those that have been inquisitive into the nature of colours; namely, that if instead of spirit of salt, or that of vinegar, you drop upon the syrrup of violets a little oyl of tartar _per deliquium_, or the like quantity of solution of potashes, and rubb them together with your finger, you shall find the blew colour of the syrrup turn'd in a moment into a perfect green, and the like may be perform'd by divers other liquors, as we may have occasion elsewhere to inform you. _annotation upon the twentieth experiment_. the use of what we lately deliver'd concerning the way of turning syrrup of violets, red or green, may be this; that, though it be a far more common and procurable liquor than the infusion of _lignum nephriticum_, it may yet be easily substituted in its room, when we have a mind to examine, whether or no the salt predominant in a liquor or other body, wherein 'tis loose and abundant, belong to the tribe of _acid_ salts or not. for if such a body turn the syrrup of a red or reddish purple colour, it does for the most part argue the body (especially if it be a distill'd liquor) to abound with acid salt. but if the syrrup be made green, that argues the predominant salt to be of a nature repugnant to that of the tribe of acids. for, as i find that either spirit of salt, or oyl of vitriol, or _aqua-fortis_, or spirit of vinegar, or juice of lemmons, or any of the acid liquors i have yet had occasion to try, will turn syrrup of violets, of a _red_, (or at least, of a _reddish_ colour, so i have found, that not only the volatile salts of all animal substances i have us'd, as spirit of harts-horn, of urine, of sal-armoniack, of blood, &c. but also all the alcalizate salts i have imploy'd, as the solution of salt of tartar, of pot-ashes, of common wood-ashes, lime-water, &c. will immediately change the blew syrrup, into a perfect green. and by the same way (to hint that upon the by) i elsewhere show you, both the changes that nature and time produce, in the more saline parts of some bodies, may be discover'd, and also how ev'n such chymically prepar'd bodies, as belong not either to the animal kingdome, or to the tribe of _alcali's_, may have their new and superinduc'd nature successfully examin'd. in this place i shall only add, that not alone the changing the colour of the syrrup, requires, that the changing body be more strong, of the acid, or other sort of salt that is predominant in it, than is requisite for the working upon the tincture of _lignum nephriticum_; but that in this is also, the operation of the formerly mention'd salts upon our syrrup, differs from their operation upon our tinctures, that in this liquor, if the cæruleous colour be _destroy'd_ by an acid salt, it may be _restor'd_ by one that is either volatile, or lixiviate; whereas in syrrup of violets, though one of these contrary salts will _destroy_ the action of the other, yet neither of them will _restore_ the syrrup to its native blew; but each of them will change it into the colour which it self doth (if i may so speak) affect, as we shall have occasion to show in the notes on the twenty fifth experiment. _experiment xxi._ there is a weed, more known to plowmen than belov'd by them, whose flowers from their colour are commonly call'd _blew-bottles_, and _corn-weed_ from their growing among corn[18]. these flowers some ladies do, upon the account of their lovely colour, think worth the being candied, which when they are, they will long retain so fair a colour, as makes them a very fine sallad in the winter. but i have try'd, that when they are freshly gather'd, they will afford a juice, which when newly express'd, (for in some cases 'twill soon enough degenerate) affords a very deep and pleasant blew. now, (to draw this to our present scope) by dropping on this fresh juice, a little spirit of salt, (that being the acid spirit i had then at hand) it immediately turn'd (as i predicted) into a red. and if instead of the sowr spirit i mingled with it a little strong solution of an alcalizate salt, it did presently disclose a lovely green; the same changes being by those differing sorts of saline liquors, producible in this _natural juice_, that we lately mention'd to have happen'd to that _factitious mixture_, the syrrup of violets. and i remember, that finding this blew liquor, when freshly made, to be capable of serving in a pen for an ink of that colour, i attempted by moistning one part of a piece of white paper with the spirit of salt i have been mentioning, and another with some alcalizate or volatile liquor, to draw a line on the leisurely dry'd paper, that should, e'vn before the ink was dry, appear partly blew, partly red, and partly green: but though the latter part of the experiment succeeded not well, (whether because volatile salts are too fugitive to be retain'd in the paper, and alcalizate ones are too unctuous, or so apt to draw moisture from the air, that they keep the paper from drying well) yet the former part succeeded well enough; the blew and red being conspicuous enough to afford a surprizing spectacle to those, i acquaint not with (what i willingly allow you to call) the _trick_. [18] _herbarists_ are wont to call this plant _cyanus vulgaris minor_. _annotation upon the one and twentieth experiment._ but lest you should be tempted to think (_pyrophilus_) that volatile or alcalizate salts change blews into green, rather upon the score of the easie transition of the former colour into the latter, than upon the account of the texture, wherein most vegetables, that afford a blew, seem, though otherwise differing, to be allied, i will add, that when i purposely dissolv'd blew vitriol in fair water, and thereby imbu'd sufficiently that liquor with that colour, a lixiviate liquor, and a urinous salt being copiously pour'd upon distinct parcels of it, did each of them, though perhaps with some difference, turn the liquor not green, but of a deep yellowish colour, almost like that of yellow oker, which colour the precipitated corpuscles retain'd, when they had leisurely subsided to the bottom. what this precipitated substance is, it is not needfull now to enquire in this place, and in another, i have shown you, that notwithstanding its colour, and its being obtainable from an acid _menstruum_ by the help of salt of tartar, it is yet far enough from being the true sulphur of vitriol. _experiment xxii._ our next experiment (_pyrophilus_) will perhaps seem to be of a contrary nature to the two former, made upon syrrup of violets, and juice of blew-bottles. for as in them by the affusion of oyl of tartar, a blewish liquor is made green, so in this, by the sole mixture of the same oyl, a greenish liquor becomes blew. the hint of this experiment was given us by the practice of some _italian_ painters, who being wont to counterfeit _ultra-marine azure_ (as they call it) by grinding verdigrease with sal-armoniack, and some other saline ingredients, and letting them rot (as they imagine) for a good while together in a dunghill, we suppos'd, that the change of colour wrought in the verdigrease by this way of preparation, must proceed from the action of certain volatile and alcalizate salts, abounding in some of the mingled concretes, and brought to make a further dissolution of the copper abounding in the verdigrease, and therefore we conjectur'd, that if both the verdigrease, and such salts were dissolv'd in fair water, the small parts of both being therein more subdivided, and set at liberty, would have better access to each other, and thereby incorporate much the more suddenly; and accordingly we found, that if upon a strong solution of good french verdigrease (for 'tis that we are wont to imploy, as the best) you pour a just quantity of oyl of tartar, and shake them well together, you shall immediately see a notable change of colour, and the mixture will grow thick, and not transparent, but if you stay a while, till the grosser part be precipitated to, and setled in the bottom, you may obtain a clear liquor of a very lovely colour, and exceeding delightfull to the eye. but, you must have a care to drop in a competent quantity of oyl of tartar, for else the colour will not be so deep, and rich; and if instead of this oyl you imploy a clear _lixivium_ of pot-ashes, you may have an azure somewhat lighter or paler than, and therefore differing from, the former. and if instead of either of these liquors, you make use of spirit of urine, or of harts-horn, you may according to the quantity and quality of the spirit you pour in, obtain some further variety (though scarce considerable) of cæruleous liquors. and yet lately by the help of this urinous spirit we made a blew liquor, which not a few ingenious persons, and among them, some, whose profession makes them very conversant with colours, have looked upon with some wonder. but these azure colour'd liquors should be freed from the subsiding matter, which the salts of tartar or urine precipitate out of them, rather by being decanted, than by filtration. for by the latter of these ways we have sometimes found, the colour of them very much impair'd, and little superiour to that of the grosser substance, that it left in the filtre. _experiment xxiii._ that roses held over the fume of sulphur, may quickly by it be depriv'd of their colour, and have as much of their leaves, as the fume works upon, burn'd pale, is an experiment, that divers others have tried, as well as i. but (_pyrophilus_) it may seem somewhat strange to one that has never consider'd the compounded nature of brimstone, that, whereas the fume of sulphur will, as we have said, whiten the leaves of roses; that liquor, which is commonly call'd oyl of sulphur _per campanam_, because it is suppos'd to be made by the condensation of these fumes in glasses shap't like bells, into a liquor, does powerfully heighten the tincture of red roses, and make it more red and vivid, as we have easily tried by putting some red-rose leaves, that had been long dried, (and so had lost much of their colour) into a vial of fair water. for a while after the affusion of a convenient quantity of the liquor we are speaking of, both the leaves themselves, and the water they were steep'd in, discover'd a very fresh and lovely colour. _experiment xxiv._ it may (_pyrophilus_) somewhat serve to illustrate, not only the doctrine of _pigments_, and of _colours_, but divers other parts of the _corpuscular philosophy_; as that explicates odours, and many other things, not as the schools by aery qualities, but by real, though extremely minute bodies; to examine, how much of a colourless liquor, a very small parcel of a pigment may imbue with a _discernable_ colour. and though there be scarce any thing of preciseness to be expected from such trials, yet i presum'd, that (at least) i should be able to show a much further subdivision of the parts of matter into _visible_ particles, than i have hitherto found taken notice of, and than most men would imagine; no body, that i know of, having yet attempted to reduce this matter to any measure. the bodies, the most promising for such a purpose, might seem to be the metalls, especially gold, because of the multitude, and minuteness of its parts, which might be argu'd from the incomparable closeness of its texture: but though we tried a solution of gold made in _aqua regia_ first, and then in fair water; yet in regard we were to determine the pigment we imploy'd, not by _bulk_ but _weight_, and because also, that the yellow colour of gold is but a faint one in comparison of the deep colour of _cochineel_, we rather chose this to make our trials with. but among divers of these it will suffice to set down one, which was carefully made in vessels conveniently shap'd; (and that in the presence of a witness, and an assistant) the sum whereof i find among my _adversaria_, registred in the following words. to which i shall only premise, (to lessen the wonder of so strange a diffusion of the pigment) that _cochineel_ will be better dissolv'd, and have its colour far more heightn'd by spirit of urine, than (i say not by common water, but) by rectify'd spirit of wine it self. the note i spoke off is this. [one grain of _cochineel_ dissolv'd in a pretty quantity of spirit of urine, and then dissolv'd further by degrees in fair water, imparted a discernable, though but a very faint colour, to about six glass-fulls of water, each of them containing about forty three ounces and an half, which amounts to above a hundred twenty five thousand times its own weight.] _experiment xxv._ it may afford a considerable hint (_pyrophilus_) to him, that would improve the art of dying, to know what change of colours may be produc'd by the three several sorts of salts already often mention'd, (some or other of which may be procur'd in quantity at reasonable rates) in the juices, decoctions, infusions, and (in a word) the more soluble parts of vegetables. and, though the design of this discourse be the improvement of knowledge, not of trades: yet thus much i shall not scruple to intimate here, that the blew liquors, mention'd in the twentieth and one and twentieth experiments, are far from being the only vegetable substances, upon which acid, urinous, and alcalizate salts have the like operations to those recited in those two experiments. for ripe _privet berries_ (for instance) being crush'd upon white paper, though they stain it with a purplish colour, yet if we let fall on some part of it two or three drops of spirit of salt, and on the other part a little more of the strong solution of pot-ashes, the former liquor immediately turn'd that part of the thick juice or pulp, on which it fell, into a lovely red, and the latter turn'd the other part of it into a delightfull green. though i will not undertake, that those colours in that substance shall not be much more orient, than lasting; and though (_pyrophilus_) this experiment may seem to be almost the same with those already deliver'd concerning syrrup of violets, and the juice of blew-bottles, yet i think it not amiss to take this occasion to inform you, that this experiment reaches much farther, than perhaps you yet imagine, and may be of good use to those, whom it concerns to know, how dying stuffs may be wrought upon by saline liquors. for, i have found this experiment to succeed in so many various berries, flowers, blossoms, and other finer parts of vegetables, that neither my memory, nor my leisure serves me to enumerate them. and it is somewhat surprizing to see, by how differingly-colour'd flowers, or blossoms, (for example) the paper being stain'd, will by an acid spirit be immediately turn'd red, and by any _alcaly_ or any urinous spirit turn'd green; insomuch that ev'n the crush'd blossoms of _meserion_, (which i gather'd in winter and frosty weather) and those of pease, crush'd upon white paper, how remote soever their colours be from green, would in a moment pass into a deep degree of that colour, upon the touch of an alcalizate liquor. to which let us add, that either of those new pigments (if i may so call them) may by the affusion of enough of a contrary liquor, be presently chang'd from red into green, and from green into red, which observation will hold also in syrrup of violets, juices of blew-bottles, &c. _annotation._ after what i have formerly deliver'd to evince, that there are many instances, wherein new colours are produc'd or acquir'd by bodies, which _chymists_ are wont to think destitute of salt, or to whose change of colours no new accession of saline particles does appear to contribute, i think we may safely enough acknowledge, that we have taken notice of so many changes made by the intervention of salts in the colours of mix'd bodies, that it has lessen'd our wonder, that though _many chymists_ are wont to ascribe the colours of such bodies to their sulphureous, and _the rest_ to their mercurial principle; yet _paracelsus_ himself directs us in the indagation of colours, to have an eye principally upon salts, as we find in that passage of his, wherein he takes upon him to oblige his readers much by instructing them, of what things they are to expect the knowledge from each of the three distinct principles of bodies. _alias_ (says he) _colorum similis ratio est: de quibus brevem institutionem hanc attendite, quod scilicet colores omnes ex sale prodeant. sal enim dat colorem, dat balsamum._[19] and a little beneath. _iam natura ipsa colores protrathit ex sale, cuique speciei dans illum, qui ipsi competit_, &c. after which he concludes; _itaque qui rerum omnium corpora cognoscere vult, huic opus est, ut ante omnia cognoscat sulphur, ab hoc, qui desiderat novisse colores is scientiam istorum petat à sale, qui scire vult virtutes, is scrutetur arcana mercurii. sic nimirum fundamentum hauserit mysteriorum, in quolibet crescenti indagandorum, prout natura cuilibet speciei ea ingessit_. but though _paracelsus_ ascribes to each of his belov'd hypostatical principles, much more than i fear will be found to belong to it; yet if we please to consider colours, not as _philosophers_, but as _dyers_, the concurrence of salts to the striking and change of colours, and their efficacy, will, i suppose, appear so considerable, that we shall not need to quarrel much with _paracelsus_, for ascribing in this place (for i dare not affirm that he uses to be still of one mind) the colours of bodies to their salts, if by salts he here understood, not only elementary salts, but such also as are commonly taken for salts, as allom, crystals of tartar, vitriol, &c. because the saline principle does chiefly abound in them, though indeed they be, as we elsewhere declare, mix'd bodies, and have most of them, besides what is saline, both sulphureous, aqueous, and gross or earthy parts. [19] paracelsus de mineral. tract. 1. pag. m. 243 but though (_pyrophilus_) i have observ'd a red and green to be produc'd, the former, by acid salts, the later by salts not acid, in the express juices of so many differing vegetable substances, that the observation, if persued, may prove (as i said) of good use: yet to show you how much e'vn these effects depend upon the particular texture of bodies, i must subjoyn some cases wherein i (who am somewhat backwards to admit observations for universal) had the curiosity to discover, that the experiments would not uniformly succeed, and of these exceptions, the chief that i now remember, are reducible to the following three. _experiment xxvi._ and, (first) i thought fit to try the operation of acid salts upon vegetable substances, that are already and by their own nature red. and accordingly i made trial upon syrrup of clove-july-flowers, the clear express'd juice of the succulent berries of _spina cervina_, or buckthorn (which i had long kept by me for the sake of its deep colour) upon red roses, infusion of brazil, and divers other vegetable substances, on some of which crush'd (as is often mention'd) upon white paper, (which is also to be understood in most of these experiments, if no circumstance of them argue otherwise) spirit of salt either made no considerable change, or alter'd the colour but from a darker to a lighter red. how it will succeed in many other vegetable juices, and infusions of the same colour, i have at present so few at hand, that i must leave you to find it out your self. but as for the operation of the other sorts of salts upon these red substances, i found it not very uniform, some red, or reddish infusions, as of roses, being turn'd thereby into a dirty colour, but yet inclining to green. nor was the syrrup of clove-july-flowers turn'd by the solution of pot-ashes to a much better, though somewhat a greener, colour. another sort of red infusions was by an _alcaly_ not turn'd into a green, but advanc'd into a crimson, as i shall have occasion to note ere long. but there were other sorts, as particularly the lovely colour'd juice of buckthorn berries, that readily pass'd into a lovely green. _experiment xxvii._ among other vegetables, which we thought likely to afford exceptions to the general observation about the differing changes of colours produc'd by acid and sulphureous salts, we thought fit to make trial upon the flowers of _jasmin_, they being both white as to colour, and esteem'd to be of a more oyly nature than other flowers. whereupon having taken the white parts only of the flowers, and rubb'd them somewhat hard with my finger upon a piece of clean paper, it appear'd very little discolour'd. nor had spirit of salt, wherewith i moisten'd one part of it, any considerable operation upon it. but spirit of urine, and somewhat more effectually a strong alcalizate solution, did immediately turn the almost colourless paper moisten'd by the juice of the _jasmin_, not as those liquors are wont to do, when put upon the juices of other flowers, of a good green, but of a deep, though somewhat greenish yellow, which experiment i did afterwards at several times repeat with the like success. but it seems not that a great degree of unctuousness is necessary to the production of the like effects, for when we try'd the experiment with the leaves of those purely white flowers that appear about the end of winter, and are commonly call'd _snow drops_, the event, was not much unlike that, which, we have been newly mentioning. _experiment xxviii._ another sort of instances to show, how much changes of colour effected by salts, depend upon the particular texture of the colour'd bodies, has been afforded me by several _yellow_ flowers, and other vegetables, as mary-gold leaves, early prim-roses, fresh madder, &c. for being rubb'd upon white paper, till they imbued it with their colour, i found not, that by the addition of alcalizate liquors, nor yet by that of an urinous spirit, they would be turn'd either green or red: nor did so acid a spirit, as that of salt, considerably alter their colour, save that it seem'd a little to dilute it. only in some early prim-roses it destroy'd the greatest part of the colour, and made the paper almost white agen. and madder also afforded some thing peculiar, and very differing from what we have newly mention'd: for having gather'd some roots of it, and, (whilst they were recent) express'd upon white paper the yellow juice, an alcalizate solution drop'd upon it did not turn it either green or white, but red. and the bruis'd madder it self being drench'd with the like alcalizate solution, exchang'd also its yellowishness for a redness. _an admonition touching the four preceding experiments._ having thus (_pyrophilus_) given you divers instances, to countenance the general observation deliver'd in the twenty fifth experiment, and divers exceptions whereby it ought to be limited; i must leave the further inquiry into these matters to your own industry. for not remembring at present many of those other trials, long since made to satisfie my self about particulars, and not having now the opportunity to repeat them, i must content my self to have given you the hint, and the ways of prosecuting the search your self; and only declare to you in general, that, as i have made many trials, unmention'd in this treatise, whose events were agreeable to those mention'd in the twenty fifth experiment, so (to name now no other instances) what i have try'd with acid and sulphureous salts upon the pulp of juniper berries, rubb'd upon white paper, inclines me to think, that among that vast multitude, and strange variety of plants that adorn the face of the earth, perhaps many other vegetables may be found, on which such _menstruums_ may not have such operations, as upon the juice of violets, pease-blossoms, &c. no nor upon any of those three other sorts of vegetables, that i have taken notice of in the three fore-going experiments. it sufficiently appearing ev'n by these, that the effects of a salt upon the juices of particular vegetables do very much depend upon their particular textures. _experiment xxix._ it may be of some use towards the discovery of the nature of these changes, which the alimental juice receives in some vegetables, according to the differing degrees of their maturity, and according to the differing kinds of plants of the same denomination, to observe what operation acid, urinous, and alcalizate salts will have upon the juices of the several sorts of the vegetable substances i have been mentioning. to declare my meaning by an example, i took from the same cluster, one blackberry full ripe, and another that had not yet gone beyond a redness, and rubbing apiece of white paper, with the former, i observ'd, that the juice adhering to it was of adark reddish colour, full of little black specks; and that this juice by a drop of a strong _lixivium_, was immediately turn'd into a greenish colour deep enough, by as much urinous spirit into a colour much of kin to the former, though somewhat differing, and fainter; and by a drop of spirit of salt into a fine and lightsome red: where as the red berry being in like manner rubb'd upon paper, left on it a red colour, which was very little alter'd by the acid spirit newly nam'd, and by the urinous and lixiviate salts receiv'd changes of colour differing from those that had been just before produc'd in the dark juice of the ripe blackberry. i remember also, that though the infusion of damask-roses would as well, though not so much, as that of red, be heightned by acid spirits to an intense degree of redness, and by lixiviate salts be brought to a darkish green; yet having for trials sake taken a rose, whose leaves, which were large and numerous, like those of a province rose, were perfectly yellow, though in a solution of salt of tartar, they afforded a green blewish tincture, yet i did not by an acid liquor obtain a red one; all that the saline spirit i imploy'd, perform'd, being (if i much misremember not) to dilute somewhat the yellowness of the leaves. i would also have tried the tincture of yellow violets, but could procure none. and if i were in those islands of _banda_, which are made famous as well as rich, by being the almost only places, where cloves will prosper, i should think it worth my curiosity to try, what operation the three differing kinds of salts, i have so often mention'd, would have upon the juice of this spice, (express'd at the several seasons of it) as it grows upon the tree. since good authors inform us, (of what is remarkable) that these whether fruits, or rudiments of fruits, are at first _white_, afterward _green_, and then _reddish_, before they be beaten off the tree, after which being dry'd before they are put up, they grow _blackish_ as we see them. and one of the recentest _herbarists_ informs us, that the flower grows upon the top of the clove it self, consisting of four small leaves, like a cherry blossom, but of an excellent _blew_. but (_pyrophilus_) to return to our own observations, i shall add, that i the rather choose, to mention to you an example drawn from roses, because that though i am apt to think, as i elsewhere advertise, that something may be guess'd at about some of the qualities of the juices of vegetables, by the resemblance or disparity that we meet with in the changes made of their colours, by the operation of the same kinds of salts; yet that those conjectures should be very warily made, may appear among other things, by the instance i have chosen to give in roses. for though, (as i formerly told you) the dry'd leaves, both of the damask, and of red ones, give a red tincture to water sharpen'd with acid salts, yet the one sort of leaves is known to have a purgative faculty,[20] and the other are often, and divers ways, imploy'd for binding. [20] see _parkinson_ th. boran. trib. 9. cap. 26. and i also choose (_pyrophilus_) to subjoyn this twenty ninth experiment to those that precede it, about the change of the colours of vegetables by salts, for these two reasons: the first, that you may not easily entertain suspitions, if in the trials of an experiment of some of the kinds formerly mention'd, you should meet with an event somewhat differing from what my relations may have made you expect. and the second, that you may hereby be invited to discern, that it may not be amiss to take notice of the particular seasons wherein you gather the vegetables which in nicer experiments you make use of. for, it i were not hindred both by haste and some justifiable considerations, i could perhaps add considerable instances, to those lately deliver'd, for the making out of this observation; but for certain reasons i shall at present substitute a remarkable passage to be met with in that laborious herbarist mr. _parkinson_, where treating of the virtues of the (already divers times mention'd) buckthorn berries, he subjoyns the following account of several pigments that are made of them, not only according to the several ways of handling them, but according to the differing seasons of maturity, at which they are gather'd; _of these berries_, (says he) _are made three several sorts of colours as they shall be gather'd, that is, being gather'd while they are green, and kept dry, are call'd sapberries, which being steep'd into some allom-water, or fresh bruis'd into allom-water, they give a reasonable fair yellow colour which painters use for their work, and book-binders to colour the edges of books, and leather-dressers to colour leather, as they use also to make a green colour, call'd sap-green, taken from the berries when they are black, being bruis'd and put into a brass or copper kettle or pan, and there suffer'd to abide three or four_ _days, or a little heated upon the fire, and some beaten allom put unto them, and afterwards press'd forth, the juice or liquor is usually put in great bladders tied with strong thred at the head and hung up untill it be dry, which is dissolv'd in water or wine, but sack_ (he affirms) _is the best to preserve the colour from starving, (as they call it) that is, from decaying, and make it hold fresh the longer. the third colour (where of none_ (says he) _that i can find have made mention but only_ tragus_) is a purplish colour, which is made of the berries suffer'd to grow upon the bushes untill the middle or end of_ november, _that they are ready to drop from the trees._ and, i remember (_pyrophilus_) that i try'd, with a success that pleas'd me well enough, to make such a kind of pigment, as painters call sap-green, by a way not unlike that, deliver'd here by our author, but i cannot now find any thing relating to that matter among my loose papers. and my trials were made so many years ago, that i dare not trust my memory for circumstances, but will rather tell you, that in a noted colour-shop, i brought them by questions to confess to me, that they made their sap-green much after the ways by our _botanist_ here mention'd. and on this occasion i shall add an observation, which though it does not strictly belong to this place, may well enough be mention'd here, namely, that i find by an account given us by the learned _clusius_, of _alaternus_, that ev'n the grosser parts of the same plant, are some of them one colour, and some another; for speaking of that plant, he tells us, that the _portugalls_ use the bark to dye their nets into a red colour, and with the chips of the wood, which are whitish, they dye a blackish blew. _experiment xxx._ among the experiments that tend to shew that the change of colours in bodies may proceed from the vary'd texture of their parts, and the consequent change of their disposition to reflect or refract the light, that sort of experiments must not be left unmention'd, which is afforded us by chymical digestions. for, if _chymists_ will believe several famous writers about what they call the philosophers stone, they must acknowledge that the same matter, seald up hermetically in a philosophical egg, will by the continuance of digestion, or if they will have it so (for it is not material in our case which of the two it be) of decoction, run through a great variety of differing colours, before it come to that of the noblest _elixir_; whether that be scarlet, or purple, or what ever other kind of red. but without building any thing on so obtruse and questionable an operation, (which yet may be pertinently represented to those that believe the thing) we may observe, that divers bodies digested in carefully-clos'd vessels, will in tract of time, change their colour: as i have elsewhere mention'd my having observ'd ev'n in rectify'd spirit of harts-horn, and as is evident in the precipitations of amalgams of gold, and mercury, without addition, where by the continuance of a due heat the silver-colour'd amalgam is reduc'd into a shining red powder. further instances of this kind you may find here and there in divers places of my other essays. and indeed it has been a thing, that has much contributed to deceive many _chymists_, that there are more bodies than one, which by digestion will be brought to exhibit that variety and succession of colours, which they imagine to be peculiar to what they call the _true matter of the philosophers_. but concerning this, i shall referr you to what you may elsewhere find in the discourse written touching the passive deceptions of _chymists_, and more about the production of colours by digestion you will meet with presently. wherefore i shall now make only this observation from what has been deliver'd, that in these operations there appears not any cause to attribute the new colours emergent to the action of a new substantial form, nor to any increase or decrement of either the salt, sulphur, or mercury of the matter that acquires new colours: for the vessels are clos'd, and these principles according to the _chymists_ are ingenerable and incorruptible; so that the effect seems to proceed from hence, that the heat agitating and shuffling the corpuscles of the body expos'd to it, does in process of time so change its texture, as that the transposed parts do modifie the incident light otherwise, than they did when the matter appear'd of another colour. _experiment xxxi._ among the several changes of colour, which bodies acquire or disclose by digestion, it it very remarkable, that _chymists_ find a redness rather than any other colour in most of the tinctures they draw, and ev'n in the more gross solutions they make of almost all concretes, that abound either with mineral or vegetable sulphur, though the _menstruum_ imploy'd about these solutions or tinctures be never so limpid or colourless. this we have observ'd in i know not how many tinctures drawn with spirit of wine from _jalap_, _guaicum_, and several other vegetables; and not only in the solutions of _amber_, _benzoin_, and divers other concretes made with the same _menstruum_, but also in divers mineral tinctures. and, not to urge that familiar instance of the ruby of sulphur, as _chymists_ upon the score of its colour, call the solution of flowers of brimstone, made with the spirit of turpentine, nor to take notice of other more known examples of the aptness of chymical oyls, to produce a red colour with the sulphur they extract, or dissolve; not to insist (i say) upon instances of this nature, i shall further represent to you, as a thing remarkable, that, both acid and alcalizate salts, though in most other cases of such contrary operations, in reference to colours, will with many bodies that abound with sulphureous, or with oyly parts, produce a red; as is manifest partly in the more vulgar instances of the tinctures, or solutions of sulphur made with _lixiviums_, either of calcin'd tartar or pot-ashes, and other obvious examples, partly by this, that the true glass of antimony extracted with some acid spirits, with or without wine, will yield a red tincture, and that i know an acid liquor, which in a moment will turn oyl of turpentine into a deep red. but among the many instances i could give you of the easie production of redness by the operation of saline spirit, as well as of spirit of wine; i remember two or three of those i have tried, which seem remarkable enough to deserve to be mention'd to you apart. _experiment xxxii._ but before we set them down, it will not perhaps appear impertinent to premise; that there seems to be a manifest disparity betwixt red liquors, so that some of them may be said to have a genuine redness in comparison of others, that have a yellowish redness: for if you take (for example) a good tincture of _chochineel_, dilute it never so much with fair water, you will not (as far as i can judge by what i have tried) be able to make it a yellow liquor. insomuch that a single drop of a rich solution of _cochineel_ in spirit of urine, being diluted with above an ounce of fair water, exhibited no yellowishness at all, but a fair (though somewhat faint) pinck or carnation; and even when _cochineel_ was by degrees diluted much beyond the newly mention'd colour, by the way formerly related to you in the twenty fourth experiment, i remember not, that there appear'd in the whole trial any yellow. but if you take balsom of sulphur (for instance) though it may appear in a glass, where it has a good thickness, to be of a deep red, yet if you shake the glass, or pour a few drops on a sheet of white paper, spreading them on it with your finger, the balsom that falls back along the sides of the glass, and that which stains the paper, will appear yellow, not red. and there are divers tinctures, such as that of amber made with spirit of wine, (to name now no more) that will appear either yellow or red, according as the vessels that they fill, are slender or broad. _experiment xxxiii._ but to proceed to the experiments i was about to deliver; _first_; oyl or spirit of turpentine, though clear as fair water, being digested upon the purely white sugar of lead, has, in a short time, afforded us a high red tincture, that some artists are pleas'd to call the balsom of _saturn_, which they very much (and probably not altogether without cause) extoll as an excellent medicine in divers outward affections. _experiment xxxiv._ _next_, take of common brimstone finely powdred five ounces, of sal-armoniack likewise pulveriz'd an equal weight, of beaten quick-lime six ounces, mix these powders exquisitely, and distill them through a retort plac'd in sand by degrees of fire, giving at length as intense a heat as you well can in sand, there will come over (if you have wrought well) a volatile tincture of sulphur, which may probably prove an excellent medicine, and should have been mention'd among the other preparations of sulphur, which we have elsewhere imparted to you, but that it is very pertinent to our present subject, the change of colours. for though none of the ingredients be red, the distill'd liquor will be so: and this liquor if it be well drawn, will upon a little agitation of the vial first unstop'd (especially if it be held in a warmer hand) lend forth a copious fume, not red, like that of nitre, but white; and sometimes this liquor may be so drawn, that i remember, not long since, i took pleasure to observe in a parcel of it, that ingredients not red, did not only yield by distillation a volatile spirit that was red, but though that liquor did upon the bare opening of the bottle it was kept in, drive us away with the plenty and sulphureous sent of a white steam which it sent forth, yet the liquor it self being touch'd by our fingers, did immediately dye them black. _experiment xxxv._ the third and _last_ experiment i shall now mention to shew, how prone bodies abounding in sulphureous parts are to afford a red colour, is one, wherein by the operation of a saline spirit upon a white or whitish body, which according to the _chymists_ should be altogether sulphureous, a redness may be produc'd, not (as in the former experiments) slowly, but in the twinkling of an eye. we took then of the essential oyl of anniseeds, which has this peculiarity, that in cold weather it loses its fluidity and the greatest part of its transparency, and looks like a white or whitish oyntment, and near at hand seems to consist of a multitude of little soft scales: of this coagulated stuff we spread a little with a knife upon a piece of white paper, and letting fall on it, and mixing with it a drop or two of oyl of vitriol, immediately (as we fore-saw) there emerg'd together with some heat and smoak, a blood-red colour, which therefore was in a trice produc'd by two bodies, whereof the one had but a whitish colour, and the other (if carefully rectify'd) had no colour at all. _experiment xxxvi._ but on this occasion (_pyrophilus_) we must add once for all, that in many of the above-recited experiments, though the changes of colour happen'd as we have mention'd them: yet the emergent or produc'd colour is oft times very subject to degenerate, both quickly and much. notwithstanding which, since the changes, we have set down, do happen presently upon the operation of the bodies upon each other, or at the times by us specify'd; _that_ is sufficient both to justifie our veracity, and to shew what we intend; it not being essential to the genuineness of a colour to be durable. for a fading leaf, that is ready to rot, and moulder into dust, may have as true a yellow, as a wedge of gold, which so obstinately resists both time and fire. and the reason, why i take occasion from the former experiment to subjoyn this general advertisement, is, that i have several times observ'd, that the mixture resulting from the oyls of vitriol, and of anniseeds, though it acquire a thicker consistence than either of the ingredients had, has quickly lost its colour, turning in a very short time into a dirty gray, at least in the superficial parts, where 'tis expos'd to the air; which last circumstance i therefore mention, because that, though it seem probable, that this degeneration of colours may oft times and in divers cases proceed from the further action of the saline corpuscles, and the other ingredients upon one another, yet in many cases much of the quick change of colours seems ascribeable to the air, as may be made probable by several reasons: the first whereof may be fetcht from the newly recited example of the two oyls; the next may be, that we have sometimes observ'd long window-curtains of light colours, to have that part of them, which was expos'd to the air, when the window was open, of one colour, and the lower part, that was sheltred from the air by the wall, of another colour: and the third argument may be fetch'd from divers observations, both of others, and our own; for of that pigment so well known in painters shops, by the name of _turnsol_, our industrious _parkinson_, in the particular account he gives of the plant that bears it, tells us also, that _the berries when they are at their full maturity, have within them between the outer skin and the inward kirnel or seed, a certain juice or moisture, which being rubb'd upon paper or cloath, at the first appears of a fresh and lovely green colour, but presently changeth into a kind of blewish purple, upon the cloath or paper, and the same cloath afterwards wet in water, and wrung forth, will colour the water into a claret wine colour, and these_ (concludes he) _are those raggs of cloath, which are usually call'd_ turnsol _in the druggists or grocers shops_[21]. and to this observation of our _botanist_ we will add an experiment of our own, (made before we met with that) which, though in many circumstances, very differing, serves to prove the same thing; for having taken of the deeply red juice of _buckthorn_ berries, which i bought of the man that uses to sell it to the apothecaries, to make their syrrup _de spina cervina_, i let some of it drop upon a piece of white paper, and having left it there for many hours, till the paper was grown dry again, i found what i was inclin'd to suspect, namely, that this juice was degenerated from a deep red to a dirty kind of greyish colour, which, in a great part of the stain'd paper seem'd not to have so much as an eye of red: though a little spirit of salt or dissolv'd _alcaly_ would turn this unpleasant colour (as formerly i told you it would change the not yet alter'd juice) into a red or green. and to satisfie my self, that this degeneration of colour did not proceed from the paper, i drop'd some of the deep red or crimson juice upon a white glaz'd tile, and suffering it to dry on there, i found that ev'n in that body, on which it could not soak, and by which it could not be wrought, it nevertheless lost its colour. and these instances (_pyrophilus_) i am the more carefull to mention to you, that you may not be much surpris'd or discourag'd, if you should sometimes miss of performing punctually what i affirm my self to have done in point of changing colours; since in these experiments the over-sight or neglect of such little circumstances, as in many others would not be perhaps considerable, may occasion the mis-carrying of a trial. and i was willing also to take this occasion of advertising you in the repeating of the experiments mention'd in this treatise, to make use of the juices of vegetables, and other things prepar'd for your trials, as soon as ever they are ready, lest one or other of them grow less fit, if not quite unfit by delay; and to estimate the event of the trials by the change, that is produc'd presently upon the due and sufficient application of actives to passives, (as they speak) because in many cases the effects of such mixtures may not be lasting, and the newly produc'd colour may in a little time degenerate. but, (_pyrophilus_) i forgot to add to the two former observations lately made about vegetables, a third of the same import, made in mineral substances, by telling you, that the better to satisfie a friend or two in this particular, i sometimes made, according to some conjectures of mine, this experiment; that having dissolv'd good silver in _aqua-fortis_, and precipitated it with spirit of salt, upon the first decanting of the liquor, the remaining matter would be purely white; but after it had lain a while uncover'd, that part of it, that was contiguous to the air, would not only lose its whiteness, but appear of a very dark and almost blackish colour, i say that part that was contiguous to the air, because if that were gently taken off, the subjacent part of the same mass would appear very white, till that also, having continu'd a while expos'd to the air, would likewise degenerate. now whether the air perform these things by the means of a subtile salt, which we elsewhere show it not to be destitute of, or by a peircing moisture, that is apt easily to insinuate it self into the pores of some bodies, and thereby change their texture, and so their colour; or by solliciting the avolation of certain parts of the bodies, to which 'tis contiguous; or by some other way, (which possibly i may elsewhere propose and consider) i have not now the leisure to discourse. and for the same reason, though i could add many other instances, of what i formerly noted touching the emergency of redness upon the digestion of many bodies, insomuch that i have often seen upon the borders of _france_ (and probably we may have the like in _england_) a sort of pears, which digested for some time with a little wine, in a vessel exactly clos'd, will in not many hours appear throughout of a deep red colour, (as also that of the juice, wherein they are stew'd, becomes) but ev'n on pure and white salt of tartar, pure spirit of wine, as clear as rock-water, will (as we elsewhere declare) by long digestion acquire a redness; though i say such instances might be multiply'd, and though there be some other obvious changes of colours, which happen so frequently, that they cannot but be as well considerable as notorious; such as is the blackness of almost all bodies burn'd in the open air: yet our haste invites us to resign you the exercise of enquiring into the causes of these changes. and certainly, the reason both _why_ the soots of such differing bodies are almost all of them all black, _why_ so much the greater part of vegetables should be rather green than of any other colour, and particularly (which more directly concerns this place) _why_ gentle heats do so frequently in chymical operations produce rather a redness than another colour in digested _menstruums_, not only sulphureous, as spirit of wine, but saline, as spirit of vinegar, may be very well worth a serious inquiry; which i shall therefore recommend to _pyrophilus_ and his ingenious friends. [21] _parkinson_, thea. bot. trib. 4 cap. 12. _experiment xxxvii._ it may seem somewhat strange, that if you take the crimson solution of _cochineel_, or the juice of black cherries, and of some other vegetables that afford the like colour, (which because many take but for a deep red, we do with them sometimes call it so) and let some of it fall upon a piece of paper, a drop or two of an acid spirit, such as spirit of salt, or _aqua-fortis_, will immediately turn it into a fair red. whereas if you make an infusion of brazil in fair water, and drop a little spirit of salt or _aqua-fortis_ into it, that will destroy its redness, and leave the liquor of a yellow, (sometimes pale) i might perhaps plausibly enough say on this occasion, that if we consider the case a little more attentively, we may take notice, that the action of the acid spirit seems in both cases, but to weaken the colour of the liquor on which it falls. and so though it destroy redness in the tincture of brazil, as well as produce red in the tincture of _chochineel_, its operations may be uniform enough, since as crimson seems to be little else than a very deep red, with (perhaps) an eye of blew, so some kinds of red seem (as i have lately noted) to be little else than heightned yellow. and consequently in such bodies, the yellow seems to be but a diluted red. and accordingly alcalizate solutions and urinous spirits, which seem dispos'd to deepen the colours of the juices and liquors of most vegetables, will not only restore the solution of _cochineel_ and the infusion of brazil to the crimson, whence the spirit of salt had chang'd them into a truer red; but will also (as i lately told you) not only heighthen the yellow juice of madder into red, but advance the red infusion of brazil to a crimson. but i know not whether it will not be much safer to derive these changes from vary'd textures, than certain kinds of bodies; and you will perhaps think it worth while, that i should add on this occasion, that it may deserve some speculation, why, notwithstanding what we have been observing, though blew and purple seem to be deeper colours than red, and therefore the juices of plants of either of the two former colours may (congruously enough to what has been just now noted) be turn'd red by spirit of salt or _aqua-fortis_, yet blew syrrup of violets and some purples should both by oyl of tartar and spirit of urine be chang'd into green, which seems to be not a deeper but a more diluted colour than blew, if not also than purple. _experiment xxxviii._ it would much contribute to the history of colours, if _chymists_ would in their laboratories take a heedfull notice, and give us a faithfull account of the colours observ'd in the steams of bodies either sublim'd or distill'd, and of the colours of those productions of the fire, that are made up by the coalition of those steams. as (for instance) we observe in the distilling of pure salt peter, that at a certain season of the operation, the body, though it seem either crystalline, or white, affords very red fumes: whereas though vitriol be green or blew, the spirit of it is observ'd to come over in whitish fumes. the like colour i have taken notice of in the fumes of several other concretes of differing colours, and natures, especially when distill'd with strong fires. and we elsewhere note, that ev'n soot, as black as it is, has fill'd our receivers with such copious white fumes, that they seem'd to have had their in-sides wash'd with milk. and no less observable may be, the distill'd liqours, into which such fumes convene, (for though we will not deny, that by skill and care a reddish liqour may be obtain'd from nitre) yet the common spirit of it, in the making ev'n of which store of these red fumes are wont to pass over into the receiver, appears not to be at all red. and besides, that neither the spirit of vitriol, nor that of soot is any thing white; and, besides also, that as far as i have observ'd, most (for i say not all) of the empyreumatical oyls of woods, and other concretes, are either of a deep red, or of a colour between red and black; besides this, i say, 'tis very remarkable that notwithstanding that great variety of colours to be met with in the herbs, flowers, and other bodies wont to be distill'd in _balneo_: yet (as far at least as our common distillers experience reacheth) all the waters and spirits that first come over by that way of distillation, leave the colours of their concretes behind them, though indeed there be one or two vegetables not commonly taken notice of, whose distill'd liqours i elsewhere observe to carry over the tincture of the concrete with them. and as in distillations, so in sublimations, it were worth while to take notice of what comes up, in reference to our present scope, by purposely performing them (as i have in some cafes done) in conveniently shap'd glasses, that the colour of the ascending fumes may be discern'd; for it may afford a naturalist good information to observe the congruities or the differences betwixt the colours of the ascending fumes, and those of the _flowers_, they compose by their convention. for it is evident, that these _flowers_, do many of them in point of colour, much differ, not only from one another, but oft times from the concretes that afforded them. thus, (not here to repeat what i formerly noted of the black soots of very differingly colour'd bodies) though camphire and brimstone afford _flowers_ much of their own colour, save that those of brimstone are wont to be a little paler, than the lumps that yielded them; yet ev'n of red _benzoin_, that sublim'd substance, which _chymists_ call its _flowers_, is wont to be white or whitish. and to omit other instances, ev'n one and the same black mineral, antimony, may be made to afford _flowers_, some of them red, and some grey, and, which is more strange, some of them purely white. and 'tis the prescription of some glass-men by exquisitely mingling a convenient proportion of brimstone, sal-armoniack, and quicksilver, and subliming them, together, to make a sublimate of an excellent blew; and though having caus'd the experiment to be made, we found the produc'd sublimate to be far from being of a lovely colour, (as was promis'd) that there and there, it seem'd blewish, and at least was of a colour differing enough from either of the ingredients, which is sufficient for our present purpose. but a much finer colour is promis'd by some of the empiricks, that pretend to secrets, who tell us, that orpiment, being sublim'd, will afford among the parts of it that fly upward, some little masses, which, though the mineral it self be of a good yellow, will be red enough to emulate rubies, both in colour and translucency. and this experiment may, for ought i know, sometimes succeed; for i remember, that having in a small bolt-head purposely sublim'd some powder'd orpiment, we could in the lower part of the sublimate discern here and there some reddish lines, though much of the upper part of the sublimate consisted of a matter, which was not alone purely yellow, but transparent almost like a powder. and we have also this way obtain'd a sublimate, the lower part whereof though it consisted not of rubies, yet the small pieces of it, which were numerous enough, were of a pleasant reddish colour, and glitter'd very prettily. but to insist on such kind of trials and observations (where the ascending fumes of bodies differ in colour from the bodies themselves) though it might indeed inrich the history of colours, would robb me of too much of the little time i have to dispatch what i have further to tell you concerning them. _experiment xxxix_ take the dry'd buds (or blossoms) of the pomegranate tree, (which are commonly call'd in the shops _balaustiums_) pull off the reddish leaves, and by a gentle ebullition of them in fair water, or by a competent infusion of them in like water well heated, extract a faint reddish tincture, which if the liquor be turbid, you may clarifie it by filtrating it into this, if you pour a little good spirit of urine, or some other spirit abounding in the like sort of volatile salts, the mixture will presently turn of a dark greenish colour, but if instead of the fore-mention'd liquor, you drop into the simple infusion a little rectify'd spirit of sea-salt, the pale and almost colourless liquor will immediately not only grow more transparent, but acquire a high redness, like that of rich claret wine, which so suddenly acquir'd colour, may as quickly be destroy'd and turn'd into a dirty blewish green, by the affusion of a competent quantity of the above-mention'd spirit of urine. _annotation._ this experiment may bring some light to, and receive some from a couple of other experiments, that i remember i have met with in the ingenious _gassendus_'s animadversions upon _epicurus_'s philosophy, whilst i was turning over the leaves of those learned commentaries; (my eyes being too weak to let me read such voluminous books quite thorough) and i the less scruple (notwithstanding my contrary custom in this treatise) to set down these experiments of another, because i shall a little improve the latter of them, and because by comparing there with that which i have last recited, we may be assisted to conjecture upon what account it is, that oyl of vitriol heightens the tincture of red-rose leaves, since spirit of salt, which is a highly acid _menstruum_, but otherwise differing enough from oyl of vitriol, does the same thing. our authors experiments then, as we made them, are these; we took about a glass-full of luke-warm water, and in it immerg'd a quantity of the leaves of _senna_, and presently upon the immersion there did not appear any redness in the water, but dropping into it a little oyl of tartar, the liquor soon discover'd a redness to the watchfull eye, whereas by a little of that acid liquor of vitriol, which is like the former, undeservedly called oyl, such a colour would not be extracted from the infused _senna_. on the other side we took some red-rose leaves dry'd, and having shaken them into a glass of fair water, they imparted to it no redness, but upon the affusion of a little oyl of vitriol the water was immediately turn'd red, which it would not have been, if instead of oyl of vitriol, we had imployed oyl of tartar to produce that colour: that these were _gassendus_ his experiments, i partly remember, and was assur'd by a friend, who lately transcribed them out of _gassendus_ his book, which i therefore add, because i have not now that book at hand. and the design of _gassendus_ in these experiments our friend affirms to be, to prove, that of things not red a redness may be made only by mixture, and the varied position of parts, wherein the doctrine of that subtil philosopher doth not a little authorize, what we have formerly delivered concerning the emergency and change of colours. but the instances, that we have out of him set down, seem not to be the most eminent, that may be produced of this truth: for our next experiment will shew the production of several colours out of liquors, which have not any of them any such colour, nor indeed any discernable one at all; and whereas though our author tells us, that there was no redness either in the water, or the leaves of _senna_, or the oyl of tartar; and though it be true, that the predominant colour of the leaves of _senna_ be another than red, yet we have try'd, that by steeping that plant a night even in cold water, it would afford a very deep yellow or reddish tincture without the help of the oyl of tartar, which seems to do little more than assist the water to extract more nimbly a plenty of that red tincture, wherewith the leaves of _senna_ do of themselves abound, and having taken off the tincture of _senna_, made only with fair water, before it grew to be reddish, and decanted it from the leaves, we could not perceive, that by dropping some oyl of tartar into it, that colour was considerable, though it were a little heightned into a redness; which might have been expected, if the particles of the oyl did eminently co-operate, otherwise than we have expressed, to the production of this redness. and as for the experiment with red-rose leaves, the same thing may be alleged, for we found that such leaves by bare infusion for a night and day in fair water, did afford us a tincture bordering at least upon redness, and that colour being conspicuous in the leaves themselves, would not by some seem so much to be produc'd as to be extracted by the affusion of oyl of vitriol. and the experiment try'd with the dry'd leaves of damask-roses succeeded but imperfectly, but that is indeed observable to our authors purpose, that oyl of tartar will not perform in this experiment what oyl of vitriol doth; but because this last named liquor is not so easily to be had, give me leave to advertise you, that the experiment will succeed, if instead of it you imploy _aqua-fortis_. and though some trials of our own formerly made, and others easily deducible from what we have already deliver'd, about the different families and operations of salt, might enable us to present you an experiment upon red-rose leaves, more accommodated to our authors purpose, than that which he hath given us; yet our reverence to so candid a philosopher, invites us rather to improve his experiment, than substitute another in its place. take therefore of the tincture of red-rose leaves, (for with damask-rose leaves the experiment succeedeth not well) made as before hath been taught with a little oyl of vitriol, and a good quantity of fair water, pour off this liquor into a clear vial, half fill'd with limpid water; till the water held against the light have acquir'd a competent redness, without losing its transparency, into this tincture drop leisurely a little good spirit of urine, and shaking the vial, which you must still hold against the light, you shall see the red liquor immediately turn'd into a fine greenish blew, which colour was not to be found in any of the bodies, upon whose mixture it emerg'd, and this change is the more observable, because in many bodies the degenerating of blew into red is usual enough, but the turning of red into blew is very unfrequent. if at every drop of spirit of urine you shake the vial containing the red tincture, you may delightfully observe a pretty variety of colours in the passage of that tincture from a red to a blew, and sometimes we have this way hit upon such a liquor, as being look't upon against and from the light, did seem faintly to emulate the above-mention'd tincture of _lignum nephriticum_. and if you make the tincture of red-roses very high, and without diluting it with fair water, pour on the spirit of urine, you may have a blew so deep, as to make the liquor opacous, but being dropt upon white paper the colour will soon disclose it self. also having made the red, and consequently the blew tincture very transparent, and suffer'd it to rest in a small open vial for a day or two, we found according to our conjecture, that not only the blew but the red colour also was vanish'd; the clear liquor being of a bright amber colour, at the bottom of which subsided a light, but copious feculency of almost the same colour, which seems to be nothing but the tincted parts of the rose leaves drawn out by the acid spirits of the oyl of vitriol, and precipitated by the volatile salt of the spirit of urine, which makes it the more probable, that the redness drawn by the oyl of vitriol, was at least as well an extraction of the tinging parts of the roses, as a production of redness; and lastly, if you be destitute of spirit of urine, you may change the colour of the tincture of roses with many other sulphureous salts, as a strong solution of pot-ashes, oyl of tartar, &c. which yet are seldome so free from feculency, as the spirituous parts of urine becomes by repeated distillation. _annotation_. on this, occasion, i call to mind, that i found, a way of producing, though not the same kind of blew, as i have been mentioning, yet a colour near of kin to it, namely, a fair purple, by imploying a liquor not made red by art, instead of the tincture of red-roses, made with an acid spirit; and my way was only to take log-wood, (a wood very well known to dyers) having by infusion the powder of it a while in fair water made that liquor red, i dropt into it a _tantillum_ of an urinous spirit, as that of sal-armoniack, (and i have done the same thing with an _alcali_) by which the colour was in a moment turn'd into a rich, and lovely purple. but care must be had, that you let not fall into a spoonfull above two or three drops, lest the colour become so deep, as to make the liquor too opacous. and (to answer the other part of _gassendus_ his experiment) if instead of fair water, i infus'd the log-wood in water made somewhat sowr by the acid spirit of salt, i should obtain neither a purple liquor, nor a red, but only a yellow one. _experiment xl._ the experiment i am now to mention to you, _pyrophilus_, is that which both you, and all the other _virtuosi_ that have seen it, have been pleas'd to think very strange; and indeed of all the experiments of colours, i have yet met with, it seems to be the fittest to recommend the doctrine propos'd in this treatise, and to shew that we need not suppose, that all colours must necessarily be inherent qualities, flowing from the substantial forms of the bodies they are said to belong to, since by a bare mechanical change of texture in the minute parts of bodies; two colours may in a moment be generated quite _de novo,_ and utterly destroy'd. for there is this difference betwixt the following experiment, and most of the others deliver'd in these papers, that in this, the colour that a body already had, is not chang'd into another, but betwixt two bodies, each of them apart devoid of colour, there is in a moment generated a very deep colour, and which if it were let alone, would be permanent; and yet by a very small parcel of a third body, that has no colour of its own, (lest some may pretend i know not what antipathy betwixt colours) this otherwise permanent colour will be in another trice so quite destroy'd, that there will remain no foot-stepts either of it or of any other colour in the whole mixture. the experiment is very easie, and it is thus perform'd: take good common sublimate, and fully satiate with it what quantity of water you please, filtre the solution carefully through clean and close paper, that it may drop down as clear and colourless as fountain water. then when you'l shew the experiment, put of it about a spoonfull into a small wine-glass, or any other convenient vessel made of clear glass, and droping in three or four drops of good oyl of tartar, _per deliquium_; well filtred that it may likewise be without colour, these two limpid liquors will in the twinkling of an eye turn into an opacous mixture of a deep orange colour, which by keeping the glass continually shaking in your hand, you must preserve from setling too soon to the bottom; and when the spectators have a little beheld this first change, then you must presently drop in about four or five drops of oyl of vitriol, and continuing to shake the glass pretty strongly, that it may the nimbler diffuse it self, the whole colour, if you have gone skilfully to work, will immediately disappear, and all the liquor in the glass will be clear and colourless as before, without so much as a sediment at the bottom. but for the more gracefull trial of this experiment, 'twill not be amiss to observe, first, that there should not be taken too much of the solution of sublimate, nor too much of the oyl of tartar drop'd in, to avoid the necessity of putting in so much oyl of vitriol as may make an ebullition, and perhaps run over the glass. secondly, that 'tis convenient to keep the glass always a little shaking, both for the better mixing of the liquors, and to keep the yellow substance from subsiding, which else it would in a short time do, though when 'tis subsided it will retain its colour, and also be capable of being depriv'd of it by the oyl newly mention'd. thirdly, that if any yellow matter stick at the sides of the glass, 'tis but inclining the glass, till the clarify'd liquor can wash alongst it, and the liquor will presently imbibe it, and deprive it of its colour. many have somewhat wondred, how i came to light upon this experiment, but the notions or conjectures i have about the differing natures of the several tribes of salts, having led me to devise the experiment, it will not be difficult for me to give you the chymical reason, if i may so speak, of the _phænomenon_. having then observ'd, that _mercury_ being dissolv'd in some _menstruums_, would yield a dark yellow precipitate, and supposing that, as to this, common water, and the salts that stick to the _mercury_ would be equivalent to those acid _menstruums_, which work upon the _quick-silver_, upon the account of their saline particles, i substituted a solution of sublimate in fair water, instead of a solution of _mercury_ in _aqua-fortis_, or spirit of _nitre_, that simple solution being both clearer and free from that very offensive smell, which accompanies the solutions of _mercury_ made with those other corrosive liquors; then i consider'd, that that, which makes the yellow colour, is indeed but a precipitate made by the means of the oyl of tartar, which we drop in, and which, as _chymists_ know, does generally precipitate metalline bodies corroded by acid salts; so that the colour in our case results from the coalition of the mercurial particles with the saline ones, wherewith they were formerly associated, and with the alcalizate particles of the salt of tartar that swim up and down in the oyl. wherefore considering also, that very many of the effects of lixiviate liquors, upon the solutions of other bodies, may be destroy'd by acid _menstruums_, as i elsewhere more particularly declare, i concluded, that if i chose a very potently acid liquor, which by its incisive power might undo the work of the oyl of tartar, and disperse again those particles, which the other had by precipitation associated, into such minute corpuscles as were before singly inconspicuous, they would become inconspicuous again, and consequently leave the liquor as colourless as before the precipitation was made. this, as i said, _pyrophilus_, seems to be the chymical reason of this experiment, that is such a reason, as, supposing the truth of those chymical notions i have elsewhere i hope evinc'd, may give such an account of the _phænomena_ as chymical notions can supply us with; but i both here and elsewhere make use of this way of speaking, to intimate that i am sufficiently aware of the difference betwixt a chymical explication of a _phænomenon_, and one that is truly philosophical or mechanical; as in our present case, i tell you something, when i tell you that the yellowness of the mercurial solution and the oyl of tartar is produc'd by the precipitation occasion'd by the affusion of the latter of those liquors, and that the destruction of the colour proceeds from the dissipation of that curdl'd matter, whose texture is destroy'd, and which is dissolv'd into minute and invisible particles by the potently acid _menstruum_, which is the reason, why there remains no sediment in the bottom, because the infused oyl takes it up, and resolves it into hidden or invisible parts, as water does salt or sugar. but when i have told you all this, i am far from thinking i have told all that such an inquisitive person as your self would know, for i presume you would desire as well as i to learn (at least) why the particles of the _mercury_, of the tartar, and of the acid salts convening together, should make rather an orange colour than a red, or a blew, or a green, for 'tis not enough to say what i related a little before, that divers mercurial solutions, though otherwise made, would yield a yellow precipitate, because the question will recurr concerning them; and to give it a satisfactory answer, is, i freely acknowledge, more than i dare as yet pretend to. but to confirm my conjecture about the chymical reason of our experiment, i may add, that as i have (_viz._ pag. 34th. of this treatise) elsewhere (on another occasion) told you, with saline liquors of another kind and nature than salt of tartar, (namely, with spirit of urine, and liquors of kin to that) i can make the _mercury_ precipitate out of the first simple solution quite of another colour than that hitherto mention'd; nay, if instead of altering the precipitating liquor, i alter'd the texture of the sublimate in such a way as my notions about salt requir'd, i could produce the same _phænomenon_. for having purposely sublim'd together equal parts (or thereabout) of sal-armoniack and sublimate, first diligently mix'd, the ascending flowers being diffolv'd in fair water, and filtred, gave a solution limpid and colourless, like that of the other sublimates, and yet an _akaly_ drop'd into this liquor did not turn it yellow but white. and upon the same grounds we may with _quick-silver_, without the help of common sublimate, prepare another sort of flowers dissoluble in water without discolouring it, with which i could likewise do what i newly mention'd; to which i shall add, (what possibly you'l somewhat wonder at) that so much does the colour depend upon the texture resulting from the convention of the several sorts of corpuscles, that though in out experiment, oyl of vitriol destroys the yellow colour, yet with _quick-silver_ and fair water, by the help of oyl of vitriol alone, we may easily make a kind of precipitate of a fair and permanent yellow, as you will e're long (in the forty second expement of this third part) be taught. and i may further add, that i chose oyl of vitriol, not so much for any other or peculiar quality, as for its being, when 'tis well rectify'd, (which 'tis somewhat hazardous to bring it to be) not only devoid of colour and in smells, but extremely strong and incisive; for though common and undephlegmated _aqua-fortis_ will not perform the same thing well, yet that which is made exceeding strong by being carefully dephlegm'd, will do it pretty well, though not so well as oyl of vitriol which is so strong, that even without rectification it may for a need be made use of. i will not here tell you what i have try'd, that i may be able to deprive at pleasure the precipitate that one of the sulphureous liquors had made, by the copious affusion of the other: because i found, though this experiment is too ticklish to let me give a full account of it in few words, i shall therefore tell you, that it is not only for once, that the other above-mention'd experiment may be made, the same numerical parcels of liquor being still imploy'd in it; for after i have clarify'd the orange colour'd liquor, by the addition of as little of the oyl of viriol as will suffice to perform the effect, i can again at pleasure re-produce the opacous colour, by the dropping in of fresh oyl of tartar, and destroy it again by the re-affusion of more of the acid _menstruum_; and yet oftner if i please, can i with these two contrariant liquors recall and disperse the colour, though by reason of the addition of so much new liquor, in reference to the mercurial particles, the colour will at length appear more dilute and faint. _an improvement of the fortieth experiment_. and, _pyrophilus_, to confirm yet further the notions that led me to think on the propos'd experiment, i shall acquaint you with another, which when i had conveniency i have sometimes added to it, and which has to the spectators appear'd little less odd than the first; and though because the liquor, requisite to make the trial succeed well, must be on purpose prepar'd anew a while before, because it will not long retain its fitness for this work, i do but seldome annex this experiment to the other, yet i shall tell you how i devis'd it, and how i make it. if you boyl crude antimony in a strong and clear _lixivium_, you shall separate a substance from it, which some modern _chymists_ are pleas'd to call its sulphur, but how deservedly i shall not here examine, having elsewhere done it in an opportune place; wherefore i shall now but need to take notice, that when this suppos'd sulphur (not now to call it rather a kind of _crocus_) is let fall by the liquor upon its refrigeration, it often settles in flakes, or such like parcels of a yellow substance, (which being by the precedent dissolution reduc'd into minute parts, may peradventure be made to take fire much more easily than the grosser powder of unprepar'd antimony would have done.) considering therefore, that common sulphur boyl'd in a _lixivium_ may be precipitated out of it by rhenish-wine or white-wine, which are sowrish liquors, and have in them, as i elsewhere shew, an acid salt; and having found also by trial, that with other acid liquors i could precipitate out of lixiviate solvents some other mineral concretions abounding with sulphureous parts, of which sort is crude antimony, i concluded it to be easie to precipitate the antimony dissolv'd, as was lately mention'd, with the acid oyl of vitriol; and though common sulphur yields a white precipitate, which the _chymists_ call _lac sulphuris_, yet i suppos'd the precipitated antimony would be of a deep yellow colour, as well, if made with oyl of vitriol, as if made only by refrigeration and length of time. from this 'twas easie to deduce this experiment, that if you put into one glass some of the freshly impregnated and filtrated solution of antimony, and into another some of the orange-colour'd mixture, (which i formerly shew'd you how to make with a mercurial solution and oyl of tartar) a few drops of oyl of vitriol dropp'd into the last mention'd glass, would, as i told you before, turn the deep yellow mixture into a cleer liquor; whereas a little of the same oyl dropp'd out of the same viol into the other glass would presently (but not without some ill sent) turn the moderately cleer solution into a deep yellow substance, but this, as i said, succeeds not well, unless you employ a _lixivium_ that has but newly dissolv'd antimony, and has not yet let it fall. but yet in summer time, if your _lixivium_ have been duly impregnated and well filtred after it is quite cold, it will for some dayes (perhaps much longer than i had occasion to try) retain antimony enough to exhibit, upon the affusion of the corrosive oyl, as much of a good yellow substance as is necessary to satisfie the beholders of the possibility of the experiment. _reflections upon the xl. experiment compared with the x. and xx._ the knowledge of the distinction of salts which we have propos'd, whereby they are discriminated into _acid, volatile,_ or _salfuginous_ (if i may for distinction sake so call the fugitive salts of animal substances) and _fix'd_ or _alcalizate_, may possibly (by that little part which we have already deliver'd, of what we could say of its applicableness) appear of so much use in natural philosophy (especially in the practick part of it) that i doubt not but it will be no unwelcome corollary of the preceding experiment, if by the help of it i teach you to distinguish, which of those salts is predominant in chymical liquors, as well as whether any of them be so or not. for though in our notes upon the x. and xx. experiments i have shown you a way by means of the tincture of _lignum nephriticum_, or of syrrup of violets, to discover whether a propounded salt be acid or not, yet you can thereby only find in general that such and such salts belong not to the tribe of acids, but cannot determine whether they belong to the tribe of urinous salts (under which for distinction sake i comprehend all those volatile salts of animal or other substances that are contrary to acids) or to that of alcalies. for as well the one as the other of these salino-sulphurous salts will restore the cæruleous colour to the tincture of _lignum nephriticum_, and turn that of syrrup of violets into green. wherefore this xl. experiment does opportunely supply the deficiency of those. for being sollicitous to find out some ready wayes of discriminating the tribes of chymical salts, i found that all those i thought fit to make tryal of, would, if they were of a lixiviate nature, make with sublimate dissolv'd in fair water an _orange tawny_ precipitate; whereas if they were of an urinous nature the precipitate would be _white_ and milky. so that having alwayes by me some syrrup of violets and some solution of sublimate, i can by the help of the first of those liquors discover in a trice, whether the propounded salt or saline body be of an acid nature or no, if it be i need (you know) inquire no further; but if it be not, i can very easily, and as readily distinguish between the other two kinds of salts, by the white or orange-colour that is immediately produc'd, by letting fall a few drops or grains of the salt to be examin'd, into a spoonfull of the cleer solution of sublimate. for example, it has been suppos'd by some eminently learned, that when sal armoniack being mingled with an alcaly is forc'd from it by the fire in close vessels, the volatile salt that will thereby be obtain'd (if the operation be skilfully perform'd,) is but a more fine and subtile sort of sal armoniack, which, 'tis presum'd, this operation do's but more exquisitely purifie, than common solutions, filtrations, and coagulations. but this opinion may be easily shown to be erroneous, as by other arguments, so particularly by the lately deliver'd method of distinguishing the tribes of salts. for the saline spirit of sal armoniack, as it is in many other manifest qualities very like the spirit of urine, so like, that it will in a trice make syrrup of violets of a lovely green, turn a solution of good verdigrease into an excellent azure, and make the solution of a sublimate yield a white precipitate, insomuch that in most (for i say not all of the experiments) where i aim onely at producing a sudden change of colour, i scruple not to use spirit of sal armoniack when it is at hand, instead of spirit of urine, as indeed it seems chiefly to consist (besides the flegm that helps to make it fluid) of the volatile urinous salt (yet not excluding that of soot) that abounds in the sal armoniack and is set at liberty from the sea salt wherewith it was formerly associated, and clogg'd, by the operation of the alcaly, that divides the ingredients of sal armoniack, and retains that sea salt with it self. what use may be made of the like way of exploration in that inquiry which puzzles so many modern naturalists, whether the rich pigment (which we have often had occasion to mention) belongs to the vegetable or animal kingdome, you may find in another place where i give you some account of what i try'd about cocheneel. but i think it needless to exemplifie here our method by any other instances, many such being to be met with in divers parts of this treatise; but i will rather advertise you, that, by this way of examining chymical liquors, you may not onely in most cases conclude _affirmatively_, but in some cases _negatively_. as since spirit of wine, and as far as i have try'd, those chymical oyles which artists call essential, did not (when i us'd them as i had us'd the several families of salts upon that syrrup) turn syrrup of violets red or green, nor the solution of sublimate white or yellow, i inferr'd it may thence be probably argued, that either they are destitute of salt, or have such as belongs not to either of the three grand families already often mention'd. when i went to examine the spirit of oak or of such like concretes forced over through a retort, i found by this means amongst others, that (as i elsewhere show) these chymists are much mistaken in it, that account it a simple liquor, and one of their hypostatical principles: for not to mention what flegm it may have, i found that with a few drops of one of this sort of spirits mix'd with a good proportion of syrrup of violets, i could change the colour and make it purplish, by the affinity of which colour to redness, i conjectur'd that this spirit had some acid corpuscles in it, and accordingly i found that as it would destroy the blewness of a tincture of _lignum nephriticum_, so being put upon corals it would corrode them, as common spirit of vinegar, and other acid liquors are wont to do. and farther to examine whether there were not a great part of the liquor that was not of an acid nature, having separated the sour or vinegar-like part from the rest, which (if i mistake not) is far the more copious, we concluded as we had conjectured, the other or remaining part, though it had a strong taste as well as smell, to be of a nature differing from that of either of the three sorts of salts above mention'd, since it did as little as spirit of wine, and chymical oyls, alter the colour either of syrrup of violets or solution of sublimate, whence we also inferr'd that the change that had been made of that syrrup into a purple colour, was effected by the vinegar, that was one of the two ingredients of the liquor, which was wont to pass for a simple or uncompounded spirit. and, upon this account, 'twas of the spirit of oak (and the like concretes) freed from it's vinegar that i elsewhere told you, that i had not then observ'd it, (and i have repeated the tryal but very lately) to destroy the cæruleous tincture of _lignum nephriticum_. but this onely, _en passant_; for the chief thing i had to add was this, that by the same way may be examin'd and discover'd, divers changes that are produc'd in bodies either by nature only, or by art; either of them being able by changing the texture of some concretes i could name, to qualifie them to operate after a new manner upon the above mention'd syrrup, or solution, or both. and by this means, to tell you that upon the by, i have been able to discover, that there may be made bodies, which though they run _per deliquium_, as readily as salt of tartar, belong in other respects, not to the family of alcaliz, much less to that of salfuginous, or that of acid salts. perhaps too, i may know a way of making a highly operative saline body that shall neither change the colour of syrrup of violets, nor precipitate the solution of sublimate; and, i can likewise if i please conceal by what liquors i perform such changes of colour, as i have been mentioning to you, by quite altering the texture of some ordinary chymical productions, the exploration of which is the main use of the fortieth experiment, which i think teaches not a little, if it teach us to discover the nature of those things (in reference to salt) that are obtain'd by the ordinary chymical analysis of mix'd bodyes, though perhaps there may be other bodyes prepar'd by chymistry which may have the same effects in the change of colours; and yet be produc'd not from what chymists call the resolution of bodies, but from their composition. but the discoursing of things of this nature is more proper for another place. i shall now onely add, what might perhaps have been more seasonably told you before; that the reason why the way of exploration of salts hitherto deliver'd, succeeds in the solution of sublimate, depends upon the particular texture of that solution, as well as upon the differing natures of the saline liquors imploy'd to precipitate it. for gold dissolv'd in _aqua regia_, whether you precipitate it with oyl of tartar which is an alcaly, or with spirit of urine, or sal armoniack which belongs to the family of volatile salts, will either way afford a yellow substance: though with such an acid liquor, as, i say not spirit of salt, the body that yields it, being upon the matter an ingredient of _aqua regis_, but oyl of vitriol it self, i did not find that i could precipitate the metall out of the solution, or destroy the colour of it, though the same oyl of vitriol would readily precipitate silver dissolv'd in _aqua-fortis_. and if you dissolve pure silver in _aqua-fortis_, and suffer it to shoot into crystals, the cleer solution of these made in fair water, will afford a very white precipitate, whether it be made with an alcaly, or an acid spirit, as that of salt, whereas, which may seem somewhat strange, with spirit of sal armoniack (that i us'd was made of quicklime) i could obtain no such white precipitate; that volatile spirit, nor (as i remember) that of urine, scarce doing any more than striking down a very small quantity of matter, which was neither white nor whitish, so that the remaining liquor being suffer'd to evaporate till the superfluous moisture was gone, the greatest part of the metalline corpuscles with the saline ones that had imbib'd them, concoagulated into salt, as is usual in such solutions, wherein the metall has not been precipitated. _experiment xli._ of kin to the last or fortieth experiment is another which i remember i have sometimes shewn to _virtuosi_ that were pleas'd not to dislike it. i took spirit of urine made by fermentation, and with a due proportion of copper brought into small parts, i obtain'd a very lovely azure solution, and when i saw the colour was such as was requisite, pouring into a clean glass, about a spoonfull of this tincted liquor, (of which i us'd to keep a quantity by me,) i could by shaking into it some drops of strong oyl of vitriol, deprive it in a trice of its deep colour, and make it look like common-water. _annotation_. this experiment brings into my mind this other, which oftentimes succceds well enough, though not quite so well as the former; namely, that if into about a small spoonfull of a solution of good french verdigrease made in fair water, i drop't and shak'd some strong spirit of salt, or rather deflegm'd _aqua fortis_, the greenness of the solution would be made in a trice almost totally to disappear, & the liquor held against the light would scarce seeme other than cleer or limpid, to any but an attentive eye, which is therefore remarkable; because we know that _aqua-fortis_ corroding copper, which is it that gives the colour to verdigrease, is wont to reduce it to a green blew solution. but if into the other altogether or almost colourless liquor i was speaking of, you drop a just quantity either of oyl of tartar or spirit of urine, you shall find that after the ebullition is ceas'd, the mixture will disclose a lively colour, though somewhat differing from that which the solution of verdigrease had at first. _experiment xlii._ that the colour (_pyrophilus_) of a body may be chang'd by a liquor which of it self is of no colour, provided it be saline, we have already manifested by a multitude of instances. nor doth it seem so strange, because saline particles swimming up and down in liquors, have been by many observ'd to be very operative in the production and change of colours. but divers of our friends that are not acquainted with chymical operations have thought it very strange that a white body, and a dry one too, should immediately acquire a rich new colour upon the bare affusion of spring-water destitute as well of adventitious salt as of tincture. and yet (_pyrophilus_) the way of producing such a change of colours may be easily enough lighted on by those that are conversant in the solutions of mercury. for we have try'd, that though by evaporating a solution of quick-silver in _aqua-fortis_, and abstracting the liquor till the remaining matter began to be well, but not too strongly dryed, fair water pour'd on the remaining _calx_ made it but somewhat yellowish; yet when we took good quick-silver, and three or four times its weight of oyl of vitriol, in case we in a glass retort plac'd in sand drew off the saline _menstruum_ from the metalline liquor, till there remain'd a dry _calx_ at the bottome, though this precipitate were a snow white body, yet upon pouring on it a large quantity of fair water, we did almost in a moment perceive it to pass from a milky colour to one of the loveliest light yellows that ever we had beheld. nor is the turbith mineral, that chymists extol for its power to salivate, and for other vertues, of a colour much inferiour to this, though it be often made with a differing proportion of the ingredients, a more troublesome way. for _beguinus_,[22] who calls it _mercurius præcipitatus optimus_, takes to one part of quick-silver, but two of liquor, and that is rectifi'd oyl of sulphur, which is (in _england_ at least) far more scarce and dear than oyl of vitriol; he also requires a previous digestion, two or three cohobations, and frequent ablutions with hot distill'd water, with other prescriptions, which though they may conduce to the goodness of the medicine, which is that he aims at, are troublesome, and, our tryals have inform'd you unneccessary to the _obtaining the lemmon colour_ which he regards not. but though we have very rarely seen either in painters shops, or elsewhere a finer yellow than that which we have divers times this way produc'd (which is the more considerable, because durable and pleasant yellows are very hard to be met with, as may appear by the great use which painters are for its colours sake fain to make of that pernicious and heavy mineral, orpiment) yet i fear our yellow is too costly, to be like to be imploy'd by painters, unless about choice pieces of work, nor do i know how well it will agree with every pigment, especially, wich oyl'd colours. and whether this experiment, though it have seem'd somewhat strange to most we have shown it to, be really of another nature than those wherein saline liquors are imploy'd, may, as we formerly also hinted, be so plausibly doubted, that whether the water pour'd on the _calx_, do barely by imbibing some of its saline parts alter its colour by altering its texture, or whether by dissolving the concoagulated salts, it does become a saline _menstruum_, and, as such, work upon the mercury, i freely leave to you (_pyrophilus_) to consider. and that i may give you some assistance in your enquiry, i will not only tell you, that i have several times with fair water wash'd from this _calx_, good store of strongly tasted corpuscles, which by the abstraction of the _menstruum_, i could reduce into salt; but i will also subjoyn an experiment, which i devis'd, to shew among other things, how much a real and permanent colour may be as it were drawn forth by a liquor that has neither colour, nor so much as saline or other active parts, provided it can but bring the parts of the body it imbibes to convene into clusters dispos'd after the manner requisite to the exhibiting of the emergent colour. the experiment was this. [22] _beguinus_, tyr. chy. lib. 2º. cap. 13º. _experiment xliii._ we took good common vitriol, and having beaten it to powder, and put it into a crucible, we kept it melted in a gentle heat, till by the evaporation of some parts, and the shuffling of the rest, it had quite lost its former colour, what remain'd we took out, and found it to be a friable _calx_, of a dirty gray. on this we pour'd fair water, which it did not colour green or blew, but only seem'd to make a muddy mixture with it, then stopping the vial wherein the ingredients were put, we let it stand in a quiet place for some dayes, and after many hours the water having dissolv'd a good part of the imperfectly calcin'd body, the vitriolate corpuscles swiming to and fro in the liquor, had time by their opportune occursions to constitute many little masses of vitriol, which gave the water they impregnated a fair vitriolate colour; and this liquor being pour'd off, the remaining dirty powder did in process of time communicate the like colour, but not so deep, to a second parcel of cleer water that we pour'd on it. but this experiment _pyrophilus_ is, (to give you that hint by the way) of too luciferous a nature to be fit to be fully prosecuted, now that i am in haste, and willing to dispatch what remains. and we have already said of it, as much as is requisite to our present purpose. _experiment xliv._ it may (_pyrophilus_) somewhat contribute towards the shewing how much some colours depend upon the less or greater mixture, and (as it were,) contemperation of the light with shades, to observe, how that sometimes the number of particles, of the same colour, receiv'd into the pores of a liquor, or swiming up and down in it, do seem much to vary the colour of it. i could here present you with particular instances to show, how in many (if not most) consistent bodyes, if the colour be not a light one, as white, yellow, or the like, the closeness of parts in the pigments makes it look blackish, though when it is display'd and laid on thinly, it will perhaps appear to be either blew, or green, or red. but the colours of consistent pigments, not being those which the preamble of this experiment has lead you to expect examples in, i shall take the instances i am now to give you, rather from liquors than dry bodyes. if then you put a little fair water into a cleer and slender vial, (or rather into one of those pipes of glass, which we shall by and by mention;) and let fall into it a few drops of a strong decoction or infusion of _cochineel_, or (for want of that) of _brazil_; you may see the tincted drops descend like little clouds into the liquor; through which, if, by shaking the vial, you diffuse them, they will turn the water either of a pinck colour, or like that which is wont to be made by the washing of raw flesh in fair water; by dropping a little more of the decoction, you may heighten the colour into a fine red, almost like that which ennobles rubies; by continuing the affusion, you may bring the liquor to a kind of a crimson, and afterwards to a dark and opacous redness, somewhat like that of clotted blood. and in the passage of the liquor from one of these colours to the other, you may observe, if you consider it attentively, divers other less noted colours belonging to red, to which it is not easie to give names; especially considering how much the proportion of the decoction to the fair water, and the strength of that decoction, together with that of the trajected light and other circumstances, may vary the phænomena of this experiment. for the convenienter making whereof, we use instead of a vial, any slender pipe of glass of about a foot or more in length, and about the thickness of a mans little finger; for, if leaving one end of this pipe open, you seal up the other hermetically, (or at least stop it exquisitely with a cork well fitted to it, and over-laid with hard sealing wax melted, and rubb'd upon it;) you shall have a glass, wherein may be observ'd the variations of the colours of liquors much better than in large vials, and wherein experiments of this nature may be well made with very small quantities of liquor. and if you please, you may in this pipe produce variety of colours in the various parts of the liquor, and keep them swimming upon one another unmix'd for a good while. and some have marveil'd to see, what variety of colours we have sometimes (but i confess rather by chance than skill) produc'd in those glasses, by the bare infusion of brazil, variously diluted with fair water, and alter'd by the infusion of several chymical spirits and other saline liquors devoid themselves of colour, and when the whole liquor is reduc'd to an uniform degree of colour, i have taken pleasure to make that very liquor seem to be of colours gradually differing, by filling with it glasses of a conical figure, (whether the glass have its basis in the ordinary position, or turn'd upwards.) and yet you need not glasses of an extraordinary shape to see an instance of what the vari'd mixture of light and shadow can do in the diversifying of the colour. for if you take but a large round vial, with a somewhat long and slender neck, and filling it with our red infusion of brazil, hold it against the light, you will discern a notable disparity betwixt the colour of that part of the liquor which is in the body of the vial, and that which is more pervious to the light in the neck. nay, i remember, that i once had a glass and a blew liquor (consisting chiefly (or only, if my memory deceive me not,) of a certain solution of verdigrease) so fitted for my purpose, that though in other glasses the experiment would not succeed, yet when that particular glass was fill'd with that solution, in the body of the vial it appear'd of a lovely blew, and in the neck, (where the light did more dilute the colour,) of a manifest green; and though i suspected there might be some latent yellowness in the substance of the neck of the glass, which might with the blew compose that green, yet was i not satisfi'd my self with my conjecture, but the thing seem'd odd to me, as well as to divers curious persons to whom it was shown. and i lately had a broad piece of glass, which being look'd on against the light seem'd clear enough, and held from the light appear'd very lightly discolour'd, and yet it was a piece knock'd off from a great lump of glass, to which if we rejoyn'd it, where it had been broken off, the whole mass was as green as grass. and i have several times us'd bottles and stopples that were both made (as those, i had them from assur'd me) of the very same metall, and yet whilst the bottle appear'd but inclining towards a green, the stopple (by reason of its great thickness) was of so deep a colour that you would hardly believe they could possibly be made of the same materials. but to satisfie some ingenious men, on another occasion, i provided my self of a flat glass (which i yet have by me,) with which if i look against the light with the broad side obverted to the eye, it appeares like a good ordinary window glass; but if i turn the edge of it to my eye, and place my eye in a convenient posture in reference to the light, it may contend for deepness of colour with an emerald. and this greeness puts me in mind of a certain thickish, but not consistent pigment i have sometimes made, and can show you when you please, which being dropp'd on a piece of white paper appears, where any quantity of it is fallen, of a somewhat crimson colour, but being with ones finger spread thinly on the paper does presently exhibit a fair green, which seems to proceed only from its disclosing its colour upon the extenuation of its depth into superficies, if the change be not somewhat help'd by the colours degenerating upon one or other of the accounts formerly mention'd. let me add, that having made divers tryals with that blew substance, which in painters shops is call'd _litmase_, we have sometimes taken pleasure to observe, that being dissolv'd in a due proportion of fair water, the solution either oppos'd to the light, or dropp'd upon white paper, did appear of a deep colour betwixt crimson and purple; and yet that being spread very thin on the paper and suffer'd to dry on there, the paper was wont to appear stain'd of a fine blew. and to satisfie my selfe, that the diversity came not from the paper, which one might suspect capable of inbibing the liquor, and altering the colour, i made the tryal upon a flat piece of purely white glass'd earth, (which i sometimes make use of about experiments of colours) with an event not unlike the former. and now i speak of _litmass_, i will add, that having this very day taken a piece of it, that i had kept by me these several years, to make tryals about colours, and having let fall a few drops of the strong infusion of it in fair water, into a fine crystal glass, shap'd like an inverted cone, and almost full of fair water, i had now (as formerly) the pleasure to see, and to show others, how these few tincted drops variously dispersing themselves through the limpid water, exhibited divers colours, or varieties of purple and crimson. and when the corpuscles of the pigment seem'd to have equally diffus'd themselves through the whole liquor, i then by putting two or three drops of spirit of salt, first made an odd change in the colour of the liquor, as well as a visible commotion among its small parts, and in a short time chang'd it wholly into a very glorious yellow, like that of a topaz. after which if i let fall a few drops of the strong and heavy solution of pot-ashes, whose weight would quickly carry it to the sharp bottome of the glass, there would soon appear four very pleasant and distinct colours; namely, a bright, but dilute colour at the picked bottome of the glass; a purple, a little higher; a deep and glorious crimson, (which crimson seem'd to terminate the operation of the salt upward) in the confines betwixt the purple and the yellow; and an excellent yellow, the same that before enobled the whole liquor, reaching from thence to the top of the glass. and if i pleas'd to pour very gently a little spirit of sal armoniack, upon the upper part of this yellow, there would also be a purple or a crimson, or both, generated there, so that the unalter'd part of the yellow liquor appear'd intercepted betwixt the two neighbouring colours. my scope in this 3d. experiment (_pyrophilus_) is manifold, as first to invite you to be wary in judging of the colour of liquors in such glasses as are therein recommended to you, and consequently as much, if not more, when you imploy other glasses. secondly, that you may not think it strange, that i often content my self to rub upon a piece of white paper, the juice of bodies i would examine, since not onely i could not easily procure a sufficient quantity of the juices of divers of them; but in several cases the tryals of the quantities of such juices in glasses would make us more lyable to mistakes, than the way that in those cases i have made use of. thirdly, i hope you will by these and divers other particulars deliver'd in this treatise, be easily induc'd to think that i may have set down many phænomena very faithfully, and just as they appear'd to me, and yet by reason of some unheeded circumstance in the conditions of the matter, and in the degree of light, or the manner of trying the experiment, you may find some things to vary from the relations i make of them. lastly, i design'd to give you an opportunity to free your self from the amazement which possesses most men, at the tricks of those mountebancks that are commonly call'd water-drinkers. for though not only the vulgar, but ev'n many persons that are far above that rank, have so much admir'd to see, a man after having drunk a great deal of fair water, to spurt it out again in the form of claret wine, sack, and milk, that they have suspected the intervening of magick, or some forbidden means to effect what they conceived above the power of art; yet having once by chance had occasion to oblige a wanderer that made profession of that and other jugling tricks, i was easily confirm'd by his ingenious confession to me, that this so much admir'd art, indeed consisted rather in a few tricks, than in any great skill, in altering the nature and colours of things. and i am easy to be perswaded; that there may be a great deal of truth in a little pamphlet printed divers years ago in english, wherein the author undertakes to discover, and that (if i mistake not) by the confession of some of the complices themselves, that a famous water-drinker then much admir'd in _england_, perform'd his pretended transmutations of liquors by the help of two or three inconsiderable preparations and mixtures of not unobvious liquors, and chiefly of an infusion of brazil variously diluted and made pale or yellowish, (and otherwise alter'd) with vinegar, the rest of their work being perform'd by the shape of the glasses, by craft and legerdemane. and for my part, that which i marvel at in this business, is, the drinkers being able to take down so much water, and spout it out with that violence; though custome and a vomit seasonably taken before hand, may in some of them much facilitate the work. but as for the changes made in the liquors, they were but few and slight in comparison of those, that the being conversant in chymical experiments, and dextrous in applying them to the transmuting of colours, may easily enough enable a man to make, as ev'n what has been newly deliver'd in this, and the foregoing experiment; especially if we add to it the things contained in the xx, the xxxix and the xl. experiments, may perhaps have already perswaded you. _experiment xlv._ you may i presume (_pyrophilus_) have taken notice, that in this whole treatise, i purposely decline (as far as i well can) the mentioning of elaborate chymical experiments, for fear of frighting you by their tediousness and difficulty; but yet in confirmation of what i have been newly telling you about the possibility of varying the colours of liquors, better than the water-drinkers are wont to do, i shall add, that _helmont_ used to make a preparation of steel, which a very ingenious chymist, his sons friend, whom you know, sometimes employes for a succedaneum to the spaw-waters, by diluting this _essentia martis liquida_ (as he calls it) with a due proportion of water. now that for which i mention to you this preparation, (which as he communicated to me, i know he will not refuse to _pyrophilus_) is this, that though the liquor (as i can shew you when you please) be almost of the colour of a german (not an oriental) amethyst, and consequently remote enough from green, yet a very few drops being let fall into a large proportion of good rhenish, or (in want of that) white wine (which yet do's not quite so well) immediately turn'd the liquor into a lovely green, as i have not without delight shown several curious persons. by which _phænomenon_ you may learn, among other things, how requisite it is in experiments about the changes of colours heedfully to mind the circumstances of them; for water will not, as i have purposely try'd, concurr to the production of any such green, nor did it give that colour to moderate spirit of wine, wherein i purposely dissolv'd it, and wine it self is a liquor that few would suspect of being able to work suddenly any such change in a metalline preparation of this nature; and to satisfie my self that this new colour proceeds rather from the peculiar texture of the wine, than from any greater acidity, that rhenish or white-wine (for that may not absurdly be suspected) has in comparison of water; i purposely sharpen'd the solution of this essence in fair water, with a good quantity of spirit of salt, notwithstanding which, the mixture acquir'd no greenness. and to vary the experiment a little, i try'd, that if into a glass of rhenish wine made green by this essence, i dropp'd an alcalizate solution, or urinous spirit, the wine would presently grow turbid, and of an odd dirty colour; but if instead of dissolving the essence in wine, i dissolv'd it in fair water sharpen'd perhaps with a little spirit of salt, then either the urinous spirit of sal armoniack, or the solution of the fix'd salt of pot-ashes would immediately turn it of a yellowish colour, the fix'd or urinous salt precipitating the vitriolate substance contain'd in the essence. but here i must not forget to take notice of a circumstance that deserves to be compar'd with some part of the foregoing experiment, for whereas our essence imparts a greenness to wine, but not to water, the industrious _olaus wormius_[23] in his late _musæum_ tells us of a rare kind of turn-sole which he calls _bezetta rubra_ given him by an apothecary that knew not how it was made, whose lovely redness would be easily communicated to water, if it were immers'd in it; but scarce to wine, and not at all to spirit of wine, in which last circumstance it agrees with what i lately told you of our essence, notwithstanding their disagreement in other particulars. [23] libr. 2do cap. 34. _experiment xlvi._ we have often taken notice, as of a remarkable thing, that metalls as they appear to the eye, before they come to be farther alter'd by other bodyes, do exhibit colours very different from those which the fire and the _menstruum_, either apart, or both together, do produce in them; especially considering that these metalline bodyes are after all these disguises reducible not only to their former metalline consistence and other more radical properties, but to their colour too, as if nature had given divers metalls to each of them a double colour, an _external_, and an _internal_; but though upon a more attentive consideration of this difference of colours, it seem'd probable to me, that divers (for i say not all) of those colours which we have just now call'd _internal_, are rather produc'd by the coalition of metalline particles with those of the salts, or other bodyes employ'd to work on them, than by the bare alteration of the parts of the metalls themselves: and though therefore we may call the obvious colours, natural or common, & the others adventitious, yet because such changes of colours, from whatsoever cause they be resolv'd to proceed may be properly enough taken in to illustrate our present subject, we shall not scruple to take notice of some of them, especially because there are among them such as are produc'd without the intervention of saline _menstruums_. of the adventitious colours of metalline bodies the chief sorts seem to be these three. the first, such colours as are produc'd without other additaments by the action of the fire upon metalls. the next such as emerge from the coalition of metalline particles with those of some _menstruum_ imploy'd to corrode a metall or precipitate it; and the last, the colours afforded by metalline bodyes either colliquated with, or otherwise penetrating into, other bodies, especially fusible ones. but these (_pyrophilus,_) are only as i told you, the _chief_ sorts of the adventitious colours of metalls, for there may others belong to them, of which i shall hereafter have occasion to take notice of some, and of which also there possibly may be others that i never took notice of. and to begin with the first sort of colours, 'tis well enough known to chymists, that tin being calcin'd by fire alone is wont to afford a white _calx_, and lead calcin'd by fire alone affords that most common red-powder we call _minium:_ copper also calcin'd _per se_, by a long or violent fire, is wont to yield (as far as i have had occasion to take notice of it) a very dark or blackish powder; that iron likewise may by the action of reverberated flames be turn'd into a colour almost like that of saffron, may be easily deduc'd from the preparation of that powder, which by reason of its colour and of the metall 'tis made of is by chymists call'd, _crocus martis per se_. and that _mercury_ made by the stress of fire, may be turn'd into a red powder, which chymists call precipitate _per se_, i elsewhere more particularly declare. _annotation i._ it is not unworthy the admonishing you, (_pyrophilus_,) and it agrees very well with our conjectures about the dependence of the change of a body's colour upon that of its texture, that the same metall may by the successive operation of the fire receive divers adventitious colours, as is evident in lead, which before it come to so deep a colour as that of _minium_, may pass through divers others. _annotation ii_. not only the _calces_, but the glasses of metalls, vitrify'd _per se_, may be of colours differing from the natural or obvious colour of the metall; as i have observ'd in the glass of lead, made by long exposing crude lead to a violent fire, and what i have observ'd about the glass or slagg of copper, (of which i can show you some of an odd kind of texture,) may be elsewhere more conveniently related. i have likewise seen a piece of very dark glass, which an ingenious artificer that show'd it me profess'd himself to have made of silver alone by an extreme _violence_ (which seems to be no more than is needfull) of the fire. _annotation iii_. minerals also by the action of the fire may be brought to afford colours very differing from their own, as i not long since noted to you about the variously colour'd flowers of antimony, to which we may add the whitish grey-colour of its _calx_, and the yellow or reddish colour of the glass, where into that _calx_ may be flux'd. and i remember, that i elsewhere told you, that vitriol calcin'd with a very gentle heat, and afterwards with higher and higher degrees of it, may be made to pass through several colours before it descends to a dark purplish colour, whereto a strong fire is wont at length to reduce it. but to insist on the colours produc'd by the operation of fire upon several minerals would take up farr more time than i have now to spare. _experiment xlvii._ the adventitious colours produc'd upon metalls, or rather with them, by saline liquors, are many of them so well known to chymists, that i would not here mention them, but that besides a not un-needed testimony, i can add something of my own, to what i shall repeat about them, and divers experiments which are familiar to chymists, are as yet unknown to the greatest part of ingenious men. that gold dissolv'd in _aqua regia_ ennobles the _menstruum_ with its own colour, is a thing that you cannot (_pyrophilus_,) but have often seen. the solutions of mercury in _aqua-fortis_ are not generally taken notice of, to give any notable tincture to the _menstruum_; but sometimes when the liquor first falls upon the quick silver, i have observ'd a very remarkable, though not durable, greenness, or blewness to be produc'd, which is a _phænomenon_ not unfit for you to consider, though i have not now the leisure to discourse upon it. tin corroded by _aqua-fortis_ till the _menstruum_ will work no farther on it, becomes exceeding white, but as we elsewhere note, does very easily of it self acquire the consistence, not of a metalline _calx_, but of a coagulated matter, which we have observ'd with pleasure to look so like, either to curdled milk, or curdled whites of eggs, that a person unacquainted with such solutions may easily be mistaken in it. but when i purposely prepar'd a _menstruum_ that would dissolve it as _aqua-fortis_ dissolves silver, and not barely corrode it, and quickly let it fall again, i remember not that i took notice of any particular colour in the solution, as if the more whitish metalls did not much tinge their _menstruums_, though the conspicuously colour'd metalls as gold, and copper, do. for lead dissolv'd in spirit of vinegar or _aqua-fortis_ gives a solution cleer enough, and if the _menstruum_ be abstracted appears either diaphanous or white. of the colour of iron we have elsewhere said something: and 'tis worth noting, that though if that metall be dissolv'd in oyl of vitriol diluted with water, it affords a salt or magistery so like in colour, as well as some other qualities, to other green vitriol, that chymists do not improperly call it _vitriolum martis_; yet i have purposely try'd, that, by changing the _menstruum_, and pouring upon the filings of steel, instead of oyl of vitriol, _aqua fortis_, (whereof as i remember, i us'd 4 parts to one of the metall) i obtain'd not a green, but a saffron colour solution; or rather a thick liquor of a deep but yellowish red. common silver, such as is to be met with in coines, being dissolv'd in _aqua fortis_, yields a solution tincted like that of copper, which is not to be wondred at, because in the coining of silver, they are wont (as we elsewhere particularly inform you) to give it an allay of copper, and that which is sold in shops for refined silver, is not (so far as we have tryed) so perfectly free from that ignobler metall, but that a solution of it in _aqua fortis_, will give a venereal tincture to the _menstruum_. but we could not observe upon the solution of some silver, which was perfectly refin'd, (such as some that we have, from which 8 or 10 times its weight of lead has been blown off) that the _menstruum_ though held against the light in a crystal vial did manifestly disclose any tincture, only it seem'd sometimes not to be quite destitute of a little, but very faint blewishness. but here i must take notice, that of all the metalls, there is not any which doth so easily and constantly disclose its unobvious colour as copper doth. for not only in acid _menstruums_ as _aqua fortis_ and spirit of vinegar, it gives a blewish green solution, but if it be almost any way corroded, it _appears of one of those_ two colours, as may be observ'd in verdigreese made several wayes, in that odd preparation of _venus_, which we elsewhere teach you to make with sublimate, and in the common vitriols of _venus_ deliver'd by chymists; and so constant is the disposition of copper, notwithstanding the disguise artists put upon it, to disclose the colour we have been mentioning, that we have by forcing it up with _sal armoniack_ obtain'd a sublimate of a blewish colour. nay a famous spagyrist affirms, that the very mercury of it is green, but till he teach us an intelligible way of making such a mercury, we must content ourselves to inform you, that we have had a cupreous body, that was præcipitated out of a distill'd liquor, that seem'd to be the the sulphur of _venus_, and seem'd even when flaming, of a greenish colour. and indeed copper is a metall so easily wrought upon by liquors of several kinds, that i should tell you, i know not any mineral, that will concurr to the production of such a variety of colours as copper dissol'd in several _menstruums_, as spirit of vinegar, _aqua fortis_, _aqua regis_, spirit of nitre, of urine, of soot, oyls of several kinds, and i know not how many other liquors, if the variety of somewhat differing colours (that copper will be made to assume, as it is wrought upon by several liquors) were not comprehended within the limits of greenish blew, or blewish green. and yet i must advertise you (_pyrophilus_) that being desirous to try if i could not make with crude copper a green solution without the blewishness that is wont to accompany its vulgar solutions, i bethought my self of using two _menstruums_, which i had not known imploy'd to work on this metall, and which i had certain reasons to make tryal of, as i successfully did. the one of these liquors (if i much misremember not) was spirit of sugar distill'd in a retort, which must be warily done, (if you will avoid breaking your glasses) and the other, oyl or spirit of turpentine, which affords a fine green solution that is useful to me on several occasions. and yet to shew that the adventitious colour may result, as well from the true and permanent copper it self, as the salts wherewith 'tis corroded, i shall add, that if you take a piece of good _dantzick_ copperis, or any other vitriol wherein _venus_ is prædominant, and having moistened it in your mouth, or with fair water, rubb it upon a whetted knife, or any other bright piece of steel or iron, it will (as we have formerly told you) present'y stain the steel with a reddish colour, like that of copper, the reason of which, we must not now stay to inquire. _annotation i._ i presume you may have taken notice (_pyrophilus_) that i have borrowed some of the instances mention'd in this 47th experiment, from the laboratories of chymists, and because in some (though very few) other passages of this essay, i have likewise made use of experiments mention'd also by some spagyrical writers, i think it not amiss to represent to you on this occasion once for all, some things besides those which i intimated in the præamble of this present experiment; for besides, that 'tis very allowable for a writer to repeat an experiment which he invented not, in case he improve it; and besides that many experiments familiar to chymists are unknown to the generality of learned men, who either never read chymical processes, or never understood their meaning, or never durst believe them; besides these things, i say, i shall represent, that, as to the few experiments i have borrowed from the chymists, if they be very vulgar, 'twould perhaps be difficult to ascribe each of them its own author, and 'tis more than the generality of chymists themselves can do: and if they be not of very known and familiar practise among them, unless the authors wherein i found them had given me cause to believe, themselves had try'd them, i know not why i might not set them down, as a part of the _phænomena_ of colours which i present you; many things unanimously enough deliver'd as matters of fact by (i know not how many chymical writers) being not to be rely'd on, upon the single authority of such authors: for instance, as some spagyrists deliver (perhaps amongst several deceitful processes) that _saccarum saturni_ with spirit of turpentine will afford a balsom, so _beguinus_ and many more tell us, that the same concrete (_saccarum saturni_) will yield an incomparably fragrant spirit, and a pretty quantity of two several oyles, and yet since many have complain'd, as well as i have done, that they could find no such odoriferous, but rather an ill-sented liquor, and scarce any oyl in their distillation of that sweet vitriol, a wary person would as little build any thing on what they say of the former experiment, as upon what they averr of the later, and therefore i scrupled not to mention this red balsom of which i have not seen any, (but what i made) among my other experiments about redness. _annot. ii._ we have sometimes had the curiosity to try what colours minerals, as tinglass, antimony, spelter, &c. would yield in several _menstruums_, nor have we forborn to try the colours of stones, of which that famous one, (which _helmont_ calls _paracelsus's ludus_) though it be digg'd out of the earth and seem a true stone, has afforded in _menstruums_ capable to dissolve so solid a stone, sometimes a yellowish, sometimes a red solution of both which i can show you. but though i have from minerals obtain'd with several _menstruums_ very differing colours, and some such as perhaps you would be surpriz'd to see drawn from such bodies: yet i must now pass by the particulars, being desirous to put an end to this treatise, before i put an end to your patience and my own. _annotation iii._ and yet before i pass to the next experiment, i must put you in mind, that the colours of metals may in many cases be further alter'd by imploying, either præcipitating salts, or other convenient substances to act upon their solutions. of this you may remember, that i have given you several instances already, to which may be added such as these, that if quicksilver be dissolv'd in _aqua fortis_, and præcipitated out of the solution, either with water impregnated with sea salt, or with the spirit of that concrete, it falls to the bottom in the form of a white powder, whereas if it be præcipitated with an alcaly, it will afford a yellowish or tawny powder, and if there be no præcipitation made, and the _menstruum_ be drawn off with a convenient fire, the corroded mercury will remain in the bottom, in the form of a substance that may be made to appear of differing colours by differing degrees of heat; as i remember that lately having purposely abstracted _aqua fortis_ from some quicksilver that we had dissolv'd in it, so that there remain'd a white _calx_, exposing that to several degrees of fire, and afterwards to a naked one, we obtain'd some new colours, and at length the greatest part of the _calx_ lying at the bottome of the vial, and being brought partly to a deep yellow, and partly to a red colour, the rest appear'd elevated to the upper part and neck of the vial, some in the form of a reddish, and some of an ash-colour sublimate. but of the differing colours which by differing wayes and working of quick silver with fire, and saline bodies, may be produc'd in precipitates, i may elsewhere have occasion to take further notice. i also told you not long since, that if you corrode quick-silver with oyl of vitriol instead of _aqua-fortis_, and abstract the _menstruum_, there will remain a white _calx_ which by the affusion of fair water presently turns into a lemmon colour. and ev'n the _succedaneum_ to a _menstruum_ may sometimes serve the turn to change the colours of a metal. the lovely red which painters call vermillion, is made of mercury, which is of the colour of silver, and of brimstone which is of kin to that of gold, sublim'd up together in a certain proportion, as is vulgarly known to spagyrists. _experiment xlviii._ the third chief sort of the adventitious colours of metals, is, that which is produc'd by associating them (especially when calcin'd) with other fusible bodies, and principally venice, and other fine glass devoid of colour. i have formerly given you an example, whereby it may appear, that a metal may impart to glass a colour much differing from its own, when i told you, how with silver, i had given glass a lovely golden colour. and i shall now add, that i have learn'd from one of the chief artificers that sells painted glass, that those of his trade colour it yellow with a preparation of the _calx_ of silver. though having lately had occasion among other tryals to mingle a few grains of shell-silver (such as is imploy'd with the pensil and pen) with a convenient proportion of powder'd crystal glass, having kept them two or three hours in fusion, i was surpriz'd to find the colliquated mass to appear upon breaking the crucible of a lovely saphirine blew, which made me suspect my servant might have brought me a wrong crucible, but he constantly affirm'd it to be the same wherein the silver was put, and considerable circumstances countenanc'd his assertion, so that till i have opportunity to make farther tryal, i cannot but suspect, either that silver which is not (which is not very probable) brought to a perfect fusion and colliquation with glass, may impart to it other colours than when neal'd upon it, or else (which is less unlikely) that though silver beaters usually chuse the finest coyn they can get, as that which is most extensive under the hammer, yet the silver-leaves of which this shel-silver was made, might retain so much copper as to enable it to give the predominant tincture to the glass. for, i must proceed to tell you (_pyrophilus_) as another instance of the adventitious colours of metals, that which is something strange, namely, that though copper calcin'd _per se_ affords but a dark and basely colour'd _calx_, yet the glassmen do with it, as themselves inform me, tinge their glass green. and i remember, that when once we took some crude copper, and by frequent ignition quenching it in water had reduc'd it to a dark and ill-colour'd powder, and afterward kept it in fusion in about a 100. times its weight of fine glass, we had, though not a green, yet a blew colour'd mass, which would perhaps have been green, if we had hit right upon the proportion of the materials, and the degree of fire, and the time wherein it ought to be kept in fusion, so plentifully does that metal abound in a venerial tincture, as artists call it, and in so many wayes does it disclose that richness. but though copper do as we have said give somewhat near the like colour to glass, which it does to _aqua-fortis_, yet it seems worth inquiry, whether those new colours which mineral bodies disclose in melted glass, proceed from the coalition of the corpuscles of the mineral with the particles of the glass as such, or from the action (excited or actuated by fire) of the alcalizate salt (which is a main ingredient of glass,) upon the mineral body, or from the concurrence of both these causes, or else from any other. but to return to that which we were saying, we may observe that _putty_ made by calcining together a proportion of tin and lead, as it is it self a white _calx_, so does it turn the _pitta di crystallo_ (as the glassmen call the matter of the purer sort of glass, wherewith it is colliquated into a white mass, which if it be opacous enough is employ'd, as we elsewhere declare, for white amel. but of the colours which the other metals may be made to produce in colourless glass, and other vitrifiable bodies, that have native colours of their own, i must leave you to inform your self upon tryal, or at least must forbear to do it till another time, considering how many annotations are to follow, upon what has in this and the two former experiments been said already. _annotation i._ when the materials of glass being melted with calcin'd tin, have compos'd a mass undiaphanous and white, this white amel is as it were the basis of all those fine concretes that goldsmiths and several artificers imploy in the curious art of enamelling. for this white and fusible substance will receive into it self, without spoyling them, the colours of divers other mineral substances, which like it will indure the fire. _annotation ii._ so that as by the present (xlviii.) experiment it appears, that divers minerals will impart to fusible masses, colours differing from their own; so by the making and compounding of amels, it may appear, that divers bodies will both retain their colour in the fire, and impart the _same_ to some others wherewith they were vitrifi'd, and in such tryals as that mention'd in the 17. experiment, where i told you, that ev'n in amels a blew and yellow will compound a green. 'tis pretty to behold, not only that some colours are of so fix'd a nature, as to be capable of mixture without receiving any detriment by the fire, that do's so easily destroy or spoyl those of other bodies; but mineral pigments may be mingled by fire little less regularly and successfully, than in ordinary dyeing fatts, the vulgar colours are wont to be mingled by the help of water. _annotation iii._ 'tis not only metalline, but other mineral bodies, that may be imploy'd, to give tinctures unto glass (and 'tis worth noting how small a quantity of some mineral substances, will tinge a comparatively vast proportion of glass, and we have sometimes attempted to colour glass, ev'n with pretious stones, and had cause to think the experiment not cast away. and 'tis known by them that have look'd into the art of glass, that the artificers use to tinge their glass blew, with that dark mineral _zaffora_, (some of my tryals on which i elsewhere acquaint you) which some would have to be a mineral earth, others a stone, and others neither the one, nor the other, but which is confessedly of a dark, but not a blew colour, though it be not agreed of what particular colour it is. 'tis likewise though a familiar yet a remarkable practise among those that deal in the making of glass, to imploy (as some of themselves have inform'd me) what they call manganess, and some authors call _magnesia_ (of which i make particular mention in another treatise) to exhibit in glass not only other colours than its own, (which is so like in darkness or blackishness to the load stone, that 'tis given by mineralists, for one of the reasons of its latine name) but colours differing from one another. for though they use it, (which is somewhat strange) to clarifye their glass, and free it from that blewish greenish colour, which else it would too often be subject to, yet they also imploy it in certain proportions, to tinge their glass both with a red colour, and with a purplish or murry, and putting in a greater quantity, they also make with it that deep obscure glass which is wont to pass for black, which agrees very well with, and may serve to confirm what we noted near the beginning of the 44th experiment, of the seeming blackness of those bodies that are overcharg'd with the corpuscles of such colours, as red, or blew, or green, &c. and as by several metals and other minerals we can give various colours to glass, so on the other side, by the differing colours that mineral oars, or other mineral powders being melted with glass disclose in it, a good conjecture may be oftentimes made of the metall or known mineral, that the oar propos'd, either holds, or is most of kin to. and this easie way of examining oars, may be in some cases of good use, and is not ill deliver'd by _glauber_, to whom i shall at present refer you, for a more particular account of it: unless your curiosity command also what i have observ'd about these matters; only i must here advertise you, that great circumspection is requisite to keep this way from proving fallacious, upon the account of the variations of colour that may be produc'd by the differing proportions that may be us'd betwixt the oar and the glass, by the richness or poorness of the oar it self, by the degree of fire, and (especially) by the length of time, during which the matter is kept in fusion; as you will easily gather from what you will quickly meet with in the following annotation upon this present 48th experiment. _annotation iv._ there is another way and differing enough from those already mention'd, by which metalls may be brought to exhibit adventitious colours: for by this, the metall do's not so much impart a colour to another body, as receive a colour from it, or rather both bodies do by the new texture resulting from their mistion produce a new colour. i will not insist to this purpose upon the examples afforded us by yellow orpiment, and common sea salt, from which, sublim'd together, chymists unanimously affirm their white or crystalline arsenick to be made: but 'tis not unworthy our noting, that though yellow orpiment be acknowledg'd to be the copiousest by far of the two ingredients of arsenick, yet this last nam'd body being duely added to the highest colour'd metall copper, when 'tis in fusion, gives it a whiteness both within and without. thus _lapis calaminaris_ changes and improves the colour of copper by turning it into brass. and i have sometimes by the help of zinck duely mix'd after a certain manner, given copper one of the richest golden colours that ever i have seen the best true gold ennobled with. but pray have a care that such hints fall not into any hands that may mis-imploy them. _annotation v._ upon the knowledge of the differing wayes of making minerals and metalls produce their adventitious colours in bodies capable of vitrification, depends the pretty art of making what chymists by a barbarous word are pleas'd to call _amanses_, that is counterfeit, or factitious gemms, as emeralds, rubies, saphires, topazes, and the like. for in the making of these, though pure sand or calcin'd crystal give the body, yet 'tis for the most part some metalline or mineral _calx_, mingled in a small proportion that gives the colour. but though i have many years since taken delight, to divert my self with this pleasing art, and have seen very pretty productions of it, yet besides that i fear i have now forgot most of the little skill i had in it, this is no place to entertain you with what would rather take up an intire discourse, than be comprehended in an annotation; wherefore the few things which i shall here take notice of to you, are only what belong to the present argument, namely, first, that i have often observ'd that calcin'd lead colliquated with fine white sand or crystal, reduc'd by ignitions and subsequent extinctions in water to a subtile powder, will of it self be brought by a due decoction to give a cleer mass colour'd like a _german_ amethyst. for though this glass of lead, is look'd upon by them that know no better way of making _amanses_, as the grand work of them all, yet which is an inconvenience that much blemishes this way, the calcin'd lead it self does not only afford matter to the _amanses_, but has also as well as other metals a colour of its own, which as i was saying, i have often found to be like that of _german_ (as many call them) not eastern amethysts. secondly, that nevertheless this colour may be easily over-powr'd by those of divers other mineral pigments (if i may so call them) so that with a glass of lead, you may emulate (for instance) the fresh and lovely greenness of an emerald, though in divers cases the colour which the lead it self upon vitrification tends to, may vitiate that of the pigment, which you would introduce into the mass. thirdly, that so much ev'n these colours depend upon texture, that in the glass of lead it self made of about three parts of _lytharge_ or _minium_ colliquated with one of very finely powder'd crystal or sand, we have taken pleasure to make the mixture pass through differing colours, as we kept it more or less in the fusion. for it was not usually till after a pretty long decoction that the mass attain'd to the amethystin colour. fourthly and lastly, that the degrees of coction and other circumstances may so vary the colour produc'd in the same mass, that in a crucible that was not great i have had fragments of the same mass, in some of which perhaps not so big as a hazel-nut, you may discern four distinct colours. _annotation vi._ you may remember (_pyrophilus_) that when i mention'd the three sorts of adventitious colours of metals, i mention'd them but as the chief, not the only. for there may be other wayes, which though they do not in so strict a sense belong to the adventitious colours of metals, may not inconveniently be reduc'd to them. and of these i shall name now a couple, without denying that there may be more. the first may be drawn from the practise of those that dye scarlet. for the famousest master in that art, either in _england_ or _holland_, has confess'd to me, that neither others, nor he can strike that lovely colour which is now wont to be call'd the _bow-dye_, without their materials be boyl'd in vessels, either made of, or lin'd with a particular metall. but of what i have known attempted in this kind, i must not as yet for fear of prejudicing or displeasing others give you any particular account.[24] the other way (_pyrophilus_) of making metals afford unobvious colours, is by imbuing divers bodies with solutions of them made in their proper _menstruum's_, as (for instance) though copper plentifully dissolv'd in _aqua fortis_, will imbue several bodies with the colour of the solution; yet some other metalls will not (as i elsewhere tell you) and have often try'd. gold dissolv'd in _aqua regia_, will, (which is not commonly known) dye the nails and skin, and hafts of knives, and other things made of ivory, not with a golden, but a purple colour, which though it manifest it self but slowly, is very durable, and scarce ever to be wash'd out. and if i misremember not, i have already told you in this treatise, that the purer crystals of fine silver made with _aqua fortis_, though they appear white, will presently dye the skin and nails, with a black, or at least a very dark colour, which water will not wash off, as it will ordinary ink from the same parts. and divers other bodies may the same way be dy'd, some of a black, and others of a blackish colour. [24] see the latter end of the fiftieth experiment. and as metalline, so likewise mineral solutions may produce colours differing enough from those of the liquors themselves. i shall not fetch an example of this, from what we daily see happen in the powdring of beef, which by the brine imploy'd about it (especially if the flesh be over salted) do's oftentimes appear at our tables of a green, and sometimes of a reddish colour, (deep enough) nor shall i insist on the practise of some that deal in salt petre, who, (as i suspected, and as themselves acknowledg'd to me) do, with the mixture of a certain proportion of that; and common salt, give a fine redness, not only to neats tongues, but which is more pretty as well as difficult, to such flesh, as would otherwise be purely white; these examples, i say, i shall decline insisting on, as chusing rather to tell you, that i have several times try'd, that a solution of the sulphur of vitriol, or ev'n of common sulphur, though the liquor appear'd clear enough, would immediately tinge a piece of new coin, or other clean silver, sometimes with a golden, sometimes with a deeper, and more reddish colour, according to the strength of the solution, and the quantity of it, that chanc'd to adhere to the metall; which may take off your wonder that the water of the hot spring at _bath_, abounding with dissolv'd substances of a very sulphureous nature, should for a while, as it were gild, the new or clean pieces of silver coyn, that are for a due time immers'd in it. and to these may be added those formerly mention'd examples of the adventitious colours of mineral bodies; which brings into my mind, that, ev'n vegetable liquors, whether by degeneration, or by altering the texture of the body that imbibes them, may stain other bodies with colours differing enough, from their own, of which very good herbarists have afforded us a notable example, by affirming that the juice of _alcanna_ being green (in which state i could never here procure it) do's yet dye the skin and nails of a lasting red. but i see this treatise is like to prove too bulky without the addition of further instances of this nature. _experiment xlix._ meeting the other day, _pyrophilus_, in an _italian_ book, that treats of other matters, with a way of preparing what the author calls a _lacca_ of vegetables, by which the _italians_ mean a kind of extract fit for painting, like that rich _lacca_ in english commonly call'd _lake_, which is imploy'd by painters as a glorious red. and finding the experiment not to be inconsiderable, and very defectively set down, it will not be amiss to acquaint you with what some tryals have inform'd us, in reference to this experiment, which both by our italian author, and by divers of his countrymen, is look'd upon as no trifling secret. take then the root call'd in latin _curcuma_, and in english turmerick, (which i made use of, because it was then at hand, and is among vegetables fit for that purpose one of the most easiest to be had) and when it is beaten, put what quantity of it you please into fair water, adding to every pound of water about a spoonfull or better of as strong a _lixivium_ or solution of potashes as you can well make, clarifying it by filtration before you put it to the decocting water. let these things boyl, or rather simper over a soft fire in a clean glaz'd earthen vessel, till you find by the immersion of a sheet of white paper (or by some other way of tryal) that the liquor is sufficiently impregnated with the golden tincture of the turmerick, then take the decoction off the fire, and filter or strain it that it may be clean, and leisurely dropping into it a strong solution of roch allum, you shall find the decoction as it were curdl'd, and the tincted part of it either to emerge, to subside, or to swim up and down, like little yellow flakes; and if you pour this mixture into a tunnel lin'd with cap paper, the liquor that filtred formerly so yellow, will now pass clean thorow the filtre, leaving its tincted, and as it were curdled parts in the filtre, upon which fair water must be so often pour'd, till you have dulcifi'd the matter therein contain'd, the sign of which dulcification is (you know) when the water that has pass'd through it, comes from it as tasteless as it was pour'd on it. and if without filtration you would gather together the flakes of this vegetable lake, you must pour a great quantity of fair water upon the decoction after the affusion of the alluminous solution, and you shall find the liquor to grow clearer, and the lake to settle together at the bottom, or emerge to the top of the water, though sometimes having not pour'd out a sufficient quantity of fair water, we have observ'd the lake partly to subside, and partly to emerge, leaving all the middle of the liquor clear. but to make this lake fit for use, it must by repeated affusions of fresh water, be dulcifi'd from the adhering salts, as well as that separated by filtration, and be spread and suffer'd to dry leisurely upon pieces of cloth, with brown paper, or chalk, or bricks under them to imbibe the moisture[25]. [page 372] _annotation i._ whereas it is presum'd that the magistery of vegetables obtain'd this way consists but of the more soluble and coloured parts of the plants that afford it, i must take the liberty to question the supposition. and for my so doing, i shall give you this account. according to the notions (such as they were) that i had concerning salts; allom, though to sense a homogeneous body, ought not to be reckon'd among true salts, but to be it self look'd upon as a kind of magistery, in regard that as native vitriol (for such i have had) contains both a saline substance and a metall, whether copper, or iron, corroded by it, and associated with it; so allom which may be of so near a kin to vitriol, that in some places of _england_ (as we are assur'd by good authority the same stone will sometimes afford both) seems manifestly to contain a peculiar kind of acid spirit, generated in the bowels of the earth, and some kind of stony matter dissolv'd by it. and though in making our ordinary allom, the workmen use the ashes of a sea weed (vulgarly call'd kelp) and urine: yet those that should know, inform us, that, here in _england_, there is besides the factitious allom, allom made by nature without the help of those additaments. now (_pyrophilus_) when i consider'd this composition of allom, and that alcalizate salts are wont to præcipitate what acid salts have dissolv'd, i could not but be prone to suspect that the curdled matter, which is call'd the magistery of vegetables, may have in it no inconsiderable proportion of a stony substance præcipitated out of the allom by the _lixivium_, wherein the vegetable had been decocted, and to shew you, that there is no necessity, that all the curdl'd substance must belong to the vegetable, i shall add, that i took a strong solution of allom, and having filtred it, by pouring in a convenient quantity of a strong solution of potashes, i presently, as i expected, turn'd the mixture into a kind of white curds, which being put to filtre, the paper retain'd a stony _calx_, copious enough, very white, and which seem'd to be of a mineral nature, both by some other signes, and this, that little bits of it being put upon a live coal, which was gently blown whilst they were on it, they did neither melt nor fly away, and you may keep a quantity of this white substance for a good while, (nay for ought i can guess for a very long one) in a red hot crucible without losing or spoiling it; nor did hot water wherein i purposely kept another parcel of such _calx_, seem to do any more than wash away the looser adhering salts from the stony substance, which therefore seem'd unlikely to be separable by ablutions (though reiterated) from the præcipitated parts of the vegetable, whose lake is intended. and to shew you, that there is likewise in allom a body, with which the fix'd salt of the alcalizate solution will concoagulate into a saline substance differing from either of them, i shall add, that i have taken pleasure to recover out of the slowly exhal'd liquor, that pass'd through the filtre, and left the foremention'd _calx_ behind, a body that at least seem'd a salt very pretty to look on, as being very white, and consisting of an innumerable company of exceeding slender, and shining particles, which would in part easily melt at the flame of a candle, and in part flye away with some little noise. but of this substance, and its odd qualities more perhaps elsewhere; for now i shall only take notice to you, that i have likewise with urinous salts, such as the spirit of sal armoniack, as well as with the spirit of urine it self, nay, (if i much mistake not) ev'n with stale urine undistil'd, easily precipitated such a white _calx_ as i was formerly speaking of, out of a limpid solution of allom, so that there is need of circumspection in judging of the natures of liquors by precipitations wherein allom intervenes, else we may sometimes mistakingly imagine that to be precipitated out of a liquor by allom, which is rather precipitated out of allom by the liquor: and this puts me in mind to tell you, that 'tis not unpleasant to behold how quickly the solution of allom (or injected lumps of allom) do's occasion the severing of the colour'd parts of the decoction from the liquor that seem'd to have so perfectly imbib'd them. [25] _the curious reader that desires further information concerning lakes, may resort to the 7th book of_ neri's _art of glass, englished (6 or 7 years since the writing of this 49th experiment) and illustrated with learned observations, by the inquisitive and experienc'd dr._ charles merret. _annot. ii._ the above mention'd way of making lakes we have tryed not only with turmerick, but also with madder, which yielded us a red lake; and with rue, which afforded us an extract, of (almost if not altogether) the same colour with that of the leaves. but in regard that 'tis principally the alcalizate salt of the pot-ashes, which enables the water to extract so powerfully the tincture of the decocted vegetables, i fear that our author may be mistaken by supposing that the decoction will alwayes be of the very same colour with the vegetable it is made off. for lixiviate salts, to which pot-ashes eminently belong, though by peircing and opening the bodies of vegetables, they prepare and dispose them to part readily with their tincture, yet some tinctures they do not only draw out, but likewise alter them, as may be easily made appear by many of the experiments already set down in this treatise, and though allom being of an acid nature, its solutions may in some cases destroy the adventitious colours produc'd by the alcaly, and restore the former: yet besides that allom is not, as i have lately shown, a meer acid salt, but a mixt body, and besides, that its operations are languid in comparison of the activity of salts freed by distillation, or by incineration and dissolution, from the most of their earthy parts, we have seen already examples, that in divers cases an acid salt will not restore a vegetable substance to the colour of which an alcalizate one had depriv'd it, but makes it assume a third very differing from both, as we formerly told you, that if syrrup of violets were by an alcaly turn'd green, (which colour, as i have try'd, may be the same way produc'd in the violet-leaves themselves without any relation to a syrrup) an acid salt would not make it blew again, but red. and though i have by this way of making lakes, made magisteries (for such they seem to be) of brazil, and as i remember of cochinele it self, and of other things, red, yellow or green which lakes were enobled with a rich colour, and others had no bad one; yet in some the colour of the lake seem'd rather inferiour than otherwise to that of the plant, and in others it seem'd both very differing, and much worse; but writing this in a time and place where i cannot provide my self of flowres and other vegetables to prosecute such tryals in a competent variety of subjects, i am content not to be positive in delivering a judgment of this way of lakes, till experience, or you, _pyrophilus_, shall have afforded me a fuller and more particular information. _annotation iii._ and on this occasion (_pyrophilus_) i must here (having forgot to do it sooner) advertise you once for all, that having written several of the foregoing experiments, not only in haste but at seasons of the year, and in places wherein i could not furnish my self with such instruments, and such a variety of materials, as the design of giving you an introduction into the history of colours requir'd, it can scarce be otherwise but that divers of the experiments, that i have set down, may afford you some matter of new tryals, if you think fit to supply the deficiencies of some of them (especially the freshly mention'd about lakes, and those that concern emphatical colours) which deficiencies for want of being befriended with accommodations i could better discern than avoid. _annotation iv._ the use of allom is very great as well as familiar in the dyers trade, and i have not been ill pleas'd with the use i have been able to make of it in preparing other pigments than those they imploy with vegetable juices. but the lucriferous practises of dyers and other tradesmen, i do, for reasons that you may know when you please, purposely forbear in this essay, though not strictly from pointing at, yet from making it a part of my present work explicitly and circumstantially to deliver, especially since i now find (though late and not without some blushes at my prolixity) that what i intended but for a short essay, is already swell'd into almost a volume. _experiment l._ yet here, _pyrophilus_, i must take leave to insert an experiment, though perhaps you'l think its coming in here an intrusion, for i confess its more proper place would have been among those experiments, that were brought as proofs and applications of our notions concerning the differences of salts; but not having remembred to insert it in its fittest place, i had rather take notice of it in this, than leave it quite unmention'd: partly because it doth somewhat differ from the rest of our experiments about colours, in the way whereby 'tis made; and partly because the grounds upon which i devis'd it, may hint to you somewhat of the method i use in designing and varying experiments about colours, and upon this account i shall inform you, not only what i did, but why i did it. i consider'd then that the work of the former experiments was either to change the colour of a body into another, or quite to destroy it, without giving it a successor, but i had a mind to give you also a way, whereby to turn a body endued with one colour into two bodies, of colours, as well as consistencies, very distinct from each other, and that by the help of a body that had it self no colour at all. in order to this, i remembred, that finding the acidity of spirit of vinegar to be wholly destroy'd by its working upon _minium_ (or calcin'd lead) whereby the saline particles of the _menstruum_ have their taste and nature quite alter'd, i had, among other conjectures i had built upon that change, rightly concluded, that the solution of lead in spirit of vinegar would alter the colour of the juices and infusions of several plants, much after the like manner that i had found oyl of tartar to do; and accordingly i was quickly satisfied upon tryal, that the infusion of rose-leaves would by a small quantity of this solution well mingl'd with it, be immediately turn'd into a somewhat sad green. and further, i had often found, that oyl of vitriol, though a potently acid _menstruum_, will yet præcipitate many bodies, both mineral and others, dissolv'd not onely in _aqua fortis_ (as some chymists have observ'd) but particularly in spirit of vinegar, and i have further found, that the _calces_ or powders præcipitated by this liquor were usually fair and white. laying these things together, 'twas not difficult to conclude, that if upon a good tincture of red rose-leaves made with fair water, i dropp'd a pretty quantity of a strong and sweet solution of _minium_, the liquor would be turn'd into the like muddy green substance, as i have formerly intimated to you, that oyl of tartar would reduce it to, and that if then i added a convenient quantity of good oyl of vitriol, this last nam'd liquor would have two distinct operations upon the mixture, the one, that it would præcipitate that resolv'd lead in the form of a white powder; the other, that it would clarifie the muddy mixture, and both restore, and exceedingly heighten the redness of the infusion of roses, which was the most copious ingredient of the green composition, and accordingly trying the experiment in a wine glass sharp at the bottom (like an inverted cone) that the subsiding powder might seem to take up the more room, and be the more conspicuous, i found that when i had shaken the green mixture, that the colour'd liquor might be the more equally dispersed, a few drops of the rectifi'd oyl of vitriol did presently turn the opacous liquor into one that was cleer and red, almost like a rubie, and threw down good store of a powder, which when 'twas settl'd, would have appear'd very white, if some interspers'd particles of the red liquor had not a little allay'd the purity, though not blemish'd the beauty of the colour. and to shew you, _pyrophilus_, that these effects do not flow from the oyl of vitriol, as it is such, but as it is a strongly acid _menstruum_, that has the property both to præcipitate lead, as well as some other concretes out of spirit of vinegar, and to heighten the colour of red rose-leaves, i add, that i have done the same thing, though perhaps not quite so well with spirit of salt, and that i could not do it with _aqua-fortis_, because though that potent _menstruum_ does as well as the others heighthen the redness of roses, yet it would not like them precipitate lead out of spirit of vinegar, but would rather have dissolv'd it, if it had not found it dissolv'd already. and as by this way we have produc'd a red liquor, and a white precipitate out of a dirty green magistery of rose-leaves, so by the same method, you may produce a fair yellow, and sometimes a red liquor, and the like precipitate, out of an infusion of a curious purple colour. for you may call to mind, that in the annotation upon the 39th. experiment i intimated to you, that i had with a few drops of an alcaly turn'd the infusion of logg-wood into a lovely purple. now if instead of this alcaly i substituted a very strong and well filtrated solution of _minium_, made with spirit of vinegar, and put about half as much of this liquor as there was of the infusion of logg-wood, (that the mixture might afford a pretty deal of precipitate,) the affusion of a convenient proportion of spirit of salt, would (if the liquors were well and nimbly stirr'd together) presently strike down a precipitate like that formerly mention'd, and turn the liquor that swam above it, for the most part into a lovely yellow. but for the advancing of this experiment a little further, i consider'd, that in case i first turn'd a spoonfull of the infusion of logg-wood purple, by a convenient proportion of the solution of _minium_, the affusion of spirit of sal armnoniack, would precipitate the corpuscles of lead conceal'd in the solution of _minium_, and yet not destroy the purple colour of the liquor; whereupon i thus proceeded; i took about a spoonfull of the _fresh_ tincture of logg-wood, (for i found that if it were _stale_ the experiment would not alwayes succeed,) and having put to it a convenient proportion of the solution of _minium_ to turn it into a deep and almost opacous purple, i then drop'd in as much spirit of sal armoniack, as i guess'd would precipitate about half or more (but not all) of the lead, and immediately stirring the mixture well together, i mingled the precipitated parts with the others, so that they fell to the bottom, partly in the form of a powder, and partly in the form of a curdled substance, that (by reason of the predominancy of the ting'd corpuscles over the white) retain'd as well as the supernatant liquor; a blewish purple colour sufficiently deep, and then instantly (but yet warily,) pouring on a pretty quantity of spirit of salt, the matter first precipitated, was, by the above specified figure of the bottome of the glass preserv'd from being reach'd by the spirituous salt; which hastily precipitated upon it a new bed (if i may so call it) of white powder, being the remaining corpuscles of the lead, that the urinous spirit had not struck down: so that there appear'd in the glass three distinct and very differingly colour'd substances; a purple or violet-colour'd precipitate at the bottom, a white and carnation (sometimes a variously colour'd) precipitate over that, and at the top of all a transparent liquor of a lovely yellow, or red. thus you see, _pyrophilus_, that though to some i may have seem'd to have lighted on this (50th.) experiment by chance, and though others may imagine, that to have excogitated it, must have proceeded from some extraordinary insight into the nature of colours, yet indeed, the devising of it need not be look'd upon as any great matter, especially to one that is a little vers'd in the notions, i have in these, and other papers hinted concerning the differences of salts. and perhaps i might add upon more than conjecture, that these very notions and some particulars scatteringly deliver'd in this treatise, being skilfully put together, may suggest divers matters (at least,) about colours, that will not be altogether despicable. but those hinted, _pyrophilus_, i must now leave such as you to prosecute, having already spent farr more time than i intended to allow my self in acquainting you with particular experiments and observations concerning the changes of colour, to which i might have added many more, but that i hope i may have presented you with a competent number to make out in some measure what i have at the beginning of this essay either propos'd as my design in this tract, or deliver'd as my conjectures concerning these matters. and it not being my present designe, as i have more than once declar'd, to deliver any positive hypothesis or solemn theory of colours, but only to furnish you with some experiments towards the framing of such a theory; i shall add nothing to what i have said already, but a request that you would not be forward to think i have been mistaken in any thing i have deliver'd as matter of fact concerning the changes of colours, in case you should not every time you trye it, find it exactly to succeed. for besides the contingencies to which we have elsewhere shewn some other experiments to be obnoxious, the omission or variation of a seemingly unconsiderable circumstance, may hinder the success of an experiment, wherein no other fault has been committed. of which truth i shall only give you that single and almost obvious, but yet illustrious instance of the art of dying scarlets, for though you should see every ingredient that is us'd about it, though i should particularly inform you of the weight of each, and though you should be present at the kindling of the fire, and at the increasing and remitting of it, when ever the degree of heat is to be alter'd, and though (in a word) you should see every thing done so particularly that you would scarce harbour the least doubt of your comprehending the whole art: yet if i should not disclose to you, that the vessels, that immediately contain the tinging ingredients, are to be made of or to be lin'd with tin, you would never be able by all that i could tell you else (at-least, if the famousest and candidest artificers do not strangely delude themselves) to bring your tincture of chochinele to dye a perfect scarlet. so much depends upon the very vessel, wherein the tinging matters are boyl'd, and so great an influence may an unheeded circumstance have on the success of experiments concerning colours. * * * * * _finis._ * * * * * a short account of some observations made by mr. _boyle_ about a _diamond_ that _shines_ in the dark. first enclosed in a letter written to a friend, and now together with it annexed to the foregoing treatise, upon the score of the affinity betwixt _light_ and _colours_. * * * * * _london,_ printed for _henry herringman_. 1664 * * * * * a copy of the letter that mr. _boyle_ wrote to sir _robert morray_, to accompany the _observations_ touching the _shining diamond_. _sir,_ though sir _robert morray_ and monsieur _zulichem_ be persons that have deserv'd so well of the commonwealth of learning, that i should think my self unworthy to be look'd upon as a member of it, if i declin'd to obey them, or to serve them; yet i should not without reluctancy send you the notes, you desire for him, if i did not hope that you will transmit together with them, some account why they are not less unworthy of his perusal; which, that you may do; i must inform you, how the writing of them was occasion'd, which in short was thus. as i was just going out of town, hearing that an ingenious gentleman of my acquaintance, lately return'd from _italy_, had a diamond, that being rubb'd, would shine in the dark, and that he was not far off, i snatch'd time from my occasions to make him a visit, but finding him ready to go abroad, and having in vain try'd to make the stone yield any light in the day time, i borrow'd it of him for that night, upon condition to restore it him within a day or two at furthest, at _gresham_ college, where we appointed to attend the meeting of the society, that was then to be at that place. and hereupon i hasted that evening out of town, and finding after supper that the stone which in the day time would afford no discernable light, was really conspicuous in the dark, i was so taken with the novelty, and so desirous to make some use of an opportunity that was like to last so little a while, that though at that time i had no body to assist me but a foot-boy, yet sitting up late, i made a shift that night to try a pretty number of such of the things that then came into my thoughts, as were not in that place and time unpracticable. and the next day being otherwise imploy'd, i was fain to make use of a drowsie part of the night to set down hastily in writing what i had observ'd, and without having the time in the morning, to stay the transcribing of it, i order'd the observations to be brought after me to _gresham_ college, where you may remember, that they were together with the stone it self shown to the royal society, by which they had the good fortune not to be dislik'd, though several things were through hast omitted, some of which you will find in the margin of the inclosed paper. the substance of this short narrative i hope you will let monsieur _zulichem_ know, that he may be kept from expecting any thing of finish'd in the observations, and be dispos'd to excuse the want of it. but such as they are, i hope they will prove (without a clinch) luciferous experiments, by setting the speculations of the curious on work, in a diligent inquiry after the nature of light, towards the discovery of which, perhaps they have not yet met with so considerable an experiment, since here we see light produc'd in a dead and opacous body, and that not as in rotten wood, or in fishes, or as in the _bolonian_ stone, by a natural corruption, or by a violent destruction of the texture of the body, but by so slight a mechanical operation upon its texture, as we seem to know what it is, and as is immediately perform'd, and that several wayes without at all prejudicing the body, or making any sensible alterations in its manifest qualities. and i am the more willing to expose my hasty tryals to monsieur _zulichem_, and to you, because, he being upon the consideration of dioptricks, so odd a _phænomenon_ relateing to the subject, as probably he treats of, light will, i hope, excite a person to consider it, that is wont to consider things he treats of very well. and for you sir, i hope you will both recrute and perfect the observations you receive, for you know that i cannot add to them, having a good while since restor'd to mr. _clayton_ the stone, which though it be now in the hands of a prince that so highly deserves, by understanding them, the greatest curiosities; yet he vouchsafes you that access to him as keeps me from doubting, you may easily obtain leave to make further tryals with it, of such a monarch as ours, that is not more inquisitive himself, than a favourer of them that are so. i doubt not but these notes will put you in mind of the motion you made to the society, to impose upon me the task of bringing in, what i had on other occasions observ'd concerning shining bodies. but though i deny not, that i sometimes made observations about the _bolonian_ stone, and try'd some experiments about some other shining bodies; yet the same reasons that reduc'd me then to be unwilling to receive ev'n their commands, must now be my apology for not answering your expectations, namely the abstruse nature of light, and my being already over-burden'd, and but too much kept imploy'd by the urgency of the press, as well as by more concerning and distracting occasions. but yet i will tell you some part of what i have met with in reference to the stone, of which i send you an account. because i find on the one side, that a great many think it no rarity upon a mistaken perswasion, that not only there are store of carbuncles, of which this is one; but that all diamonds and other glistering jewels shine in the dark. whereas on the other side there are very learn'd men, who (plausibly enough) deny that there are any carbuncles or shining stones at all. and certainly, those judicious men have much more to say for themselves, than the others commonly plead, and therefore did deservedly look upon mr. _clayton_'s diamond as a great rarity. for not only _boetius de boot_, who is judg'd the best author on this subject, ascribes no such virtue to diamonds, but begins what he delivers of carbuncles, with this passage.[26] _magna fama est carbunculi. is vulgo putatur in tenebris carbonis instar lucere; fortassis quia pyropus seu anthrax appellatus a veteribus fuit. verum hactenus nemo nunquam verè asserere ausus fuit, se gemmam noctu lucentem vidisse. garcias ab horto proregis indiæ medicus, refert se allocutum fuisse, qui se vidisse affirmarent. sed iis fidem non habuit._ and a later author, the diligent and judicious _johannes de laet_ in his chapter of carbuncles and of rubies, has this passage. _quia autem carbunculi, pyropi & anthraces a veteribus nominantur, vulgo creditum fuit, carbonis instar in tenebris lucere, quod tamen nullâ gemmâ hastenus deprehensum, licet à quibusdam temerè jactetur._ and the recentest writer i have met with on this subject, _olaus wormius_, in his account of his well furnish'd _musæum_, do's, where he treats of rubies, concurr with the former writers by these words.[27] _sunt qui rubinum veterum carbunculum esse existimant, sed deest una illa nota, quod in tenebris instar anthracis non luceat: ast talem carbunculum in rerum naturâ non inveniri major pars authoram existimant. licet unum aut alterum in india apud magnates quosdam reperiri scribant, cum tamen ex aliorum relatione id habeant saltem, sed ipsi non viderint._ in confirmation of which i shall only add, that hearing of a rubie, so very vivid, that the jewellers themselves have several times begg'd leave of the fair lady to whom it belong'd, that they might try their choicest rubies by comparing them with that, i had the opportunity by the favour of this lady and her husband, (both which i have the honour to be acquainted with) to make a trial of this famous rubie in the night, and in a room well darkn'd, but not only could not discern any thing of light, by looking on the stone before any thing had been done to it, but could not by all my rubbing bring it to afford the least glimmering of light. [26] boetius de boot. gem. & lapid. histor. lib. 3. cap. 8. [27] musæi wormiani. cap. 17. but, sir, though i be very backward to admit strange things for truths, yet i am not very forward to reject them as impossibilities, and therefore i would not discourage any from making further inquiry, whether or no there be really in _rerum natura_, any such thing as a true carbuncle or stone that without rubbing will shine in the dark. for if such a thing can be found, it may afford no small assistance to the curious in the investigation of light, besides the nobleness and rarity of the thing it selfe. and though _vartomannus_ was not an eye witness of what he relates, that the king of _pegu_, one of the chief kings of the _east-indies_, had a true carbuncle of that bigness and splendour, that it shin'd very gloriously in the dark, and though _garcias ab horto_, the _indian_ vice-roys physician, speaks of another carbuncle, only upon the report of one, that he discours'd with, who affirmed himself to have seen it; yet as we are not sure that these men that gave themselves out to be eye-witnesses speak true, yet they may have done so for ought we know to the contrary. and i could present you with a much considerabler testimony to the same purpose, if i had the permission of a person concern'd, without whose leave i must not do it. i might tell you that _marcus paulus venetus_[28] (whose suppos'd fables, divers of our later travellours and navigatours have since found to be truths) speaking of the king of _zeilan_ that then was, tells us, that he was said to have the best rubie in the world, a palm long and as big as a mans arm, without spot, shining like a fire, and he subjoyns, that the great _cham_, under whom _paulus_ was a considerable officer, sent and offer'd the value of a city for it; but the king answer'd, he would not give it for the treasure of the world, nor part with it, having been his ancestours. and i could add, that in the relation made by two _russian_ cossacks of their journey into _catay_[29], written to their emperour, they mention'd their having been told by the people of those parts, that their king had a stone, which lights as the sun both day and night, call'd in their language _sarra_, which those cossacks interpret a ruby. but these relations are too uncertain for me to build any thing upon, and therefore i shall proceed to tell you, that there came hither about two years since out of _america_, the governour of one of the principal colonies there, an ancient _virtuoso_, and one that has the honour to be a member of the royal society; this gentleman finding some of the chief affairs of his country committed to another and me, made me divers visits, and in one of them when i enquir'd what rare stones they had in those parts of the _indies_ he belong'd to, he told me, that the _indians_ had a tradition that in a certain hardly accessible hill, a pretty way up in the country, there was a stone which in the night time shin'd very vividly, and to a great distance, and he assur'd me, that though he thought it not fit to venture himself so far among those savages, yet he purposely sent thither a bold _englishman_, with some natives to be his guides, and that this messenger brought him back word, that at a distance from the hillock he had plainly perceiv'd such a shining substance as the _indians_ tradition mention'd, and being stimulated by curiosity, had slighted those superstitious fears of the inhabitants, and with much ado by reason of the difficulty of the way, had made a shift to clamber up to that part of the hill, where, by a very heedful observation, he suppos'd himself to have seen the light: but whether 'twere that he had mistaken the place, or for some other reason, he could not find it there, though when he was return'd to his former station, he did agen see the light shining in the same place where it shone before. a further account of this light i expect from the gentleman that gave me this, who lately sent me the news of his being landed in that country. and though i reserve to my self a full liberty of believing no more than i see cause; yet i do the less scruple to relate this, because a good part of it agrees well enough with another story that i shall in the next place have occasion to subjoyn, in order whereunto i shall tell you, that though the learned authors i formerly mention'd, tell us, that no writer has affirm'd his having himself seen a real carbuncle, yet, considering the light of mr. _claytons_ diamond, it recall'd into my mind, that some years before, when i was inquisitive about stones, i had met with an old _italian_ book highly extoll'd to me by very competent judges, and that though the book were very scarce, i had purchas'd it at a dear rate, for the sake of a few considerable passages i met with in it, and particularly one, which being very remarkable in it self, and pertinent to our present argument, i shall put it for you, though not word for word, which i fear i have forgot to do, yet as to the sense, into _english_. [28] _purchas_'s pilgrim. lib. 1. cap. 4. pag. 104. [29] in the year 1619. _having promis'd_ (says our author)[30] _to say something of that most precious sort of jewels,_ carbuncles, _because they are very rarely to be met with, we shall briefly deliver what we know of them. in_ clement _the seventh's time, i happen'd to see one of_ _them at a certain_ ragusian _merchants, nam'd_ beigoio di bona, _this was a carbuncle white, of that kind of whiteness which we said was to be found in those rubies of which we made mention a little above,_ (where he had said that those rubies had a kind of livid whiteness or paleness like that of a calcidonian) _but it had in it a lustre so pleasing and so marveilous, that it shin'd in the dark, but not as much as colour'd carbuncles, though it be true, that in an exceeding dark place i saw it shine in the manner of fire almost gone out. but as for colour'd carbuncles, it has not been my fortune to have seen any, wherefore i will onely set down what i learn'd about them discoursing in my youth with a_ roman _gentleman of antient experience in matters of jewels, who told me, that one_ jacopo cola _being by night in a vineyard of his, and espying something in the midst of it, that shin'd like a little_ glowing coal, at the foot of a vine, went near towards the place where he thought himself to have seen that fire, but not finding it, he said, that being return'd to the same place, whence he had first descry'd it, and perceiving there the same splendor as before, he mark'd it so heedfully, that he came at length to it, where he took up a very little stone, which he carry'd away with transports and joy. and the next day carrying it about to show it divers of his friends, whilst he was relating after what manner he found it, there casually interven'd a _venetian_ embassadour, exceedingly expert in jewels, who presently knowing it to be a carbuncle, did craftily before he and the said _jacopo_ parted (so that there was no body present that understood the worth of so precious a gemm) purchase it for the value of 10. crowns, and the next day left _rome_ to shun the being necessitated to restore it, and (as he affirm'd) it was known within some while after that the said _venetian_ gentleman did in _constantinople_ sell that carbuncle to the then grand seignior, newly come to the empire, for a hundred thousand crowns. _and this is what i can say_ concerning _carbuncles_, and this is not a little at least as to the first part of this account, where our _cellini_ affirms himself to have seen a real carbuncle with his own eyes, especially since this author appears wary in what he delivers, and is inclin'd rather to lessen, than increase the wonder of it. and his testimony is the more considerable, because though he were born a subject neither to the pope nor the then king of _france_ (that royal _virtuoso_ _francis_ the first) yet both the one and the other of those princes imploy'd him much about making of their noblest jewels. what is now reported concerning a shining substance to be seen in one of the islands about _scotland_, were very improper for me to mention to sr. _robert morray_, to whom the first information was originally brought, and from whom i expect a farther (for i scarce dare expect a convincing) account of it. but i must not omit that some _virtuoso_ questioning me the other day at _white-hall_ about mr. _claytons_ diamond, and meeting amongst them an ingenious _dutch_ gentleman, whose father was long embassador for the netherlands in _england_, i learn'd of him, that, he is acquainted with a person, whose name he told (but i do not well remember it) who was admiral of the _dutch_ in the _east-indies_, and who assur'd this gentleman _monsieur boreel_, that at his return from thence he brought back with him into _holland_ a stone, which though it look'd but like a pale dull diamond, such as he saw mr. _claytons_ to be, yet was it a real carbuncle, and did without rubbing shine so much, that when the admiral had occasion to open a chest which he kept under deck in a dark place, where 'twas forbidden to bring candles for fear of mischances, as soon as he open'd the trunck, the stone would by its native light, shine so as to illustrate a great part of it, and this gentleman having very civilly and readily granted me the request i made him, to write to the admiral, who is yet alive in _holland_, (and probably may still have the jewel by him,) for a particular account of this stone, i hope ere long to receive it, which will be the more welcome to me, not onely because so unlikely a thing needs a cleer evidence, but because i have had some suspition of that (supposing the truth of the thing) what may be a shining stone in a very hot countrey as the _east-indies_, may perhaps cease to be so (at least in certain seasons,) in one as cold as _holland_. for i observ'd in the diamond i send you an account of, that not onely rubbing but a very moderate degree of warmth, though excited by other wayes, would make it shine a little. and 'tis not impossible that there may be stones as much more susceptible than that, of the alterations requisite to make a diamond shine, as that appeares to be more susceptible of them, than ordinary diamonds. and i confess to you, that this is not the only odd suspition (for they are not so much as conjectures) that what i try'd upon this diamond suggested to me. for not here to entertain you with the changes i think may be effected ev'n in harder sorts of stones, by wayes not vulgar, nor very promising, because i may elsewhere have occasion to speak of them, and this letter is but too prolix already, that which i shall now acknowledge to you is, that i began to doubt whether there may not in some cases be some truth in what is said of the right turquois, that it often changes colour as the wearer is sick or well, and manifestly loses its splendor at his death. for when i found that ev'n the warmth of an affriction that lasted not above a quarter of a minute, nay, that of my body, (whose constitution you know is none of the hottest) would make a manifest change in the solidest of stones a diamond, it seem'd not impossible, that certain warm and saline steams issuing from the body of a living man, may by their plenty or paucity, or by their peculiar nature, or by the total absence of them, diversifie the colour, and the splendor of so soft a stone as the turquois. and though i admir'd to see, that i know not how many men otherwise learn'd, should confidently ascribe to jewels such virtues as seem no way competible to inanimate agents, if to any corporeal ones at all, yet as to what is affirm'd concerning the turquois's changing colour, i know not well how to reject the affirmation of so learned (and which in this case is much more considerable) so judicious a lapidary as _boetius de boot_[31], who upon his own particular and repeated experience delivers so memorable a narrative of the turquois's changing colour, that i cannot but think it worth your perusal, especially since a much later and very experienc'd author, _olaus wormius_,[32] where he treats of that stone, confirms it with this testimony. _imprimis memorandum exemplum quod anshelmus boetius de seipso refert, tam mutati coloris, quam à casu preservationis. cui & ipse haud dissimile adferre possum, nisi ex anshelmo petitum quis putaret._ i remember that i saw two or three years since a _turcois_ (worn in a ring) wherein there were some small spots, which the _virtuoso_ whose it was asur'd me he had observ'd to grow sometimes greater sometimes less, and to be sometimes in one part of the stone, sometimes in another. and i having encourag'd to make pictures from time to time of the stone, and of the situation of the cloudy parts, thatso their motion may be more indisputable, and better observ'd, he came to me about the midle of this very week, and assur'd me that he had, as i wish'd, made from time to time schemes or pictures of the differing parts of the stone, whereby the several removes and motions of the above mentioned clouds are very manifest, though the cause seem'd to him very occult: these pictures he has promis'd to show me, and is very ready to put the stone it self into my hands. but the ring having been the other day casually broken upon his finger, unless it can be taken out, and set again without any considerable heat, he is loath to have it medled with, for fear its peculiarity should be thereby destroy'd. and possibly his apprehension would have been strengthen'd, if i had had opportunity to tell him what is related by the learned _wormius_[33] of an acquaintance of his, that had a _nephritick_ stone, of whose eminent virtues he had often experience ev'n in himself, and for that cause wore it still about his wrist; and yet going upon a time into a bath of fair water only, wherein certain herbs had been boyl'd, the stone by being wetted with this decoction, was depriv'd of all his virtue, whence _wormius_ takes occasion to advertise the sick, to lay by such stones whensoever they make use of a bath. and we might expect to find _turcos_ likewise, easily to be wrought upon in point of colour, if that were true, which the curious _antonio neri_, in his ingenious _arte vetraria_[34] teaches of it, namely, that _turcois's discolour'd_ and grown white, will regain and acquire an excellent colour, if you but keep them two or three days at most cover'd with oyl of sweet almonds kept in a temperate heat by warm ashes, i say if it were true, because i doubt whether it be so, and have not as yet had opportunity to satisfie my self by tryals, because i find by the confession of the most skilfull persons among whom i have laid out for _turcoises_, that the true ones are great rarities, though others be not at all so. and therefore i shall now only mind you of one thing that you know as well as i, namely, that the rare stone which is called _oculus mundi_, if it be good in its kind, will have so great a change made in its texture by being barely left a while in the languidest of liquors, common waters, that from opacous it will become transparent, and acquire a lustre of which it will again be depriv'd, without using any other art or violence, by leaving it a while in the air. and before experience had satisfy'd us of the truth of this, it seem'd as unlikely that common water or air, should work such great changes in that gemm, as it now seems that the effluviums of a human body should effect lesser changes in a _turcois_, especially if more susceptible of them, than other stones of the same kind. but both my watch and my eyes tell me that 'tis now high time to think of going to sleep, matters of this nature, will be better, as well as more easily, clear'd by conference, than writing. and therefore since i think you know me too well to make it needfull for me to disclame credulity, notwithstanding my having entertain'd you with all these extravagancies; for you know well, how wide a difference i am wont to put betwixt things that barely _may be_, and things that _are_, and between those relations that are but not unworthy to be inquir'd into, and those that are not worthy to be actually believ'd; without making apologies for my ravings, i shall readily comply with the drowsiness that calls upon me to release you, and the rather, because monsieur _zulichem_ being concern'd in your desire to know the few things i have observed about the shining stone. to entertain those with suspicions that are accustomed not to acquiesce but in demonstrations, were a thing that cannot be look'd upon as other than very improper by, sir, _your most affectionate_ and _most faithfull servant,_ ro. boyle. [30] benvonuto cellini _nell arte del_ gioiellare, _lib._ 1. _pag._ 10. [31] the narrative in the authors own words, is this. _ego_ (sayes he) _sanctè affirmare possum me unam aureo annulo inclusam perpetuo gestare, cujus facultatem (si gemmæ est) nunquam satis admirari potui. gestaverat enim ante triginta annos hispanus quidam non procula puternis ædibus habitans. is cum vitâ functus esset, & ipsius suspellex (ut moris apud nos est) venum exposita esset, inter cætera etiam turcois exponebatur. verum nemo (licet complures eo concurrissent, ut eam propter coloris elegantiam, quam vivo domino habuerat emerent) sibi emptam voluit, pristinum enim nitorem & colorem prorsus amiserat, ut potius malachites, quam turcois videretur. aderat tum temporis gemmæ habendæ desiderio etiam parens & frater meus, qui antea sæpius gratiam & elegantiam ipsius viderant, mirabundi eam nunc tam esse deformem, emit eam nihilominus pater, satisque vili pretio, qua omnibus contemptui erat, ac presentes non eam esse quam hispanus gestarat, arbitrarentur. domum reversus pater, qui tam turpem gemmam gestare sibi indecorum putabat, eam mihi dono dat, inquiens; quandoquidem, fili mi, vulgi fama est, turcoidem, ut facultates suas exercere possit, dono dari debere tibi eam devoveo, ego acceptam gemmam sculptori trado, at gentilitia mea insignia illi, quamadmodum fieri solet, in jaspide chalcedono, aliisque ignobilioribus gemmis, insculperat. turpe enim existimabam, hujusmodi gemmâ ornatus gratia, dum gratiam nullam haberet, uti. paret sculptor redditque gemmam, quam gesto pro annulo signatorio. vix per mensem gestaram, redit illi pristinus color, sed non ita nitens propter sculpturam, ac inæqualem superficiem. miramur omnes gemmam, atque id præcipuè quod color indies pulchrior fieret. id quià observabam, nunquam fere eam à manu deposui, ita ut nunc adhuc candem gestem._ [32] _olaus wormius, in musæ. 18º pag. 186._ [33] _musæ. worm._ pag. 99. [34] arte vetraria, lib. 7 cap. 102. * * * * * observations made this 27th.[35] of _october_ 1663. about mr. _clayton's_ diamond.[36] being look'd on in the day time, though in a bed, whose curtains were carefully drawn, i could not discern it to shine at all, though well rubb'd, but about a little after sun-set, whilst the twilight yet lasted, nay, this morning[37] a pretty while after sun-rising, (but before i had been abroad in the more freely inlightned air of the chamber) i could upon a light affriction easily perceive the stone to shine. [35] these were brought in and read before the royal society, (the day following) _oct._ 28. 1663. [36] _the stone it self being to be shown to the royal society, when the observations were deliver'd, i was willing (being in haste) to omit the description of it, which is in short, that it was a flat or table diamond, of about a third part of an inch in length, and somewhat less in breadth, that it was a dull stone, and of a very bad water, having in the day time very little of the vividness of ev'n ordinary diamonds, and being blemished with a whitish cloud about the middle of it, which covered near a third part of the stone._ [37] _hast made me forget to take notice that i went abroad the same morning, the sun shining forth clear enough, to look upon the diamond though a_ microscope, _that i might try whether by that magnifying glass any thing of peculiar could be discern'd in the texture of the stone, and especially of the whitish cloud that possest a good part of it. but for all my attention i could not discover any peculiarity worth mentioning._ secondly, the candles being removed, i could not in a dark place discern the stone to have any light, when i looked on it, without having rubb'd or otherwise prepar'd it. thirdly, by two white pibbles though hard rubb'd one against another, nor by the long and vehement affriction of rock crystal against a piece of red cloath, nor yet by rubbing two diamonds set in ring, as i had rubb'd this stone, i could produce any sensible degree of light. fourthly, i found this diamond hard enough, not only to enable me to write readily with it upon glass, but to grave on rock crystal it self. fifthly, i found this to have like other diamonds, an electrical faculty.[38] [38] v. _for it drew light bodies like amber, jet, and other concretes that are noted to do so; but its attractive power seem'd inferiour to theirs._ sixthly, being rubb'd upon my cloaths, as is usual for the exciting of amber, wax, and other electrical bodies, it did in the dark manifestly shine like rotten wood, or the scales of whitings, or other putrified fish. seventhly, but this conspicuousness was fainter than that of the scales, and slabber (if i may so call it) of whitings, and much fainter than the light of a glow-worm, by which i have been sometimes able to read a short word, whereas after an ordinary affriction of this diamond i was not able to discern distinctly by the light of it any of the nearest bodies: and this glimmering also did very manifestly and considerably decay presently upon the ceasing of the affriction, though the stone continued visible some while after. eighthly, but if it were rubb'd upon a convenient body for a pretty while, and briskly enough, i found the light would be for some moments much more considerable, almost like the light of a glow-worm, insomuch after i ceased rubbing, i could with the chaf'd stone exhibit a little luminous circle, like that, but not so bright as that which children make by moving a stick fir'd at the end, and in this case it would continue visible about seven or eight times as long as i had been in rubbing it. ninthly, i found that holding it a while near[39] the flame of a candle, (from which yet i was carefull to avert my eyes) and being immediately remov'd into the dark, it disclosed some faint glimmering, but inferiour to that, it was wont to acquire by rubbing. and afterward holding it near a fire that had but little flame, i found the stone to be rather less than more excited, than it had been by the candle. [39] ix. _we durst not hold it in the flame of a candle, no more than put it into a naked fire; for fear too violent a heat (which has been observ'd to spoil many other precious stones) should vitiate and impair a jewel, that was but borrow'd, and was suppos'd to be the only one of its kind._ tenthly, i likewise indeavour'd to make it shine, by holding it a pretty while in a very dark place, over a thick piece of iron, that was well heated, but not to that degree as to be visibly so. and though at length i found, that by this way also, the stone acquired some glimmering, yet it was less than by either of the other ways above mention'd. eleventhly, i also brought it to some kind of glimmering light, by taking it into bed with me, and holding it a good while upon a warm part of my naked body. twelfthly, to satisfie my self, whether the motion introduc'd into the stone did generate the light upon the account of its producing heat there, i held it near the flame of a candle, till it was qualify'd to shine pretty well in the dark, and then immediately i apply'd a slender hair to try whether it would attract it, but found not that it did so; though if it were made to shine by rubbing, it was as i formerly noted electrical. and for further confirmation, though i once purposedly kept it so near the hot iron i just now mention'd, as to make it sensibly warm, yet it shin'd more dimly than it had done by affriction or the flame of a candle, though by both those ways it had not acquir'd any warmth that was sensible. thirteenthly, having purposely rubb'd it upon several bodies differing as to colour, and as to texture, there seem'd to be some little disparity in the excitation (if i may so call it) of light. upon white and red cloths it seem'd to succeed best, especially in comparison of black ones. fourteenthly, but to try what it would do rubb'd upon bodies more hard, and less apt to yield heat upon a light affriction, than cloath, i first rubb'd it upon a white wooden box, by which it was excited, and afterwards upon a piece of purely glazed earth, which seem'd during the attrition to make it shine better than any of the other bodies had done, without excepting the white ones, which i add, lest the effect should be wholly ascrib'd to the disposition white bodies are wont to have to reflect much light. fifteenthly, having well excited the stone, i nimbly plung'd it under water[40], that i had provided for that purpose, and perceiv'd it to shine whilst it was beneath the surface of that liquor, and this i did divers times. but when i indeavour'd to produce a light by rubbing it upon the lately mentioned cover of the box, the stone and it being both held beneath the surface of the water, i did not well satisfie my self in the event of the trial; but this i found, if i took the stone out, and rubb'd it upon a piece of cloath, it would not as else it was wont to do, presently acquire a luminousness, but needed to be rubb'd manifestly much longer before the desired effect was found. [40] xv. _we likewise plung'd it as soon as we had excited it, under liquors of several sorts, as spirit of wine, oyl both chymical and express'd, an acid spirit, and as i remember an alcalizate solution, and found not any of those various liquors to destroy its shining property._ sixteenthly, i also try'd several times, that by covering it with my warm spittle (having no warm water at hand) it did not lose his light.[41] [41] xvi. _having found by this observation, that a warm liquor would not extinguish light in the diamond, i thought fit to try, whether by reason of its warmth it would not excite it, and divers times i found, that if it were kept therein, till the water had leisure to communicate some of its heat to it, it would often shine as soon as it was taken out, and probably we should have seen it shine more, whilst it was in the water, if some degree of opacity which heated water is wont to acquire, upon the score of the numerous little bubbles generated in it, had not kept us from discerning the lustre of the stone._ seventeenthly, finding that by rubbing the stone with the flat side downwards, i did by reason of the opacity of the ring; and the sudden decay of light upon the ceasing of the attrition, probably lose the sight of the stones greatest vividness; and supposing that the commotion made in one part of the stone will be easily propagated all over, i sometimes held the piece of cloath upon which i rubb'd it, so, that one side of the stone was exposed to my eye, whilst i was rubbing the other, whereby it appear'd more vivid than formerly, and to make luminous tracts by its motions too and fro. and sometimes holding the stone upwards, i rubb'd its broad side with a fine smooth piece of transparent horn, by which means the light through that diaphanous substance, did whilst i was actually rubbing the stone, appear so brisk that sometimes and in some places it seem'd to have little sparks of fire. eighteenthly, i took also a piece of flat blew glass, and having rubb'd the diamond well upon a cloath, and nimbly clapt the glass upon it, to try whether in case the light could peirce it, it would by appearing green, or of some other colour than blew, assist me to guess whether it self were sincere or no. but finding the glass impervious to so faint a light, i then thought it fit to try whether that hard bodies would not by attrition increase the diamonds light so as to become penetrable thereby, and accordingly when i rubb'd the glass briskly upon the stone, i found the light to be conspicuous enough, and somewhat dy'd in its passage, but found it not easie to give a name to the colour it exhibited. lastly, to comply with the suspition i had upon the whole matter, that the chief manifest change wrought in the stone, was by compression of its parts, rather than incalescence, i took a piece of white tile well glaz'd, and if i press'd the stone hard against it, it seem'd though i did not rub it to and fro, to shine at the sides: and however it did both very manifestly and vigorously shine, if whilst i so press'd it, i mov'd it any way upon the surface of the tile, though i did not make it draw a line of above a quarter of an inch long, or thereabouts. and though i made it not move to and fro, but only from one end of the short line to the other, without any return or lateral motion. nay, after it had been often rubb'd, and suffer'd to lose its light again, not only it seem'd more easie to be excited than at the beginning of the night; but if i did press hard upon it with my finger, at the very instant that i drew it briskly off, it would disclose a very vivid but exceeding short liv'd splendour, not to call it a little coruscation.[42] so that a _cartesian_ would scarce scruple to think he had found in this stone no slight confirmation of his ingenious masters _hypothesis_, touching the generation of light in sublunary bodies, not sensibly hot. [42] _i after bethought my self of imploying a way, which produc'd the desir'd effect both sooner and better. for holding betwixt my fingers a steel bodkin, near the lower part of it, i press'd the point hard against the surface of the diamond, and much more if i struck the point against it, the coruscation would be extremely suddain, and very vivid, though very vanishing too, and this way which commonly much surpris'd and pleas'd the spectators, seem'd far more proper than the other, to show that pressure alone, if forcible enough, though it were so suddain, and short, that it could not well be suppos'd to give the stone any thing near a sensible degree of warmth, as may be suspected of rubbing, yet 'tis sufficient to generate a very vivid light._ * * * * * a postscript. annexed some hours after the observations were written. _so many particulars taken notice of in one night, may make this stone appear a kind of prodigie, and the rather, because having try'd as i formerly noted, not only a fine artificial crystal, and some also that is natural, but a ruby and two diamonds, i did not find that any of these disclos'd the like glimmering of light;[43] yet after all, perceiving by the hardness, and the testimony of a skilfull goldsmith, that this was rather a natural than artificial stone; for fear lest there might be some difference in the way of setting, or in the shape of the diamonds i made use of, neither of which was like this, a flat table-stone, i thought fit to make a farther trial of my own diamonds, by such a brisk and assiduous affriction as might make amends for the disadvantages above-mention'd, in case they were the cause of the unsuccessfulness of the former attempts: and accordingly i found, that by this way i could easily bring a diamond i wore on my finger to disclose a light, that was sensible enough, and continued so though i cover'd it with spittle, and us'd some other trials about it. and this will much lessen the wonder of all the formerly mention'd observations, by shewing that the properties that are so strange are not peculiar to one diamond, but may be found in others also, and perhaps in divers other hard and_ diaphanous _stones. yet i hope that what this discovery takes away from the wonder of these observations, it will add to the instructiveness of them, by affording pregnants hints, towards the investigation of the nature of light._ [43] we afterwards, try'd precious stones, as diamonds, rubies, saphires, and emeralls, &c. but found not any of them to shine except some diamonds, and of these we were not upon so little practice, able to fore-tell before hand, which would be brought to shine, and which would not; for several very good diamonds, either would not shine at all, or much less than others that were farr inferiour to them. and yet those ingenious men are mistaken, that think a diamond must be foul and cloudy, as mr. _claytons_ was, to be fit for shining; for as we could bring some such to afford a glimmering light, so with some clear and excellent diamonds, we could do the like. but none of those many that we try'd of all kinds, were equal to the diamond on which the observations were made, not only considering the degree of light it afforded, but the easiness wherewith it was excited, and the comparatively great duration of its shining. finis. * * * * * transcriber's notes. the errata of the printed book have all been corrected. they were as follows: pag. 142. l. 20. these words, and to manifest, with the rest of what is by a mistake further printed in this fourth experiment, belongeth, and is to be referred to the end of the second eperiment, p.137. pag. 145. l. 1. leg. matter. 146. l. 4. leg. bolts-head. pag 161. in the marginal note l. 2. dele de ib. l. 3. lege lib 1. p 163. l. ult. insert where between the words places and the. p. 164 l. 1. dele that. ibid, l. 8. leg epidermis. ibid. l. 19 leg. 300. for 200. p. 169. l. 22. leg. into it. p. 170. l. 23. & 24. leg. some solutions hereafter to be mentioned, for the solutions of potashes, and other lixiviate salts. p. 171. l. 6. insert part of between the words most and dissolved p. 176. l. ult. insert the participle it between the words judged and not p. 234. l. 4. leg. woud-wax or wood-wax. p. 320 l. 29. leg. urine for urne. in addition i have corrected the following original typos: the preface: i devis'd tbem -> i devis'd them the preface: make expements -> make experiments the publisher to the reader: made of eperiments -> made of experiments i. ch. iii.6 divers expements -> divers experiments i. ch. iii.13 epecially with some sorts -> especially with some sorts ii. ch. ii.8 slightet texture -> slightest texture ii. exp. i two colonrs -> two colours ii. exp. xiii were the change of colour -> where the change iii. exp. xii avoiding of ambignity -> avoiding of ambiguity iii. exp. xxix juice of this sipce -> juice of this spice iii. exp. xl forty second expement -> forty second experiment iii. exp. xliv keep them swimning -> keep them swimming iii. exp. xlvi it seem'd propable to me -> it seem'd probable to me iii. exp. xlvii where not comprehended -> were not comprehended iii. exp. xlviii frequent igintion -> frequent ignition iii. exp. l i could tell yon -> i could tell you a copy of the letter: nemo unqnam vere -> nemo nunquam vere (ib.): what is reladed -> what is related observations: carefulsy drawn -> carefully drawn and emended phoenomenon/a to phaenomenon/a 10 times and coeruleous etc. -> caeruleous 20 times 