The Mixed Blessings of Pragmatism. Jean-Baptiste Dumas 

and the (Al)chemical Quest for Metallic Transmutation 
 

 

by Leonardo Anatrini 

Dipartimento di Lettere e Filosofia (DILEF) - Università degli Studi di Firenze 

Via della Pergola, 60 - 50121 Firenze – leo.anatrini@gmail.com 

Via Alessandro Lazzerini, 21/1 - 59100 Prato – (+39) 339 7972288 

ORCID: 0000-0001-9001-3240 

 

 

Received: Jun 01, 2023 Revised: Jun 26, 2023 Just Accepted Online: Jul 03, 2023 Published: Xxx 

 

This article has been accepted for publication and undergone full peer review but has not been through 

the copyediting, typesetting, pagination and proofreading process, which may lead to differences 

between this version and the Version of Record. 

 

Please cite this article as: 

L. Anatrini (2023) The Mixed Blessings of Pragmatism. Jean-Baptiste Dumas and the (Al)chemical 

Quest for Metallic Transmutation. Substantia. Just Accepted. DOI: 10.36253/Substantia-2169 

 

Abstract - There were at least three prerequisites for the transmutability of metals to become once 

again a scientifically acceptable subject of research from the 1810s: new hypotheses concerning the 

mutual reducibility of certain elements, such as those of integer multiples and protyle put forward by 

the British chemist and physician William Prout; the experimental confirmation that chemical 

compounds with the same percentage composition could be substances with very different properties, 

i.e. the discovery of isomerism and allotropy; the comparison between metals and compound radicals 

of organic chemistry. This paper aims at illustrating how these premises were exploited by Jean-

Baptiste Dumas, one of the leading French chemists of the 19th century, to reintroduce in the chemical 

discourse the alchemical topic of transmutation. 

 

Keywords – Transmutation, Jean-Baptiste Dumas, Ammonium, Jöns Jacob Berzelius, Cyprien-

Théodore Tiffereau 

 

Introduction 

 The experimentation conducted towards the end of the 18th century, which helped to 

describe the regularity and reproducibility that characterised a wide range of chemical compositions 

and led, for example, to the enunciation of the law of definite proportions by Joseph-Louis Proust 

(1754 - 1826), were propaedeutic to the spread of a new idea of atomism. After all, with a simple 

logical step, it was possible to deduce, from the regularities observed in chemical reactions, a 

mailto:leo.anatrini@gmail.com


 

 

necessary regularity in the composition of matter of a corpuscular nature. The atom originally 

theorised in Democritus’ time (c. 460 - c. 370 BC), however, was the minimal entity of a uniform and 

continuous matter understood ontologically and not instrumentally, whose essentially identical parts 

differed only in size, form and motion. In such a system, chemical change was generated by 

alterations - occurring in a vacuum - in the ordering of atoms into molecular structures. Nevertheless, 

everything since the results produced by the chemical reform of Georg Ernst Stahl (1659 - 1734), 

suggested the existence of a whole range of elements characterised by exclusive qualities. 

 Stemming from the desire and need to quantify the ultimate units of matter for calculative 

purposes, aiming at a consequent mathematisation of chemistry, the atomic theory of John Dalton 

(1766 - 1844) was born. With it, the English scientist united quantitative speculations inspired by 

Democritus with a qualitatively categorised matter, overcoming the very limits beyond which Antoine 

Lavoisier (1743 - 1794) had relegated a purely philosophical investigation of Empedoclean descent. 

In an effort of hopeful pragmatism, Dalton’s atom was no longer the omnipresent manifestation of 

matter, becoming instead the physical unit of measurement of Lavoisier’s substances simples1. 

Although the acceptance of the physical reality of the Daltonian atom in the first half of the 

19th century was certainly not extraordinarily widespread in France, the theorisations of the English 

scientist had emphasised the importance of the quantification guaranteed by the system of atomic 

weights in the elaboration of the categorisations and classifications necessary to establish the 

foundations of a science of chemical relationships, a prodrome to structural chemistry. And it was 

precisely in this field that in 1826 one of the fathers of organic chemistry, Jean-Baptiste Dumas (1800 

- 1884), brought his research to the attention of the international scientific community2. By 

experimentally applying the hypothesis of Amedeo Avogadro (1776 – 1856)3 - which he knew and 

studied through André-Marie Ampère (1775 - 1836)4 -, he proposed new methods for determining 

the molecular weight of gases, obtained through volume density, succeeding in optimising and even 

correcting the data of Jöns Jacob Berzelius (1779 - 1848), who, with his calculation of the atomic 

weights of 45 different elements and the centesimal composition of some 2000 chemical compounds, 

is remembered as the greatest experimenter of the early 19th century5. In 1818, he was able to theorise 

a first set of atomic weights based on entirely experimental data6, disproving the possibility of a total 

generalisation of the hypothesis developed in 1815 by the physician and chemist William Prout (1785 

- 1850) aimed at illustrating the atomic weights of the elements as integer multiples of that of 

hydrogen7. Then, from 1826 onwards, Berzelius refounded his investigation - and in this context, the 

desire for revenge provoked by Dumas’ essay must have played no small part - through the 

instrumental adoption of two innovations of particular importance for chemical research. 



 

 

In 1819, chemist Pierre Louis Dulong (1785 - 1838) and physicist Alexis Thérèse Petit (1791 

- 1820), succeeded in calculating the specific heat of 13 different elements (11 metals, tellurium and 

sulphur) and discovered their similar heat capacity (between 0.3675 and 0.3830, for O = 1 and H2O 

having c = 1), i.e. the constant describing the product between the relative atomic weight of an 

element and its specific heat8. In the same year, the German Eilhard Mitscherlich (1794 - 1863), in 

the course of lengthy crystallographic experiments, put forward a hypothesis concerning the 

possibility that substances with similar chemical properties and crystalline form, called isomorphic 

by Berzelius himself, might have similar formulae9. 

 

Believing is seeing: the convictions of a scientist 

Dumas desired to succeed in obtaining stable and experimentally consistent principles, and 

the opportunity that Avogadro’s hypothesis offered was unrepeatable. However, from the time of his 

first major publication - as is also evident from his 1832 doctoral thesis - the young chemist had been 

grappling with a problem difficult to surmount, found in the measurement of the molecular volumes 

of the phosphorus contained in his trichloride (PCl3) and the sulphur contained in hydrogen sulphide 

(H2S)10. 

In the particular case of phosphorus and chlorine, by reacting one volume of the former with 

three volumes of the latter, Dumas could not explain how it was possible that, if Avogadro and 

Ampère had been right, not one but two volumes of phosphorus trichloride would be generated11. The 

cause of the problem lay in the widespread terminological confusion linked to the atomistic lexicon, 

which Dumas had declined from Ampère’s, even going so far as to hypothesise the divisibility of the 

elementary molecules, although he did not realise the tetratomicity of liquid phosphorus and the 

diatomicity of chlorine in the gaseous state (and, more generally, not imagining that elements placed 

in reaction could give rise to variations in atomicity), finally resorting to expressions that were 

variously criticised, when not entirely oxymoronic, such as that of ‘half-atom’12. Moreover, the values 

he calculated were based on Berzelius’ 1818 atomic weights, which for phosphorus and chlorine were 

twice as high as they should have been. Thus, he would have expected a synthesis reaction of the type 

P + 3Cl → PCl3, whereas what he obtained was P4 + 6Cl2 → 4PCl313. 

From 1828 onwards, Dumas endeavoured to adopt the Avogadrian criterion of the distinction 

between the physical particle and the chemical particle, constantly emphasising the material reality 

of the former and the purely instrumental dimension of the latter, with a methodology partly borrowed 

from the thought of William Hyde Wollaston (1766 - 1828)14. This latter, in fact, decided to address 

the shortcomings caused by an ontologically understood atomism from a decidedly more pragmatic 

point of view, emphasising the priority of practical effects and purposes of chemical research. In a 



 

 

celebrated 1814 essay entitled A Synoptic Scale of Chemical Equivalents, he introduced a stable 

categorisation to define the minimum quantities required for elements to enter combinations forming 

compounds15. 

Dumas, however, was not satisfied with a utilitarian implementation of Wollaston’s 

equivalents16. In fact, by the time his colleague Marc Antoine Gaudin (1804 - 1880), with his 

Recherche sur la structure intime des corps inorganiques (1833), had brought to the attention of the 

scientific community the importance of a stable nomenclature that provided a clear distinction 

between concepts such as ‘molecule’ and ‘atom’, especially in virtue of the increasingly encouraging 

results provided by research into atomic weights (regarding which Gaudin was the first to hypothesise 

the polyatomicity of certain elements), Dumas had become definitively convinced that the results of 

his experiments offered a clear refutation of Avogadro’s hypothesis17. 

As has been persuasively illustrated by some scholars, at the basis of Dumas’ rejection was 

surely the perception that atomism was little more than a faith and that, in the end, no experimentation 

would be able to account for the existence of ultimate physical entities18. Therefore, faced with the 

results of his experiments, rather than questioning the ontological value of what he probably 

considered to be non-essential abstractions, he chose, while recognising the instrumental usefulness 

of the system developed by Dalton, not to engage in theoretical elaborations concerning the physical 

dimension of ultimate entities. Conversely, he showed an increasing interest in another hypothesis, 

based on experimental data which, although variously manipulated and aiming at an even more 

general theorisation, were plausibly preferred as they could be used to investigate the relationships 

between the various elements without necessarily delving into lucubrations on the nature of matter. 

The hypothesis in question is that of the integer multiples of hydrogen elaborated by Prout, which 

Dumas no doubt became acquainted with thanks to the French edition of An Attempt to Establish the 

First Principles of Chemistry by Experiment (1825), by Dalton’s pupil and first biographer, Thomas 

Thomson (1773 - 1852)19. Added to this, there were two other factors which plausibly, at a time 

before proper research on valence and stereochemistry, led Dumas to increasingly doubt the value of 

atomic theory. 

In 1828, the German chemist Friedrich Wöhler (1800 - 1882) documented the first case of 

isomerism, unintentionally demonstrating the convertibility between organic and inorganic 

compounds. Trying to obtain ammonium cyanate (CH4N2O - an inorganic salt), he succeeded instead 

in synthesising urea (CO(NH2)2 - an organic compound contained in the urine of almost all tetrapod 

organisms) by reacting purely inorganic substances such as silver cyanide (AgCN) and ammonium 

chloride (NH4Cl). This experience led to the formulation of the principle of isomerism, whereby 

substances with very different physical properties and chemical behaviour can have the same 



 

 

molecular mass and percentage composition20. Something similar was observed for elementary 

substances (at the time mainly in carbon and sulphur), thanks to the polymorphic nature of certain 

corps simples, describing phenomena to which Berzelius would give the name allotropy in 184121. 

Convinced of the absolute precedence of experimental data in the elaboration of hypotheses 

otherwise judged arbitrary and aprioristic, Dumas, perhaps due to a lack of imagination and an excess 

of faith in the mathematisation of scientific research, abandoned the prophetic intuitions of Avogadro 

and Ampère in favour of data useful to quantify an illusion. 

At this point, it would be as easy as it would be wrong to make Dumas a follower also of 

Prout’s other famous hypothesis, enunciated for the first time one year after the hypothesis of integer 

multiples of hydrogen, as distinct from (though superimposable to) it, defining the hypothetical unity 

of matter as originating from a mysterious primordial element called protyle22. As already mentioned, 

the former became acquainted with the latter’s work through the mediation of Thomson, who was as 

enchanted by the hypothesis of integer multiples as he was certainly annoyed - especially in virtue of 

the degree of probability he attributed to the Daltonian theory - by the possibility of discussing the 

unity of matter once again. 

Dumas had shrewdly foreseen how the explanation of isomerism and the various phenomena 

of polymorphism, such as allotropy, passed through the investigation not only of the percentage 

composition of bodies but also of the structural arrangement of their constituents. However, in the 

absence of stable terminology and a clear distinction between atom and molecule, the constraint 

indicating the element as the limit of qualitative decomposability was lost. Thus, faced with the 

apparent superimposability and proportionality between the atomic weights of inorganic elements, it 

must have seemed natural to Dumas to ask himself whether it was not indeed possible to convert one 

species into another, to transmute matter. As if this were not enough, there was a whole tradition of 

studies revolving around the concept of transmutation of metals, which, within the elite of French 

scientific research came back to make its authority felt, as witnessed by one of Dumas’ most famous 

works, the Leçons sur la philosophie chimique, published in 1837. Particularly interesting, and useful 

in clarifying how Dumas’ alchemical knowledge came from a thoughtful as well as partial study of 

primary sources, is the attempted description in chemical terms of a supposed procedure for making 

the philosopher’s stone, extracted from a work by the 15th-century English alchemist George Ripley 

(c. 1415 - 1490). Dumas adopted a hermeneutic oblivious of the philosophical and symbolic values 

of his chosen writing, interpreting it in the light of his own chemical knowledge and using the visual 

and thermal variations described as his only compass, decoding the various entities as the signifiers 

of an allegory and coming to the conclusion that Ripley’s philosopher’s stone was nothing more than 

acetone (C3H6O), obtained by repeated distillations of lead diacetate - Pb(CH3COO)223. 



 

 

It is curious to note, in such an attitude, the adoption of a mirror-image approach to written 

testimony by the scientists and those who were to become, in the second half of the century, the new 

alchemists. For if the latter could be accused of anti-scientific behaviour in their constant substitution 

of the experimental method for textual authority, to which they generally attributed far greater value, 

the former resorted to anti-historical methods, carefully selecting the only data useful for the 

elaboration of a tradition no less unreal than that on which the hermeticists based their hermeneutics. 

Considering the inescapable precedence that Dumas attached to experimental data, it is 

difficult to imagine that he could have devoted himself to such a felt study of alchemical texts before 

his calculations of atomic weights aroused probabilistic doubts in him. The fact remains that the 

motivations that led him to establish the possibility of some link between the superposition and 

proportionality of the atomic weights of many metals and the concept of transmutation stemmed from 

his inability to interpret the data of his experiments while preserving Avogadro’s hypothesis. To seek 

an answer in the millenary tradition that glorified a process that could perhaps resolve his doubts, 

represented the crystallisation of a human limit, which concealed an insatiable desire for knowledge 

and not necessarily adherence to any form of esoteric thought. And Dumas certainly believed he could 

overcome the incompatibility between chemistry and alchemy by quantifying the study of the latter, 

so as to extract data useful for his research. However, this was a dangerous process, especially from 

a value-based point of view. Alchemy had been brought into play in order to reach a truth that 

chemistry, although hypothetically, was not even managing to describe comprehensively. The 

implicit risk was that of attributing a similar if not overlapping gnoseological value to the two 

disciplines, placing alchemy, which had already long since arrived at the concept of transmutation, in 

a privileged position, thus establishing an epistemologically null but logically consistent and easily 

misunderstandable parallel between textual authority and scientific authoritativeness that were no 

longer clearly distinct. Not to mention that every alchemical theory rested on concepts of unity of 

matter that, in the face of possible scientific confirmation of transmutation, would have offered an 

opportunity for generalisation that would have been difficult to avoid. 

In spite of his ideals, Dumas chose to believe in order to see. Nonetheless, he probably never 

fully realised how contingent the value of the data from his experimental research was on his personal 

interpretation of them. Furthermore, as mentioned, there was a third factor that led him to question 

the plausibility of the elemental nature of many of the simple substances in mineral chemistry, namely 

the possibility to put in relation metals and compound radicals of organic chemistry. This factor arose 

from the field of investigation in which he recorded some of his greatest successes, that of chemical 

substitutions. 



 

 

By 1833, Dumas and his students had embarked on an intensive experimental campaign 

concerning the chlorination processes of organic compounds and by the following year, he had 

collected sufficient data concerning the action of chlorine on turpentine essence and ethanol 

(C2H5OH) to affirm the ability of the said element to replace hydrogen ‘atom by atom’ in these 

compounds, which nevertheless had almost identical chemical properties24. In doing so, he reinforced 

his belief that these properties depended more on the arrangement than on the nature of the particles. 

In the eighth of the Leçons, Dumas’ observations on the hypothetical transmutability of 

elements were based on three different principles: isomerism, allotropy and supposed direct 

proportionality observable according to the atomic weight of different elements (16 metals, tellurium 

and sulphur)25. These formulations and observations could describe the change of species produced 

by a transmutation but were not proof of the composite nature of metals. Hence the circumspection 

in the choice of words with which Dumas described the possibility and not the probability of a feat 

of alchemical memory. There was, however, at least one sensata esperienza that could have been 

used as evidence. Nevertheless, such evidence was carefully omitted in the Leçons (only a veiled 

allusion is made)26 by virtue of the interpretability of the phenomenon on which this datum was based 

and the fact that, as the only useful experimental evidence, it certainly did not meet the criteria of 

exhaustiveness and rigour on which a theory should be based. 

In 1808, Berzelius, together with his friend and future court physician Magnus Martin de 

Pontin (1781 - 1858), replicated the experiments that the previous year had led Humphry Davy (1778 

- 1829) to the discovery of sodium and potassium, obtained from their hydroxides27. The two Swedes 

extended Davy’s research to another substance that resembled the so-called caustic alkalis in chemical 

properties, i.e. ammonia (NH3). By subjecting a negatively electrified quantity of mercury to 

electrolysis and placing it in contact with an aqueous ammonia solution, they produced a substance 

that had the appearance of an amalgam28. In this regard, the sentence at the end of the first part of 

Berzelius and de Pontin’s account of their experiments is particularly interesting, in which the two 

scientists, apologising for the ‘almost alchemical’ tone of their lucubrations, observe how the 

phenomenon they investigated could have led to the ‘decomposition of metals’ and the discovery of 

the processes necessary to perform chrysopoeia, as already suspected by ‘many chemists’: 

 

«And even if these discoveries do not bring us any closer to the goal [i.e. the 

transmutation of metals] so unsuccessfully pursued for so many centuries, they do 

at least give us a clearer idea of the decomposability of metals, making the 

possibility somewhat intelligible. We may be forgiven this almost alchemical 

argument; however, many chemists had already predicted [...] that one day we 

would discover the composition of gold and devise the means to assemble its 

components»29. 

 



 

 

So, how to explain such a phenomenon, considering that the composite nature of ammonia 

was well known? 

When confronted with the work of his colleagues, Davy was enthusiastic and inclined to 

devise a classification of metals - described as hydrogenated compounds - at the basis of which, given 

its instability and discernible composite nature, was the hypothetical metallic element that together 

with mercury formed the amalgam, called ammonium: 

 

«The more the properties of the amalgam obtained from ammonia are 

considered, the more extraordinary do they appear. 

Mercury by combination with about 1/12000 part of its weight of new 

matter, is rendered a solid, yet has its specific gravity diminished from 13.5 to less 

than 3, and it retains all its metallic characters; its colour, lustre, opacity, and 

conducting powers remaining unimpaired. 

It is scarcely possible to conceive that a substance which forms with 

mercury so perfect an amalgam, should not be metallic in its own nature; and on 

this idea to assist the discussion concerning it, it may be conveniently termed 

ammonium» 30. 

 

The Stahlian dream of a metallising phlogistic principle seemed within reach once again, 

especially in light of the fact that ammonia was composed of non-metallic elements 31. From the study 

of the amalgam, the formula for ammonium was logically deduced, parallel to that of today’s 

ammonium ion (although it should be specified that the amalgam is formed after the alkaline or 

electrolytic reduction of the cation NH4+ into the ammonium radical NH4
.
). 

Thus Berzelius, in the first edition of the second volume of his Lärbok i kemien (1812), did 

not hesitate to include ammonium in the list of elements that could be obtained from earths and alkalis, 

being all metals32. Moreover, it is in this book that can be found the first clear conceptual overlap 

between the radicals of organic chemistry and metals, observable in the title of the relevant chapter: 

«Alkaliernas och jordarternas metalliska radicaler» (Metallic radicals of alkalis and earths)33. 

The problem also interested some of the leading French scientists of the time. First Claude-

Louis Berthollet (1748 - 1822), then Ampère34 examined the potential of Berzelius and de Pontin’s 

discovery. Anyway, the scientific community, faced with the impossibility of finding a solution, and 

building on the results of an increasing number of studies based on better-established concepts of 

element, atom and molecule, although remembering the ammonium amalgam phenomenon, ended up 

shelving it almost completely until the mid-20th century35. One of the few scientists who continued to 

take an interest in ammonium was exactly Dumas, who on three separate occasions while writing his 

Traité de chimie - one of the most important manuals dedicated to technical-industrial applications 

of chemical research of the period, the editing of which kept him busy for eighteen years, between 

1828 and 1846 - dealt with Berzelius and de Pontin’s discovery and what it might entail36. Seeking 



 

 

to establish a classification of metals on the basis of their respective chemical properties, after 

observing and describing the isomorphism of potassium, sodium, lithium, barium, strontium and 

calcium, he put forward a conjecture about the composite nature of metals (the highly speculative 

nature of which he himself affirmed), observing how, from the known data, it might be plausible to 

conclude that «ammonia is transformed into a metal when, to the three volumes of hydrogen it 

contains, a fourth is added»37. 

In the fifth volume (1835), on the other hand, building on the discoveries that led him to the 

substitution theory, attempting an initial classification of nitrogen and hydrogen compounds, Dumas 

identifies ammonium as a ‘metal-like body’, with a related discussion concerning the advantage that 

the identification of its oxide would represent. Firstly because, just as ammonium in the amalgam 

experiment was shown to be able to replace potassium, the hypothetical oxide would have confirmed 

the superposition of its chemical properties with those of sodium and potassium hydroxides. Second, 

because an entity such as ammonium oxide would have led to the assumption of «the existence of a 

large number of unknown combinations, which would replace all known hydrogenated compounds 

in the products they form by uniting with acids»38. This statement is only apparently obscure since 

after a few lines it becomes clear what Dumas is aiming at, namely extending his theory of ethers to 

inorganic chemistry. 

Between 1827 and 1828, together with his colleague and pharmacist Félix-Polydore Boullay 

(1806 - 1835), Dumas had arrived at the enunciation of the formula for the synthesis of ethers - CnH(2n 

+ 2)O -, compounds formed, in the authors’ words, from ‘an acid combined with two volumes of 

ethylene - C2H4, called oleophilic gas - and one volume of water vapour’; a description elaborated by 

generalising to an entire class of compounds the values describing the components of diethyl ether, 

at the time known as sulphuric ether (C4H10O)39. But this generalisation, since supported by serious 

experimentation, had proved to be accurate, producing, as Charles Adolphe Wurtz (1817 - 1884) 

defined it forty years later in his history of chemistry, the first occasion on which: 

 

«in organic chemistry a series of similar phenomena was grouped together by 

theory and [...] the facts relating to the formation, composition and metamorphoses 

of an entire class of bodies were given a simple interpretation, using atomic 

formulae and equations»40. 

 

In their account, Dumas and Boullay offer a term of comparison which, interpreted in the light 

of the mystery of ammonium, serves to clarify the curious digressions in the fifth volume of the Traité. 

The two had in fact described in an analogical key the function of ethylene in the formation of ethers 

with that of ammonia in the formation of ammonia salts, by virtue of the latter’s ability to decompose 

diethyl ether41. 



 

 

The choice of comparative term stemmed from the observation of the properties of ammonia, 

which described capacities for the analysis of organic compounds and the synthesis of saline 

compounds in the presence of acids that overlapped and even exceeded those attributed to metal 

hydroxides used for the same purposes. 

Years passed, and by the time Dumas wrote the next passage of the Traité, the constant 

comparison between ammonium, alkalis and earths had matured in him a definite conviction. Faced 

with the impossibility of isolating the fabled metal, obtaining its oxide would have provided solid 

proof not of the existence of a metallic phase of the radical NH4
.
 (a concept unknown to the chemistry 

of the time), but of the composite nature of metals, since the properties of the new element would 

have fallen squarely within the casuistry described by the alkaline and alkaline-earth metals (as we 

have already seen with Berzelius): 

«Nevertheless, this is the place to bring out a theory already proposed by 

Ampère, on the occasion of the singular combinations that have been described 

under the names of ammoniacal hydrides of mercury or potassium and mercury. 

According to Ampère, these compounds, which have so often been compared to 

alloys, contain a kind of metal made up of 2 parts nitrogen to 8 parts hydrogen42. 

There is nothing to prevent us from classifying such a compound alongside the 

metals when we already classify cyanogen alongside chlorine and other similar non-

metallic bodies. 

If we assume this base, we would have the following series: 

 

Az2 H4 a chlorine-like substance found in amines. 

Az2 H6 ammonia. 

Az2 H8 a metal-like substance. Ammonium. 

Az2 H8 O ammonium protoxide. 

Az2 H8, Ch2 ammonia hydrochlorate or rather ammonium chloride. 

Az2 H8 O, S O3 ammonia sulphate or rather ammonium protoxide sulphate, 

 

and so on for the different ammonia salts known. With regard to the combination 

formed between anhydrous sulphuric acid, for example, and ammonia, it would 

necessarily be considered an amine. 

Here are the main advantages of this theory, as far as I can appreciate them. 

It explains the formation of the remarkable amalgams that first gave us the 

idea. 

It eliminates hydrochlorates, hydriodates and other similar ammonia salts, 

whose existence embarrasses the theory of chlorides, iodides, etc. 

It gives perfect simplicity to the formulae of double chlorides, double iodides 

and other similar compounds containing ammoniacal combinations, whereas in the 

other theory, these formulae are complicated and of an unusual form. 

It gives a good idea of the basic role of ammonia since it is no longer ammonia 

that plays the role of base, but an oxide produced by the union of ammonia and 

water. This oxide is therefore completely comparable to potash or soda. 

This better explains the isomorphism of ammoniacal salts with similar 

combinations of potassium or sodium; since, for example, ammonium replaces 

potassium everywhere, and ammonium oxide replaces potash. 

Now here are its disadvantages: 



 

 

It is based on the existence of a combination Az2 H8, which has not been 

isolated. 

And on the existence of an ammonium oxide, Az2 H8 O, which is completely 

unknown to us, although ammonia and water can produce it by combining and these 

two bodies have been brought together in circumstances most favourable to 

combination. 

It leads us to suppose the existence of a large number of unknown 

combinations, which would replace all the known hydrogenated compounds, in the 

products that these form by uniting with acids. 

It therefore forces us to admit a large number of hypothetical hydrogen 

carbides, playing the role of metals, which is possible, but difficult to admit without 

proof. 

Thus, as has already been pointed out, the theory of ethers and that of 

ammoniacal combinations are so closely linked that they will probably be decided 

by each other. Those who attribute the role of a base to the sulphuric ether will 

admit ammonium oxide; those who regard ammonia as a base must attribute the 

same role to carbonated hydrogen and its analogues. By showing that both theories 

are admissible, we have given a fair idea of the state of the question; by preferring 

the latter point of view, we have followed the general opinion. 

Chemists who have turned their attention to the philosophy of science have 

all been struck by the difficulties that the history of ammonia has given rise to, and 

have long sought to discover some metallic radical in it, in order to bring this body 

back into the great family of oxides. After the useless attempts made by Davy and 

Berzelius twenty years ago, they returned to the original idea of considering 

ammonia as a base in itself. This discussion, almost forgotten, has been rejuvenated 

by its connection with the ether theory. 

It is impossible to ignore what is broad and great in the point of view that 

would bring all these so diverse combinations back to the known laws that regulate 

those of metal oxides […]. 

On the other hand, however, it is not an uncommon fact that ammonia is 

considered to be an alkaline base. It is a consequence of a principle that is no less 

extensive than the previous one, nor less worthy of attention. Is it not natural to 

admit, in fact, that hydrogen, by uniting with simple bodies, can sometimes 

constitute acids, sometimes bases, depending on whether its properties predominate 

or succumb in the presence of the antagonistic element? 

If the ammonium theory had been generally accepted, sulphuric ether and its 

analogues would have been given the role of base. Of all the known phenomena, 

only those relating to the theory of substitutions can be explained by a single 

hypothesis, the one accepted in this book […]. 

Leaving aside these hypotheses, we shall confine ourselves here to the pure 

and simple expression of facts […]. We will therefore consider ammonia as a base 

in itself»43. 

 

Before asserting the plausibility of a hypothesis, Dumas considered it necessary to produce 

empirical proof. Otherwise, claiming its veracity on a logical-consequential basis would have led 

beyond the limits of a scientifically provable analogical correspondence, trespassing into the domain 

of personal convictions to which one could arbitrarily attribute the function of principles. So much so 

that the problem of ammonium in the Leçons, a work with historical ambitions but with a strongly 



 

 

programmatic slant, is only hinted at transversally through recourse to the authority of certain 

‘illustrious chemists’, Berzelius in the lead (and the only one to be cited by name), who had «put 

forward conjectures such as to make the composite nature of nitrogen conceivable»44. Hence Dumas’ 

progressive (and definitive) rejection of physical atomism, which he increasingly saw as a set of 

aleatory speculations about an invisible world, in favour of research with far greater classificatory 

potential, one that was devoted to the radicals of organic chemistry. On the strength of his successes 

in the elaboration of the substitution theory, in the same year of publication of the Leçons, he drafted, 

together with another great organic chemist of the time and long-time rival, Justus von Liebig (1803 

- 1873), a programmatic article, almost a manifesto, with which the quest to finally bring order to the 

tumultuous sea of organic compounds was inaugurated, entitled Note sur l’état actuel de la chimie 

organique45. 

The historiography of chemistry has always emphasised how Dumas, at least from the early 

1830s onwards, set atomism aside in favour of recourse to immediately measurable quantities such 

as equivalents; and that is true. However, the instrumental value of atomism was never denied by 

him, and in order to lend solid mathematical representability to his research, in the aftermath of the 

Leçons the scientist prepared an experimental investigation aimed once again at calculating the atomic 

weights of the principal agents of organic chemistry (carbon, hydrogen, oxygen and nitrogen). The 

results of this investigation, together with the theory of substitution and that of types, earned him the 

Copley Medal of the Royal Society in 1843. In the very definition of chemical type offered by Dumas, 

in fact, the recourse to atomistic concepts remained central, while to have been partially excluded 

was the concept of element, instrumentally necessary but functionally replaced by that of type46. 

As is well known, the idyll between Dumas and Liebig was very short-lived due to 

disagreements at a theoretical level47. Ironically, it was Liebig’s theory of compound radicals48 that 

provided the rationale for hypothesising the analogy that Dumas, in the absence of ammonium oxide, 

had refused to enunciate openly out of methodological rigour. One of the fathers of structural 

chemistry, Alexandre-Édouard Baudrimont (1806 - 1880), who in turn adopted at least in part Prout’s 

integer multiples hypothesis, was the one who performed the feat. Epitomising his words, in inorganic 

chemistry, oxygen, chlorine and sulphur could be combined with a metal to produce compounds in 

which the latter played the role of a radical, which, on the other hand, in organic chemistry never 

consisted of a single element. From the juxtaposition of the relevant data, Baudrimont concluded that 

metals not only could, but plausibly should, be corps composés: 

 

«Just as a chemical element can only be analysed with its own matter, so it 

can only be produced with this same matter; thus, in the present state of chemistry, 

nothing other than gold can be found in gold, and gold can only be made with gold. 



 

 

This is the limit of experience; the rest is mere conjecture or supposition. It is 

known, however, that alchemists claim to have made gold from bodies that were 

not gold, but these facts, although often presented with candour and with 

testimonies that leave little room for doubt, will only be accepted by science when 

they can be proved experimentally. 

However, despite the deliberate obscurity that reigns in the writings of the 

alchemical philosophers, we can say with certainty that they did not produce gold 

by combinations, but by imprinting on the nature of the bodies a modification of 

the kind that gives rise to isomerism, under the influence of a catalytic agent. The 

bodies on which they worked were lead and mercury; their agent was the 

projection powder: this product they produced with such slow and arduous 

labour. 

To the alchemists, we can add the theoretical ideas of Prout, who believes 

that all bodies are formed from one and the same material, the disposition of 

which alone causes the differences that we observe in bodies considered simple 

[…]. 

Liebig’s theory, at least in most if not all cases, establishes radicals that are 

entirely comparable to metals. The theory I have defended leads us to suspect that 

metals are composed, and I believe this view to be as well-founded as that of 

Lavoisier, who thought that earths and alkalis could well be metallic oxides. Let us 

hope that a new Davy will resolve this question. Hydrogen would be the link that 

binds the constituent parts of metals together. If this bond could be broken, they 

could undoubtedly take on new arrangements, and metallic transmutation would 

take place»49. 

 

In a period during which Berzelius’ electrochemical dualism was slowly being replaced by 

unitary theories also thanks to the discoveries of Michael Faraday (1791 - 1867) but immediately 

preceding the first studies on valence and the dawn of stereochemistry - yet still far from the 

refinement of nomenclature and atomistic conceptualisation brought about by Stanislao Cannizzaro 

(1826 - 1910) in the late 1850s -, the plausibility of hypotheses such as the transmutation of metals 

was hardly questionable. 

 

Seeing is believing: the dreams of an inventor 

 During one of the sessions devoted to chemistry at the 21st annual conference of the British 

Association for the Advancement of Science, held in Ipswich in July 1851, Michael Faraday returned 

to emphasise how many scholars (including himself) expected future developments that would restore 

a simpler view of matter to physical and chemical research. This attitude implied a strong desire to 

curb that multiplicative drift characterised by an increasingly crowded pool of chemical elements, 

still interpreted by more than one scholar in the mid-century as an illogical break from an organisation 

of the physical world of (albeit now distant) Democritean and Empedoclean ancestry. Galvanised by 

Faraday’s words, Jean-Baptiste Dumas took the opportunity to present his own convictions 

concerning the plausibility of transmutation to an audience of scholars. Carefully avoiding the edge 



 

 

case of ammonium, Dumas resorted to the categorisation principles developed more than twenty years 

earlier by his German colleague Johann Wolfgang Döbereiner (1780 - 1849). This latter, after more 

than a decade of experimentation, had managed in 1829 to group fifteen elements into triads 

characterised by physical and chemical affinities, the middle term of which had an atomic weight 

equal to or close to the average of the sum of the atomic weights of the two extremes50. Such research, 

further developed after the middle of the century, sanctioned a turning point that in the following 

decade culminated, thanks to the work of Dmitrij Ivanovič Mendeleev (1834 - 1907), in a stable 

theorisation of the periodicity of the elements51, while Dumas chose instead to resort to such 

organisational criteria for the purpose of revaluation. According to a rather obvious analogical process 

(and arguably influenced also by Baudrimont’s lucubrations concerning the transmutability of 

matter), the French chemist saw in the triadic organisation of certain elements the possibility of 

deriving numerical ratios parallel to those of compound radicals. In this way, his observations became 

part of a possible confirmation of Prout’s ‘integer multiples’ hypothesis, by which the elements that 

constituted triads in inorganic chemistry were characterised by an analogical relationship with the 

components of organic chemistry’s homologous series52. Always well aware of the highly speculative 

nature of this kind of hypothesis, Dumas undertook further laboratory research before presenting them 

at the Académie des Sciences (where they ended up at the centre of a heated debate between 1858 and 

1859)53. Thus, on the occasion of the conference, he chose not to submit any paper, as indicated by 

the fact that the related Report contains no contribution of his own, nor any mention of the matter by 

Faraday. The only valuable, detailed account of the affair was published anonymously in the 12 July 

1851 issue of The Athenaeum, the leading English generalist weekly magazine devoted to art and 

literature as well as scientific news and dissemination. Taking into account the technical knowledge 

required to produce such an account, we can attribute it with a fair degree of certainty to the scientist 

and politician Lyon Playfair (1818 - 1898), at the time co-chairman of the committee of the British 

Association’s section dedicated to chemical research54, as well as correspondent of The Athenaeum55: 

 

«[…] Dr. Faraday expressed an opinion that chemists had of late years 

viewed with regret the increase in the number of metals, and hoped that the day was 

not far distant when some of the metals would afford honour to chemists by new 

modes of investigation leading to their decomposition. 

[…] Prof. Dumas gave many examples of groups of bodies, such as the 

alkalies, earths, &c., arranged in the order of their affinities. He called the attention 

in the Triad groups, to the intermediate body having most of its qualities 

intermediate with the properties of the extremes, and also that the atomic or 

combining number was also of the middle term, exactly half of the extremes added 

together; thus, sulphur 16, selenium 40, and tellurium 64. Half of the extremes give 

40, the number for the middle term. Chlorine 35, bromine 80, and iodine 125. Or 

the alkalies, lithia, soda, and potassa, or earths, lime, strontia, and baryta, afford, 



 

 

with many others, examples of this coincidence; hence the suggestion, that in a 

series of bodies, if the extremes were known by some law, intermediate bodies 

might be discovered; and in the spirit of these remarks, if bodies are to be 

transformed or decomposed into others the suggestion of suspicion is thrown upon 

the possibility of intermediate body being composed of the extremes of the series, 

and transmutable changes thus hoped for. Prof. Dumas then showed that in the 

metals similar properties are found to those of non-metallic bodies; alluding to the 

possibility that metals that were similar in their relations, and which may be 

substituted one for the other in certain compounds, might also be found 

transmutable the one into the other. He then took up the inorganic bodies where 

substitutions took place which he stated much resembled the metals. After 

discussing groups in triads, Prof. Dumas alluded to the ideas of the ancients of the 

transmutation of metals and their desire to change lead into silver and mercury into 

gold; but these metals do not appear to have the requisite similar relations to render 

these changes possible. He then passed to the changes of other bodies, such as the 

transmutation of diamonds into black lead under the voltaic arc. After elaborate 

reasoning and offering many analogies from the stores of chemical analysis, Prof. 

Dumas expressed the idea that the law of the substitution of one body for another 

in groups of compounds might lead to the transformation of one group into another 

at will; and should endeavour to devise means to divide the molecules of one body 

of one of these groups into two parts, and also of a third body, and then unite them, 

and probably the intermediate body might be the result. In this way, if bodies of 

similar properties and often associated together were transmutable one into the 

other, then by changes portions of one might often, if not always, be associated with 

the other […]. 

Dr. Faraday expressed his hope that Prof. Dumas was setting chemists in the 

right path; and although conversationally acquainted with the subject, yet he had 

been by no means prepared for the multitude of analogies pointed out»56. 

 

At the time, Dumas could not have known that a young researcher, Cyprien-Théodore 

Tiffereau (1819 - 1909), had sent a memoir to the Académie in January of the same year entitled 

Nouveau point de vue sous lequel nous devons envisager les métaux, basé sur un fait acquis à la 

science par l’expérimentation (A new way of looking at metals, based on a fact acquired by science 

through experimentation), which stated that the theory of a metallising principle, openly borrowed 

from Stahl’s thought, was one step away from experimental confirmation57. That young man, who by 

mid-century was already making a name for himself as an inventor and photographer, is today mainly 

remembered for his dream of succeeding in transmuting metals, which accompanied and haunted him 

for 60 years58. 

Having completed a scientific education of which we know very little, Tiffereau, a native of 

a small village in the Vendée, after working as a chemical preparator at the École Professionelle in 

Nantes, embarked for Mexico in 1842, eager to further his studies on the terrains in which precious 

metals are found and the technologies used for their mining. As can be deduced from the numerous 

biographical passages in the contributions he published after his return to France59, during the period 

between 1843 and 1845 he travelled extensively, producing a considerable amount of photographic 



 

 

evidence of his mining and chemical research, unfortunately lost today. It is, however, easy to see 

that his studies aimed at technological development in the field of photography were the occasion (if 

not even the pretext) to deepen chemical experimentation that was already tending towards the desire 

to confirm the transmutability of metals. In fact, it is impossible not to see clear points of contact 

between the methodologies employed at the time for the development of daguerreotypes and the 

particular transmuting procedures prepared by Tiffereau, which, by then, retained only a vague 

memory of the alchemical tradition. 

In 1846, he decided to settle semi-permanently in Guadalajara, where he earned a living as a 

photographer (which also allowed him to subsidise his chemical research). It was at this juncture that 

Tiffereau became convinced, thanks to an experiment that was successfully replicated twice more 

over the next year, that he had achieved the synthesis of artificial gold. After subjecting nitric acid 

(HNO3) to the direct action of sunlight for a few days, he added filings of a copper-silver alloy, 

leaving everything exposed to the sun again until the partial dissolution of said alloy. The next step, 

consisting almost of a trivial parody of the alchemical solve et coagula, involved cooking the metals 

until the solvent evaporated, which was again added and evaporated until the solid residue, initially 

blackish in colour, became progressively lighter. Once a bright yellow metallic hue was reached, the 

assay confirmed the successful transmutation into gold: 

 

«I reduced 10 grams of silver alloyed with copper to filings and projected 

them into a flask 2/3 full of pure nitric acid at 36° [Bè]. At first, there was a lively 

release of nitrous gas; a little later, the attack having diminished in intensity, the 

release slowed down almost all of a sudden and remained barely noticeable, but 

nevertheless uniform, until the end of the operation; on the other hand, the 

unattacked filings seemed to increase a little in volume. After 3 weeks, I boiled the 

liquor in the sun on my terrace. The nitrous vapours ceased to be released and the 

boiling, which continued until it was dry, showed me a dull matter tending towards 

black, aggregated into a single whole: I noted no deposit of any saline part or any 

impurity. 

I poured nitric acid at 36° [Bè] over the residue thus obtained. I boiled it and 

pushed the operation to complete dryness: I obtained, as before, an agglomerated 

whole but whose black colour took on a greenish appearance. Further attacks and 

successive boiling with concentrated acid gave me a residue that was still 

agglomerated but whose colour gradually changed from greenish to yellowish. 

Finally, during the last boiling to dryness, the dry matter, which had previously 

always been agglomerated, separated into a number of particles, making it perfectly 

clear that they consisted of filings that were easily crushed under the hammer. These 

various particles all had a clear golden yellow colour»60. 

 

This procedure, in all likelihood at least partly borrowed from alchemical readings that 

Tiffereau never explicitly quoted, was influenced by the traditional idea of accelerating the ripening 

time of metallic substances combined with a concept of photosensitivity attributed to metals and 



 

 

acidic materials that was nevertheless foreign to traditional literature (which spoke at most of the 

astrological circumstances favourable or adverse to the Great Work). Tiffereau’s experiments recalled 

instead the photographic impression procedures regulated by precise exposure times, considering how 

the development of daguerreotypes took place through the direct action of light on silver plates. The 

extent of the alchemical contribution to the genesis of Tiffereau’s transmutational hypotheses remains 

unknown to this day, so to trace them back to the cross-reading of precise alchemical texts would 

represent mere conjecture. 

Shortly after the outbreak of the Mexican-American War (1846-48), Tiffereau was forced to 

leave the New World. Already planning an industrialisation process to put his incredible discovery to 

good use, he sailed from Tampico to Paris in early 1848, but once back home, he came up against an 

obstacle he would never be able to overcome. For unknown reasons, it was impossible for him to 

successfully replicate his Mexican experiences. In the period immediately following his return, 

Tiffereau nevertheless managed to consolidate his position by establishing himself as a photographer 

and inventor. Over the next twenty years, several devices of his own creation, such as hourglasses for 

calculating the exposure times of photosensitive materials used in photography, laboratory 

gasometers and hydraulic clocks, became very popular and earned him academic prizes and awards. 

So much so that his first contact with the Académie des Sciences came by way of a pli cacheté dated 

November 1850 in which he discussed the possibility of using special aerostatic devices to irrigate 

cultivated fields61. 

While Tiffereau was privately continuing his experiments in an attempt to carry out the 

transmutation once again, on 31 May 1852 he sent the Académie a sample of the artificial gold that 

had been transmuted in Guadalajara in 1846, together with a second missive, in which he stated that 

apart from himself, the only person made aware, on 23 June 1851, of the procedure successfully used 

in Mexico, was none other than Napoleon III (1808 - 1873), at the time Président de la République, 

who on that occasion granted the ambitious researcher financial support for his investigations62. When 

he felt ready to divulge his discovery, in June 1853 Tiffereau published a short memoir eloquently 

entitled Les métaux ne sont pas des corps simples, mais bien des corps composés (Metals are not 

simple bodies, they are compound bodies), of which he sent a copy to the Académie clamouring for 

its judgement, plausibly ignoring the rule by which this institution refrained from commenting on 

scientific contributions already published in France. Surprisingly, it was nevertheless decided to 

summon him and so, on 17 October, Tiffereau presented the account of his Mexican experiences 

before the French scientific gotha, showing more samples of artificial gold. The aspiring transmuter 

must have realised early on that presenting a hypothesis partially based on the recovery of Stahl’s 

phlogiston, considered for decades to be a pseudoscientific device, would not have been received as 



 

 

a wise or inspired choice. Thus, he reshaped his ideas about transmutation on more recent concepts, 

considered at least probable and shared by more chemists, from the comparison between the 

compound radicals of organic chemistry and metals dear to Baudrimont and Dumas to Prout’s integer 

multiples hypothesis. The attempt at theoretical generalisation, constructed using language more in 

keeping with mid-century chemical research, thus revolved around the possibility that metals, defined 

as isomer compounds (in deference to what Dumas had suspected since his Leçons sur la philosophie 

chimique), whose unknown radical would consist of one or even more allotropic states of hydrogen 

(in homage to Prout’s integer multiples), could be transmuted through oxidation processes regulated 

by the catalytic and fermentative action of nitrogen (with indirect reference to the phenomenon of 

ammonium). Metals were thus presented as oxyhydrides, the more inert and dense the more the 

amount of oxygen present in them increased, thus justifying the use of nitric acid, a known oxidising 

agent. 

Bearing in mind the decades-long debate about the actual ‘simplicity’ of metals, it should 

come as no surprise that the Académie responded by setting up a commission of enquiry63, chaired 

by the leading expert on the subject, Jean-Baptiste Dumas; his mentor Louis-Jacques Thénard (1777 

- 1857), since the 1810s accustomed to studying related topics, as we have seen in the case of 

ammonium64; the most knowledgeable scholar of alchemical sources available to the institution, 

Michel-Eugène Chevreul (1786 - 1889), one of the founders of modern organic chemistry and a 

pioneer of fatty acid chemistry. On 7 November, the committee members informed Tiffereau that 

they would need more technical data to reach a judgement. In essence, they were asking him to reveal 

his experimental protocol. It took six months to formulate a response, for a rather obvious reason. 

Realising the magnitude of the economic and financial repercussions that would result from the 

confirmation of his hypothesis and, consequently, the achievement of the technical reproducibility of 

transmutation, Tiffereau wished to protect himself as the inventor of the procedure. To this end, on 

22 December he applied for a fifteen-year patent - registered by imperial decree on 10 February 1855 

- «for transmuting metals into one another»65. 

The new memoir, which reached the members of the commission in May 1854, finally 

explained the terms and methods of the experiments conducted in Mexico between 1846 and 1847, 

also asking for the scientific community’s help in unravelling the mystery behind the impossibility 

of reproducing transmutations on French soil. However, Tiffereau received no further response. 

During the same year, he sent three more papers to the Académie, after which, having obtained the 

patent, he broke his silence and collected the communications sent to the institute in 1853-54 in a 

booklet with another self-explanatory title: Les métaux sont des corps composés (Metals are 

compound bodies). The fifth of these communications (sent to the Académie on 16 October 1854) is 



 

 

of particular interest, as it testifies to the repetition of Tiffereau’s experiments at the Imperial Mint 

under the direction of the essayer and prominent metallurgist Alexandre Irénée François Levol (1808 

- 1876)66. The results, although ambiguous, were deemed conclusive and Tiffereau’s request for 

further examinations was rejected67. Between the end of 1855 and 1858, he produced two more 

memoirs, but, faced with the indifference of the experts, he temporarily shelved the enterprise and 

concentrated on his career. He married and had four children, and after he retired to private life in 

1884 after selling the now-famous photographic atelier located at 130 rue du Théâtre to one of his 

employees, he resumed his research into transmutation, updating his hypotheses in the light of the 

latest chemical discoveries. 

 

Conclusions 

 It could be argued that it was Dumas himself who indirectly took up Tiffereau’s baton. The 

former, in fact, having long since abandoned all hope of confirmation of Avogadro’s principle but 

constantly searching for criteria of categorisation and ordering useful in chemical research, between 

1857 and 1859 produced a series of contributions of extreme interest in fully understanding the 

reasons for the survival of speculations concerning the transmutability of matter in the chemical 

field68. 

First with a Mémoire sur les équivalents des corps simples (1857) and then with a Note on the 

same subject published the following year, Dumas, building on the successes achieved through the 

application of his substitutions and types theories, made explicit his strategy aimed at achieving two 

co-implicating aims. One was the validation of Prout's hypothesis of integer multiples for as many 

corps simples as possible. The other, representing a crucial step towards analogical generalisations 

informed more by speculations typical of magical thinking than by scientifically plausible inductive 

inferences, involved the demonstration of the existence, between elements belonging to the same 

family, of relationships analogous to those of the homologous series of organic chemistry (just like 

speculated during the Ipswich conference of 1851)69. Thus, Dumas implicitly repeated that 

comparison between radicals from organic chemistry and elements from inorganic chemistry that we 

found in Berzelius as the conceptual overlay that later evolved into a true hypothesis with 

Baudrimont. 

Dumas, however, could not have known that in that same period his Italian colleague Stanislao 

Cannizzaro, with his Sunto di un corso di filosofia chimica (1858), was laying the foundations for 

one of the first turning points towards the acceptance of the physical reality of atoms. And it was 

Cannizzaro himself who emphasised first the methodological shortcomings of Dumas’ hypotheses by 

reiterating what had been stated in his Sunto: 



 

 

 

«Dumas has set out to resolve one of the most important and general questions 

of natural philosophy; but for this purpose, it seems to me that one should compare 

not the quantities of bodies that are substituted, but the weights of those last 

particles of theirs that always enter their molecules whole, and of their compounds, 

namely the atomic weights»70. 

 

Regardless of Cannizzaro’s remarks, the following year Dumas came to a definitive 

systematisation of his research into the équivalents des corps simples. In a long essay, characterised 

by philosophical digressions and almost prophetic accents, the scientist’s arguments culminate in the 

hope of finally achieving the ‘decomposition of the radicals of inorganic chemistry’: 

 

«It is no more necessary to teach chemists that bodies they cannot 

decompose do not decompose than it would be to teach them that compound bodies 

decompose; these are two truths of the same order. 

Chemists have taken their analysis as far as the power of the forces at their 

disposal or the energy of the reactions whose formulas they know. 

They have done even better, for by this analysis they have reduced all the 

natural bodies to certain metallic or non-metallic bodies, showing by indisputable 

common characteristics and by an energetic mutual affinity that they are all radicals 

of the same order. 

When, in this state of affairs, there appears to be a reason to doubt that these 

radicals are simple bodies and that chemistry has said its last word about them, is it 

necessary to repeat this series of perfectly established demonstrations which prove 

that it has not hitherto been possible to decompose them? I do not think so. The 

infinite manipulations of the laboratories of science and industry over the last 

century have left no clouds in people’s minds on this subject. There is no question 

of going back to the past; what it has left us, everyone takes to be true and 

sufficiently proven. It is a question of looking to the future and seeing if we can go 

one step further. But it is a difficult step, the most difficult, in my opinion, that 

human science has ever attempted, and which requires something other than the use 

of heat or the application of ordinary electrical forces. 

Chemistry may be a new science, but chemical phenomena are as old as the 

world itself, and the radicals of inorganic chemistry that are to be subjected to 

further decomposition have been known to mankind for a long time. Their existence 

is revealed from the earliest historical times when their immutability is also revealed 

in a way […]. 

Decomposing the radicals of inorganic chemistry would therefore be a more 

difficult task than the one Lavoisier had the pleasure of undertaking and 

accomplishing. For it would mean revealing not only new and unknown beings, as 

we discover from time to time, but beings of a new and unknown nature whose 

appearances and properties our minds cannot by any analogy imagine. This would 

mean taking the analysis of matter to a point that neither the most energetic natural 

forces nor the combinations and processes of the most powerful science have ever 

reached. It would mean harnessing forces that we are unaware of, or reactions that 

no one has imagined. 

It's one of those problems that human thought needs to ponder for centuries 

[…]»71. 



 

 

 

Nowadays, we can safely assume that this essay represents one of the last academic 

contributions to that chemical research on metallic transmutation influenced by concepts, images and 

speculations of alchemical derivation. Moreover, when in 1888 Tiffereau returned to the question of 

how to replicate the Mexican transmutations of over forty years earlier, his interlocutor would no 

longer be Academia, but the elite of the Second Generation of French occultism72. Within the fin de 

siècle occultist milieu, constantly seeking an epistemologically impossible synthesis between science 

and esoteric beliefs, speculations on the unity of matter would know a new phase, aiming at a 

representation and study of matter understood as an epiphenomenon of ether, described in turn as the 

material and vital principle of the entire phenomenic reality73. 

By contributing to the acceptance of an atomism physically intended - which, however, in 

France would prevail only in the early 20th century74 - Cannizzaro’s reform, crowned by the 

endorsement of the greater part of the chemistry community gathered in Karlsruhe for its first 

international conference (3-5 September 1860)75, in all likelihood also contributed to the demise of 

theoretical elaborations such as those of Dumas. 

Just as alchemy did not meet its end with the birth of modern chemistry during the second half 

of the 18th century, it did not continue to exist, from then on, solely as an esoteric discipline governed 

by gnoseological paradigms irreconcilable with any modern idea of science. In this respect, the 

enquiry into the relationships between chemistry and alchemy during the 19th century offers an 

excellent chance to investigate in a more in-depth and impartial fashion not only debates on the nature 

and behaviour of matter on the one hand and esoteric conceptualisations on the other. Such an enquiry 

grants also the opportunity to analyse the set of biases, convictions and personal beliefs (often part of 

unconscious cognitive processes) that characterised the history of both disciplines during a period of 

epochal transformations. The case of Dumas dealt with on this occasion has been chosen both for its 

relevance and to illustrate how it does not represent a rare exception, but rather part of a large and 

multi-faceted chapter in the history of science and ideas still largely to be written. 

 

 
1 W. H. Brock, From Protyle to Proton. William Prout and the Nature of Matter, 1785-1985, Adam Hilger Ltd., Bristol-

Boston, 1985, pp. 83-84; M. P. Banchetti-Robino, in What Is a Chemical Element? A Collection of Essays by Chemists, 

Philosophers, Historians, and Educators (Eds. E. Scerri, M. Ghibaudi), Oxford University Press, Oxford-New York, 

2020, pp. 87-108; B. Bensaude-Vincent, ivi, pp. 32-52. 
2 J.-B. Dumas, Annales de chimie et de physique, 1826, 33, 337-391; M. Chaigneau, J.-B. Dumas, chimiste et homme 
politique. Sa vie, son oeuvre: 1800-1884, Guy Le Prat, Paris, 1984, pp. 81-88; M. Novitski, Auguste Laurent and the 

Prehistory of Valence, Harwood Academic Publishers, Chur [etc.], 1992, pp. 15-16. 
3 A. Avogadro, Journal de physique, de chimie, d’histoire naturelle et des arts, 1811, 73, 58-76. 
4 A.-M. Ampère, Annales de chimie, ou recueil de mémoires concernant la chimie et les arts qui en dépendent, 1814, 90, 

43-86. 
5 J. I. Solov’ev, Эволюция основных теоретических проблем химии, Наука, Москва, 1971, p. 128. Dumas certainly 

came to know the results of Berzelius’ research on the calculation of atomic weights - published both in the third volume 



 

 

 
of his Lärbok i kemien and in the fifth of the journal he founded together with Wilhelm Hisinger, 1766 - 1852 

(Afhandlingar i fysik, kemi och mineralogi) - through their French edition, the publication of which was supervised by 

the author himself; J. J. Berzelius, Lärbok i kemien, Tryckt hos Direct. Henr. A. Nordström, Stockholm, 1808-18 (3 vols.), 

III (1818); Id., Essai sur la théorie des proportions chimique et sur l’influence chimique de l’électricité […], chez 

Méquignon-Marvis, libraire pour la partie de Médecine, rue de l’École de Médecine, n. 3, près celle de la Harpe, Paris, 

1819. 
6 See ref. 5 (Berzelius 1808-18), III, pp. 104-130; E. M. Melhado, Jacob Berzelius: The Emergence of his Chemical 

System, Almqvist & Wiksell, Stockholm; University of Wisconsin Press, Madison (WI), 1981, pp. 270-278; G. Eriksson 

in Enlightenment Science in the Romantic Era: The Chemistry of Berzelius and its Cultural Setting (Eds.: E. M. Melhado, 

T. L. Frängsmyr), Cambridge University Press, Cambridge, 1992, pp. 56-84. 
7 W. Prout, Annals of Philosophy, 1815, 6, pp. 321-330; see ref. 1 (Brock), pp. 82-89. 
8 P. L. Dulong, A. T. Petit, Annales de chimie et de physique, 1819, 19, pp. 395-413; R. Fox, The British Journal for the 

History of Science, 1968, 4,1, pp. 1-22. To appreciate the degree of accuracy achieved by the two scientists in calculating 

the constant (equal to 6.2 cal/°C), it is only necessary to multiply the average of the values describing the heat capacity 

of the elements by the atomic weight unit derived from Berzelius’ data (O = 100) and divide it by the correct atomic 

weight of the same element (O = 15.9994). The result obtained is 6.004. 
9 E. Mitscherlich, Annales de chimie et de physique, 1820, 14, pp. 172-191; Id., Kongliga vetenskaps akademiens 

handlingar, 1821, 9, pp. 4-79; E. M. Melhado, Historical Studies in the Physical Sciences, 1980, 11,1, pp. 87-123; H.-W. 

Schütt, Eilhard Mitscherlich: Baumeister am Fundament der Chemie, Oldenbourg, München, 1992, pp. 81-90. 

On Berzelius’ application of Dulong-Petit law and isomorphism to the calculation of atomic weights, see J. W. van 

Spronsen, Chymia, 1967, 12, pp. 157-169; J. I. Solov’ev, V. I. Kurinnoi, Якоб Берцелиус: Жизнь и деятельность, 

Наука, Москва, 19802, pp. 78-83; H.-W. Schütt in ref. 6 (E. M. Melhado, T. L. Frängsmyr), pp. 171-179. Berzelius’ 

results were disseminated in France through a new translation of the Lärbok and a second edition of the 1819 monograph; 

cf. J. J. Berzelius, Traité de chimie minérale, végétale et animale, Firmin-Didot Frères, Libraires-Éditeurs, Paris, 1829-

33 (8 vols.); Id., Théorie des proportions chimiques, et table synoptique des poids atomiques des corps simples et de leurs 

combinaisons les plus importantes, Firmin-Didot Frères, Libraires-Éditeurs, Paris, 1835. 
10 J.-B. Dumas, Dissertation sur la densité de la vapeur de quelques corps simples, Imprimerie de M.e V.e Thuau, Paris, 

1832. 
11 See ref. 2 (Dumas), pp. 354-355. 
12 Ivi, p. 339; Id., Traité de chimie, appliquée aux arts, Chez Béchet jeune, Paris, 1828-46 (8 vols. and 1 atl.), I, pp. 

xxxviii-xxxix. 
13 See ref. 5 (Berzelius 1808-18), III, pp. 106-107. Cl = 221.325 (O = 100) → Cl = 69.164 instead of 35.453; weight of 

diatomic phosphorus contained in the molecule of phosphorus pentoxide (P2O5 but described as PO5 by then) = 196.15 

→ P = 61.71 instead of 30.973. 
14 M. G. Faershtein, История учения о молекуле в химии (До 1860 г.), Наука, Москва, 1961, pp. 70-88, 123-126. 
15 W. H. Wollaston, Philosophical Transactions of the Royal Society of London, 1814, 104, pp. 1-22; M. C. Usselman, 

Pure Intelligence: The Life of William Hyde Wollaston, The University of Chicago Press, Chicago, 2015, pp. 190-239. 
16 J. Petrel, La négation de l’atome dans la chimie du XIXème siècle: cas de Jean-Baptiste Dumas, Centre national de la 

recherche scientifique, Centre de documentation sciences humaines, Paris, 1979, pp. 19-29. 
17 M. A. Gaudin, Annales de chimie et de physique, 1833, 52, pp. 113-133; T. M. Cole, Isis, 1975, 66,3, pp. 334-360; see 

refs. 2 (Chaigneau), pp. 83-84, and 14 (Faershtein), pp. 88-98. 
18 See ref. 16 (Petrel); L. J. Klosterman, Annals of Science, 1985, 42,1, pp. 1-80: 73-80. 
19 Thomas Thomson, An Attempt to Establish the First Principles of Chemistry by Experiment, Printed for Baldwin, 

Craddock, and Joy, London, 1825 (2 vols.); Id., Principes de la chimie, établis par les expériences; ou essai sur les 

proportions définies dans la composition des corps […], Crevot, libraire-éditeur, rue de l’École de médecine, n. 3, près 

celle de la Harpe, Paris, 1825 (2 vols.); M. P. Crosland, in John Dalton and the Progress of Science (Ed.: D. S. L. 

Cardwell), Manchester University Press, Manchester, 1968, pp. 274-287. 
20 R. Keen, The Life and Work of Friedrich Wöhler (1800-1882), Traugott Bautz, Nordhausen, 2005, pp. 73-102; K. C. 

Nicolaou, Angewandte Chemie International Edition, 2013, 52,1, pp. 131-146. 
21 W. B. Jensen, Journal of Chemical Education, 2006, 83,6, pp. 838-839. 
22 W. Prout, Annals of Philosophy, 1816, 7, pp. 111-113; see ref. 1 (Brock), pp. 97-108. 
23 J.-B. Dumas, Leçons sur la philosophie chimique, Bechet jeune, Paris, 1837, pp. 30-32. 
24 J.-B. Dumas, Annales de chimie et de physique, 1834, 56, pp. 113-154; A. Dumon, R. Luft, Naissance de la chimie 

structurale, EDP Sciences, Les Ulis, 2008, pp. 31-38. 
25 See ref. 23 (Dumas), pp. 316-320. 
26 Ivi, p. 267. 
27 R. Siegfried, Isis, 1963, 54,2, pp. 147-158. 
28

 J. J. Berzelius, M. M de Pontin, Economiska Annaler med Kongl. Maj:ts Nådigste Tillstånd utgisna af Kongl. 

Vetenskaps-Academien, 1808, 6 (May), pp. 110-130; 6 (June), pp. 113-118 (maxime pp. 122-130); see ref. 9 (Solov’ev, 

Kurinnoi), pp. 59-63; see ref. 6 (Melhado), pp. 203-210. 

The curious amalgam was independently discovered and similarly described during the same year by Thomas  Johann 

Seebeck (1770 - 1831) and Johann Friedrich August Göttling (1753 - 1809); cf. T. J. Seebeck, Journal der Chemie, Physik 



 

 

 
und Mineralogie, 1808, 5, pp. 482-483; J. F. A. Göttling, Elementarbuch der chemischen Experimentirkunst, Bey H. Ch. 

W. Seidler, Jena, 1808-9 (2 vols.), I, pp. 247-249; J. R. Partington, A History of Chemistry, Macmillan, London, 1961-70 

(4 vols.), IV, p. 48. 
29 See ref. 28 (Berzelius, de Pontin), p. 130. 
30 H. Davy, The Collected Works of Sir Humphry Davy, Bart. (Ed.: J. Davy), Smith, Elder and Co., Cornhill, London, 

1839-40 (9 voll.), V, pp. 102-139 (Electro-Chemical Researches on the Decomposition of the Earths - 30 June 1808): 

130-131. 
31 R. Siegfried, Chymia, 1964, 9, pp. 117-124. 
32 See ref. 5 (Berzelius 1808-18), II, pp. 48-65. 
33 Ivi, pp. v, 45-68. 
34 C.-L. Berthollet, Nouveau bulletin des sciences, par la Société Philomathique de Paris, 1808, 1, pp. 150-152; A.-M. 

Ampère, Annales de chimie et de physique, 1816, 2, pp. 5-32: 16. Joseph Louis Gay-Lussac (1778  1850) and Louis 

Jacques Thénard - Dumas’ mentor - for some time were even inclined to believe in the existence of a phlogistic principle 

whereby metals would be hydrogenated compounds: J. L. Lussac, L. J. Thénard, Annales de chimie, ou recueil de 

mémoires concernant la chimie et les arts qui en dépendent, 1808, 65, pp. 325-326; Idd., ivi, 1808, 66, pp. 205-217; Idd., 

ivi, 1810, 73, pp. 197-214. 
35 M. Bernal, J. M. Harrie, S. W. Massey, Monthly Notices of the Royal Astronomical Society, 1954, 114,2, pp. 172-179; 

D. J. Stevenson, Nature, 1975, 258,5532, pp. 222-223; A. Baranski, W. Lu, Electroanalytical Chemistry, 1993, 355,1/2, 

pp. 205-207. The solution to the problem required knowledge that would not be within the reach of physicochemical 

research for several decades yet. Moreover, the reasons behind the behaviour of ammonium remain largely to be clarified, 

after stabilisation of the metallic phase of the compound. So far, it has only been theorised and plausibly believed to exist 

under particular conditions of temperature and pressure, such as those hypothetically detectable in the cores of planets 

like Uranus and Neptune. 
36 See ref. 12 (Dumas), II, pp. 39-44; III, pp. 634-637; V. pp. 691-692. 
37 Ivi, II, p. 43. 
38 Ivi, V, p. 692. 
39 See ref. 2 (Chaigneau), pp. 96-102; J.-B. Dumas, F.-P. Boullay, Annales de chimie et de physique, 1827, 36, pp. 294-

310; Idd., ivi, 1828, 37, pp. 15-53; U. Klein, Experiments, Models, Paper Tools: Cultures of Organic Chemistry in the 

Nineteenth Century, Stanford University Press, Stanford, 2003, pp. 118-129, 133-137. 
40 C.-A. Wurtz, Histoire des doctrines chimiques depuis Lavoisier jusqu'à nos jours, Librairie de L. Hachette et Cie, 

Boulevard Saint-Germain, n° 77, Paris, 1869, p. 77. 
41 See ref. 39 (Dumas, Boullay 1828), pp. 36-37. 
42 See ref. 34 (Ampère). 
43 See ref. 12 (Dumas), V, pp. 690-694. 
44 See ref. 23 (Dumas), p. 267. In chronological order, maybe the first of the ‘illustrious chemists’ Dumas was thinking 

of was Christoph Girtanner (1760 - 1800), who already prophesied an alchemical vengeance ushered by the decomposition 

of bodies deemed elementary, starting with nitrogen: “There is no refuted opinion to which we may not recur, and again 

examine. Philosophy acknowledges no authority which can proscribe it from admitting, or forbid it to examine. There are 

many other opinions, long ago refuted, to which we ought still to recur; for example, that of the transmutation of metals. 

What chemist at present will dare to deny the possibility of it? The change of one metal into another ought to appear less 

difficult than the conversion of the sweetest body (sugar) into the sourest (oxalic acid); than the change of the hardest 

body (the diamond) into the softest (carbonic acid gas); than the change of the most transparent (the diamond) into the 

most opake (charcoal). In the 19th century the transmutation of metals will be generally known and practised”; C. 

Girtanner, The Philosophical Magazine, 1800, 6, pp. 335-354: 353. 
45 J.-B. Dumas, J. von Liebig, Comptes rendus de l’Académie des Sciences, 1837, 5, pp. 567-572; O. T. Benfey, From 

Vital Force to Structural Formulas, Houghton Mifflin Co., Boston, 1964, pp. 36-37; see ref. 39 (Klein), pp. 161-163. 
46 J.-B. Dumas, Comptes rendus de l’Académie des Sciences, 1840, 10, pp. 149-178: 158; Id., Annales de chimie et de 

physique, 1840, 73, pp. 73-100; Id., Justus Liebigs Annalen der Chemie, 1840, 33, pp. 259-300; see ref. 2 (Chaigneau), 

pp. 117-131; C. Gérard, L’actualité chimique, 2002, 254, pp. 38-46; see ref. 39 (Klein), pp. 188-202. 
47 See ref. 2 (Chaigneau), pp. 78-79; W. H. Brock, Justus von Liebig: The Chemical Gatekeeper, Cambridge University 

Press, Cambridge, 1995, pp. 80-87; A. J. Rocke, Nationalizing Science: Adolphe Wurtz and the Battle for French 

Chemistry, The MIT Press, Cambridge (MA)-London, 2001, pp. 94-95; J. Drulhon, Jean-Baptiste Dumas (1800-1884). 

La vie d’un chimiste dans les allées de la science et du pouvoir, Hermann, Paris, 2011, pp. 84-87. 
48 E. I. Hjelt, Sammlung chemischer und chemisch-technischer Vorträge, 1908, 12, pp. 447-482 (or. ed. Berzelius - Liebig 

- Dumas i deras förhållande till radikalteorin 1832-1840, Edlundska bokhandeln, Helsingfors, 1903). 
49 A.-É. Baudrimont, Traité de chimie générale et expérimentale, avec les applications aux Arts, à la Médecine et à la 

Pharmacie, chez J.-B. Baillière, Paris, 1844-46 (2 vols.), I, pp. 68-69, 275. 
50 J. W. Döbereiner, Annalen der Physik und Chemie, 1829, 15, pp. 301-307; E. Scerri, The Periodic Table: Its Story and 

Its Significance, Oxford University Press, Oxford-New York, 20202, pp. 46-54. 
51 Id., Foundations of Chemistry, 2010, 12,1, pp. 69-83; see ref. 50 (Scerri), pp. 33-135. 



 

 

 
52 L. Cerruti, in S. Cannizzaro, Sunto di un corso di filosofia chimica (Ed.: L. Cerruti), Sellerio, Palermo, 1991, pp. 73-

282: 185; L. Anatrini, M. Ciardi, La scienza impossibile. Percorsi dell’alchimia in Francia tra Ottocento e Novecento, 

Carocci, Roma, 2019, p. 39-41, see ref. 50 (Scerri), p. 56. 
53 W. V. Farrar, The British Journal for the History of Science, 1965, 2,4, pp. 297-323: 305-306; see ref. 52 (Cerruti), pp. 

185-190. 
54 Report of the Twenty-first Meeting of the British Association for the Advancement of Science; held at Ipswich in July 

1851, John Murray, Albemarle Street, London, 1852, p. xxi. 
55 L. A. Marchand, The Athenaeum: A Mirror of Victorian Culture, The University of North Carolina Press, Chapel Hill 

(NC), 1941, p. 226. 
56 [L. Playfair], The Athenaeum: Journal of Literature, Science, and the Fine Arts, 12 July 1851, 1237, p. 750; see ref. 53 

(Farrar), p. 304. 
57 This kind of papers, sent in the form of pli cacheté to be kept sealed, was used in disputes concerning discoveries and 

inventions, in order to establish paternity. The senders made use of them in particular, as in the case of Tiffereau, when 

they considered the results of their research not yet definitive, and therefore not disclosable. Thus, in most cases, as no 

dispute arose, these papers remained secret and their content known only to the authors. The Académie des Sciences, since 

the early 1980s, has adopted a new policy whereby papers dating back at least one hundred years can be opened; É. Brian, 

C. Demeulenaere-Douyère, Histoire et mémoire de l’Académie des sciences: guide des recherches, Tec & Doc, Paris, 

1996, pp. 73-74. The contents of the memoir sent by Tiffereau on 6 January 1851 only became known on 9 June 1983; 

Archives de l’Académie des Sciences, pli cacheté 1070. 
58 Tiffereau is one of the very few protagonists of 19th century alchemical research on whose work a dedicated study has 

been conducted: L. M. Principe, Alchemy and Chemistry. Breaking Up and Making Up (Again and Again), Smithsonian 

Libraries, Washington D.C., 2017, pp. 24-53. For a detailed biographical profile of Tiffereau, see P. Virat, Vaugirard-

Grenelle: Bulletin de la Société Historique et Archéologique du XVe Arrondissement de Paris, 2015, 45, pp. 47-58. 
59 C.-T. Tiffereau, Les métaux sont des corps composés. Production artificielle de l’or […], Imprimerie A. Quelquejeu, 

rue Gerbert, 10, Paris, 1888, pp. 9-20, Id., La science en face de la transmutation des métaux. Production chimique de 

l’or, Imprimerie Billon, rue du Commerce, 47, Paris, 1906, pp. 4-8. 
60 Id., La transmutation des métaux. Les métaux sont des corps composés ainsi que les gaz, preuves incontestables basées 

sur des faits indéniables, chez l’Auteur, Vaugirard; Imprimerie A. Quelquejeu, rue Gerbert, 10, Paris, 1900, pp. 4-5. Of 

the numerous accounts of the experiment provided by Tiffereau, this is arguably the most detailed one. 
61 Archives de l’Académie des Sciences, pli cacheté 1052; C.-T. Tiffereau, Nouveaux procédés d’irrigation, de 

desséchement et de drainage spécialement applicables à la grande et à la petite industrie agricole […], Imprimerie de L. 

Martinet, rue Mignon, 2, Paris, 1854. 
62 This other pli remained sealed until 1983, while the incredible annex containing the artificial gold sample was not 

opened until 2015 (related chemical analyses have yet to be conducted); see ref. 58 (Principe), pp. 28-33; Id., L’actualité 

chimique, 2017, 424, pp. 68-71: 70-71. 
63 Comptes rendus de l’Académie des Sciences, 1853, 37, p. 579. 
64 See ref. 34 (Gay-Lussac, Thénard). 
65 Bulletin des lois de l’empire français. XIe série, Imprimerie impériale, Paris, 1853-69 (34 voll.), V (1855), pp. 1161, 

1178. 
66 J. C. Poggendorff, Biographisch-literarisches Handwörterbuch zur Geschichte der exacten Wissenschaften […], Verlag 

von Johann Ambrosius Barth, Leipzig, 1863 (2 vols.), I, col. 1442; F. Szabadváry, History of Analytical Chemistry, 

Pergamon, Oxford, 1966, p. 274. 
67 C.-T. Tiffereau, Les métaux sont des corps composés […], Imprimerie d’Alfred Choisnet, rue de l’Église, 6 et 8, 

Vaugirard, 1855, pp. 47-52. As carefully pointed out - see ref. 58 (Principe), p. 74 - the experimental protocol followed 

by Levol at the mint differed from the one originally developed by Tiffereau in Mexico. Unfortunately, the same goes 

with the only known reproduction conducted in more recent times; cf. A. Truman Schwartz, G. B. Kauffman, Journal of 

Chemical Education, 1976, 53,3, pp. 136-138, 53,4, pp. 235-239: 238. 
68 J.-B. Dumas, Comptes rendus de l’Académie des Sciences, 1857, 45, pp. 709-731; Id., ivi, 1858, 46, pp. 951-953; 47, 

pp. 1026-1034 ; Id., ivi, 1859, 48, pp. 139-142, 372-375; Id., Annales de chimie et de physique, 1859, 55, pp. 129-210. 
69 See ref. 2 (Chaigneau), pp. 178-183. 
70 S. Cannizzaro, Nuovo Cimento, 1858, 8, pp. 16-17: 16. 
71 See refs. 68 (Dumas 1859 Annales), pp. 207-209, 52 (Cerruti), pp. 188-189, and 52 (Anatrini, Ciardi), pp. 39-40. 
72 See ref. 58 (Principe), p. 51. 
73 See ref. 52 (Anatrini, Ciardi), pp. 117-118, 160-161. On the role of ether physics in late 19th-century chemical research 

and esoteric discourse, see Conceptions of Ether. Studies in the History of Ether Theories, 1740-1900 (Eds.: G. N. Cantor, 

M. J. S. Hodge), Cambridge University Press, Cambridge, 1981; H. Kragh, Ambix, 1989, 36,2, pp. 49-65; E. Asprem, 

Aries. Journal for the Study of Western Esotericism, 2011, 11,2, pp. 129-165. 
74 P. Colmant, Revues des questions scientifiques, 1972, 33, pp. 493-519; A. J. Rocke, Chemical Atomism in Nineteenth 

Century, Ohio State University Press, Columbus (OH), 1984, pp. 321-326. 
75 See refs. 14 (Faershtein), pp. 342-343, 5 (Solov’ev), p. 151, and 52 (Cerruti), pp. 207-214; H. Hartley in Studies in the 

History of Chemistry, Clarendon Press, Oxford, 1971, pp. 185-194; M. Ciardi, Reazioni tricolori. Aspetti della chimica 

italiana nell’età del Risorgimento, Franco Angeli, Milano, 2010, pp. 182-183.