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Dumas, Jean-Baptiste-André

Dumas, Jean-Baptiste-André

(b. Alès [formerly Alais], Gard, France, 14 July 1800; d. Cannes, France, 11 April 1884)

chemistry.

Dumas, son of the town clerk of Alès, was educated at the classical collège in that southern town and then was apprenticed to an apothecary. In 1816 he emigrated to Geneva, where he studied pharmacy and was taught chemistry by Gaspard de La Rive, physics by Marc Pictet, and botany by Augustin de Candolle. He was given permission to conduct experiments in the chemical laboratory of Le Royer, a local pharmaceutical firm.

Dumas’s earliest researches were in medicine and physiology. In 1823 he returned to France and was appointed répétiteur in chemistry at the École Polytechnique. Shortly afterward he succeeded to Robiquet’s chair of chemistry at the Athenaeum, where evening classes were held for adults.

In 1824, with Adolphe Brongniart and J. V. Audouin, Dumas founded Annales des sciences naturelles. Two years later he married Hermine Brongniart, daughter of Alexandre Brongniart, director of the royal porcelain works at Sèvres. In 1828 he published the first volume of his Traité de chimie appliquée aux arts, and the following year he was a cofounder of the École Centrale des Arts et Manufactures. Dumas was appointed assistant professor at the Sorbonne and became full professor in 1841, a position he held until his retirement in 1868. Since the contemporary practice was to hold several academic appointments at once, Dumas also occupied a chair at the École Polytechnique (from 1835) and in 1839 became professor of organic chemistry at the École de Médecine. He lectured occasionally at the Collège de France and gave instruction in experimental chemistry at his private laboratory from 1832 to 1848. From 1840 he was an editor of Annales de chimie et de physique.

Dumas, a moderate conservative, became actively involved in politics after the February Revolution of 1848 and was elected to the legislative assembly from Valenciennes immediately after the fall of Louis Philippe. He was minister of agriculture from 1850 to 1851, and when Napoleon III became emperor he was made a senator. He was also a member, vicepresident (1855), and president (1859) of the Paris Municipal Council. With Haussmann, Dumas undertook the transformation and modernization of the capital, supervising the installation of modern drainage systems, water supply, and electrical systems. He became permanent secretary of the Academy of Sciences in 1868.

Dumas was a brilliant teacher and trained a galaxy of chemists, including Laurent, Stas, Leblanc, and Louis Melsens. The iniquitous system of multiple professorships was responsible for a great deal of bitterness directed against him by some of the younger chemists, a few of them his former pupils. Dumas, however, refrained from indulging in retaliatory measures, even though he was repeatedly subjected to unfounded attacks.

Dumas’s work is notable for its wide range rather than for its depth and insight. His most original contributions stemmed from the adaptation of existing ideas and not from the desire to make revolutionary breakthroughs. This was partly the result of his eminently practical personality, always willing to compromise; but it was chiefly the result of his familiarity with the historical tradition of chemistry, which enabled him to situate every problem within a broader perspective. His historically oriented Leçons sur la philosophie chimique was very influential upon subsequent studies in the history of chemistry

Dumas’s practical interests resulted in numerous contributions to applied chemistry, including the publication of Traité de chimie appliquée aux arts. He investigated problems in metallurgy, such as the preparation of calcium and the treatment of iron ores; he studied the nature and properties of different kinds of commercial glass; and he was interested in questions as diverse as the materials used in thirteenthcentury frescoes and the nature of the compounds of phosphorus and of minium. Dumas’s researches on dyes were probably his most lasting contributions to industry: he analyzed indigo and established the relationship between the colorless and blue types. He was also the first chemist to show that picric acid, the yellow organic compound commonly used for dyeing during the period, was a derivative of phenol. Dumas made extensive studies in pharmaceutics and established the correct formulas for several alkaloids, chloroform, and other substances. His interest in animal and plant physiology led him to suggest numerous improvements in those fields.

He investigated the mechanism involved in the formation of animal fat and attempted to establish that it was utilized in the maintenance of body heat and combustion while it formed a reserve, stored in the body tissues, which could be released for metabolism whenever required. He also showed that there was a close analogy between vegetable and animal metabolism. Because of the growing exasperation of German scientists with the dominant position of French science, this period saw an increasing number of violent diatribes against any major discoveries made in France. J. Liebig was the undisputed champion of this growing and squalid German nationalism in scientific affairs. Along with the discoveries of most other major French chemists—including Laurent, Gerhardt, and Chevreul—he abusively attacked the physiological discoveries of Dumas in the most violent and unjustified manner.

The most important problem with which Dumas was concerned throughout his career was the classification of chemical substances. He sought to devise comprehensive classificatory schemes for organic compounds and for the elements. Dumas’s earliest contribution to organic chemistry was his study of nine alkaloids, published in 1823, jointly with Pierre Pelletier.1 He analyzed the elemental constituents of these organic “bases” and attempted to prove that their relative proportions of oxygen followed Dalton’s law of multiple proportions. He had embraced the ideas of the two reigning theories in contemporary chemistry: dualism, with its division of substances into electronegative (acid) and electropositive (alkaline); and atomism, which Dalton had used to explain his law. Dumas spent the next few years attempting to create an adequate system of classification of organic compounds based upon these two theories.

In 1826 Dumas developed a new method for directly measuring the vapor densities, and indirectly (by calculation) the relative molecular weights of different substances in the gaseous state. His method, which had the merit of being both precise and simple, is still used in chemical analysis. Dumas used the method himself to determine the molecular weights of phosphorus, arsenic, and boron

Although he explicitly referred to Avogadro and Ampère, Dumas nevertheless failed to make a clear distinction between molecules and atoms. He thought that the atomic weights of gaseous substances could be derived directly by measuring their densities. Dumas circumvented the limitation imposed upon the application of this principle by the small number of elements observed in a gaseous state with the help of Gay-Lussac’s law of combining volumes. Since those elements formed gaseous compounds, it was relatively easy to determine the simple volumetric proportions in which they combined. Atomic weights could then be indirectly calculated from the measurement of the density and the application of Boyle’s law and Gay-Lussac’s law.

However, Dumas’s original enthusiasm for this method was soon tempered by his realization of its obvious inadequacies, which could have been removed only by a clearer recognition of Avogadro’s distinction between a molecule and an atom. Dumas pointed out several anomalies. For instance, a liter of chlorine and a liter of hydrogen contained the same number of atoms—say 1,000—at a given temperature and pressure. Upon combination, one atom of either element united with an atom of the other to form a single atom of hydrochloric acid gas. If it were true that all gases contained the same number of atoms under the same conditions, hydrogen and chlorine in the example above would have combined to produce one liter of hydrochloric acid gas containing 1,000 atoms. But this was not the case: two liters of the gas resulted. Therefore chlorine and hydrogen atoms could not be indivisible: they must have divided in two before combination in order to produce as many atoms of the compound gas as of the two elemental gases taken together—2,000—assuming that a liter of any gas contained 1,000 atoms. Dumas’s initial hypothesis that the vapor density of a gas could give a direct measurement of its relative atomic weight was thus disproved.

Dumas tried to save the situation by postulating a distinction between two types of particles: those corresponding to molecules, which could not be split any further by purely physical means (such as heat), and the true chemical atoms, which were the smallest units entering into any chemical reaction. It was only the former whose relative weights could be determined by comparing vapor densities. In spite of this classification, Dumas’s ideas on the subject were not always consistent; he accepted the concept of an atom grudgingly as his career advanced. He cited the particles found in identical numbers in all gases under similar conditions as examples of physical atoms. He found it impossible, however, to ascertain that the smallest particles involved in any chemical reaction were genuine examples of chemical atoms because there was always the chance that reactions were possible only with aggregates of chemical atoms rather than with single atoms.

He was, however, so far from rejecting atomism that from 1840 onward he carried out an important revision of the atomic weights of thirty elements. His most valuable contribution in this field was his very precise determination of the atomic weight of carbon (jointly with his pupil Stas) in 1840.2 A previously accepted weight, determined by Berzelius as C = 12.20 (O = 16), was shown to be incorrect. Dumas proved that C = 12±.002 (O = 16) or C = 75 (O = 100). The analysis was made by burning diamond and artificial and natural graphite in oxygen; the carbon dioxide formed was weighed in potash solution. The results were in close agreement. The “new” weight of carbon had a great effect on the progress of organic chemistry.

Dumas never doubted that organic compounds were to be classified according to their structures, which depended upon their having an atomic (or particulate) constitution. His first important contribution to classificatory organic chemistry came in 1827, when he and his assistant Polydore Boullay published the first part of a study of ether; the final part appeared the following year. This paper assumed that the composition of organic compounds was dualistic, consisting of two parts corresponding to the acidic and basic constituents of an inorganic salt. First, the composition of alcohol and ether was determined by analysis and vapor density measurements. It was concluded that they were both hydrates of ethylene (“hydrogene bicarbone”); alcohol contained twice as much water combined with the hydrocarbon as ether did. Extending the analysis to “compound ethers” (i.e., esters) of nitrous, benzoic, oxalic, acetic, and other acids with alcohol, it was shown that “compound ethers” could be divided into two kinds: those that were formed by oxyacids, which contained no water and were the salts of ether and anhydrous acids; and those that were formed by hydracids, which contained water and were salts of ether and hydrated acids.

Dumas affirmed that this dualistic interpretation should be related to the nature of ethylene rather than to that of ether. In all these cases it was the hydrocarbon that played the role of a powerful base, having a saturation capacity equal to that of ammonia. If it did not act upon litmus paper and other indicators, this was due to its insolubility in water. (The suggestion that ethylene was a strong base had originally been made by Chevreul.) This view was extended by Dumas to cover a large number of other cases. For instance, he suggested that cane sugar and grape sugar were salts formed by carbonic acid, ethylene, and water.

The dualistic theory was interpreted by Dumas in electrochemical terms in 1828; and he maintained this view for another ten years, although with diminishing enthusiasm as the discrepancies accumulated over the years. Until 1835 he was convinced that the electrochemical theory had been established with almost complete certainty. “All present-day chemistry is based upon the view that there is opposition between substances, which is admirably borne out by the evidence from electrical phenomena”.3 The constitution of oxamide (analogous to ethers), also investigated by Dumas, was explained by postulating the existence of the amide radical (N2H4) which remained after ammonia (N2H6) had lost hydrogen at the negative pole. Oxamide was a binary compound formed by the combination of carbon [mon]oxide (C2O) with the amide radical. Even though the latter had not been isolated, its presence was to be assumed because it helped to explain, predict, and classify a large number of phenomena. For example, urea was best understood as being made up of carbon [mon]oxide (C2O) combined with two amide radicals: C2O + 2N2H4 (1830). Similarly, the strongly electropositive alkaline metals, sodium and potassium, formed amides, with the amide radical functioning electronegatively, like chlorine in metallic chlorides.

In 1835, through his investigations into “spirit of 1 wood” (methyl alcohol), Dumas showed how the presence of a radical gave rise to a whole series of compounds. Something new was added to the earlier dualistic theories in this conception: isomerism. He had found that in various hydrocarbons, such as naphthalene and anthracene, or ethylene and isobutylene, carbon and hydrogen were combined in the same relative proportions but were “more closely packed together in one member than in the other.” This discovery led Dumas to postulate the existence of a third hydrocarbon analogous to ethylene and isobutylene, where hydrogen and carbon were combined in a 1:1 ratio, although in different states of condensation. He suggested that the three hydrocarbons would constitute a series such that the condensation for each successive term was twice that of its immediate predecessor. In other words, ethylene was C2H2 (C = 6) and isobutylene C4H4; the new member would be CH, the immediate predecessor of ethylene. By this reasoning, based purely upon analogy, Dumas predicted and succeeded in discovering the whole methyl series. The first member of the series (CH) was called “methyl.” In this way Dumas not only established a link between ethyl and methyl alcohols but also discovered the radical of cetyl alcohol, which had been known from Chevreul’s earlier investigations.

From the known constitution of ethyl alcohol—interpreted as being composed of a hydrocarbon, ethylene (C8H8), and water—Dumas reasoned that there must be similar hydrocarbons to be found in other alcohols if their water could be extracted. Thus he succeeded in discovering, although not necessarily isolating, hydrocarbons combined with water in methyl alcohol, cetyl alcohol, etc.

A second set of analogies, worked out in conjunction with the hydrocarbon contained in methyl alcohol, indicated that this hydrocarbon could be made to combine with a host of substances—nitric acid, ammonia, chlorine, etc.—and give rise to a complete series of compounds in which the hydrocarbon is transferred from one combination to another. At the same time he realized that in certain hydrocarbons, carbon and hydrogen were contained in the same relative proportions, although not in the same relative quantities.

The Theory of Substitutions. The theory of substitutions (or “métalepsie”) was stated by Dumas in 1834. Its main assertion was that the hydrogen in any compound could be replaced by an equivalent amount of a halogen, oxygen, or other element. Furthermore, in order to explain the action of chlorine on a substance containing hydrogen linked to oxygen (rather than to carbon), the theory maintained that “if the hydrogenized compound contains water (i.e., hydrogen linked to oxygen), the hydrogen is eliminated without replacement; but if a further quantity of hydrogen in subsequently removed, then it is replaced by an equivalent amount of chlorine, etc.”

The importance of this law, which was the first to explain the mechanism of substitution reactions in organic chemistry, cannot be overestimated. Its historical origin has been explained in various fashions. The most likely explanation is the one offered by Dumas himself, which the context renders probable: he was interested in testing the correctness of his dualistic theory of the constitution of alcohols by examining the action of the halogens on these compounds. Both ethyl and methyl alcohol produced chloroform when subjected to the action of chlorine. This led him indirectly to the theory of substitutions.

In January 1834, Dumas had read to the Académie des Sciences the results of significant research4 in which the correct molecular formulas for chloroform, bromoform, iodoform, and chloral were given for the first time. He had also observed during his investigations of the action of chlorine on alcohol to give chloral that ten volumes of hydrogen (C = 6) were removed from alcohol but were replaced by only six volumes of chlorine. This was contrary to the evidence he had obtained earlier when studying the action of chlorine on essence of turpentine, where each atom of hydrogen had been replaced by one of chlorine. However, the reaction of alcohol and chlorine was explicable if it were assumed that an atom of hydrogen directly combined with oxygen behaved differently from hydrogen atoms combined with carbon in an organic compound. In other words, if Dumas’s theory of the constitution of alcohol were correct, it followed that the water molecule would react differently from the ethylene molecule. The action of chlorine on alcohol thus appeared to constitute a direct proof of the correctness of Dumas’s dualistic theory: the hydrogen atoms lost by ethylene were replaced by chlorine; those eliminated from water were not, as was shown by the following equation:

Dumas continued his researches on the theory of substitution in order to seek further proof for his view of the constitution of alcohol and the ethers. Paradoxically, the theory was correct only for that part which Dumas had thought was subsidiary to his main proof, a proof based upon erroneous assumptions.

The Theory of Types. From 1837 he became progressively dissatisfied with the electrochemical dualistic theory because of the numerous difficulties that it could not resolve. Encouraged by the example of several young chemists who had developed alternative modes of explanation and classification in organic chemistry while ignoring electrochemical ideas, Dumas was also progressively led to abandon the dualistic theory in favor of a unitary view in which the whole molecule was conceived of as a single structure without polarization into negative and positive parts. Laurent had pointed out (1837) that within a series generated by a hydrocarbon, all the hydrogen molecules could be replaced by their equivalents of the halogens, oxygen, or other substance without the fundamental chemical characteristics of the compound being markedly affected. He therefore assumed that all molecules were unitary structures whose properties were dependent upon the position and arrangement of their component elements and not upon the intrinsic natures of the latter, whether electropositive or electronegative.

In 1839 Dumas discovered that the action of chlorine upon acetic acid formed a new compound (trichloroacetic acid) in which the hydrogen atoms of the acetic acid had been replaced by chlorine. But the new compound had virtually the same physical and chemical characteristics as the acetic acid, even though electronegative chlorine had replaced the strongly electropositive hydrogen. Dumas was converted to the unitary view by this experiment.

The role of his younger contemporaries in his adoption of the unitary theory was admitted by Dumas. He explicitly recognized the contributions of Laurent, Regnault, Faustino Malaguti, Rafaelle Piria, and J. P. Couerbe in his earliest papers, before a rather distasteful set of accusations about priorities were made against him in print by Laurent, Baudrimont, and several others. Dumas’s fairness is demonstrated by his reference to Couerbe, who had emphasized the role of arrangement and position of atoms within a molecule in determining its properties: “I attribute the properties of alkaline compounds to the physical form of the molecule, a form produced by the grouping of the elementary atoms of this molecule. This idea, which I have generalized, is the cause, if not primary, at least the secondary cause, of its properties.”5 Dumas affiliated his views on unitary structures with those of his predecessors. In fact, Dumas was so generous that he did not even claim to have discovered the law of substitutions entirely by himself and contented himself with the modest role of having generalized a discovery made by a group of contemporary chemists: “I do not claim to have discovered it (the law of substitutions), for it does no more than reproduce more precisely and in a more generalized form, opinions that could be found in the writings of a large number of chemists....”6

It is, however, of interest to see the gradual evolution of Dumas’s thought on this subject, even during the period when he was convinced of the quasi certainty of the electrochemical theory. In 1828 he had already declared that the electrochemical theory was powerless to account for the dual behavior of certain elements that were negative in some combinations and positive in others. This implied the contradictory assumption that some molecules were both negatively and positively charged. For example, the halogenschlorine, bromine, and iodine—were positive toward oxygen and negative toward hydrogen. Even more difficult to explain was the fact that while chlorine was positive toward oxygen and both chlorine and oxygen were negative in their compounds with calcium, chlorine displaced oxygen from calcium oxide.

In order to avoid a complete impasse, Dumas hinted at another mode of explanation: “It must be admitted that electrical relations are not alone in determining chemical reactions; in certain cases, the number of molecules, their relative positions7 were perhaps equally influential in modifying the outcome.

By 1834 these anomalous cases had vastly increased because of Dumas’s interpretation that frequently, in binary organic compounds, carbon acted both electronegatively and electropositively. Often it was electropositive in an organic acid and negative in the corresponding base. For example, oxalic ester was composed of an acid (oxalic acid), a base (ethylene), and water; in it carbon functioned positively in the first constituent and negatively in the second. It is strange that the replacement of hydrogen by the electronegative halogens, in alcohols and other compounds, did not appear anomalous to Dumas when he formulated the law of substitution. In fact, he was still persuaded that hydrogen was the only absolutely electropositive element. This is all the more difficult to reconcile with his later (1838) remark to Berzelius that his theory of substitution was a simple empirical rule that described but did not explain phenomena, especially since almost immediately afterward he abandoned electrochemistry because of the anomalous role of hydrogen in substitution reactions. In fact, it is closer to the truth to say that Laurent and Baudrimont’s conclusions about the unitary structure of molecules had been associated with the discovery of substitution reactions by Dumas as early as 1836, when a new note of caution crept into the latter’s attitude toward electrochemistry. The dogmatic certainty of this theory had been replaced by Dumas’s admission that the electrochemical theory was nothing more than a series of hypotheses for which no final proof was forthcoming.

After 1840 Dumas developed the type theory, in which he classified compounds according to two types: chemical and mechanical. The former were substances like acetic and chloroacetic acids, which have similar chemical properties, while the latter had more obscure analogies, basically of a physical kind. Dumas’s mechanical type, whose origin he attributed to Regnault’s work on the ethers, was shown to be untenable by Laurent.

Whereas Laurent had adopted a static model for his fundamental types, based upon an analogy with crystalline structures, Dumas had adopted a dynamic planetary model in which the atoms in a molecule were seen as analogous to the planets in the solar system. Laurent’s model was ultimately derived from Haüy, while Dumas was influenced by Berthollet.

Dumas and the Classification of Elements. In 1831, after the discovery of isomerism in compounds, Dumas had been led to speculate upon the possibility of isomerism among the elements: different elements might in fact be nothing but multiple structures in which the same fundamental element was duplicated or “condensed.” This was supported by the comparison of atomic weights, since several elements had atomic weights which were whole-number multiples of one another, as was shown by the following table8 drawn up at the time:

Zinc403.22
Yttrium401.84
1/2 Antimony403.22
1/2 Tellurium403.22
1/2 Sulfur402.22
Platinum1233.26
Indium1233.26
Osmium1244.21
Gold1243.01
Bismuth1330.37
2 palladium1331.68
Cobalt369.99
Nickel369.67
1/2 Tin367.64
Cerium574.7
Tantalum576.8
Copper395.7
1/2 Iodine394.6
Molybdenum598.5
1/2 Tungsten596.5
Silicium277.4
2 Boron271.9

After his revision of atomic weights in the 1840’s, Dumas had wanted to revive the speculation about a materia prima in conjunction with Prout’s hypothesis that all elements were multiples of the hydrogen atom. In 1851 he read a paper to the British Association in which he attempted to establish how certain regular patterns might be found in arranging elements, such that the heavier atoms were derived from combinations of lighter ones. He also published two papers9 in which he tried to develop the view that for the classification of the elements it was possible to discover “generating” relations similar to those defining the series of organic compounds. The elements could be divided into “natural families.” The atomic weights of all the members of the same family were linked by a simple arithmetic relationship; they increased by multiples of sixteen:

Li7
Na7 + (1 × 16) = 23
K7 + (2 × 16) = 39
O16
S16 + (1 × 16) = 32
Se16 + (4 × 16) = 80
Te16 + (7 × 16) = 128
Mg24
Ca24 + (1 × 16) = 40
Sr24 + (4 × 16) = 88
Ba24 + (7 × 16) = 136

NOTES

1. “Recherches sur la composition eléméntaire et sur quelques propriéiés caractéristiques des bases salifiables,” in Annales de chimie et de physique, 24 (1823), 163–191.

2. “Sur le véritable poids atomique du carbone,” ibid., 1 (1841), 5–55, written with J. S. Stas; also in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 11 (1840), 991–1008.

3.Journal de pharmacie, 20 (1834), 262.

4. “Recherches de chimie organique,” in Annales de chimie et de physique, 56 (1854), 113–154; repr., with a few adds., as “Recherches de chimie organique, relative à l’action du chlore sur l’alcool,” in Mémoires de l’Acadimie des sciences, 15 (1838), 519–556.

5. J. P. Couerbe, “Du cerveau considéré sous le point de vue chimiquc et physique,” in Annales de chimie et de physique, 56 (1834), 189 n.

6. “Mémoire sur la loi des substitutions et la théorie des types,” in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 10 (1840), 178.

7. See the intro. to the Traité de chimie appliquée aux arts, I (Paris, 1828). 1x; the italics are the author’s.

8. “Lettre de M. Dumas à M. Ampère sur l’isomérie,” in Annales de chimie et de physique, 47 (1831), 335.

9. “Sur les equivalents des corps simples,” in Comptes rendus hebdomadaires des séances de l’Académie des sciences, 45 (1857), 709—731; 46 (1858), 951–953; and 47 (1858), 1026–1034; also in Annales de chimie et de physique, 55 (1859), 129-210.

BIBLIOGRAPHY

I. Original Works. Dumas published most of his work in the Annales de chimie et de physique and in the Mémoiresand the Comptes rendus of the Académic des Sciences. See the indexes for titles.

His books are Phénomènes qui accompagnent la contraction de la fibre musculaire (Paris, 1823); Traité de chimie appliquée aux arts, 8 vols. (Paris, 1828); Leçons sur la philosophie chimique (Paris, 1837); Thèse sur la question de l’action du calorique sur les corps organiques (Paris, 1838); Essai sur la statique chimique destres organisés (Paris, 1841).

II. Secondary Literature. On Dumas’s life and work see J.-B. Dumas, La vie de J.-B. Dumas, par le général. J.-B. Dumas son fils (Paris, 1924), 230 mimeographed pp.; S. C. Kapoor, “Dumas and Organic Classification”in Ambix, 16 (1969), 1–65; and E. Maindron, L’oevre de J.-B. Dumas (1886).

Satish C. Kapoor

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Dumas, Jean-Baptiste-Andre

DUMAS, JEAN-BAPTISTE-ANDRE

(b. Alais [now Alès], Gard, France, 14 July 1800;

d. Cannes, France, 11 April 1884), chemistry. For the original article on Dumas see DSB, vol. 4.

Dumas was one of the most eminent chemists in the world in the second quarter of the nineteenth century, overshadowed only by the fame of Justus von Liebig. Liebig’s own reputation was built on what he had learned in the same Paris milieu. Dumas’s greatest contribution was to organic chemistry but two significant areas of Dumas’s influence hitherto unexamined are his research school and his advocacy of the importance of Antoine Lavoisier in the history of chemistry.

Although the work of the novelist Alexandre Dumas is better known to the general public, this was apparently not so evident in the mid-nineteenth century when the novelist wrote to the scientist: “You have made our name known throughout Europe” (Académie des Sciences Archives, Carton 28). By 1832 Dumas had established a name for himself and had even been elected to the prestigious Academy of Sciences. He was able that same year to establish his own private chemical laboratory and to invite students to work with him. He was soon to form a laboratory-based research school, comparable to the school established by Liebig.

The Research School . As a professor of chemistry and an outstanding lecturer, Dumas came into contact with thousands of science students. A small proportion of these were enthused by the prospect of chemical research and, if they were accepted by Dumas in his private laboratory in the rue Cuvier, they would often later identify themselves by publications in which they would express their indebtedness to their master as “chef d’école.” The pharmacist Polydore Boullay was Dumas’s first research student, since he started working in Dumas’s laboratory at the École Polytechnique in 1826, when he was only twenty. Most of the later research students were under thirty, many working on their doctorates, supervised by Dumas. Of the twenty-two students who worked in Dumas’s laboratory, seventeen were French citizens, of whom the most eminent included Auguste Cahours, Charles Gerhardt, Auguste Laurent, Louis Pasteur, Eugène Péligot, Henri-Étienne Sainte-Claire Deville, and Adolphe Wurtz.

Dumas encouraged collaboration in research, both with himself and with fellow students. For example, he

collaborated with Boullay on ethers. He asked Péligot to join him in his investigation of ordinary alcohol and they were able to show that “wood spirit” was also an alcohol. Analogy was a valuable guide in their research and they established that ethal was also an alcohol. A difficult revision of the precise atomic weight of carbon was carried out with the collaboration of the Belgian Jean-Servais Stas, whose later reputation was built on his determination of atomic weights. With the help of Cahours Dumas carried out many analyses of proteins. The most famous collaboration between his students was that over many years between Gerhardt and Laurent.

The basic characteristics of a research school are a talented leader, a pool of committed juniors, and one or more research programs. It is also usual for the research to end in publication. This was, of course, a period when organic chemistry was in its infancy. Whereas Liebig’s basic research program was focused on the simple analysis of organic compounds, Dumas was determined to go further with a goal of their general classification. Inspired by Lavoisier’s success in classifying mineral compounds Dumas was determined to penetrate the forest of the organic world. Casting aside the traditional separate classification of natural and artificial organic compounds, Dumas and Boullay published a new classification in 1828. Based largely on analogy with the binary constitution of ammonium salts, they were able to present the respective formulas of ether, alcohol, and alcohol derivatives in this way. Also there was also now work in inorganic chemistry arising from the rapidly expanding number of new elements and compounds.

It is possible to distinguish five research programs, of which three were in organic chemistry. In some ways they merged one into the other as research proceeded. The ether program together with his chlorination studies led to the theory of substitution (program 2). His later rejection of simple ideas of substitution led to program 3, the type theory. Dumas later returned to his early physiological studies in Geneva (program 4). The fifth program was the redetermination of atomic weights of all the elements, for which he was helped by his special interest in vapor density. All this was obviously much more than could ever be achieved by one man and indeed it involved his whole research school.

Dumas’s study of ethers began with the simple study of acids on ordinary alcohol. With sulfuric acid this would produce common ether. He was assisted by Faustino Malaguti in the chlorination of ether. A full year’s laboratory work with Péligot led to the discovery that “wood spirit” was analogous to ordinary alcohol, hence laying the foundation for a study of a group of similar compounds. The existence of a whole class of alcohols was confirmed by Cahours’s discovery that potato oil was another alcohol.

Substitution reactions are important in organic chemistry but work in this area presented a challenge. Dumas was early convinced by Jöns Jakob Berzelius’s theory of electrochemical dualism that made a firm distinction between electropositive and electronegative elements. A major problem arose when Dumas found in 1838 that, in the chlorination of acetic acid, the intensely electronegative chlorine could replace the electropositive hydrogen to produce a similar acid. It was only in 1840, after considerable hesitation, that Dumas finally abandoned Berzelius’s theory for a unitary theory more helpful for classification.

The third program, therefore, was the theory of chemical types, which owed something to botany in so far as Dumas and his students now thought of compounds as belonging to a genus. Compounds might belong to a particular type if they had the same number of equivalents. Ordinary alcohol belonged to the acetic acid group, while ethylene was linked with marsh gas (methane). The theory stimulated the search for new compounds. For example, in 1842 Dumas was able to predict the existence of seventeen fatty acids, of which only nine were known. The series went from margaric acid down to the simplest, formic acid. Within three years nearly all the other acids had been isolated. This was an early example of a homologous series, the term being introduced by Gerhardt. Although Dumas received great credit for the type theory, he was criticized by Laurent, who claimed that it was similar to his earlier nuclear theory. It was, however, Dumas whom most chemists followed.

Dumas made great efforts to secure academic positions for his students, many at the École Centrale in Paris. He was also able to secure appointments for them in faculties of science in many provincial universities. Most appointees were grateful but Gerhardt and particularly Laurent complained that living in the provinces deprived them of contact with the key academic center, Paris, and even that Dumas was claiming credit for ideas that were originally their own. In 1837 Dumas in a joint paper with Liebig made interesting remarks about collaboration that echo some used by Lavoisier in the introduction to his Traité elémentaire de chimie about the pooling of ideas between colleagues.

We have opened our laboratory to many young men. We have worked under their eyes and we have made them work under ours in such a way that we have surrounded ourselves with young people eager to emulate us. They are the future hope of science, whose work will be added to ours, may even be confounded with ours. (Dumas and Liebig, 1837, pp. 567–572; italics added)

The Rediscovery of Lavoisier . Dumas also has a place in the historiography of science. After Lavoisier’s show trial and execution at the height of the French Revolution, memory of his pioneering work in bringing about the “chemical revolution” had quickly faded. Not only was his execution an embarrassment for his surviving colleagues and for the French state, but the new oxygen theory quickly came to be taken for granted in France and new ideas gained prominence, particularly electrochemistry and John Dalton’s atomic theory, both fields foreign to Lavoisier’s inheritance. Lavoisier’s widow was a solitary figure in trying to perpetuate his memory, calling for the condemnation of those who had condoned the crime. It was only after her death in February 1836 that others felt able to remind the scientific community of the work of their fellow countryman, whose chemistry had previously been taken for granted.

Dumas had obviously been waiting for the earliest opportunity to remind French scientists of their debt to Lavoisier, for in May 1836 he used the anniversary of the death of the chemist to deliver a series of lectures at the Collège de France (Leçons sur la philosophie chimique, 1837) to make an emotional appeal, deploring the neglect of his predecessor. Using religious language, he pledged to work to prepare a complete edition of the writings of Lavoisier, saying: “I will present chemists with their sacred text (leur évangile).” When in 1843 Dumas was elected to the honorary position of annual president of the Academy of Sciences, he took advantage of his position to write to the minister of education, asking for government funds to defray the cost of a complete edition of Lavoisier’s works. Dumas himself was able to supervise the publication of the first four (1864–1869) of six volumes. He was also the author of a Traité élémentaire de chimie (1st ed., 4 vols., Paris, 1813–1815; 6th ed., 5 vols. 1834–1836).

A Powerful Figure . In 1828 he was one of the cofounders of the École Centrale des Arts et Manufactures, one of the first institutions that could be properly called an industrial school—very different from the elitist École Polytechnique. In Dumas’s early years he was heavily committed to this institution and to joint editorship of a related periodical. In 1840 he was appointed as one of the editors of the key journal for chemistry, the Annales de chimie et de physique. His position gave him control over the publication of papers on chemical research. Gerhardt and Laurent, unhappy by his treatment of their work, founded their own journal.

Many of the positions Dumas held were largely due to the patronage of Louis Jacques Thenard, culminating in the important post of dean in the Paris Faculty of Science (1842). Even more prestigious was the post of secretary to the Academy of Sciences, to which he was elected in 1848. His earlier career had been considerably assisted by his marriage (1826), to the daughter of the wealthy director of the Sèvres porcelain factory and professor of mineralogy Alexandre Brongniart, without which he might not have been able to set up his own laboratory.

SUPPLEMENTARY BIBLIOGRAPHY

WORKS BY DUMAS

Traité elémentaire de chimie. Paris: Cuchet, 1789.

Leçons sur la philosophie chimique. Edited by M. Bineau. Paris: Ébrard, 1837.

With Justus Liebig. “Sur l’état de la chimie organique.” Comptes rendus de l’Académie des Sciences 5 (1837): 567–572.

OTHER SOURCES

Crosland, Maurice. In the Shadow of Lavoisier: The Annales de chimie and the Establishment of a New Science. Oxford: British Society for the History of Science, 1994.

———. “Research Schools of Chemistry from Lavoisier to Wurtz.” British Journal for the History of Science 36 (2003): 333–361.

Jacques, Jean. “Auguste Laurent et J. B. Dumas d’après leur correspondance inédite.” Revue d’Histoire des Sciences 6 (1953): 329–349.

Klein, Ursula. Experiments, Models, Paper Trails: Cultures of Organic Chemistry in the Nineteenth Century. Stanford, CA: Stanford University Press, 2003.

Klosterman, Leo. “Studies in the Life and Work of Jean Baptiste André Dumas (1800–84): The Period up to 1850.” Thesis, University of Kent, Canterbury, 1976.

———. “A Research School of Chemistry in the 19th Century: Jean Baptiste Dumas and His Students.” Parts 1 and 2. Annals of Science42 (1985): 1–40, 41–80.

Rocke, Alan J. Nationalizing Science: Adolphe Wurtz and the Battle for French Chemistry. Cambridge, MA: MIT Press, 2001.

Maurice Crosland

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Jean Baptiste André Dumas

Jean Baptiste André Dumas

The French chemist Jean Baptiste André Dumas (1800-1884) worked in the field of organic chemistry and developed the "type" theory of organic structure.

On July 14, 1800, Jean Baptiste Dumas was born at Alais. In his youth he was apprenticed to an apothecary. In 1816 he moved to Geneva and studied physiological chemistry in the laboratory of A. Le Royer. In Geneva, Dumas met the famous scientist Alexander von Humboldt, who persuaded Dumas to move to Paris, where he would find greater scientific opportunities. This he did in 1823, and he was engaged as a lecture assistant in chemistry at the École Polytechnique; he became professor of chemistry in 1835. During this period Dumas began to work on his major book, Treatise on Chemistry, and he also participated in the founding of the Central School for Arts and Manufactures.

In 1830 Dumas challenged the so-called dualistic theory of the great Swedish chemist Jöns Jacob Berzelius. The dualistic theory stated that all compounds could be divided into positive and negative parts. Dumas presented instead a unitary theory which held that atoms of opposite charges could be substituted in compounds without causing much alteration in the basic properties of the compound. This theory was related to his belief in families of organic compounds, in which substitutions could be made with the fundamental characteristics of the family remaining unchanged. At this time Berzelius was at the height of his eminence and would accept no affront to his authority; such was the strength of his attack on Dumas that the latter did not continue the dispute. Later researches proved Dumas to have been more correct in his theories than was the Swedish master.

Dumas isolated various essences and oils from coal tar; developed a method for measuring the amount of nitrogen in organic compounds, which made quantitative organic analysis possible; and developed a new method of determining vapor densities. He also concerned himself with determining the atomic weights of such elements as carbon and oxygen and published a new list of the weights of some 30 elements in 1858-1860.

In addition to his scientific achievements, Dumas led an active public life during the reign of Napoleon III. He was minister of agriculture and commerce and then minister of education. He was also a senator, master of the French mint, and president of the municipal council of Paris. His public life ended with the downfall of the Second Empire in 1871. Dumas died in 1884 in Paris.

Further Reading

There is a chapter on Dumas by Georges Urbain, "Jean-Baptiste Dumas and Charles-Adolphe Wurtz," in Eduard Farber, ed., Great Chemists (1961). Particularly useful is James R. Partington's monumental four-volume History of Chemistry (1962-1969). The life and work of Dumas are discussed in Aaron J. Ihde, The Development of Modern Chemistry (1964), and Isaac Asimov, A Short History of Chemistry (1965). □

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Dumas, Jean Baptiste André

Jean Baptiste André Dumas (zhäN bätēst´ äNdrā´ dümä´), 1800–1884, French organic chemist. He was distinguished for his researches on atomic weights, esters, vapor densities, the oxidation products of alcohols, and the laws of substitution. He taught in several institutions, including the Sorbonne; served as minister of agriculture and commerce, as senator, and as vice president of the High Council of Education; and in 1868 became perpetual secretary of the Academy of Sciences. His works include Traité de chimie appliquée aux arts (8 vol., 1828–45).

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