BERTHOLLET, CLAUDE LOUIS

Talloires, near Annecy, Savoy, 9 December 1748; d. Arcueil, France, 6 November 1822)

pure and applied chemistry. For the original article on Berthollet see DSB, vol. 2.

Berthollet was one of the leading French chemists in the late eighteenth century. He became a close associate of Antoine Lavoisier. As the founder of the Society of Arcueil in the opening years of the nineteenth century he began a further career, not only with his own ideas on chemical reactions, but also as the patron and friend of a group of

talented young scientists. Some areas of Berthollet’s life and work previously unexamined are: (1) his association with Lavoisier; (2) his activities during the French Revolution; (3) his founding of the Society of Arcueil and his friendship with Pierre-Simon Laplace; and (4) his influence.

Life. Berthollet was broad in build, amiable, and even homely in disposition, a character quite different from most of his scientific colleagues. He was the first major convert to Lavoisier’s oxygen theory (1785) despite justifiable disagreement on the idea of oxygen as the principle of acidity. Only slightly junior, Berthollet worked closely together with Lavoisier. His importance in the Lavoisier school is suggested by the inclusion of his name on the title page of the collaborative Méthode de nomenclature chimique (Paris, 1787), despite the fact that successive chapters of the book appear only under the names of his colleagues Lavoisier, Louis-Bernard Guyton de Morveau, and Antoine Fourcroy. Again when the key chemical journal the Annales de chimie began publication in 1789 Berthollet’s name appeared on the title page as a founding member of the editorial board. He was active in soliciting contributions to the journal. When finally it had reached nearly its hundredth volume in 1815 it was he who organized a new series with his protégés Louis-Joseph GayLussac and François Arago as editors.

All “the big four” (authors of the Méthode) were appointed to different major positions of responsibility during the momentous revolutionary period, with the tragic death of one (Lavoisier, 1794) and Berthollet as the last survivor (d. 1822). In 1791 Berthollet was appointed successively as commissioner of the mint and member of the Bureau de Consultation des Arts et Métiers, concerned with rewarding artisans for their inventions. He joined the Bureau of Weights and Measures in 1793 at a time when several members had been arbitrarily excluded as politically unreliable. (Berthollet prudently avoided all political association.) Also in 1793 he became a member of the Commission des Arts, where his duties included making an inventory of the contents of the laboratory of the unfortunate Lavoisier. In 1794 he was appointed to the Commission for Agriculture.

Yet all these posts were arguably less important than those involving the direct application of chemistry to the war effort. In September 1793 he and two others were ordered by the minister for war to write a booklet to explain the manufacture of iron and steel. As the discoverer of potassium chlorate and its dangerous explosive properties (1787), probably his main contribution to the war effort was in the manufacture of gunpowder and the extraction of its main constituent saltpeter (potassium nitrate). For example, in December 1793 he was put in charge of a new refinery of saltpeter. In 1794, together with Guyton and Fourcroy, he taught a crash course to prospective gunners on the manufacture of gunpowder.

A more constructive period followed after the fall of Maximilien Robespierre (July 1794), when many educational plans were made. November 1794 saw the foundation of the École Normale, where Berthollet was appointed as professor of chemistry. Yet the students were an astonishingly mixed crowd and Berthollet was a poor teacher. He had a little more success as professor at the École Polytechnique (September 1795), where its students had been selected by examination.

Yet Berthollet’s role as professor was to be interrupted in May 1796, when he was sent to Italy as a member of a commission to confiscate art treasures in the territory newly conquered by General Napoléon Bonaparte. Contact with the future emperor was to affect Berthollet’s future. The chemist was chosen again in May 1798 to accompany Bonaparte to Egypt. Bonaparte returned suddenly to Paris in November 1799, leaving the army behind but taking with him Berthollet and his friend Gaspard Monge.

The turn of the next century was to find Berthollet at Arcueil, then a village a few miles south of Paris. He bought a country house, built a chemistry laboratory, and invited Gay-Lussac, a promising young graduate from the École Polytechnique, to join him as an assistant. This was to lead to the foundation of the private Society of Arcueil that announced its existence to the world by the publication of its first volume of Mémoires in 1807. Berthollet had recently been joined by the distinguished mathematician Laplace, who had bought a neighboring house at Arcueil, a summer retreat away from the noise and pollution of Paris. They assembled a small group of outstanding young men of science whom they advised and encouraged, even helping several to become members of the first class of the institute, which now replaced the former Royal Academy of Sciences.

In 1803 Bonaparte had made Berthollet a senator, a position which carried a large income. Yet the chemist did not handle his fortune well and by 1807 was in some difficulty. Laplace, also a friend of the head of state, wrote to Napoléon, mentioning the plight of his friend. The emperor immediately authorized payment of a substantial sum for the man he once called “his chemist.”

In 1783 Berthollet had met Charles Blagden, very soon to be appointed secretary to the Royal Society of London, then on one of his many visits to Paris. They soon became great friends, reinforced by their common early medical careers, and they kept up a correspondence for the next forty years. The letters were of great importance in conveying scientific news between the two capitals. In 1784 Blagden was appointed as one of the official correspondents of the Academy of Sciences. Berthollet was also to correspond with many other foreign men of science, including Martin van Marum, Joseph Proust, and Jöns Jakob Berzelius.

Work. The close association of Berthollet with Laplace in the Arcueil period was based on more than personal friendship. They shared a common interest in the legacy of Isaac Newton’s theory of gravitational attraction. This had played a prominent part in Laplace’s previous astronomical work, but in the early 1800s he became interested in attraction on the microscale, that is, the short-range attraction between particles of matter. Having explained satisfactorily capillary attraction, he directed his ambition towards a theory of “the identity of the attractive forces governing capillarity with those responsible for [chemical] affinities” (see also Crosland, 2006). He tried unsuccessfully for some time but eventually realized that his equations would have to take into consideration the size and the shape of the ultimate particles—an impossible task.

Of course chemical affinity was one of Berthollet’s great interests since his visit to Egypt, where he had discovered that large masses of reactants could overwhelm normal affinities. Thus he had set out to study what he called “chemical statics,” as in the title of his book. He even introduced the term chemical mass (1803, vol. 1, p. 16).

Although John Dalton published his atomic theory only in 1808, it had been described in Thomas Thomson’s textbook of 1807. Thomson sent Berthollet a copy and Berthollet had it translated into French (9 volumes, 1809). Berthollet wrote a long introduction and, although he was critical, describing Dalton’s atoms as “an ingenious hypothesis,” it was often through this book that, in time of war, Dalton’s theory was known on the continent of Europe.

The defeat of Napoléon marked the effective end of the Society of Arcueil but Berthollet decided to work on a second edition of his Essai, taking into account recent research. In particular he was able to comment on the work of Dalton, William Wollaston, and Berzelius. He was still critical of Proust’s theory of definite proportions despite growing evidence in its favor but he allowed for its possibility in certain cases. The new edition of the Essai was never published but the manuscript has recently been found and analyzed. Although the Society of Arcueil was no longer in existence, Berthollet managed in 1817 to bring out a final volume of its Mémoires, consisting of papers by some of its former members.

Influence. The person on whom Berthollet had the greatest immediate influence was Gay-Lussac who, for example, suspected that “oxymuriatic acid” (chlorine) was a simple substance but said that “it appeared so extraordinary that

M. Berthollet prevailed upon us to state it with the greatest reserve” (1814, p. 97). It was Berthollet who had discovered the bleaching action of “oxymuriatic acid,” which was simply and logically explained as oxidation due to its oxygen content. Thus the French chemists lost any claim to the discovery of the elementary nature of chlorine, which went to Humphry Davy. Even after Berthollet’s death Gay-Lussac admitted that he still felt the influence of his mentor in the interpretation of chemical phenomena. In 1823 Jean-Baptiste Dumas, the young aspiring chemist from Geneva, had hoped to study under Berthollet, whose works he had studied, but when he arrived in Paris he found that the great chemist had died in the previous year. After this Berthollet’s work seems to have been largely forgotten until the time of Cato Maximilian Guldberg and Peter Waage with their law of mass action (1867).

They referred to Berthollet’s work but he had not gone far enough with the question of mass for them. When Wilhelm Ostwald in 1896 republished Berthollet’s Essai in his series of science classics, he remarked that the book was often praised but seldom read.

SUPPLEMENTARY BIBLIOGRAPHY

WORK BY BERTHOLLET

Essai de statique chimique. 2 vols. Paris, 1803.

OTHER SOURCES

Crosland, Maurice. Introduction to reprint of Essai de statique chimique [1803], by Claude Louis Berthollet. 2 vols. New York: Johnson Reprint Corp., 1952.

———.The Society of Arcueil: A View of French Science at theTime of Napoleon I. London: Heineman, 1967.

———. “A Science Empire in Napoleonic France.” History ofScience 44 (2006): 29–48.

Cuvier, Georges. “Eloge historique de M. le comte Berthollet.” In Recueil des éloges historiques, vol. 3. Paris, 1827.

Gay-Lussac, Joseph-Louis. Mémoire sur l’iode.” Annales deChimie (31 July 1814): 5–160.

Grapí, Pere. “The Marginalization of Berthollet’s Chemical Affinities in the French Textbook Tradition at the Beginning of the Nineteenth Century.” Annals of Science58 (2001): 111–135.

Laplace, Pierre-Simon. Mécanique céleste, vol. 4, Supplément à la théorie de l’action capillaire. Paris, 1807.

Sadoun-Goupil, Michelle. Le chimiste Claude-Louis Berthollet,

1748–1822: Sa vie, son œuvre. Paris: J. Vrin, 1977. This includes correspondence and a full bibliography of Berthollet’s publications.

———, ed. Revue de l’Essai de statique chimique, by Claude Louis Berthollet. Paris: École Polytechnique, 1980.

———.Du flou au clair? Histoire de l’affinité chimique. Paris: Editions du Comité des Travaux historiques et scientifiques, 1991.

Thomson, Thomas. Système de chimie. Translated by Jean Riffault. 9 vols. Paris, 1809. With an introduction by Berthollet.

Maurice Crosland