French chemist (1748–1822)

Born in Talloires, France, Berthollet studied medicine at Turin and gained his MD in 1768. He went to Paris in 1772 where he began publishing chemical researches in 1776 and was elected a member of the Académie Française in 1780. His Italian medical degree was not recognized in France so he obtained a Parisian degree in 1778.

When Berthollet published his important paper on chlorine, Mémoire sur l'acide marin déphlogistique (1785), he was the first French chemist to accept Antoine Lavoisier's new system. Unfortunately, he also accepted Lavoisier's erroneous idea that chlorine contains oxygen. In 1784 Berthollet became inspector of a dyeworks and he discovered and developed the use of chlorine as a bleach. He published a standard text on dyeing Eléments de l'art de la teinture (1791).

Berthollet was neither a great manipulator nor a persuasive lecturer, but he did original work in many fields. He analyzed ammonia (1785), prussic acid (hydrogen cyanide, 1787), hydrogen sulfide (1798), and discovered potassium chlorate (1787). Although a convert, he remained skeptical about Lavoisier's oxygen theory of acidity: his analyses showed no oxygen in prussic acid or hydrogen sulfide, despite their undoubted acidity. Berthollet attempted to use his newly discovered potassium chlorate in gunpowder but it proved too unstable, destroying a powder mill at Essones in 1788. More productive were his analyses of iron and steel, which resulted in better quality steel.

After the French Revolution of 1789 Berthollet was a member of various commissions and in 1795 he became a director of the national mint. In 1798 he was entrusted by Napoleon with the organization of scientific work on the expedition to Egypt and he established an Institute of Egypt. On his return to Paris in 1799 Berthollet bought a large house at Arcueil in the suburbs of Paris, where he set up a laboratory and subsequently founded the Société d'Arcueil, which included Pierre de Laplace, Alexander von Humboldt, Jean Biot, Louis Thenard, and Joseph-Louis Gay-Lussac. At Arcueil, Berthollet produced his magnum opus, the Essai de statique chimique (1803), in which he propounded a theory of indefinite proportions. By 1808, following the work of John Dalton, Jöns Berzelius, and Gay-Lussac. indefinite proportions was decisively rejected, but Berthollet's idea that mass influences the course of chemical reactions was eventually vindicated in the law of mass action of Cato Guldberg and Peter Waage (1864).

Berthollet was made a senator in 1804 and in his later years was regarded as the elder statesman of French science.

The French chemist Claude Louis Berthollet (1748-1822) made many original contributions to both theoretical and applied chemistry. He was one of the foremost disciples of Lavoisier.

Claude Louis Berthollet was born on Dec. 9, 1748, in the village of Galloire on Lake Annecy. He attended the University of Turin in Italy, where he graduated in medicine in 1770. He moved to Paris in 1772 to study chemistry.

In 1778 Berthollet married and took a second doctorate in medicine at the University of Paris, where his Italian degree was not recognized. By 1780 his published research on chemistry had earned him admission to the Royal Academy of Sciences in Paris, and 4 years later he was appointed director of the Gobelin tapestry works. Here he made a special study of the chemistry of dyeing, on which he published an important two-volume work in 1791.

In 1785 Berthollet adopted the new system of chemistry based upon the oxidation theory of combustion, developed by the French chemist A. L. Lavoisier. In the same year Berthollet published an important paper on chlorine, describing the bleaching action of this gas in a solution of alkali, which revolutionized the bleaching industry. Unlike his mentor Lavoisier, Berthollet emerged from the French Revolution unscathed, having served the Revolutionary government as an adviser on technical matters.

A Scientific Debate

Berthollet's career reached its climax during the Napoleonic era. In 1798 Napoleon, who had a well-informed interest in science, chose Berthollet to accompany him on the expedition to Egypt as a scientific adviser. Berthollet became a prominent member of the scientific and archeological institute which Napoleon established in Cairo. It was to this institute that Berthollet read his first papers on the subject of chemical affinity, that is, the forces by which chemical substances are attracted to one another. These papers formed the bases of his two important works on theoretical chemistry, Researches into the Laws of Chemical Affinity (1801) and Essay on Chemical Statics (1803). Berthollet maintained that the masses of substances involved in a chemical reaction could influence the products and that a chemical reaction could be reversed by varying the quantities of the substances. These views led Berthollet into a protracted scientific debate with J. L. Proust. Proust said that chemical compounds were formed in fixed proportions by weight of their elements. Berthollet argued that the proportion by weight of the elements in a compound could vary according to the mass of the reactants from which the compound resulted. Proust's view seemed vindicated in the light of John Dalton's atomic theory, which depends on the law of fixed proportions. However, the outcome was that Berthollet's important insight into the role of reacting masses was neglected for more than 40 years.

Berthollet's country home at Arcueil, near Paris, became the center for a group of distinguished young chemists and physicists, to whom he offered the facilities of his private laboratory. This group organized themselves into the Society of Arcueil in 1807 under Berthollet's leadership. His last days were clouded by the suicide of his son in 1810 following the failure of a chemical factory in which he had a major interest. Berthollet died at Arcueil on Nov. 6, 1822.

Further Reading

There is no full-length biography of Berthollet, but Maurice P. Crosland, The Society of Arcueil (1967), contains much information about Berthollet and French science during the Napoleonic era. J. R. Partington devotes an entire chapter to Berthollet in A History of Chemistry, vol. 3 (1962), and provides lengthy discussions in vol. 4 (1964). A section on Berthollet is in Eduard Farber, ed., Great Chemists (1961). The scientific environment of the time is covered in Abraham Wolf, A History of Science, Technology and Philosophy in the Eighteenth Century (1939). See also Eduard Farber, The Evolution of Chemistry: A History of Its Ideas, Methods and Materials (1952; 2d ed. 1969); Henry M. Leicester and Herbert S. Klickstein, eds., A Source Book in Chemistry: 1400-1900 (1952); and Aaron J. Ihde, The Development of Modern Chemistry (1964).

(klōd lwē, kôNt bĕrtōlā') , 1748–1822, French chemist. His contributions to chemistry include the analysis of ammonia and prussic acid and the discovery of the bleaching properties of chlorine. He collaborated with Antoine Lavoisier in his researches and in reforming chemical nomenclature and supported him in his theory of combustion. His greatest contribution was in his Essai de statique chimique (1803), in which he presented his speculations on chemical affinity and his discovery of the reversibility of reactions.

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