Claude Louis Berthollet

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 on Claude Louis Berthollet

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).