Claude Louis Berthollet

Claude Louis Berthollet (1749-1822), French chemist, who made contributions to several fields of chemistry. Berthollet was born in Talloires, and educated at the University of Turin. In 1785 Berthollet proposed the use of chlorine as a bleaching agent. After years of skepticism, Berthollet was one of the first to support the correct antiphlogistic (see Phlogiston) combustion theories of the French chemist Antoine Lavoisier, although he opposed Lavoisier's erroneous theory that oxygen is the fundamental acidifying principle. With Lavoisier and others, Berthollet helped devise a new system of chemical nomenclature in 1787 that is the basis of the system currently used. He made important contributions to the knowledge of the chemistry of explosives and the metallurgy of iron. Berthollet's significant work, Essai de statique chimique (Essay on the State of Chemistry, 2 volumes, 1803), presented his theories on chemical affinity and the reversibility of reactions.

In 1780 Berthollet became a member of the French Academy of Sciences, and in 1794 he became a professor at the École Normale in Paris. In 1798 Berthollet was one of the scholars who accompanied Napoleon to Egypt. Napoleon made him a senator in 1804, later a grand officer of the Légion d'Honneur, and under the empire a count.