Berthollet, Claude Louis, Comte de 1749-1822
French chemist

Born in Talloires, Savoy, he studied medicine at Turin and Paris. He helped Antoine Lavoisier with his research on gunpowder and also with the creation of a new system of chemical nomenclature which is still in use today. He accepted Lavoisier's antiphlogistic doctrines, but disproved his theory that all acids contain oxygen. He was the first chemist to realize that there is a connection between the manner in which a chemical reaction proceeds and the mass of the reagents; this insight led others to formulate the law of definite proportions later stated by Joseph Louis Proust. He also demonstrated that chemical affinities are affected by the temperature and concentration of the reagents. Following Joseph Priestley's discovery that ammonia is composed of hydrogen and nitrogen, Berthollet made the first accurate analysis of their proportions. He was elected to the Academy of Sciences in 1781 and was active during the French Revolution. After accompanying Napoleon I to Egypt he remained there for two years, helping to reorganize the educational system. He voted for Napoleon's deposition in 1814, and on the restoration of the Bourbons was created a count.