Claude Louis Berthollet

Claude Louis Berthollet (1748 to 1822) was a Savoyard-French chemist, trained in medicine at Turin, who became an active participant of the Academy of Sciences in Paris in 1780. He worked with Antoine Lavoisier and others on the 1788 chemical nomenclature that underlies the modern system of naming compounds. He was the first to show the bleaching action of chlorine gas and to produce a hypochlorite bleach, the weak solution once sold as Eau de Javel, and he determined the composition of ammonia in 1785. Berthollet recognised reverse reactions and so the idea of chemical equilibrium, and he argued with Joseph Proust over the law of definite proportions; compounds that depart from fixed ratios are called berthollides in his honour. He accompanied Napoleon to Egypt and served as vice president of the French Senate in 1804.