BERTHOLLET, CLAUDE LOUIS (1748-182 2 ), French chemist, was born at Talloire, near Annecy, Savoy, on Dec. 9, 1748. He studied first at Chambery and afterwards at Turin, where he graduated in medicine. He settled in Paris in 1772. In 1785 he declared himself an adherent of the Lavoisierian school, though he did not accept. Lavoisier's view of oxygen as the only and universal acidifying principle, and he took part in the reform in chemical nomenclature carried out by Lavoisier and his associates in 1787. Among the substances of which he investi gated the composition were ammonia, sulphuretted hydrogen and prussic acid, and his experiments on chlorine, which he regarded, not as an element, but as oxygenated muriatic (oxymuriatic) acid, led him to propose it as a bleaching agent in 1785. He also prepared potassium chlorate and attempted to use it in the manu facture of gunpowder as a substitute for saltpetre. During the French Revolution he served on many technical committees. After 1794 he was teacher of chemistry in the polytechnic and normal schools of Paris, and in 1795 he took an active part in remodelling the Academy as the Institut National. In the follow ing year he and Gaspard Monge were chosen chiefs of a corn mission charged with selecting in Italy the choicest specimens of ancient and modern art for the national galleries of Paris; and in 1798 he was one of the band of scientific men who accom panied Napoleon to Egypt, there forming themselves into the Institute of Egypt on the plan of the Institut National. On the fall of the Directory he was made a senator and grand officer of the Legion of Honour ; under the empire he became a count; and after the restoration of the Bourbons he took his seat as a peer. In the later years of his life he had at Arcueil, where he died on Nov. 6, 1822, a well-equipped laboratory, which became a centre frequented by some of the most distinguished scientific men of the time, their proceedings being published in three volumes, between 1807 and 1817, as the Memoires de la society d'Arcueil. Berthollet's most remarkable contribution to chemistry was his Essai de statique chimique (1803), the first systematic attempt to grapple with the problems of chemical physics. His speculations, in particular his insistence on the influence of the relative masses of the acting substances in chemical reactions, have exercised a dominating influence on the modern develop ments of the theory of chemical affinity, of which, far more than T. O. Bergman, whom he controverted, he must be regarded as the founder.