Claude Louis Berthollet, a French chemist, born at Talloire, near Annecy, in Savoy, Nov! 9, 1748, died at Arcueil, near Paris, Nov. 6, 1822. He took his medical degree at the university of Turin, and in 1772 went to Paris, was appointed physician to the duke of Orleans, and applied himself to chemistry. He soon became known by his "Essays" on this branch of science, and in 1780 was elected a member of the academy of sciences. Some years later the duke of Orleans procured for him the office of government commissary and superintendent of dyeing processes, a position previously held by Macquer. To this appointment chemistry is indebted for his work on the theory and practice of the art of dyeing, which is much superior to anything of the kind ever published before. In 1785 Berthollet, at a meeting of the academy of sciences, announced his belief in the antiphlogistic doctrines propounded by Lavoisier, in opposition to the phlogistic theory then in vogue, and he was the first French chemist of celebrity who did so.

He differed from Lavoisier, however, on one point: not admitting oxygen to be the acidifying principle, he cited sulphuretted hydrogen as a compound possessing the properties of an acid; and the justness of Berthollet's views has been confirmed by the discovery of other acids into the composition of which oxygen does not enter. During the same year he discovered the composition of ammonia, and published his first essay on dephlogisticated marine acid, now called chlorine, proposing the use of it in the process of bleaching. During the revolutionary war, while the ports of France were blockaded, he visited almost every part of the country for the purpose of pointing out the means of obtaining saltpetre, and was engaged with others in teaching the processes of smelting iron and converting it into steel. In 1792 he was appointed one of the commissioners of the mint, and in 1794 a member of the commission of agriculture and arts, and professor of chemistry at the polytechnic and normal schools. In 1795 he became a member of the newly organized institute of France, and in the following year he was appointed by the directory to proceed to Italy with Monge, to select works of art and science for the French capital.

On this occasion he became acquainted with Bonaparte, and was led to join the expedition to Egypt, where he took part in the formation of the institute of Cairo. Berthollet cooperated with Lavoisier, Guyton de Morveau, and Four-croy in establishing a new and more philosophical system of chemical nomenclature. He was the author of more than 80 scientific papers, some of which were inserted in the memoirs of the academy, and others were printed in the Annales de chimie, Journal de physique, and the Memoires de physique et de chimie de la societe d'Arcueil, so called from the place where Berthollet lived, the meetings of the society being held at his house. In some of the first memoirs published by Berthollet on sulphuric acid, on the volatile alkali, and the decomposition of nitre, he adopted the phlogistic theory; but subsequently, in a paper on soaps, he showed that they are chemical compounds, in which the oil, by combining with the alkali, acts the part of an acid. Berthollet was the discoverer of the ammo-niuret of silver, commonly called fulminating silver. He also first obtained hydrate of potash in a state of purity, by dissolving it in alcohol.

In 1803 he published his Essai de statique chimique, in which he attempts to confute the opinion of Bergman with regard to the nature of chemical affinity. Sir Humphry Davy, in his "Elements of Chemical Philosophy," gives a synopsis of the views of Berthollet on this point, and shows them to be incorrect. In a controversy with Proust, Berthollet maintained that inorganic bodies are capable of combining in all proportions; but the views of Proust have been since corroborated by the doctrine of definite proportions. - On his return from Egypt, Berthollet was made a senator, and afterward grand officer of the legion of honor and grand cross of the "order of reunion." He was created count by Napoleon, and after the restoration of the Bourbons he was made a peer of France. These distinctions did not affect his studious and simple mode of life; and being obliged to adopt armorial bearings, he selected the figure of his dog. Berthollet studied the antiseptic properties of charcoal, and by his advice Admiral Krusenstern preserved water fresh by placing it in charred barrels during a long voyage.

He first showed how to reduce the complicated combinations of animal and vegetable substances by combustion in one of his last memoirs, entitled Considerations sur l'analyse vegetale et l'analyse animale (1817). - His only son, Amedee, born in 1783, died in Marseilles in 1811. He assisted his father in the second edition of the Elements de l'art de la teinture, avec un description du blanchiment par l'acide muria-tique oxigene (2 vols. 8vo, Paris, 2d ed., 1804), and was a member of the society founded by his father at Arcueil. He distinguished himself as a chemist, and established a manufactory of carbonate of soda according to his father's process; but competition preventing his success, he fell into dissipated courses, and committed suicide by suffocation with charcoal gas, seating himself at a table with a watch and writing materials before him, and carefully noting his sensations as long as he could hold the pen.