BERTRAND, a celebrated chemical philosopher, was born at Bayonne in 1761, and very soon discovered a strong predilection for the sciences, to cherish which he had every thing in his father's house that could be reasonably desired, and here he ac- quired the elements of that art for which he was after- wards so famous. His subsequent progress he made under Darcey, who admitted him among the pupils at- tached to the chemical laboratory of France. Five years intense application under such a master, gave him a stock of knowledge very uncommon at his years. As a convincing proof of this, he published, when only 21, a number of valuable observations on arsenic acid, pro- ving, contrary to the opinion of Macquer, that sulphuric acid distilled from the arseniate of potash, disengages the acid of arsenic.

Encouraged by the success which attended his first labours of a chemical nature, he communicated his re- marks on the crystallization of sulphur, cinnabar, and the deliquescent salts; the examination of zeolites, par- ticularly the false zeolite of Freiburg, which he disco- vered to be merely an ore of zinc. He also made ob- servations on the oxygenated muriatic acid, in reference to the absorption of oxygen; on the formation of others, chiefly the muriatic and the acetous; and a number of memoirs on the operation of phosphorus made in the large way; its conversion into phosphoric acid, and its combination with sulphur and most metallic substances.

It was by his operations on phosphorus that he burnt himself so severely as nearly to endanger his life. Imme- diately on his recovery he began the analysis of different varieties of plumbago from France, England, Germany, Spain, and America, and gave both novelty and interest to his work, even after the labours of Scheele on the same subject had made their appearance. The analysis of carbonate of barites led him to make experiments on animals, from which he discovered that this earth is a real poison, in whatever way administered. Strontites was also analyzed by this celebrated chemist, which was found to contain a new earth.

Pelletier discovered a process for preparing verditer in the large way, equal, it is said, in beauty to that Pelletier which is manufactured in England. He was also among the first who showed the possibility of refining bell metal, and separating the tin. His first experiments were performed at Paris, after which he went to the foundry at Romilly, to prove their accuracy in the large way. He was soon after this admitted a member of the Academy of Sciences at Paris, and afterwards accompanied Borda and General Daboyville to La Fere, to assist in experiments on a new species of gunpowder. Being obliged to pass great part of the day in the open air during a cold and moist season, in order to render his experiments more decisive, his health, which was naturally delicate, was very much impaired. He partly recovered it, but again fell a victim to his thirst after knowledge, for he was at one time nearly destroyed by inspiring the oxygenated muriatic acid gas, which occasioned a convulsive asthma, which at times appeared to abate, but was found to be incurable. The affluence of art was insufficient to save him, and he died at Paris on the 21st of July 1797, of a pulmonary consumption, in the flower of his age, being only 36.