At the age of twenty-two, he presented to the Academy of Sciences an analysis of gypsum. At twenty-five he was admitted a member of the Academy, an unusually early age. In his next year he succeeded his father in his lucrative office. He then married the daughter of another farmer-general, and having made this provision for a life of luxury or public employment, with all that political ambition might offer in the old _régime_ of France, he collected his books about him, shut himself up in his study, and gave up his time, fortune, and energy to the advancement of science. After occupying himself for a brief period with geology, he commenced his chemical career by refuting the theories alike of Margraff and Stahl on the conversion of water into earth. The chemistry of the gases had made rapid progress in England; and the names of Black, Priestley, and Cavendish, had already attracted the attention of scientific Europe. Lavoisier followed in their track by a series of experiments in the calcination of metals, pursued with remarkable intelligence and industry. The biographer observes that he was now on the verge of two dazzling discoveries--the composition of the atmosphere, and the identity of the diamond with carbon. But he stopped short, and left the glory to more fortunate investigators. We hasten from the controversies to which the claim of priority in those distinguished discoveries gave rise, and come to the more authentic services of Lavoisier. He was appointed by the minister to superintend the royal manufacture of gunpowder, which his chemical knowledge enabled him greatly to improve. He next, by appointment of the National Assembly, drew up his laborious and valuable memoir on the _Territorial Wealth of France_. He was now appointed one of the commissioners of the treasury, and introduced an unexampled regularity into the public accounts. He aided the formation of the metrical system, the security of the assignats against forgery, and seems to have borne an active part in every public matter in which practical science was concerned. In the mean time he employed himself in scientific agriculture, and set apart a tract of land on his estate for experimental farming. His style of living in Paris was at once rational and splendid. His house was open twice a-week for the reception of distinguished persons, both foreigners and natives, and especially if they brought with them the recommendation of scientific ability. With the finest philosophical apparatus in the possession of any individual in France, he was constantly carrying on experiments on his own account, or performing them for others whose means could not meet their expense. This conduct, united to remarkable amiability of manners, made him popular, and placed him at the head of French science in his day. But the evil time had come when opulence was to be a crime, and virtue was to be no longer a safe-guard. The democratic triumvirate of 1794 issued an order for the seizure of