Antoine Laurent Lavoisier (26.08.1743-8.05.1794) was a French chemist, one of the founders of chemistry, and a member of the Paris Academy of Sciences (1772). He was born in Paris. He graduated from the University of Paris (1764), taking the degree of licentiate of laws, but he gave up a legal career and took up the natural sciences, in particular chemistry and physics, which he had studied while still at the university.
He created a well-equipped laboratory in which he carried out various research. He actively opposed the phlogiston hypothesis and showed by a number of experiments that it was mistaken. In 1775-77 he proved that air has a complex composition and was the first to explain combustion correctly, developing the main propositions of the oxygen theory. In the words of F. Engels, it was by this that Lavoisier “for the first time set the whole of chemistry, which in its phlogistic form had stood on its head, on its feet”. In 1786-87, starting from his oxygen theory, he drew up a new chemical nomenclature, which later became generally accepted. In his chemical research he systematically used quantitative methods based on exact measurements. In 1774 he found experimentally that the mass of a substance is conserved in chemical reactions (this law of the conservation of mass had already been established in 1756 by M. V. Lomonosov).
His work also concerned calorimetry. Together with P. Laplace he constructed the ice calorimeter and determined the heat of combustion of a number of substances, as well as heat capacities, coefficients of thermal expansion and other thermal characteristics. In explaining the nature of heat he started from the theory of the “thermal fluid”, that is, of caloric, although he was well acquainted with the molecular-kinetic theory of heat. In philosophical questions he stood on the positions of mechanistic and metaphysical materialism.