LAVOISIEII, ANTOINE-LAURENT, an eminent chemical philo sopher, was born at Park on the 16th of August 1743. His father, who was opulent, spared no expense in his education, in which he acquired at the College Mazarin a profound knowledge of astronomy, mathematics, botany, and chemistry. After some hesitation as to what particular science be should more particularly dedicate himself, be was determined in the choice of chemistry by tho brilliant dis coveries with which Dr. Black and others had then recently enriched that science. When only twenty-ono years of age he obtained the prize offered by the government for the beet essay on lighting the streets of Paris ; and it is stated, that in order to enable himself to judge of the intensity of the light afforded by lamps, he kept himself during six weeks iu a room from which the light of any was entirely excluded. In 1763 he WAS admitted an associate of the French Academy, and fiuding that he incurred cousiderable expense in the prosecution of his chemical researches, he naked, and in 1769 obtained, the appolutmcnt of one of the farmers-gencral of the revenue, and his purse and his laboratory were equally open to the young inquirers in science. He was afterwards appointed to superintend tho numerous saltpetre-worke of France.
During the reign of terror Lavoisior was accused of having, as a fartner-gonernl, mixed water and noxious Ingredients with tobacco : to avoid arrest he accreted himself for some days; but hearing that his colleagues, and amoug them his father-in-law, were imprisoned, ho voluntarily surrendered himself, and was condemned to death. In answer to a request for a respite of some days, in order to finish some experiments with which ho had been recently engaged, and which ho stated were of importance to the interests of maukiud, he was coldly informed by the public) accuser that the republic had no need of chemists, and that the court of justice could not be delayed. Deeply regretted by every mail of science and by the numerous friends whom his amiable manners had attached to him, he was consigned to the guillotine on the 8th of May 1794, leaving a widow, who many years afterwards was married to Count Rumford.
His publications were numerous and highly important; for besides the larger works which we shall presently mention, he was the author of nearly sixty memoirs printed in the Memoir.' of the Academy,
and other periodicals. His principal separate works are: ' Opuscules Chimiques et Physiques; 2 vole. 8vo, I775; 'Trait6 Elementaire de Chinsie,' 2 vole. Svo, 1789; 'Instructions sur lee Nitrieres, et sur la Fabrication de Salpatre,' 8vo, 1777.
In a posthumous and iucomplete publication, consisting of two octavo volumes, entitled Mdmoires de Chimie,' Lavoisier, alluding to the term commonly employed of the ' French theory,' claims it entirely and exclusively as his own ; and although it will be impossible fur us to enter minutely into a consideration of the Lavoisieran or antiphlogistic theory, yet we shall state, from his 'Eldinens de Chimie ' his peculiar views on some important subjects, and ono of the first of these is the nature of heat. Having mentioned its expansive and repulsive powers, ho says that "it is difficult to comprehend these phenomena without admitting them as the effects of a real end mate rial substance, or very subtile fluid, which insinuating itself between the particles of bodies separates them from each other." lie admits that the doctrine is hypothetical, but asserts that it explains the phe nomena of nature in a satisfactory manner, and that considering it as the cause of beat, or the sensation of warmth, he at first gave it the name of 'igneous fluid,' and 'matter of heat,' but afterwards, in a work on chemical nomenclature by himself, Morveau, and Berthollet, be adds, "We have distinguished the cause of heat, or that exqui sitely elastic fluid which produces it, by the term of calorie, without being obliged to suppose it to be a real substance, but as the repulsive cause which separates the particles of matter from each other." ' Free' caloric be defines to be that which is not united in any way with any other body; 'combined' caloric is that which is fixed in bodies by affinity or elective attraction, so as to form part of the substance of the body ; and by 'specific' caloric of bodies be under stands the respective quantities of caloric requisite for raising a number of bodies of the same weight to an equal temperature, and the proportional quantity depends on the 'capacity' of bodies for calorie.