Chemist, philosopher, economist; born in Paris, 26 August, 1743; guillotined 8 May, 1794. He was the son of Jean-Antoine Lavoisier, a lawyer of distinction, and Emilie Punctis, who belonged to a rich and influential family, and who died when Antoine-Laurent was five years old. His early years were most carefully guarded by his aunt, Mlle Constance Punctis, to whom he was devotedly attached; and through her assistance he was secured the advantage of a good education. He attended the College Mazarin, which was noted for its faculty of science, and here he studied mathematics and astronomy under Abbé de la Caille, who had built an observatory at the college after having won renown by measuring an arc of the meridian at the Cape of Good Hope, by determining the length of the second's pendulum, and by his catalogue of the stars. Young Lavoisier also received instruction from Bernard de Jussieu in botany, from Guettard in geology and mineralogy, and from Rouelle in chemistry. In logic he was influenced by the writings of Abbé de Condillac, as he frequently acknowledges in his "Traité Elementaire de Chimi." He began his career by entering the profession of the law, but soon abandoned this to return to his favourite studies of chemistry and mineralogy. His first scientific communication to the Academy was upon the composition and properties of gypsum and plaster of Paris, and this is to-day a classic and a valuable contribution to our knowledge of crystallizing cements. He early learned to look to the balance for help in the definition of facts, and found its great value particularly when he began to study the phenomena we now know under the terms combustion or oxidation, and reduction or deoxidation.

The most advanced chemical philosophers of his day taught that there was something in every combustible substance which was driven out by the burning, that the reduction of an oxide of a metal to the metallic state meant the absorption of this substance or principle, which Stahl had called phlogiston. Lavoisier studied the teaching of the phlogistonists, but having also a mastery of physics and of pneumatic experimentation he became dissatisfied with their theory. He seized upon two important discoveries, that of oxygen by Priestley (1774), and that of the compound nature of water by Cavendish (1781) and by a masterly stroke of genius reconciled discordant appearances and threw the light of day upon every phase of the world's reacting elements. His theory, for a long time thereafter known as the antiphlogists' theory, was really the reverse of that of the phlogistonists, and was simply that something ponderable was absorbed when combustion took place; that it was obtained from the surrounding air; that the increase in the weight of a metallic substance when burned was equal to the decrease in the weight of the air used; that most substances thus burning were converted into acids, or metals into metallic oxides. Priestly had called this absorbed substance or gas dephlogisticated air; Scheele called it empyreal air; Lavoisier "air strictly pure" or "very respirable air" as distinct from the other and non-respirable constituent of the atmosphere. Later, he called it oxygen because it was acid-making (oxys, and geinomai).

So great a change ensued in experimental chemistry, and in theory and nomenclature, and such a mass of facts was co-ordinated and explained by Lavoisier that he has been justly called "the father of modern chemistry." He was the first to explain definitely, the formation of acids and salts, to enunciate the principle of conservation as set forth by chemical equations, to develop quantitative analysis, gas analysis, and calorimetry, and to create a consistent system of chemical nomenclature. He made deep researches in organic chemistry, and studied the metabolism of organic compounds. His memoirs and contributions to the Academiy were of extraordinary number and variety. His life in other fields was romantic, full of interest and a social triumph, but sadly destined to end in tragedy. Happily married, and having the aid of his wife even to the extent of employing her in the prosecution and recording of his experiments, he drew around his fireside and to his library at the State Gunpowder Works a circle of brilliant French savants and distinguished travellers from other lands. Early in his career he felt the need of increasing his resources to meet the necessities caused by his scientific experiments. With this in view he became a deputy fermier-général, whereby his income was much increased. But joining this association of State-protected tax-collectors only prepared the way for many years of bitter attack and a share of the public odium attaching to their privilege. He headed many public commissions requiring scientific investigation, he aimed at bringing France to such a state of agricultural and industrial expansion that the peasant and the working-man would have profitable employment and the small landed proprietor relief from the burdensome taxes hitherto purposely increased to make grants to corrupt favourites of the Court. Having incurred the hatred of Marat he found himself, together with his fellow fermiers-général, growing more and more unpopular during the terrible days of the Revolution. Finally in 1794 he was imprisoned with twenty-seven others. A farcical trial speedily followed, in which he was charged with "incivism" in that he had damaged public health by adding water to tobacco. He and his companions, amongst them Jacques Alexis Paulze, his father-in-law, were condemned to death. Lavoisier, who was devotedly attached to him, was obliged to stand and see M. Paulze's head fall under the guillotine, 8 May, 1794. Lavoisier was then 51 years old. His biographers say little as to his last hours. Grimaux relates that all the condemned men were silent and carried themselves with dignity and courage in the face of death. What Lavoisier's sentiments were can be assumed from a passage in Grimaux (p. 53) who had been the first biographer to obtain access to Lavoiosier's papers.

His goods and chattels and all his scientific instruments were listed and appropriated on the day following his execution, though Mme Lavoisier succeeded in having some restored to her. She was childless and long survived him. THORPE in Contempory Review, Antonine Laurent Lavoisier (Dec., 1890); GRIMAUX, Lavoisier 1743-1794 (Paris, 1888); THORPE, Priestly, Cavendish, Lavoisier and La Revolution Chimique in Brit. Assoc. Address (Leeds, 1890); BERTHELOT, La Revolution Chimique (Paris, 1890); KOPP, Entdeckung der Chemie in der neueren Zeit (1874); HOFER, Histoire de la Chimie, II, 490; VON MEYER, Geschichte der Chemie (Leipzig, 1888); LAVOISIER, Memoires de Chimie (1805); Œuvres de Lavoisier, published by the Ministry of Public Instruction (Paris, 1864-8); DUMAS, Lecons sur la Philosophie Chimique.

C.F. MCKENNA