Lavoisier, Antoine Laurent (1743–1794)

French chemist. He proved that combustion needs only a part of the air, which he called oxygen, thereby destroying the theory of phlogiston (an imaginary ‘fire element’ released during combustion). With astronomer and mathematician Pierre de Laplace, he showed in 1783 that water is a compound of oxygen and hydrogen. In this way he established the basic rules of chemical combination.

Lavoisier established that organic compounds contain carbon, hydrogen, and oxygen. From quantitative measurements of the changes during breathing, he showed that carbon dioxide and water are normal products of respiration.

Lavoisier was born in Paris and studied at the Collège Mazarin. He worked as a tax collector and became director of the Academy of Sciences 1785. Two years later he became a member of the provincial assembly of Orléans. During the French Revolution, left-wing leader Jean-Paul Marat, whose membership of the Academy of Sciences had been blocked by Lavoisier, accused him of imprisoning Paris and preventing air circulation because of the wall he had built round the city 1787. He fled from his home and laboratory 1792 but was later arrested, tried, and guillotined.

When English chemist Joseph Priestley produced ‘dephlogisticated air’, Lavoisier, who had already been studying combustion, grasped the true explanation. He went on to burn various organic compounds in oxygen and determined their composition by weighing the carbon dioxide and water produced – the first experiments in quantitative organic analysis. He also showed by weighing that matter is conserved during fermentation as in more conventional chemical reactions.

In Traité élémentaire de chimie 1789, Lavoisier listed all the chemical elements then known.