Lavoisier (lä-vwä-zyā') Pronunciation Key
French chemist who is regarded as one of the founders of modern chemistry. In 1778 he discovered that air consists of a mixture of two gases, which he called oxygen and nitrogen. Lavoisier also discovered the law of conservation of mass and devised the modern method of naming chemical compounds. His wife Marie (1758-1836) assisted him with his laboratory work and translated a number of important chemistry texts.
Our Living Language: Antoine Lavoisier's superior organizational skills made it possible for him to interpret and extend the research of other scientists, leading to the important experiments and discoveries that designate him as one of the founders of modern chemistry. He introduced a rigorous experimental approach to the field based on the determination of the weights of reagents and products in chemical reactions. In his Elementary Treatise of Chemistry, published in 1789, he presented a systematic and unified view of new theories and established a system of nomenclature for chemical compounds. His classification of substances laid the foundation for the modern distinction between chemicals and compounds. Lavoisier also disproved the longstanding phlogiston theory of combustion, which for centuries held that a substance called phlogiston, a volatile part of all combustible substances, was released during the process of combustion. By repeating the experiments of Joseph Priestley, Lavoisier demonstrated that during combustion the burning substance combines with a constituent of the air, the gas he named oxygen. He also described the role of oxygen in the respiration of both animals and plants, and he proved that water is made up of oxygen and hydrogen.