Berthollet, Claude Louis (1748–1822)

French chemist who carried out research into dyes and bleaches (introducing the use of chlorine as a bleach) and determined the composition of ammonia. Modern chemical nomenclature is based on a system worked out by Berthollet and Antoine Lavoisier.

Berthollet was born in the then Italian region of Savoy. He qualified as a physician at the University of Turin, moving to Paris to study chemistry. As private physician in the household of the duke of Orléans, he carried out research in the laboratory at the Palais Royale. He was appointed inspector of dyeworks and director of the Gobelins tapestry factory 1784. He taught chemistry to Napoleon and went with him to Egypt 1798. There he observed the high concentration of sodium carbonate (soda) by Lake Natron on the edge of the desert. He reasoned that, under the prevailing physical conditions, sodium chloride in the upper layer of soil had reacted with calcium carbonate from nearby limestone hills – the beginning of his theory that chemical affinities are affected by physical conditions, in this case the heat and high concentration of calcium carbonate. In 1804 he became a senator but ten years later voted for the deposition of Napoleon.