Chevreul, Michel-Eugène (1786–1889)

French chemist who studied the composition of fats and identified a number of fatty acids, including ‘margaric acid’, which became the basis of margarine. He also studied sugars and dyes.

Chevreul was born in Angers, Maine-et-Loire, and studied in Paris. From 1824 he was director of dyeing at the Gobelins tapestry factory. He became professor of chemistry at the Museum of Natural History, and its director 1864.

By treating soaps with hydrochloric acid, Chevreul obtained and identified various fatty acids, including stearic, palmitic, oleic, caproic, and valeric acids. He realized that the soapmaking process is the treatment of a glyceryl ester of fatty acids with an alkali to form fatty acid salts (soap) and glycerol.

In 1825 Chevreul and Joseph Gay-Lussac patented a process for making candles from stearin (crude stearic acid), providing a cleaner and less odorous alternative to tallow candles. Chevreul determined the purity of fatty acids by measuring their melting points, and constancy of melting point soon became a criterion of purity throughout preparative and analytical organic chemistry.

At the Gobelins dyeworks he made various chemical discoveries, and his interest in the creation of the illusion of continuous colour gradation by using massed small monochromatic dots (as in an embroidery or tapestry) later influenced the pointillist and Impressionist painters.