In 1813 he then became professor of physics at the Lycee Charlemagne. Fats are used in manufacturing soap and as a young man Chevreul was involved in that business. He discovered the first fatty acid whole studying potassium soap made from pig fat.
He was able to isolate different insoluble organics acids - also called carbonic acids, or fatty acids. He named several fatty acids, including oleic, butyric, caproic and capric acids and stearic acid.
Chevreul also demonstrated that all fatty acids are composed of a carboxylic acid (-COOH) with a long carbon tail (4-24 carbon atoms in length).
His discovery of extract stearic acid from animal fat in 1823, led to the development of stearin wax. Candles made from stearin wax were harder and burned longer and cleaner than unrefined tallow candles.
He also discovered hematoxylin, which became an important stain for tissue microscopy, and investigated how a color image could be formed from large numbers of small spots each of a single color (currently call pixels).
Michel-Eugene Chevreul (1786-1889)