Stearin, , is one of the fats occurring in animals and plants. Like the other fats it may be regarded as an ether of the triatomic alcohol glycerine, all three hydroxyl molecules being replaced by radicles of the fatty acid—stearic acid, .
It is the chief constituent of the more solid fats, such as mutton suet, and is characterised by its high melting-point—from to C.—by its slight solubility in alcohol as compared with palmitin and olein, and by its crystallising from its alcoholic solution in the form of brilliant quadrangular plates. Like the other fats it may be readily split into glycerine and a fatty acid, and if an alkali be present the acid combines with this to form a soap. Stearoptene is the crystalline solid substance which separates from volatile Oils (q.v.) on long standing or at low temperatures. For Physiology of Fats, see FAT. See also CANDLES.