A substance made by boiling animal fats with sodium hydroxide. The reaction involves the hydrolysis of glyceride esters of fatty acids to glycerol and sodium salts of the acids present (mainly the stearate, oleate, and palmitate), giving a soft semisolid with detergent action. Potassium hydroxide gives a more liquid product (soft soap). By extension, other metal salts of long-chain fatty acids are also called soaps. See also saponification.
Subjects: Chemistry — History.