Stearic acid, also called octadecanoic acid, CH₃(CH₂)₁₆COOH, is a white solid carboxylic acid obtained from its ester, glyceryl tristearate (tristearin), which is found in many natural fats and oils. Sodium stearate is a principal constituents of many soaps. Relative density 0.85; melting point 70° (158°F).