In aluminum stearate precipitated from aqueous solution there are present: 1. (1) Free fatty acid, readily dissolved to form solutions of concentration up to that of the saturated solution of the fatty acid itself. 2. (2) Loosely bound or sorbed fatty acid, amounting to about 0.6 mole/g.-at. of aluminum which may without difficulty be dissolved out of the soap to form solutions of concentration below that of the fully saturated solution of the fatty acid. 3. (3) Firmly bound fatty acid, resistant to solvent, amounting to approximately 2 moles/g.-at. of aluminum, leaving the composition of the distearate Al(OH)Str 2. Hydrolysis of aluminum soap by moist acetone may be repressed by the presence of dissolved fatty acid.