a water-soluble mixture of ammonium bicarbonate and ammonium carbamate, occurring either as a white powder or in colorless, hard, crystalline masses: used chiefly in the manufacture of smelling salts and baking powder.
British Dictionary definitions for ammonium carbonate
an unstable pungent soluble white powder that is a double salt of ammonium bicarbonate and ammonium carbamate: used in the manufacture of baking powder, smelling salts, and ammonium compounds. Formula: (NH4)HCO3.(NH4)CO2NH2
an unstable substance that is produced by treating this compound with ammonia. Formula: (NH4)2CO3