Ammonium Carbonate, also known as baker’s ammonia or hartshorn, is a white, crystalline salt with the chemical formula (NH4)2CO3. Commercial samples labeled ammonium carbonate no longer contain this compound, but a mixture that has similar ammonia content. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as a smelling salt. It was a predecessor to the more modern leavening agents baking soda and baking powder. It is also used in some smokeless tobacco products and as an active ingredient in cough syrup to relieve the symptoms of bronchitis.