Baker's Ammonia (Ammonium Carbonate) is a leavening ingredient called for in many old fashioned recipes. It is also called "hartshorn".
Baker's Ammonia is used to make extra-crisp cookies or crackers. Unlike baking powder or soda, it does not leave an alkaline off-flavor in baked goods. It is not used for leavening in cakes or other large-volume items as the ammonia gas will not evaporate entirely.
