Sodium bicarbonate refined grade is in the form of small opaque, monoclinic crystals or as a white minutely crystalline powder, free from dirt and other foreign matter. It is liable to lumping if exposed to dampness or subjected to too high a pressure. Sodium bicarbonate is obtained as an intermediate during the production of synthetic soda ash using the ammonia-soda process, popularly known as the Solvay process. Calcium carbonate (limestone) on heating releases carbon dioxide, which is passed into an ammoniated salt solution producing a sodium bicarbonate precipitate.
