Ammonium, Bicarbonate of

HNH 4 CO 3 . Prep. By digesting cold water on sesquicarbonate of ammonia in considerable exce , until the whole of the pungent neutral carbonate is di olved out. If the salt is reduced to powder the operation is facilitated. To powdered sesquicarbonate of ammonia add boiling water just sufficient to di olve it, and immediately close the ve el; crystals form as the liquid cools, containing 2 1 ⁄ 2 equiv. of water. Prop., . For the most part similar to the sesquicarbonate, except in having a taste and smell which is only faintly ammoniacal, and hence more palatable. Crystallises in oblique prisms, which, as usually obtained, contain about 23% of water. It requires 8 parts of cold water to di olve it. It is distinguished from the previous carbonates by the almost entire absence of ammoniacal odour, and by its solution giving no immediate precipitate with chloride of barium, but by standing, or on the addition of a little liquor of ammonia, a white earthy precipitate, accompanied with the evolution of carbonic acid gas. A saturated solution of this salt, evaporated by a very gentle heat, or refrigerated, gives small prismatic crystals having neither smell nor taste. Uses, . Similar to those of the other carbonates.— Dose , 6 or 7 to 20 or 25 gr.