Synonym. - Calcarea Arsenica.

Present name. - Tricalcic Diarseniate. Ca32AsO4.

Characters and Tests. - A light, white amorphous powder, insoluble in water, but readily soluble in diluted Nitric Acid. The solution continues clear when an excess of Acetate of Soda is added to it, but gives a white precipitate on the subsequent addition of Oxalate of Ammonia. A small quantity boiled with an excess of Caustic Soda and filtered, gives, when exactly neutralized by Nitric Acid, a brick-red precipitate on the addition of solution of Nitrate of Silver.

Dr. Hering, of Philadelphia, recommended this upwards of twenty years ago for epilepsy, and more recently it has been used as a cardiac tonic. No reference to any proving has been found.

Preparation. - Trituration.