Prep. One quarter of an ounce of nitrate of silver in crystals (Ag O, No5), is dissolved in eight fluid ounces of distilled water, and half an ounce or a sufficiency of solution of ammonia added so as nearly to redissolve the precipitate which is at first formed. The ammonio-nitrate of silver is represented by the formula (Ag O, No5+2 Nh3).

Use. This is directed to be used for testing arsenious acid and phosphoric acid, with the aqueous solutions of which it gives a yellow precipitate of arsenite and phosphate of silver, which are soluble in excess both of ammonia and nitric acid.