Prep. A solution of half an ounce of nitrate of silver in four fluid ounces of distilled water, is poured into four pints or a sufficiency of lime water, and the mixture well shaken, and set aside to allow the deposit to settle; the supernatant fluid having been drawn off, the deposit should be collected on a filter, washed with distilled water, and afterwards dried at a temperature not exceeding 212° Fah., and kept in a stoppered bottle. [In the P. U. S. solution of Potassa is used instead of lime water.]

Prop. & Comp. The oxide of silver (Ag O) is a dark olive-brown powder, becoming black by age; insoluble in water, but soluble in ammonia and likewise in nitric acid without the evolution of any gas; readily decomposed by heat, and even by the action of light, when long continued, into metallic silver and oxygen.

Therapeutics. Very similar to the nitrate, except that the topical action is slight; after absorption, its effects are probably the same. It has been asserted to be a very valuable astringent in haemorrhages. It may be used when the remote action of silver is required, as in diseases of the nervous system, as a nervine tonic.

Dose. 1/2 gr. to 2 gr., in the form of pill.

Tests for purity. Twenty-nine grains of oxide of silver yield 27 grains of metallic silver when heated to redness. The equivalent of the oxide is 116, and of metallic silver 108; and 116 is to 108 as 29 to 27.

Incompatibles. Oxide of silver, from the readiness with which it parts with its oxygen, decomposes many organic substances. It is particularly incompatible with creasote, with which it forms a compound, liable to spontaneous combustion.

The Chloride of Silver has also been given as a remedy: its action is probably similar to that of the oxide.