Two salts of this metal are officinal, the nitrate and the oxide.

Argentum Purificatum. - Refined Silver. Pure Metallic Silver.

Impurities. - Lead and copper.

From Argentum is made:

Argenti Nitras. - Nitrate of Silver. AgNO3. Lunar Caustic.

Source. - Made by dissolving Silver in Diluted Nitric Acid.

Characters. - Colourless tabular right rhombic prisms, or white cylindrical rods. Solubility, 100 gr. in 50 min. of water.

Impurities. - Other nitrates; detected by evaporation of filtrate after precipitation with HC1.

Dose. - 1/6 to 1/3 gr.

From Argenti Nitras is made:

Argenti Oxidum. - Oxide of Silver. Ag2O.

Source. - Made by precipitating a solution of Nitrate of Silver with Lime-Water - 2AgNO3 +

Ca2HO = Ag2O + Ca2NO3 + H1O.

Characters. - An olive-brown powder; insoluble in water. Incompatible with creasote, with which it forms an explosive substance.

Impurities. - Metallic silver, evolving gas with nitric acid.

Dose. - 1/2 to 2 gr.

Action And Uses. 1. Immediate Local Action And Uses

Externally. - In the form of the solid pencil, nitrate of silver is a caustic causing destruction, with deep staining of the superficial layers, acute pain, inflammation of the deeper layers, separation of the part as a slough, and then rapid healing. Unlike potash, its effects are limited to the area of application. On this account it is the best caustic for ordinary use, to destroy the affected part in bites of dogs, serpents, and other venomous animals, in post-mortem wounds and chancres, or to remove small growths. Solutions of the nitrate, when applied to the broken skin or a mucous membrane, exert much the same action as lead, but in a greater degree: precipitating the albumins and the chlorides of the plasma or secretions; coagulating the protoplasm of the young cells of the part; causing active contraction of the arteries, veins, and capillaries; and very rapidly coagulating the blood both within and without them. Nitrate of silver is therefore the best local antiphlogistic known, controlling the exudation, growth, and vascular disturbance of the inflammatory process. It is employed to touch callous and weak ulcers, including bed-sores; to control local inflammations in accessible parts; and, as an injection, to wash inflamed surfaces, for example, the urethra, vagina, os uteri, bladder, and conjunctiva. A weak solution is used to harden the skin in threatening bed-sores. Solid caustic is an excellent haemostatic on bleeding from leech-bites.

Internally. - In the mouth, silver causes a nauseous astringent metallic taste. Meeting with chlorides and albuminous fluids, it combines with these, and acts upon the surface of the mucous membrane as it does upon the skin. It is a useful remedy in inflammation of the tonsils and pharynx, whether applied in the solid form as an antiphlogistic in acute cases, or in solution as an astringent in relaxed, chronic states.

Reaching the stomach, nitrate of silver is decomposed by the hydrochloric acid and mucus, and cannot act as an irritant upon the mucous membrane unless given in poisonous doses. Its use in ulcers of the stomach must therefore be questioned. When given for ulceration of the bowels, it is administered per rectum.

2. Action In The Blood

Silver enters the blood either as albuminate, or is absorbed as the pure metal by the intestinal epithelium and lacteals, after the manner of fat. It has no appreciable effect on the blood.

3. Specific Action And Uses

Silver becomes locked up in all the connective tissues of the body, in the metallic form, staining exposed parts a dusky black brown, incapable of removal. It probably, therefore, remains inert within the body; but some authorities believe that it affects the nervous tissues, and recommend it in epilepsy, chorea, and locomotor ataxy. The permanent unsightly discoloration of the skin, which comes on after its use for several months, is a serious objection to its employment.

4. Remote Local Action

As we have just seen, silver once admitted to the tissues is not excreted. A certain amount has, however, been found in the urine; and a proportion always passes through the bowels unabsorbed, appearing on the faeces as sulphide. No use is made of these facts.

5. Action And Uses Of The Different Salts Of Silver

The Nitrate is almost invariably used both externally and internally. The Oxide is less irritant, and is chiefly given internally in the form of pill.