Prep. Three ounces of refined silver are dissolved by the aid of a gentle heat in one fluid ounce and three quarters of nitric acid, previously diluted with five ounces of water; the clear solution is then evaporated and allowed to crystallize.
Prop, & Comp. Nitrate of silver (Ag O, No5), when crystallized, is in colourless right rhombic prisms; when fused, in the form of small white pencils or sticks, crystalline in structure. It is soluble in its own weight of water at 60° Fah., insoluble in alcohol, but soluble in rectified spirit. It gives a copious white precipitate with hydrochloric acid, which becomes dark by exposure to light; soluble in solution of ammonia, but not in nitric acid. Ten grains dissolved in distilled water give with hydrochloric acid a precipitate which when washed and dried weighs 8.44 grains, and the filtrate when evaporated by a water bath leaves no residue; indicating the proper amount of the metal, and the absence of impurities. It stains the skin black, and forms insoluble compounds with animal tissues. It should be kept from the light.
Of. Prep. Volumetric Solution of Nitrate of Silver. (Nitrate of silver, 148.75 grains; distilled water, twenty fluid ounces.) This solution is used for the quantitative estimation of hydrocyanic acid, and likewise as a qualitative test for the presence of chlorides, etc.
Therapeutics. Externally it is astringent, irritant, vesicant, or even escharotic, according to the mode of its application; it may be used in solution of the strength of from half a grain to half a drachm to the fluid ounce, or in the solid form. Internally, in small doses, it acts as an astringent and alterative to the mucous membrane of the stomach and intestines, is absorbed and produces remote astringent effects, and also influences the nervous system as a tonic; when long continued, it may stain the surface of the body of a blue or leaden hue, but such an effect has not been known to occur under less than three months' continuous use of the drug.
It is used to poisoned wounds, pustules, ulcers (venereal or others), and erysipelatous inflamed parts; also to diminish or destroy morbid growths. Occasionally it is rubbed on the skin, to produce vesication.
In solutions of different strengths, it is used as a lotion, injection, or collyrium. Internally, it is often of great value in gastric affections of a chronic inflammatory character, accompanied by gas-trodynia, pyrosis, or vomiting; also in certain forms of diarrhoea; and as a nervous tonic in chorea and epilepsy.
Dose, 1/4 gr. to 1/2 gr. or more, made into a pill with crumb of bread or some ingredient which does not decompose the salt.
Incompatibles. Its solution should be made with distilled water, as the chlorides decompose the silver salt; nitrate of silver is seldom given in the form of solution on account of its very disagreeable taste, and its decomposing almost all vegetable infusions, which could be prescribed with it; probably the chloride of silver and other insoluble compounds would act as therapeutic agents.
Adulteration. It is apt to contain copper, and lead, or, when in the fused form, nitrate of potash; if copper, its solution, after complete precipitation by common salt, will be blackened by sulphuretted hydrogen; if lead, the precipitate formed by the addition of common salt, is not entirely dissolved by ammonia; if nitre or any other substance, then seventeen grains of the silver salt will not be sufficient to precipitate entirely six grains of chloride of sodium, or the salt will not answer the test given above.
[Argenti nitras fusa. Fused nitrate of silver. Nitrate of silver melted and run into suitable moulds.]