Formula

AgNo3.

Derivation

Nitrate of Silver is obtained by dissolving silver in nitric acid and distilled water, and evaporating the solution. It is in the form of a heavy, colorless, anhydrous salt, and crystallizes in shining, rhombic plates. The action of light and organic matters cause it to turn black. It is wholly soluble in distilled water, the only preparation of water that should be employed in forming solutions of this salt. It has a strong, metallic, styptic taste. In the preparation of the solid form of sticks, it is first melted and poured into moulds, exposure to the light causing the sticks to become gray, and more or less dark, owing to the reduction of the silver by the sulphuretted hydrogen contained in the atmosphere; hence, on account of the decomposition of this salt, it should be carefully excluded from the light.

Medical Properties And Action

Nitrate of silver is tonic, antispasmodic, sedative and astringent, but not irritant. The pure form when locally applied is a powerful caustic, very superficial in its effects, coagulating the albumen with which it comes in contact, and forming a protective coat to the tissues beneath. It is eliminated very slowly from the system. When applied to the skin, mucous membrane, or ulcers, it produces, at first, a white appearance, owing to its union with the coagulated albumen of the cuticle, but this gradually changes to a bluish-gray, purple, and finally, black color, on account of the partial reduction of the silver by the sulphuretted hydrogen. Small doses, administered for a long time, give a peculiar blue appearance to the skin. When internally administered, it has an astringent action on the mucous coats of the intestines. It is a powerful tonic to the nervous system, and has been chiefly employed as an antispasmodic tonic. It is chiefly used externally, as a stimulant, vesicant, and escharotic. If applied, even lightly, three or four times, to the moistened skin, it will cause vesication in a few hours. The blue appearance on the skin, when small doses are long continued, is said to be preceded by a peculiar blue line on the gums, like that from lead poisoning. A very minute quantity of this salt, when internally administered, is eliminated by the kidneys, as most of it escapes by the liver and the intestinal glands, a portion remaining permanently deposited in the tissues, when its use has been long continued. Six weeks is the length of time it is safe to continue its internal use, and during that time occasional purgatives should be given, to promote its elimination. The persistent use of iodide of potassium and the hyposulphite of soda will cause the absorption and excretion of the silver deposits, in cases of skin discoloration from its long-continued use, aided by baths of the hyposulphites, and the very careful use of lotions containing cyanide of potassium, which possesses a solvent power over silver deposits. As long as inflammation is present, it should not be internally administered, and during a course, it should be occasionally intermitted for a few days, and a purgative used. The gums and fauces should be frequently examined, and if the slightest blue discoloration is observed, the remedy should be discontinued. Exposure to the sun should be avoided.

Therapeutic Uses

Nitrate of Silver is internally employed in dyspepsia, chronic gastritis, chronic diarrhoea and dysentery, cholera, diseases of the eye, chorea, epilepsy, asthma and whooping-cough.

Externally in ophthalmia and other diseases of the eyes, cutaneous diseases, diphtheria, erysipelas, hydrophobia, enlargement of glands, diseases of the genito-urinary organs, diseases of the ear, burns, ulcers, hemorrhage, etc., etc.

Dose

Of nitrate of silver, gr. 1/6, gradually increased to gr. 1/2 three times a day, in pill made of some vegetable powder, or in solution. The fused nitrate of silver - Argenti Nitras Fusa - or solid form, is used externally.

Dental Uses

Nitrate of silver is one of the comparatively limited number of astringents applicable to mucous surfaces which are not irritant as well as astringent. For inflamed and ulcerated conditions of the mucous membrane of the mouth, nitrate of silver is a valuable application, in the form of injections or solutions of various strengths, from gr. ij to 3ss of distilled water ; also in diseases of the antrum and fistula, as an injection. It is also used as a styptic, for the arrest of alveolar hemorrhage, but is not so reliable as tannic acid, gallic acid, etc., on account of the coagulum or clot formed by it, being soluble in an excess of albumen. It is also employed to obtund the sensitiveness of dentine, especially where the cause is mechanical abrasion; also in aphthae, mercurial stomatitis, ulceration of the gums, salivary fistula, alveolar abscess. For obtunding sensitive dentine, the stick form (one end of a stick inserted into a quill, or fused on the end of a platinum wire) is employed; or the end of a silver wire may be immersed in nitric acid, and applied to the sensitive surface, taking care to limit its action to the part on which it is to act. When applied to sensitive dentine, it acts on the gelatinous portion of the tooth, destroying its vitality to the extent of the combination which takes place. The objection to its use in such cases is the discoloration it causes.

Dr. C. N. Peirce recommends saturating blotting paper with a 40 per cent. solution of nitrate of silver for application to children's teeth, as it cauterizes the soft issues and acts upon the hard in a satisfactory manner, without danger or staining the fingers; asbestos paper or felt may also be saturated with the nitrate of silver for use in the mouth. Dr. Kirk recommends thin asbestos felt, as being better than paper. Before saturating the asbestos felt, it should be heated to redness over a Bunsen burner to burn out any organic matter with which it may be accidentally contaminated.

Dr. Black recommends nitrate of silver as useful in the treatment of caries of the teeth "under some certain conditions;" mostly in deciduous teeth, but occasionally in the permanent teeth also. His method is as follows: In the case of broad, shallow cavities in children's teeth, a full exposure of the decayed area as practicable, is made, and then the outer portion of the carious material only should be removed. Then the rubber dam is adjusted, the decayed area dried, and some pulverized nitrate of silver is laid upon the carious area, with just enough of water to dissolve it, and insure the saturation of the whole of the softened dentine. This should remain from five to fifteen minutes, the longer time if the patience of the child will allow, the surplus removed with absorbent cotton, and the cavity lightly washed with water and again dried. After such treatment the carious cavity should assume a deep black color within two or three days. In cavities so treated the progress of decay will generally be arrested either permanently, or for a considerable time.

As salt decomposes the nitrate of silver, a solution of the chloride of sodium will relieve the excessive pain following its application to sensitive dentine, or to ulcers of the mouth ; such a solution will also remove recent stains, if followed by the application of a solution of ammonia. Old stains may be removed with tincture of iodine, followed by cyanide of potassium.

A convenient way to keep nitrate of silver ready for use is. to soak asbestos fibre in a saturated solution, and allow it to dry.

The antidote in cases of poisoning by nitrate of silver is chloride of sodium (common salt), which converts it into chloride of silver, to be followed by emetics, and the proper antiphlogistic treatment. A solution of cyanide of potassium will remove recent stains of nitrate of silver.

Dental Formulae

For Inflamed and Ulcerated Mucous Membrane.

Argenti nitratis . . Aquae destillatae . . SlGna. - To be used as a lotion.

Dental Formulae 670Dental Formulae 671

For Diseases of the Antrum.

Argenti nitratis . . gr. j to gr. v Aquae destillatae . . .

Signa

To be used as an injection.

Signa 672Signa 673

For Ulcers and Aphtha.

Argenti nitratis .... Aquae destillatae ....

Signa

To be applied with a camel's-hair brush.

Signa 674Signa 675

For Mercurial Stomatitis.

Argenti nitratis . . . gr. ss Aquae destillatae . . .

Signa

To be used as a mouth wash.

Signa 676Signa 677