Page 295 - My FlipBook

NITRATE OF SILVER. 293

ARGENTI NITRAS—NITRATE OF SILVER.
LUNAR CAUSTIC.
Formula.—AgNOg.
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 crys-
tallizes in shining, rhombic plates. The action of light and or-
ganic matters cause it to turn black. It is wholly soluble in dis-
tilled water, the only preparation of water that should be em-
ployed 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 caus-
ing 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, anti-
spasmodic, 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, adminis-
tered 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 antispas-
modic tonic. It is chiefly used externally, as a stimulant, vesi-
cant, and escharotic. If applied, even lightly, three or four times,
to the moistened skin, it will cause vesication in a ^^vi hours.
The blue appearance on the skin, when small doses are long con-
tinued, is said to be preceded by a peculiar blue line on the gums,
like that from lead poisoning. A very minute quantity of this