Nitrate of Silver. AgO, NO5. Called also Argentum Nitratum, Argentum Nitrieum, Lunar Caustic. A compound of Oxide of Silver 68.24, Nitric Acid 31.76, in 100 parts, or 1 Eq. Oxide of Silver = 116 + 1 Nitric Acid = 54 =170, Eq. Wt Med. Prop. and Action. Tonic, anti-spasmodic, and sedative, in doses of from gr. 1/4 to gr. j. or gr. ij. In very large doses, it is a corrosive poison If taken in small doses lor a great length of time (two or three months), it occasionally communicates a peculiar blue appearance to the skin. When applied to the skin, mucous membranes, or ulcers, it produces a white mark, owing to the union, according to Dr. Pereira, of the salt with the coagulated albumen of the cuticle: this gradually becomes bluish groy, purple, and ultimately black, owing to the partial reduction of the silver. Its probable action, when given internally, is that of astringing the mucous coats of the intestines. It is also a powerful tonic of the nervous system, but its modus operandi, in the latter case has not yet been satisfactorily explained. Heller* carefully examined the blood and urine of epileptics who had undergone long courses of the Nitrate, but failed to detect any traces of Silver, whilst he found the fAeces to contain, in the form of the Chloride, the greater part of the Silver which had been administered Still we are justified in believing that a portion of the salt becomes absorbed, and exercises a tonic influence on the nervous system, independent of the local chemical action it may exercise on the mucous coats of the stomach and intestinal canal with which it comes in contact Externally applied, it is stimulant, vesicant, and escharotic. The Nitrate lightly applied three or four times to the moistened skin causes vesi-cation in a few hours. In most persons, it creates less irritation than Cantha-rides; whilst, in others, it causes acute pain. In rare cases, delirium has follewed its application to the scalp.

Dose, gr. 1/4 - gr. j. or more.

314. Obs. on the Use of the Nitrate of Silver.

1. Previous to commencing a course of the Nitrate of Silver, administer a mild aperient (Ol Ricini) to carry off any superabundant acid or fAecal accumulations.

i It is rarely admissible as long as inflammation is present. When this is subdued, it may be given with advantage.

3. It is best given in some mild vegetable powder with mucilage or extract; the usual vehicle, bread crumbs, is objectionable, from their usually containing a portion of common salt, which decomposes the Nitrate.

4. The Nitrate Should Be Finely Powdered Before Being Made Into Pills

Its efficacy is thereby greatly promoted.

5. During A Course Of This Medicine, It Should

be occasionally intermitted for a day or two and a mild aperient administered. If this is done, the course may be continued for a longer period without any of the ill consequences which would otherwise ensue. The gums and fauces should be frequently and carefully examined, and the slightest discoloration indicates the necessity of immediately discontinuing the salt.

6. During its use the quantity of salt or salt food taken should be small, and never immediately before or after the remedy.

* Archiv fur Physiol. 1846, vol. i. p. 324.