This is prepared by adding solution of potassa to a solution of nitrate of silver, the oxide being precipitated. It is an olive-brown powder, inodorous, nearly tasteless, and very slightly soluble in water; and consists of one equivalent of silver and one of oxygen. Though used as a medicine, on the continent of Europe, during the last century, it attracted little notice until proposed by Dr. Butler Lane, as a substitute for the nitrate, in the various diseases in which that remedy has been used.

Oxide of silver acts locally as a slight irritant and astringent, but is wholly destitute of the property, which renders the nitrate so valuable, of combining with the tissues. Taken into the stomach, it is either absorbed, or forms soluble compounds which are absorbed; for it produces occasional soreness of the gums and salivation, and has even caused discoloration of the skin.

* A case is recorded in which the daily use of half a grain, for eight months consecutively, produced a striking and universal discoloration of the surface. (Archives Generales, 5e ser., ix. 358).

It was substituted for the nitrate as a milder remedy, and capable of producing its constitutional impression, with less danger of affecting the skin; but the want of the property of combining with the superficial part of the tissues, incapacitates it for those local alterative effects on diseased surfaces which give its highest value to the nitrate; and, in proportion as it may be less liable to discolour the skin, it will probably prove less efficacious as a medicine; the liability to produce that effect being incidental to the absorption of the silver, no matter in what form it may be taken up, and consequently in some degree a test of its constitutional influence. It seems to me, therefore, that little is gained by the substitution. Nevertheless, the oxide has been found useful, by Dr. Lane and others, in gastralgia, pyrosis, gnteralgia, dysentery, diarrhoea, idiopathic night-sweats, dysmenorrhoea, leucorrhoea, and uterine hemorrhage. In the last-mentioned affection, the favourable report of Dr. Lane is supported by the experience of Dr. Golding Bird; and Dr. Thweatt, of Petersburg, Va., published several cases of menorrhagia, in which the medicine appeared to have proved efficacious. (Am. Journ. of Med. Sci., N. S., xviii. 69.) The oxide would seem to promise most fairly as a substitute for the nitrate in epilepsy, and other spasmodic complaints; but, though it may probably be given with less risk in large doses, experience has not proved that it possesses superior advantages as a remedy. It is said to have been used successfully in taenia.

The dose is a grain, repeated twice or three times a day, which may be gradually increased to two grains. In the larger quantity, it sometimes occasions a little griping and tenesmus, which may be checked by an anodyne enema. (Thweatt, Ibid.) The same caution is requisite, in relation to the continuance of the dose, as when the nitrate is employed. It may be given in powder or pill.

The oxide has been used also externally, in powder or ointment, in ophthalmia, excoriated nipples, irritable ulcers, and venereal sores; and, smeared on a bougie, has been employed in gonorrhoea. The ointment may be prepared with a drachm of the powder and an ounce of lard.