Solutio Sulphatis Zinci. Edin. Solution of Sulphate of Zinc

"Take of sulphate of zinc, sixteen grains; water, eight ounces; diluted sulphuric acid, sixteen drops. Dissolve the sulphate of zinc in the water, and having added the acid, filter the solution through paper."

This formula is given under the idea of the common sulphate of zinc (which often contains some excess of oxide, and some oxide of iron) being employed. The superabundant oxide, if present, is dissolved by the acid, so that a solution of an uniform strength is always obtained. It is rather too strong for the purposes of a collyrium in chronic ophthalmia; and the addition of the acid renders it less fit to be used as an injection in gonorrhoea.

Solutio Acetatis Zinci. Edin. Solution of Acetate of Zinc

"Take of sulphate of zinc, one drachm; acetate of lead, four scruples; distilled water, twenty ounces. Dissolve. Mix the salts separately in ten ounces of the water; then mix the olutions, and after the precipitate subsides, filter."

Syn. Dissolution d' Acetate de Zinc (P.), Liquore de 1' Acetto di Zinco (I.).

In this process a double decomposition takes place: the sulphuric acid of the sulphate of zinc unites with the oxide of the acetate of lead, whilst its acid combines with the disengaged oxide of zinc. The former salt being insoluble it is precipitated in the form of a heavy, white powder, but the acetate of zinc remains dissolved; and thus its solution, which is colourless and limpid, is easily separated by filtration; it consists of 1 eq. of the oxide of zinc = 40.3 +1 of acetic acid =

51.48 + 7 of water =63; making the equivalent 154.78 (Zn A).

Medical properties and uses. - This solution is astringent; and was long employed before it was introduced into the Pharmacopoeia, and even before its nature was clearly understood. It is an useful collyrium in chronic ophthalmia, and in the acute variety of this disease, after the inflamed vessels are unloaded, and the inflammatory action subdued. It is also an useful injection in the advanced stage of gonorrhoea

Tinctura Acetatis Zinci. Dub. Tincture of Acetate of Zinc

"Take of sulphate of zinc, acetate of potassa, of each one part. Rub them together, and add of rectified spirit of wine, sixteen parts. Macerate for a week, with occasional agitation, and filter through paper."

In this process, a double decomposition also takes place, acetate of zinc and sulphate of potassa being produced; the former of which is dissolved in the spirit, while the latter remains undissolved, and, therefore, is easily separated. It is a tedious process, and possesses no advantages over the former to recommend it.

Medical properties and uses. - This tincture is astringent; but requires to be diluted with water, before it can be used either as a collyrium or an injection. It might be advantageously employed as an internal remedy in dyspepsia, and other debilities of the stomach.