When a solution of this salt, in 6 of water, is boiled with a little nitric acid, and a solution of ammonia is then added until the oxide of zinc at first precipitated is all redissolved, no yellow precipitate remains, or a trace only, and the solution is colourless.
Uses. In medicine, as a tonic, antispasmodic, &c.; in doses of 1 to 2 gr., twice daily; as an emetic, 10 to 30 gr. In large doses it is poisonous. It has been employed with benefit in dyspepsia, fluor albus, chorea, epilepsy, hooping-cough, and other convulsive and nervous affections, generally combined with bitters, foxglove, hemlock, henbane, or opium. As an emetic, it acts almost immediately, and is therefore well suited to empty the stomach at the commencement of a fit of ague, and in cases of poisoning, &c. It is also extensively used externally, to form astringent and repellant collyria, injections and lotions.
Zinc, Sulpho-carbolate. The acid prepared as in sulpho-carbolate of soda (which see) is saturated by aid of a gentle heat with oxide of zinc, filtered, and crystals allowed to form. The crystals should be dried by exposure to the air.
Zinc, Vale′′rianate of. Zn(C5H9O2)2. Syn. Zinci valerianas (B. P., Ph. D.) Prep. (Ph. D.) Valerianate of sodium, 21⁄2 oz., and sulphate of zinc, 2 oz. 7 dr., are each separately dissolved in distilled water, 1 pint; the solutions are then heated to 200° Fahr., mixed, and the resulting crystals skimmed off; the liquid is next evaporated at a temperature not higher than 200°, until it measures 4 fl. oz., the crystals,
as they form, being removed from the surface; the salt thus obtained is steeped, for an hour, in distilled water, just sufficient to cover it, after which the whole is transferred to a paper filter, on which it is at first drained, and then dried at a heat not exceeding 100°.
Prop., &c. Brilliant white, pearly scales; very light; astringent; smells strongly of valerianic acid; only slightly soluble in cold water, more so in hot water, and freely soluble in alcohol and ether; exposure to heat rapidly decomposes it; exposure to the air also decomposes it, but more slowly. It is regarded as powerfully antispasmodic and tonic.—Dose, 1 to 3 gr., thrice daily, made into pills; in neuralgia, tic douloureux, nervous headaches (more particularly hemicrania), hysteria, palpitation of the heart, vertigo, chorea, epilepsy, &c.
Obs. Butyrate of zinc, scented with valerianic acid, which is often sold for the above compound, may be detected by distilling it with sulphuric acid; the distillate, tested with a strong solution of acetate of copper, gives a bluish-white precipitate if it contains butyric acid. The valerianate is distinguished from the other salts of zinc by its extreme lightness.
ZINC-E′THYL. Zn(C2H5)2. A curious liquid body, discovered by Dr Frankland, and formed, along with iodide of zinc, when iodide of ethyl is heated with pure zinc in a sealed glass tube. The mixed white product, by distillation in a current of hydrogen, yields pure zinc-ethyl. It is a highly volatile liquid, having a rather disagreeable odour, and so rapidly decomposed by contact with the air that it takes fire. Water resolves it into hydride of ethyl, and other products.
ZINC-ME′THYL. Zn(CH3)2. Obtained by the action of zinc upon iodide of methyl, as zinc-ethyl. It takes fire on coming in contact with the air.
ZINC′ING. Syn. Zinking. Vessels of copper and brass may be covered with a firmly adherent layer of pure zinc, by boiling them in a solution of chloride of zinc, pure zinc turnings being at the same time present in considerable excess. The same object may be effected by means of zinc and a solution of chloride of ammonium or hydrate of potassium.