Uses, &c.—Zinc is used to form galvanic plates; in fireworks, and in medicine. Of late years it has also been extensively used in the manufacture of vessels of capacity, tubing, sheets for roofing, and other things that require lightness and durability.
Zinc, Amalgamated, which is employed for voltaic batteries, is prepared as follows:—The plates, having been scoured with emery, are immersed for a few seconds in dilute sulphuric
acid, then rinsed in clean soft water, and, after the loose water has drained from their surface, dipped into a strong solution of either mercuric nitrate or chloride, or into equal parts of a mixture of saturated solutions of mercuric chloride and acetate of lead; the plates are, lastly, dipped into water, and then rubbed with a soft cloth. Another and simpler method is to rub mercury over the plates while wet with dilute sulphuric acid.
Zinc, Granulated. Syn. Zincum granulatum (B. P.). Fuse commercial zinc in a crucible, pour it in a very thin stream into a bucket of cold water, and afterwards dry the zinc.
Zinc, Ac′etate of. Zn(C2H3O2)2. Syn. Zinci acetas, L. Prep. 1. (Ph. D.) Acetate of lead, 1 lb., is dissolved in distilled water, 21⁄2 pints, and the solution being placed in a cylindrical jar, sheet zinc, 4 oz., rolled into a coil, is immersed therein; after 24 hours the liquid is decanted, evaporated to 15 oz., and solution of hypochlorite of calcium added drop by drop, until a reddish precipitate ceases to form; the liquid is then filtered, acidulated by the addition of a few drops of acetic acid, reduced by evaporation to 10 fl. oz., and set aside to crystallise; the crystals are dried on bibulous paper set on a porous brick, and then preserved in a well-stopped bottle. More crystals may be obtained from the mother-liquor.
2. (B. P.) Add 2 oz. of carbonate of zinc in successive portions to 3 fl. oz. of acetic acid, previously mixed with 6 fl. oz. of distilled water, in a flask; heat gently, add by degrees 2 fl. oz. of acid, or q. s., till the carbonate is dissolved; boil for a few minutes, filter while hot, and set it aside for two days to crystallise. Decant the mother liquor, evaporate to one half, and again set it aside for two days to crystallise. Place the crystals in a funnel to drain, then spread them on filtering paper on a porous tile; and dry them by exposure to the air at ordinary temperatures.
Prop., &c. Efflorescent, white, hexagonal plates, having a powerful styptic taste; very soluble in water; less soluble in alcohol; decomposed by heat. It is tonic, antispasmodic, and emetic.—Dose, 1 to 2 gr.; as an emetic, 10 to 20 gr.; externally, 2 or 3 gr. to water, 1 fl. oz., as an astringent lotion or injection.
Zinc, Bro′mide of. ZnBr2. Syn. Zinci bromidum, L. Prepared like the corresponding salt of iron.
Zinc, Car′bonate of. ZnCO3. Syn. Zinci carbonas purum, Zinci carbonas (B. P., Ph. D.), L. Prep. 1. (Ph. D.) Solution of chloride of zinc (Ph. D.), 1 pint is added, in successive portions, to a solution of crystallised carbonate of sodium of commerce, 2 lbs., dissolved in boiling distilled water, 6 pints, and the whole is boiled until gas ceases to be evolved; the precipitate is then washed, and dried, at first on blotting-paper, and, finally, by a steam or water heat.
2. (B. P.) Dissolve 101⁄2 oz. carbonate of soda with 1 pint of boiling water in a capacious porcelain vessel, and pour into it 10 oz. of sulphate of zinc, also dissolved in 1 pint of water, stirring diligently. Boil for 15 minutes after effervescence has ceased, and let the precipitate subside. Decant the supernatant liquor, pour on the precipitate 3 pints of boiling distilled water, agitating briskly; let the precipitate again subside, and repeat the process of affusion of hot distilled water and subsidence till the washings are no longer precipitated by chloride of barium. Collect the precipitate on calico, let it drain, and dry it with a gentle heat.