ZINCI OXIDUM - OXIDE OF ZINC, ZnO,=81.

Preparation

By exposure of the carbonate to a dull red heat until all the carbonic acid is driven off. "Hubbuck's" oxide of zinc is obtained by combustion of the metal in air.

Characters And Tests

A white heavy powder, without taste or odor, insoluble in water, soluble in acids; moderate heat renders it yellow. Commercial specimens are often impure from presence of carbonates, sulphates, chlorides, iron, etc.

ZINCI CHLORIDUM-CHLORIDE OF ZINC, ZnCl2, = 136.

Preparation

By dissolving zinc in hydrochloric acid, and evaporating the solution; chlorine water is then added (to combine as chloride with the iron usually present), and afterward zinc carbonate, which forms more zinc chloride and precipitates ferric oxide.

Characters

Chloride of zinc is soft, white or semi-transparent, crystalline or waxy, and is met with either in opaque tablets or in pencils like nitrate of silver. It is very soluble and deliquescent, but if mixed with an equal part of oxide (oxychloride), may be kept dry for a long time.

Zinci Sulphas - Sulphate Of Zinc - White Vitriol, ZnSO47H1O, = 287.

Preparation

By dissolving zinc in dilute sulphuric acid: chlorine water and carbonic of zinc are added, as in the last preparation, and for the same purpose, viz., to remove any iron that may be present.

Characters

Occurs in prismatic crystals, which may be large or small. The latter much resemble in appearance those of sulphate of magnesia, but their strong styptic taste will distinguish them from the bitter magnesian salt (v. p. 233): they redden litmus and effloresce in air.

ZINCI CARBONAS - CARBONATE OF ZINC, ZnCO3(ZnO)22H1O, = 341.4.

Preparation

By adding carbonate of sodium to a boiling solution of sulphate of zinc, and drying the precipitate; if cold solutions be used, the precipitate is gelatinous. (The compound formed is really a hydrated oxycarbonate, as in the formula.)

Characters

A soft, white powder, resembling magnesia, insoluble in water, tasteless and inodorous. The native impure carbonate (calamine, lapis calaminaris) was formerly officinal, but the pink powder sold under that name was almost always spurious, consisting of barium sulphate colored with iron.

ZINCI ACETAS - ACETATE OF ZINC, Zn(C2H3O2)22H1O, = 219.

Preparation

By dissolving the carbonate in acetic acid. Occurs in thin, ustrous, micaceous plates, having a sharp astringent taste.

ZINCI VALERIANAS - VALERIANATE OF ZINC, Zn(C5H9O2)2, = 267.

Preparation

By mixing concentrated solutions of sulphate of zinc and valerianate of sodium.

Characters

Occurs in brilliant scaly crystals, which have an odor of valerian, and a metallic taste; soluble slightly in cold water or ether, freely in hot water and in alcohol. It is liable to be contaminated with butyrate of zinc.