Origin. - Obtained by roasting the native zinc sulphide or carbonate, and reducing the resulting oxide with charcoal.

Description and Properties - A bluish-white metal, showing a crystalline fracture and having a specific gravity ranging from 6.9 when it is cast to 7.2 after it is rolled. Soluble in diluted sulphuric or hydrochloric acid, with evolution of hydrogen gas.

Metallic zinc occurs in the form of thin sheets or in irregular, granulated pieces, or moulded into thin pencils, or in a state of fine powder.

Official Salts

Zinci Acetas - Zinci Acetatis - Zinc Acetate. - Origin. - Obtained by dissolving zinc acetate in acetic acid and water and boiling: zinc acetate crystallizes out.

Description and Properties. - Soft, white, six-sided, monoclinic plates, of a pearly luster, having a faintly acetous odor and an astringent, metallic taste. Exposed to the air, the salt gradually effloresces and loses some of its acid. Soluble in 2.5 parts of water and 36 parts of alcohol. Zinc acetate should be kept in well-stoppered bottles.

Dose. - As a tonic, 1/2-2 grains (0.03-0.12 Gm.); as an emetic, 10-30 grains (0.6-2.0 Gm.); but principally used externally and locally [2 grains (o.12Gm.),U. S. P.

Dose. - As a tonic, 1/2-2 grains (0.03-0.12 Gm.); as an emetic, 10-30 grains (0.6-2.0 Gm.); but principally used externally and locally [2 grains (0.12 Gm.), U. S. P.].

Zinci Carbonas Praecipitatus - Zinci Carbonatis Praecipitati - Precipitated Zinc Carbonate. - Origin. - Prepared by pouring together solutions of zinc sulphate and sodium carbonate, and drying the precipitated zinc salt.

Description and Properties. - An impalpable white powder, of somewhat variable chemical composition, without odor or taste; permanent in the air. Insoluble in water or alcohol.

Dose. - 2-3 grains (0.12-0.18 Gm.). Chiefly used externally.

Zinci Chloridum-Zinci Chloridi - Zinc Chloride (U. S. P.).

A white, granular powder or porcelain-like masses. Very deliquescent. Not used internally.

Zinci Iodidum - Zinci Iodidi - Zinc Iodide. - Origin. - Prepared by dissolving zinc oxide or carbonate in hydriodic acid.

Description and Properties. - A white, granular powder, odorless, having a sharp, saline, and metallic taste. Very deliquescent and liable to absorb oxygen from the air, becoming brown from liberated iodine. Readily soluble in water, alcohol, or ether. Zinc iodide should be kept in small glass-stoppered bottles.

Dose. - 1/2-2 grains (0.03-0.12 Gm.). Also used externally. [1 grain (0.065 Gm.), U. S. P.].

Zinci Oxidum - Zinci Oxidi - Zinc Oxide. - Origin. - Prepared by heating zinc carbonate to redness in a crucible.

Description and Properties. - An amorphous white powder without odor or taste. Insoluble in water or alcohol. It should be kept in well-stoppered bottles.

Dose. - 1/4-5 grains (0.015-0.3 Gm.).

Zinci Phenolsulphonas - Zinci Phenolsulphonatis - Zinc Phenolsulpho-nate. - Zn(C6H4(OH)SO3)2 + 8H1O, commonly known as zinc sulphocarbolate. It should contain not less than 99.5 per cent. zinc paraphenolsulphonate. (C6H4(OH)-SO3)2Zn 1:4 + 8H10.

Description and Properties. - Colorless, transparent, rhombic prisms or tabular crystals, odorless, and having an astringent, metallic taste; effloresces on exposure and may become pink. Easily soluble in water or alcohol. The aqueous solution is acid to litmus.

Dose. - Average dose: 2 grains (0.12 Gm. = 125 milligrammes), U. S. P.

Zinci Stearas - Zinci Stearatis - Zinc Stearate. - Used in preparing unguen-tum zinci stearatis, 50 per cent.

Zinci Sulphas - Zinci Sulphatis - Zinc Sulphate. - Origin. - Prepared by dissolving granulated zinc in sulphuric acid, certain precautions being taken to remove impurities.

Description and Properties. - Colorless, transparent, rhombic crystals, without odor, and having an astringent, metallic taste. Efflorescent in dry air. Soluble in 0.6 part of water and in 3 parts of glycerin; insoluble in alcohol. Zinc sulphate should be kept in well-stoppered bottles.

Dose. - 1-3 grains (0.06-0.18 Gm.); as an emetic, 10-60 grains (0.6-4.0 Gm.). [15 grains (1 Gm.), U. S. P.].

Unguentum Zinci Oxidi - Unguenti Zinci Oxidi - Ointment of Zinc Oxide (20 per cent.). - Used externally and locally.

Zinci Valeras. - See Valerian.

Antagonists and Incompatibles. - The salts of zinc are incompatible with the vegetable astringents, alkalies and their carbonates, lime water, the sulphides, silver nitrate, lead acetate, and milk.

Physiological Action. - Externally and Locally. - The soluble zinc salts resemble the lead salts in their action, but they are less powerful astringents. They are also to a slight extent hemostatic. The chloride is exceedingly caustic. The insoluble zinc compounds are mildly antiseptic and astringent.

Internally. - Digestive System. - The sulphate of zinc and, in a slight degree, the carbonate are specific emetics, causing rapid emesis, with but little nausea or depression. It is believed that their effects are due to local action on the stomach. Central nervous action may play a part in the emesis.

The salts of zinc also act as astringents upon the gastro-intestinal mucous membrane. Dyspepsia, constipation, or diarrhea frequently follow its ingestion even in small quantities.

Circulation. - Zinc salts, when introduced into the circulation directly, cause a depression of the heart's action, resembling in that, as in other regards, the action of copper, with which metal its general effects are most closely allied. The blood-pressure is affected but slightly. The pulse is somewhat slowed, especially just before death. With the blood, zinc forms new hemoglobin compounds (zinc-hemol).

Nervous System. - Zinc produces a depression of the central nervous system. When introduced intravenously, it may cause paralysis of the extremities.

Absorption and Elimination. - Zinc is taken up from the stomach and intestine and is found in largest quantities in the liver and bile. It is also found in the kidneys, pancreas, spleen, and thyroid. It is not held in the body in as stable a condition as the lead salts, and is less liable to bring about chronic poisoning. It is largely eliminated by the kidneys and bile. The salivary, milk, and intestinal secretions also eliminate some. In its passage through the kidneys zinc is an irritant, causing, in poisoning, a parenchymatous nephritis.