Zincun Granulatum. - Made by pouring fused zinc into cold water.

From Zincum Granulatum are made: a. Zinci Chloridum. - Chloride of Zinc. ZnCl2.

Source. - Made by dissolving Zinc in Diluted Hydrochloric Acid, and evaporating; Chlorine Water and Carbonate of Zinc being used in the process, to precipitate iron or tin present as impurities.

Characters. - Colourless rods or tablets, very deliquescent, and caustic. Solubility, 10 in 4 of water, freely in rectified spirit and ether.

Impurities. - Sulphates, iron, and calcium.

b. Liquor Zinci Chloridi.

Source. - Made as above, without evaporation. Characters. - Colourless. Used externally only.

c. Zinci Sulphas. - Sulphate of Zinc. ZnSO4.7H1O. Source. - Made from Zinc and Sulphuric Acid, like the Chloride, with the same precautions.

Characters. - Colourless prisms, with a metallic styptic taste.

Impurities. - Iron, lead, copper, arsenic.

Dose. - 1 to 3 gr. as a tonic; 10 to 30 gr. as an emetic.

From Zinci Sulphas are made: a. Zinci Carbonas. - Carbonate of Zinc. ZnCO3(ZnO)23H1O. "Calamine."

Source. - Made by decomposing a solution of Sulphate of Zinc with a solution of Carbonate of Soda. (1) ZnSO4 + Na2CO3 = ZnCO3 + Na2SO4. (2) 3ZnCO3 + 3H1O = ZnCO32(ZnO),3H1O + 2CO2.

Characters. - A white, tasteless, inodorous powder, insoluble in water; an impure carbonate.

Impurities. - Sulphates, chlorides, copper.

From Zinci Carbonas are made:

(i) Zinci Oxidum. - Oxide of Zinc. ZnO.

Source. - Made by heating the Carbonate.

Characters. - A soft, nearly white, tasteless, and inodorous powder, insoluble in water.

Impurities. - The carbonate; effervescing with acids. And its impurities.

Dose. - 2 to 10 gr.

Preparation.

Unguentum Zinci Oxidi. - 80 gr. to 1 oz. Benzoated Lard.

(ii) Zinci Acetas. - Acetate of Zinc. Zn(C2H3O2)2.2H1O.

Source. - Made by dissolving Carbonate of Zinc in Acetic Acid and Water, and crystallising. ZnCO3,2ZnO.3H1O + 6C2H4O2 = 3(Zn2C2H3O2) + 6H1O + CO2.

Characters. - Thin colourless crystalline plates, of a pearly lustre, with sharp, unpleasant taste. Solubility, 10 in 25 of water.

Impurities. - Those of the carbonate.

Dose. - 1 to 2 gr. as tonic; 10 to 20 gr. as an emetic.

Zinci Carbonas is also used in making Zinci Chloridum and Zinci Sulphas.

. Zinci Valerianas. -Valerianate of Zinc.

Zn(C5H9O2)2.

Source. - Made by mixing solutions of Sulphate of Zinc and Valerianate of Soda, and crystallising.

Characters. - Brilliant white, pearly, tabular crystals, with an odour of valerianic acid, and a metallic taste. Solubility, 1 in 120 of water; 1 in 60 of spirit.

Impurities. - Sulphate and hutyrate of zinc.

Dose. - 1 to 3 gr.

Non-officinal Preparations of Zinc.

Calamina Praeparata. - Calamine. Impure Oxide of Zinc, obtained by calcining native Carbonate of Zinc, and reducing it to an impalpable powder. A greyish or flesh-coloured powder.

Oleate of Zinc. - Made by heating Oxide of Zinc with Oleic Acid. 1 to 8.

Incompatibles of Zinc Salts in general.

Alkalies and their carbonates, lime-water, acetate of lead, nitrate of silver, astringent vegetable infusions or decoctions, and milk.

Action And Uses. 1. Immediate Local Action And Uses

Externally. - The salts of zinc closely resemble in their action the salts of lead, silver, and copper, being caustic in their stronger forms, astringent or antiphlogistic in their weaker forms. Zinc presents every degree of this action, according to the salt employed, that is probably according to the solubility and diffusion-power of the particular combination of the metal. Thus the chloride, which is highly deliquescent, penetrates the tissues, and is a powerful eseharotic, causing destruction of the part, with severe pain, separation of a slough, and subsequent healing. It is employed to destroy morbid growths, chronic ulcers, and gangrenous parts, in the form of a paste or of solid arrows made with plaster of Paris or flour, or as a itrong solution. The sulphate and acetate have less affinity for water, and are much less powerful than the chloride. When applied to the broken skin, an ulcer, or an exposed mucous surface, they precipitate the albuminous juices or secretions, coagulate the protoplasm of the upper layers of growing cells, and indirectly cause contraction of the vessels, though less than silver and lead. The sulphate of zinc is the most common of all applications for healing ulcers and wounds, limiting the amount of discharge, checking excessive or "weak" growth, and modifying the intensity of the inflammatory process with which the healing is associated. A solution of this salt is the basis of the ordinary "red lotion" of many hospital pharmacopoeias; and other weak solutions of the same may he employed as a wash or injection for the eyes, urethra, vagina, and other accessible mucous tracts. The oxide and carbonate of zinc, and calamine, act locally as mild astringents in inflamed conditions of the superficial layers of the skin, such as eczema, controlling exudation and hyperaemia, and protecting the parts from the air. Being insoluble in water, they are applied in the form either of powder or of the ointment.

Internally, the local action of zinc corresponds. It is but little used in the mouth or throat, but its effect on the stomach as a local irritant furnishes us with the most familiar of our direct emetics. Sulphate of zinc, in doses of 20 grains, causes rapid and complete vomiting, attended by less immediate depression and less subsequent nausea than antimony and ipecacuan. It is much employed in narcotic poisoning; more rarely in croup, diphtheria, and phthisis, to clear the air passages; or even to empty the stomach in painful dyspepsia. The oxide on reaching the stomach is dissolved, and acts like the soluble salts of zinc.

In the intestine the irritant action of zinc is continued, if it be given in large doses, but this effect is never desired therapeutically. On the contrary, the oxide, in sufficient doses to relieve a moderate superficial catarrh, is often a very efficacious astringent in the treatment of diarrhoea in children.

2. Action In The Blood

Zinc readily enters the circulation, but nothing is known respecting its influence on the plasma or corpuscles which can be turned to therapeutical account.

3. Specific Action And Uses

The action of zinc upon the tissues has been learned chiefly from its effect in certain diseased conditions in man, and is but imperfectly understood. It appears to bo a depressant to the nervous and muscular systems, and has been employed with unquestionable success in epilepsy, chorea, and whooping cough, all of which are characterised by nervo-muscular excitement. Observations on animals, in which the irritability of the voluntary and cardiac muscles is found to be decidedly reduced by zinc, confirm this experience.

4. Remote Local Action And Uses

The kidneys and mammary gland, and probably the mucous surfaces and skin, are the channels of elimination of zinc. It is possible that the metal exerts a second or remote astringent effect on these parts as it is leaving the system; for the sulphate and oxide appear to have the power of arresting chronic discharges from remote mucous passages, such as the uterus and vagina, even when given internally; and it is certain that the oxide diminishes the perspirations of phthisis in some instances.

5. Actions And Uses Of The Different Salts Of Zinc

These have been sufficiently indicated in the preceding description. The Chloride stands alone as a powerful escharotic, never to be given internally; it possesses also disinfectant properties, as the Liquor Zinci Chloridi, which is used to mop out very foul wounds, and very extensively to wash infected rooms, flush drains, etc. The Sulphate and Acetate closely resemble each other in their action, but the acetate is little used. The Oxide and Carbonate are similarly allied to each other, the former being generally employed. Zinci Valerianas probably acts as a zinc salt only, the valerianic acid appearing to be inert. See Valeriana Radix.