Sources of Zinc. - The chief are native carbonate or calamine (ZnC03) and zinc blende (ZnS).

General Reactions of Zinc Salts. - The most characteristic test is that it forms a white sulphide, which is precipitated on the addition of ammonium sulphide to a solution, and which is insoluble in caustic alkalies. Caustic potash, soda, or ammonia give a white precipitate of hydrate, soluble in excess; ammonium carbonate gives a similar precipitate, soluble in excess; but sodium and potassium carbonate give a white precipitate, insoluble in excess.

General Preparation Of Zinc Salts




Zinc, B. and U.S.P. .

Zinc blende or calamine

Boasting, to drive off sulphur or carbonic acid, and then distilling the oxide with charcoal.

Granulated zinc, B.P.

Zinc ....

Melting and throwing into water.

Zinc chloride, B. and U.S.P.

Zinc ....

Dissolving in hydrochloric acid (Zn2 + 4HC1 = 2ZnCl2 + 2H2) :

it is then purified from lead or iron by passing chlorine through it, and adding carbonate of zinc,

2FeCl2 Ferrous chloride

+ Cl2 = Chlorine


Ferric chloride.

Fe2Cl6 + Ferric chloride

3ZnCO3 +

Carbonate of zinc

O =


Ferric hydrate

+ 3ZnCl2 Chloride of zinc

+ 3CO2.

Carbonic acid gas.

PbCl2 +

Chloride of lead

Cl2 +


2ZnCO3 =

Carbonate of zinc.

PbO2 +

Peroxide of lead

2ZnCl2 + Chloride of zinc


Carbonic acid gas.

Zinc sulphate, B. and U.S.P.

Zinc ....

Dissolving in sulphuric acid, and purifying in the same way as chloride.

Zinc carbonate. B. and U.S.P.

Zinc sulphate . . .

Precipitating with carbonate of sodium.

General Preparation Of Zinc Salts - Continued




Zinc acetate, B. and


Zinc carbonate.

Dissolving in acetic acid.

Zinc oxide, B. and




Zinc oleate, B.P.

Zinc oxide

By dissolving in oleic acid.

Zinc valerianate, B.

and U.S.P.

Zinc sulphate .

Mixing with sodium valerianate.

Zinc bromide, U.S.P.


Mixing with hot solution of potassium bromide, precipitating potassium sulphate by alcohol, filtering and evaporating. Or by acting on zinc with bromine.

Zinc iodide, U.S.P. .

Zinc ....

Digesting with iodine in water and evaporating.

Zinc phosphide.

U.S. P.


Passing phosphorus vapour in dry hydrogen over melted zinc.

Zinc sulphocarbolate,


Zinc oxide . .

Heating a mixture of carbolic acid and sulphuric acid, saturating the product with zinc oxide, evaporating and crystallising.

General Impurities of Zinc Salts. - Iron, lead, copper, and arsenic.

General Tests. - A solution of zinc salt acidulated with hydrochloric acid gives no precipitate with sulphuretted hydrogen (absence of lead, copper, or arsenic). The absence of copper is further ascertained by ammonia giving with a solution of zinc salts a white precipitate, soluble in excess without colour. If copper be present the solution would be blue. Solutions should give no blue with ferro- or ferri-cyanide of potassium, nor any black colour with tincture of galls (absence of iron).

General Action of Salts of Zinc. - They combine with albumen and coagulate it. The chloride of zinc thus acts as an escharotic after the epidermis has been previously removed by caustic potash. Neither it, nor the sulphate, nor acetate of zinc has any action on the unbroken skin, but when applied to mucous membranes, they will act as irritants in large, and as astringents in small doses.

Sulphate and acetate of zinc are prompt emetics, causing rapid evacuation of the contents of the stomach with little nausea or depression.

The mode of action of zinc salts as emetics has not been perfectly determined. It is probably partly due to the local effect upon the stomach, and partly to the stimulant action upon the vomiting centre in the medulla oblongata after absorption into the circulation.

Vomiting is produced by the injection of zinc salts into the circulation, but this may be partly due to irritation of the stomach by the zinc salts during the process of excretion by its mucous membrane, as well as to the action upon the medulla.

In small doses zinc salts act also as nervine tonics, and lessen sweating.