The zinc (zincum) salts fall into two distinct classes, viz., those which are irritant locally, and those which are soothing locally.

The irritant salts are the sulphate and the chloride. Their action resembles that of copper sulphate. The sulphate is employed in 1 to 5 per cent. solution in urethritis, vaginitis, and conjunctivitis. To produce vomiting the dose is 30 grains (2 gm.). The chloride is also caustic, but its chief use is in 1 per cent. solution as an odorless disinfectant.

The soothing salts are the stearate, which is a light, fluffy, rather greasy, white powder, and the oxide and carbonate, which are heavy white powders. They are insoluble in water and very slightly astringent, and are of value as soothing protectives to inflamed surfaces. They may be employed in lotion or ointment form, or as dusting-powders in chafed or inflamed skin, as in eczema or dermatitis. They are rarely used internally, as they tend to form the irritant chloride.

Zinc ointment, a 20 per cent. admixture with benzoinated lard, is very widely employed, either by itself or as a vehicle for other drugs in the treatment of the skin. Calamine, a natural impure carbonate of zinc, is red from the presence of iron, and sometimes slightly gritty. The official precipitated carbonate of zinc, which is white, is a pure form. Calamine lotion (unofficial) is a mixture of zinc oxide, calamine, glycerin, lime-water, and rose-water.

The oxide and the sulphate in 2-grain (0.15 gm.) doses were at one time employed in epilepsy, chorea, whooping-cough, and other spasmodic nervous affections, but are scarcely used internally at present.

Zinc chills (spelter chills, brass chills, brass shakes, brazier's chills, brass founder's ague) occur where zinc is volatilized and usually after work is over, probably because sweating stops. Their appearance is favored by indulgence in alcohol. After a period of lassitude, dull headache, oppression in the chest and sometimes nausea, the chill comes on with muscular pains, the temperature rising as high as 103° F. The chill subsides with the onset of profuse sweating, zinc being eliminated in urine and feces. Swelling of the spleen and albumin in the urine are reported, but, as a rule, the shakes are looked upon merely as an inconvenience and are not often reported to a doctor (U. S. Bureau of Mines, Bulletin 73).