MILD (INSOLUBLE). — Zinci oxidum (U. S. P.), 1 to 5 grains.
TJnguentum zinci oxidi (U. S. P.).
Zinci carbonas preecipitatas (U. S. P.), 1 to 2 grains (emetic, 20 grains).
Zincum, U. S. P. (metallic zinc).
Physiological Action. — The common action of the soluble salts of zinc is as tringent and irritant. These properties are manifested in unequal degrees on ac count of their different degrees of solu bility and their varying affinity for water, and, perhaps, for the tissues.
The chloride and iodide, on account of their high diffusion power and great affinity for water, are the most energetic of the zinc salts. When placed upon the unbroken skin they are almost inert; when the cuticle is removed, they pene trate the tissues and destroy them for a considerable depth, producing at first a sensation of warmth, which increases to a burning pain, lasting seven or eight hours, by which time the tissues are de stroyed, and a white eschar is formed which separates in from seven to twelve days (Ringer). The chloride is a cor rosive poison.
The sulphate, having a lower diffusion power, exerts a more superficial action upon the tissues. In small doses it in creases for a time the appetite and di gestion, but later causes gastro-intestinal catarrh, nausea, and anorexia.
The soluble salts of zinc form insolu ble compounds with albumin, condense the tissues, and contract the blood vessels. They are stimulant and astrin gent, lessen the secretions, and promote healthy reparative action.
The carbonate and oxide are insoluble, or but slightly soluble, in the animal fluids. They possess no affinity for water, and, though their action upon the tissues is very weak, they are slightly astringent.
The carbonate in large doses produces some nausea and vomiting. The sul phate, in full doses, acts more speedily, is a safe emetic, producing little pros tration or nausea, and, as it generally empties the stomach in one complete evacuation, is the best emetic in cases of poisoning (Ringer). No satisfactory ex planation has yet been given of the emetic action of the zinc salts. The sul
phate excites vomiting when injected into the blood, or when mixed with al bumin. Sulphate of zinc in large doses is an irritant poison. The oxide, being insoluble, exerts but little action upon the stomach.
Zinc does not appear to remain in the body, nor to produce chronic poisoning like lead and mercury. The salts are eliminated less rapidly than some other metals, passing out of the system in small quantities by the urine. The chief part may be recovered from the feces, being probably excreted by the in testinal mucous membrane and with the bile.
Poisoning by Zinc Salts.—The chlo ride is an irritant poison, causing heat and a source of constriction of the throat, a strong metallic taste, a burning pain in the stomach, nausea, vomiting, profound depression of the pulse, cold ness of the surface, cold clammy sweats, cramps of the leg-muscles, etc. The mind remains unaffected. In a few in stances nervous symptoms have followed, besides the cramps, and in one notable case there was loss of the senses of taste and smell (Bartholow).
Sulphate of zinc in large doses acts as an irritant poison, producing vomit ing. colicky pains, diarrhoea, prostra tion, etc.: symptoms almost identical with those produced by the sulphate of copper.
Zinc-smelters, according to Schloc kow, rarely live beyond forty-five, and die, some of bronchial or gastro-intes tinal catarrh, others of a peculiar nerv ous affection which commences with burning superficial pains, exalted sensi bility, and reflex activity in the legs, and afterward puts on still more clearly the features of myelitis. A. Sadler finds that the intravenous injection of very large doses of zinc salts produces paral ysis of the voluntary muscles.
Epidemic of zinc poisoning among the soldiers stationed at Pahant,?, was caused by drinking water collected from roofs covered with galvanized iron. The water had become contaminated with zinc in such proportion as to cause disease.