PRECIPITATED ZINC CARBONATE 145 



Doae.—H. & C, 3i-ii, (4-8); Sh. & Sw., gr.x-xx, (.6-1.3); D., gr.ii-iii, (.12-.2); 

 Emetic — D., gr.x-xv, (.6-1). 



ZiNci Cakbokas Prjecipitatps. Precipitated Zinc Carbonate. (U. S. P.) 



Synonym.- — Zinci carbonas, B. P.; precipitated zinc carbonate, E.; carbonate 

 (sous-) de zinc hydrate, hydrocarbonate de zinc, Fr. ; kohlensaures zinkoxyd, G. 



Derivation. — Solutions of nearly equal weight of sodium carbonate and zinc 

 sulphate are boiled together; dry precipitate. 2 ZnCOs, 3 J^n(0H)2? (hydrated 

 basic zinc carbonate) results. This, salt is in reality a mixture of zinc carbonate 

 and oxide, containing not less than 60% of ZnO, with water of crystallization. 



Properties. — An impalpable white powder, without odor or taste; insoluble in 

 water or alcohol. It is permanent in the air. 



Zinci Oxidum. Zinc Oxide. Zn O. (U. S. & B. P.) 



Synonym. — Flores zinci, oxyde de zinc, Fr. ; zinkoxyd, G. ; zincum oxydatum, 

 P. G. 



Derivation. — Heat the carbonate to redness. 



Properties. — A very fine amorphous, white or yellowish-white ppwder, free 

 from gritty particles, without odor or taste. It gradually absorbs carbon dioxide 

 from the air. Insoluble in water or alcohol. 



Dose.—n. & C, 3i-ii, (4-8); D., gr.v-x, (.3-.6). 



PREPARATION. 



Unguentum Zinci Oxidi. Ointment of Zinc Oxide. (U. S. & B. P.) 

 Zinc oxide, 200; benzoinated lard, 800. (U. S. P.) 

 ZiNoi AcETAs. Zinc Acetate. Zn (C^HjO^)^ -(- 2 HA (U. S. & B. P.) 

 Derivation. — Dissolve zinc oxide in diluted acetic acid and boil. 

 ZnO -I- 2 HC2H5O2 = Zn(CjH302)2 + H^O. Evaporate and crystallize. 

 Properties. — Soft, white, six-sided monoclinic plates, of a; pearly lustre, hav- 

 ing a faintly acetous odor, and, in dilute solutions, an astringent metallic taste. 

 Exposed to the air the salt gradually effloresces and loses some of its acid; reac- 

 tion acid; soluble in 2.3 parts of water and in 30 parts of alcohol. 

 Incompatibles. — Same as sulphate. 

 Cos«.— -Same as sulphate. 



ACTION OF THE ZINC SALTS. 



External. — The salts of zinc (except the chloride) have an astringent 

 action on raw surfaces and mucous membranes in precipitating solutions 

 of proteids, as zinc albuminate, notably the sulphate and acetate. Ab- 

 sorption is not followed by poisoning, as most of the zinc is stored in the 

 liver. They resemble other astringents, especially copper salts, and are 

 more irritating than lead acetate or subacetate. 



Internal. — In the alimentary tract very large doses of the sulphate 

 or acetate may induce gastro-enteritis, which is to be treated with demul- 

 cents and alkaline carbonates in order to form insoluble compouAds. 

 Vomiting will relieve camivora; otherwise the stomach tube must be re- 

 sorted to. 



Zinc salts apparently produce no remote effect upon the body when 

 ingested. Given intravenously (double salts) to mammals, zinc causes 

 vomiting, diarrhea, muscular weakness and paralysis. It is eliminated 

 chiefly by the alimentary tract and slightly in the bile and urine. In 

 therapeutic doses the zinc salts are astringent, diminishing secretion in 

 the digestive tract. 



USES OF ZINC SALTS. 



External. — Zinc sulphate is in common use as an astringent coUyrium 

 ■ for subacute conjunctivitis (gr.ss.-ii. to gi.). It is also employed in the 



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