ZINC SULPHATE 171 



into fistulous tracts to destroy their walls. It is not used 

 internally. 



ZiNCi Sulphas. Zinc Sulphate. ZnSo^ 4- 7 H2O. 

 (U. S. & B. P.) 



Derivation. — Prepared by dissolving zinc in sulphuric 

 acid. Zn, + 2 H,SO, = 2 ZnSO, + 2 H,. 



Iron and tin exist as impurities, and are removed by 

 chlorine solution and zinc carbonate. 



Properties. — Colorless, transparent, rhombic crystals, 

 without odor, and having an astringent, metallic taste. 

 Efflorescent in dry air; reaction acid ; soluble in 0.6 part of 

 water, in 3 parts of glycerin ; insoluble in alcohol. 



Incompatihles. — Lead acetate, silver nitrate, lime water, 

 alkalies and carbonates, vegetable decoctions or infusions, 

 and milk. 



Dose.—H. k C, 3 i.-ii. (4.-8.); Sh. & Sw., gr.x.-xx. (.6-1.3); 

 D., gr.ii.-iii. (.12.2); Emetic, D., gr.x.-xv. (.6-1.). 



Zmci Caebonas Pilecipitatus. Precipitated Zinc Carbonate. 



(U. S. P.) 



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

 bonate, kohlensaures zinkoxyd, G. 



Derivation. — Solutions of nearly equal weight of sodium 

 carbonate and zinc sulphate are boiled together ; dry pre- 

 cipitate. S ZnSO, + 8 Na,C03 + 2 H,0 = 2 (Zn C03)3 Zn 

 (0H)2 ? (hydrated basic zinc carbonate) + 8 NagSO^ + 2 

 CO2. This salt is in reality a mixture of zinc carbonate and 

 oxide, in varying proportions, with water of crystallization. 



Properties. — An impalpable white powder, of somewhat 

 variable chemical composition, without odor or taste ; insol- 

 uble in water or alcohol. 



ZiNCi OxiDUM. Zinc Oxide. Zn O. (U. S. & B. P.) ^ 



Derivation. — Heat the carbonate to redness. 



2 (Zn C03)3 Zq(0H)2 = 8 ZnO + 2 H^O + 6 CO^. 



