ZINO SULPHATE 183 



solution, dried, and introduced -under the skin about the 

 base of tumors to cause their destruction by sloughing. It 

 is employed in the form of pencils on unhealthy, granulating 

 surfaces, as in "foot rot," and injected in strong solution 

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

 internally. 



ZiNCi Sulphas. Zinc Sulphate. ZnSo^ + 7 H^O. 

 (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. 



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

 alkalies and carbonates, vegetable decoctions or infusions, 

 and milk. 



Z>06e.— H. & C, 3 i.-ii. (4.-8.); 8h. & Sw., gr.x.-xx. (.6-1.3); 

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



ZiNCi Caebonas Pe^cipitatus. Precipitated Zinc Carbonate. 



(U. S. P.) 



Synonym. — Zinci carbonaa, 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 (Za 00^3 Zn 

 (OH)j? (hydrated- basic zinc carbonate) + 8 Na^SO, + 2 

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

 oxide, in varying proportions, with water of crystallization. 



Properties. — kn impalpable white powder, of somewhat 

 variable chemical composition, without odor or taste ; insol- 

 uble in water or alcohol. 



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