ZINC. 161 



however, is soluble in an excess of either of the alkaline 

 hydrates. 



Zinc chloride, Zinci chloridum, ZnCl 2 = 135.7 (Chloride of zinc}. 

 Made by dissolving zinc or zinc carbonate in hydrochloric acid 

 and evaporating the solution to dryness : 



Zn + 2HC1 = ZnCl,.+ 2H. 



It is met with either as a white, crystalline powder, or in white, 

 opaque pieces ; it is very deliquescent and easily soluble in water 

 and alcohol ; it combines readily with albuminoid substances ; it 

 fuses at about 115, and is volatilized, with partial decomposi- 

 tion, at a higher temperature. 



Zinc bromide, Zinci bromidum, ZnBr 2 = 224.5 (Bromide of zinc}. 

 Obtained analogously to the chloride by dissolving zinc in 

 hydrobromic acid : 



Zn + 2HBr = ZnBr 2 + 2H. 



A white powder, resembling the chloride in its properties. 



Zinc iodide, Zinci iodidum, ZnI 2 = 318.1 (Iodide of zinc}. The 

 two elements zinc and iodine combine readily when heated 

 with water; the colorless solution when evaporated to dryness, 

 yields a powder whose physical properties resemble those of the 

 chloride. 



Zinc carbonate, Zinci carbonas prsecipitatus, 2(ZnC0 3 ).3(Zn2HO) 

 = 546.5 (Precipitated carbonate of zinc, Zinc-white). Solutions of 

 equal quantities of zinc sulphate and sodium carbonate are 

 mixed and boiled, when a white precipitate is formed which is a 

 mixture of the carbonate and hydrate of zinc, while carbon 

 dioxide escapes and sodium sulphate remains in solution : 



5ZnSO 4 + 5Na 2 C0 3 + 3H 2 O = 3C0 2 + 5Na 2 SO 4 + 2(ZnCo 3 ).3(Zn2HO). 



Precipitated zinc carbonate is a white, impalpable powder, 

 odorless and tasteless, insoluble in water, soluble in acids. 



Zinc sulphate, Zinci sulphas, ZnS0 4 .7H 2 = 286.9 (Sulphate of 

 zinc, White vitriol), is obtained by dissolving zinc in diluted sul- 

 phuric acid : 



H 2 SO 4 + *H 2 O + Zn = ZnSO 4 + *H 2 O + 2H. 

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