ZINC. 573 



stream of chlorine gas. It does not combine with acids, and in 

 other respects resembles peroxide of cobalt. 



Besides a protosulpuhret, NiS. a subsulphuret of nickel, Ni 2 S, 

 is formed, like that of manganese, by decomposing, the ignited 

 sulphate of nickel by hydrogen. A bisulphuret of nickel also 

 exists in combination as a constituent of the mineral, nickel- 

 glance, NiS 2 + NiAs. 



Chloride of nickel, NiCl, forms a solution of an emerald 

 green colour, and yields by evaporation a hydrated salt of the 

 same colour, which becomes yellow when deprived of its water 

 of crystallization. Chloride of nickel, sublimed at a high tem- 

 perature without access of air, forms golden scales, which 

 dissolve with difficulty. 



Sulphate of nickel crystallizes from a strong solution in 

 slender green prisms, isomorphous with epsom salt, of which 

 the composition is NiO, SO 3 -f 7HO. At a higher temperature, 

 it crystallizes with 6 eq. of water, NiO, SO 3 + 6HO, like the 

 magnesia and cobalt salt, and in the same form. M. Mitscher- 

 lich has made the singular observation, that when the crystals 

 containing 7 eq. of water are exposed, in a close glass vessel, to 

 a day of sunshine, or kept for some time in a temperate place, 

 they change their form, becoming a mass of small crystals, of 

 which the form is the regular octohedron. The original crystals 

 become opaque from this change, but lose none of their com- 

 bined water. Sulphate of nickel forms the usual double salts 

 with sulphates of potash and ammonia. 



The useful white alloy of nickel* German silver, or packfong, 

 is formed by fusing together 100 parts of copper, 60 of zinc, 

 and 40 of nickel. 



SECTION V. 



ZINC. 

 Eq. 403.2 or 32.31; Zn. 



The principal ores of zinc are calamine, or the carbonate, a 

 pulverulent mineral generally of a reddish or flesh colour, and 

 zinc blende, a massive mineral of an adamantine lustre, and often 

 black. The oxide, from the carbonate or from the calcined 

 sulphuret, is reduced by means of carbonaceous matter. This 

 process is conducted in a distillatory apparatus, of a particular 



