NICKEL (Ni). A well known elementary metal. It is extensively used in the manufacture of the so-called nickel-silvcr, GERMAN-SILVER, and similar white alloys. Its natural history and physical properties together with the source and composition of its ores have already been described. [NICKEL, in NAT. HIST. Drv.] A method of reducing nickel from its natural combinations has also been given, but on account of the increasing demand for it, greater 'attention has of late years been paid to the metallurgy of this metal, and the following pro cess is according to Louyct, the one now generally adopted in Birming ham. Speiss, an arsenio-sulphido of nickel and other metals, obtained in tho manufacture of smalt [COBALT], is first fused with chalk and fluor spar and the resulting metallic mass reduced to powder and roasted to expel arsenic ; the residue is then treated with hydrochloric acid, aud bleaching powder gradually added to the solution till the iron is peroxidised. Milk of lime being now cautiously poured in tho iron is thrown down as peroxide, any traces of arsenic lucing carried down with it ; the clear liquid is treated with a current of eulphuretted hydrogen to precipitate copper, bismuth, and lead, and the cobalt got rid of as peroxide by a second addition of solution of bleaching powder. Finally the nickel is precipitated as hydrated oxide by adding sufficient milk of lime, and the metal obtained on strongly heating, in a wind furnace, a mixture of black flux and the dried oxide.
The equivalent of nickel is 29.54 and its specific gravity, Oxygen and Nickel combine in two proportions, forming the prot• oxide and sesqui-oxide or peroxide.
Protoxide of Nickel (NiU) may be obtained by adding potash or soda to a solution of any salt of nickel, by which a green hydrate (Ni0,1I0) is precipitated; this, heated to redness, hoses water and becomes of a dark olive-green colour. It may also be procured by heating nitrate of nickel to redness. It in insoluble in water, readily dissolved by moat acids, and yields green solutions. It is not reducible to the metallic state by heat alone, and is not attracted by the limpet. When fused with borax a hyacinth-yellow bead is produced, becoming lighter in colour on cooling. Oxide of nickel is insoluble in potash or soda, but readily dissolves in ammonia ; the solution has a fine azure blue colour, and is decomposed by potash or soda. It is the base of all
the salts of nickel.
Peroxide of Nickel may he obtained by adding a solution of chloride (hypochlorite) of soda to one of nitrate of uickel, or by transmitting chlorine gas through water in which hydrate of nickel is suepended. The peroxide thus obtained is of a black colour, insoluble in dilute acids, potash. or soda. When added to a mixture of ammonia and its carbonate, nitrogen gas is evolved, and the peroxide, becom ing protoxide, is dissolved. With hydrochloric acid it gives out chlorire gas, and forms chloride of nickel. At a red heat it yields oxygen gas.
Chloride.of Nickel (NiCI) is formed by dissolving either the pro. toxide or peroxide of the metal in hydrochloric acid. Its colour is A fine emerald-green ; and by evaporating the solution, green filamentous crystals containing water are formed. This salt deliquesces in a moist atmosphere. When deprived of water it has a yellow colour and a micaceous appearance; it is volatile, end when sublimed at a high temperature is obtained in beautiful golden-yellow crystalline scales. Its solution is decomposed by the alkalies and their carbonates, but ammonia added in excess redissolve, the precipitate at first formed.
The jtueride (NiFI), bromide (NiBr), and iodide of nickel (Nil), are of but little importance. The bromide and iodide form hydrated salts containing six equivalents of water.
Sulphur and Nickel combine in three proportions, forming the sul phide, disulphide, and bisulphide.
Sulphide of Nickel (NiS) is prepared either by heating metallic nickel or the oxide with sulphur ; or it may be'procured by adding a hydrosulphate to a solution of nickel. The precipitated sulphide is nearly black, and dissolves in hydrochloric acid with the evolution of hydneulphuric acid gas ; the sulphide procured in the dry way is of a grayish-yellow colour, and requires aqua regia (or nascent chlorine) for solution. Sulphide of nickel is also found native. [NICKEL, in NAT. HIST. DIV.) Disulphide of Nickel (Ni,S) may be prepared by transmitting hydro. gen gas over sulphate of nickel at a red heat. Its colour is lighter, and it is snore fusible than the solphide.