NICKEL. A white metal, which, when obtained pure, is both ductile and malle able. It may be forged into very thin plates, their thickness not being greater than 0.01 of an inch. Its colour is inter mediate between that of silver and tin, and is not altered by the air. It is nearly as hard as iron. Its specific gravity is 8.279; and when forged 8.666.
The species of nickel ores are, its alloy with arsenic, and a little sulphur and its oxide.
The first is the most abundant, and the one from which nickel is usually extract ed. It is known to mineralogists by the name of kupfer-nickel, or copper-nickel, from its colour and appearance. It oc curs generally massive and disseminated; its colour is copper-red of various shades; its lustre is. weakly, shining, and metal lic ; it is perfectly opaque ; its fracture is uneven ; it is hard, has no malleability, but is not easily broken ; its specific gra vity is from 6.6 to 7.5. Urged by the flame of the blow-pipe, it gives vapours with a strong arsenical odour, and melts with difficulty. It dissolves in acids, giv ing a green solution. Bergman found it to be composed of nickel, iron, cobalt, arsenic, and sulphur. Vauquelin regards it as essentially an alloy of nickel and ar senic, the iron, cobalt, and sulphur, be ing accidental.
The other species, the oxide of nickel, occurs generally as an incrustation, some times also disseminated, of a friable tex ture and earthy appearance ; of an apple green colour, without lustre. It is not al tered by the heat of the blow-pipe ; but when mixed with borax gives to It a yel lowish red colour. Its solution in acids is of a green colour. It occurs generally with kupfer-nickel, or with certain cobalt ores. It is also contained in small quanti ties in a fossil of the siliceous genus, chry soprase, to which it communicates an ap ple-green colour.
Nickel is extracted from the kupfer nickel, but it is extremely difficult to free it entirely from the metals with which it 'a associated. The process given by Che
nevix is the most simple. The metal ob tained from kupfer-nickel, by roasting and fusion with three times its own weight of black flux, is dissolved in nitric acid, the solution being boiled, so that the arsenic present receiving oxygen from the acid may be converted into ar senic acid ; a solution of nitrate of lead is then dropped in, and the liquor evaporat ed by a very gentle heat, but not quite to dryness. Alcohol poured into this solu tion precipitates every salt, but the ni trate of nickel, which has been formed by the double decomposition of the arse mate of nickel and the nitrate of lead. The alcohol of the solution of nitrate of nickel being evaporated, the metallic salt is redissolved in water and decomposed by potash. The oxide, well washed and dried, is reduced in an Hessian crucible lined with lamp-black.
By the experiments that have been made on nickel in its pure state, it ap pears to be proved that it is possessed of magnetic power, and that therefore iron is not the only metal to which it belongs. The magnetic properties of nickel had often been observed ; but as, in the usual processes by which it is obtained, it is al ways alloyed with iron, it was concluded, with probability, that the magnetism it exhibited was owing to the presence of that metal. Since methods, however, have since been discovered of obtaining nickel in a purer state, the error of this conclusion has been discovered. The ef fect of the magnet on it is very little in ferior to that which it exerts on iron; and the metal itself becomes magnetic itself by friction with a magnet, or even by beating with a hammer. Magnetic nee dles have even been constructed of it in France, and have been preferred to those of steel, as resisting better the action of the air. The nickel preserves its mag netic property when alloyed with cop per, though it is somewhat diminished; by a small portion of arsenic it is com pletely destroyed.