NICKEL (ante). Nickel has three sulphides, or sulphurets, a subsulphide, Ni,S, which is formed fly reducing the sulphate with charcoal or hydrogen; the protosulphide. NIS, foamed by, ItisIng'sulphur itnil 'nickel, and also found liativein the mineral millerito; and the disulphide obtained by heating the carbonates of nickel and potash with sulphur to redness. An anhydrous carbonate is made by heat ing chloride of nickel with carbonate of potash or soda in a sealed tube. It crystallizes in minute rhoinboliedrons. A hydrocarbonate, NiCO2, 2 Ni (H20)2, also exists as a native mineral, called emerald nickel, and found iu mines iu the form of incrustations and short stalactites; sometimes massive; pearly luster, emerald-green color, transparent, translu cent; hardness 3 to 3.25; sp. gr. 2.57 to 2.69. Lancaster co., Penn., asso ciated with serpentine, and also in the Shetlaud islands. The nitrate crystallizes in 8-sided emerald-green prisms, soluble in twice their weight of cold water. It is made by dissolving the metal in nitric acid. Sulphate of nickel, NiSO471120 crys tallizes in green rhombic prisms, soluble in 3 parts of cold water. it is made by the action of dilute sulphuric acid 'on the metal. When these crystals are exposed to the light they subdivide, without falling apart, into minute regular octahedrons. If the crystallization takes place between 59° and 77° F. it will be octahedral, and instead of 7, there will be only 6 molecules of water. The methods of smelting and working nickel ores are complicated, and some of them are not generally known. The uses of nickel until recently were principally for forming alloys with other metals. In sonic countries
besides the United States, coins of small value have been made of an alloy of nickel, zinc, and copper. The U. S. cent, authorized by the act of Feb. 21, 1857, was composed of 88 per copper and 12 per cent of nickel. The metal is used in the prep aration of the alloy called German silver, which contains 2 parts of copper and 1 of zinc and nickel each. White copper, or pakfong, of China, consists of copper, 40.4; nickel, 31.6; zinc, 23.4; iron, 2.6. Recently nickel has been used for plating other metals, and this use has made it one of the most valuable of metals. Chemists had for some time known that a brilliant deposit of nickel could be obtained by electrolysis from solu tions of nickel salts, but no advantage was taken of this knowledge till Mr. Isaac Adams of Boston devised a method of rendering nickel-plating practicable and profitable. He employs a double chloride of nickel and ammonium, or of sulphate of nickel and ammo nium. See Electrolysis, Electro-ffetallurgy, and Electrotype, in art. GALVANISM, ante. It is important to have the salt which is used in the process perfectly pure, and it must therefore be made from pure nickel. Mr. Adams found that it was not practical to use a plate of pure metal as the anode, because it would not dissolve sufficiently fast to satisfy the demands of the solution (the deposit of metal on the cathode, and consequently its separation from the salt, being the greater). This was remedied by combining the nickel anode with carbon, forming a carbide. This causes the metal to dissolve exactly as fast as it is deposited.