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Originally appearing in Volume V19, Page 660 of the 1911 Encyclopedia Britannica.
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NEW CALEDONIA 1900. 1901. 1902. 1903. 1904. 1905. 1906. 1907. 1908. Metric tons . 100,319 133,676 129,653 77,360 98,665 125,289 130,688 101,708 120,028 (See Rothwell's Mineral Industry (1908), PP. 666, 67o). The metal may also be obtained on the small scale by the reduction of the oxide by hydrogen or by carbon, by ignition of the oxalate or of nickel ammonium oxalate (J. J. Berzelius), by reduction of the chloride in a current of hydrogen (E. Peligot), by electrolysis of nickel ammonium sulphate (Winkler, Zeit. anorg. Chem. 1894, 8, p. I), and by reduction of the chloride with calcium carbide. It is a greyish white metal, and is very malleable and ductile. Its specific gravity varies according to the method employed for its preparation, the extreme values being 8.279 and 9.25. It melts between 1400-1600° C. Its specific heat increases with rise of temperature, the mean value from 15° to loo C. being o• 1084 (A. Naccari, Gaze., 1888, 18, p. 13). It is magnetic, but loses its magnetism when heated, the loss being complete at about 340-3500 C. On the physical constants see H. Copaux, Comptes rend us, 1905, 140, p. 651. Nickel occludes hydrogen readily, is attacked by the halogen elements, and oxidizes easily when heated in air. In the massive state it is unacted upon by dry air, but if moistened with acidified water, oxidation takes place slowly. When obtained by reduction processes at as low a temperature as possible the finely divided metal so formed is pyrophoric, and according to P. Schutzenberger (Comptes rendus, 1891, 113, p. 177) dry hydrochloric acid gas converts this form into nickel chloride and a volatile compound of composition NiHC1. It decomposes water at a red heat. According to E. St Edme (Comptes rend us, 1886, ro6, p. 1079) sheet nickel is passive to nitric acid, and the metal remains passive even when heated to redness in a current of hydrogen. On the reduction of organic compounds by hydrogen in the presence of metallic nickel see P. Sabatier and J. B. Senderens, Ann. Chico. Phys., 1905 [8], 4, pp. 319, 433. It rapidly oxidizes when fused with caustic soda, but is scarcely acted upon by caustic potash (W. Dittmar, Jour. Soc. Chem. Ind., 1884, 3, p. 103). Hydrochloric and sulphuric acids are almost without action on the metal, but it dissolves readily in dilute nitric acid. Nickel salts are antiseptic; they arrest fermentation and stop the growth of plants. Nickel carbonyl, however, is extremely poisonous. On the toxic properties of (Liebig). M. Ilinski and G. v. Knorre (Ber., 1885, 18, p. 169) separate the metals by adding nitroso-,8-naphthol in the presence of 50 % acetic acid, a precipitate of cobalti nitroso-$-naphthol, [CioH6O(NO)]aCo, insoluble in hydrochloric acid, being formed, whilst the corresponding nickel compound dissolves in hydrochloric acid. E. Pinerua separates the metals by taking advantage of the fact that cobalt chloride is soluble in ether which has been saturated with hydrochloric acid gas at low temperature. For an examination of the above and other methods see E. Hintz, Zeit. anal. Chem., 1891, 30, p. 227. Nickel fluoride, NiF2, obtained by the action of hydrofluoric acid on nickel chloride, crystallizes in yellowish green prisms which volatilise above loon° C. It is difficultly soluble in water, and combines with the alkaline fluorides to form double salts. Nickel chloride, NiC12, is obtained in the anhydrous condition by heating the hydrated salt to 14o° C., or by gently heating the finely divided metal in a current of chlorine. It readily sublimes when heated in a current of chlorine, forming golden yellow scales. It is easily reduced when heated in hydrogen. It forms crystalline compounds with ammonia and the organic bases. It is soluble in alcohol and in water. Three hydrated forms are known, viz. a mono-, di-, and hexa-hydrate; the latter being the form usually obtained by the solution of the oxide or carbonate in hydrochloric acid. Nickel chloride ammonia, NiC12.6NHa, is obtained as a white powder when anhydrous nickel chloride is exposed to the action of ammonia gas (H. Rose, Pogg. Ann., 1830, 96, p. 155), or in the form of blue octahedra by evaporating a solution of nickel chloride in aqueous ammonia. When heated to loo° C. it loses four molecules of ammonia. Two hydrated forms have been described, one containing three molecules of water and the other half a molecule. Numerous double chlorides of nickel and other metals are known. The bromide and iodide of nickel resemble the chloride and are prepared in a similar fashion. Several sulphides of the element have been obtained. A sub-sulphide, Ni2S(?), results when the sulphate is heated with sulphur or when the precipitated monosulphide is heated in a current of hydrogen. It forms a light yellow amorphous mass which is almost insoluble in acids. The monosulphide, NiS, is obtained by heating nickel with sulphur, by heating the monoxide with sulphuretted hydrogen to a red heat, and by heating potassium sulphide with nickel chloride to 16o-18o° C. When prepared by dry methods it is an exceedingly stable, yellowish, somewhat crystalline mass. When prepared by the precipitation of nickel salts with alkaline sulphide in neutral solution it is a greyish black amorphous compound which readily oxidizes in moist air, forming a basic nickel sulphate. The freshly precipitated sulphide is soluble in sulphurous acid and some-what soluble in hydrochloric acid and yellow ammonium sulphide (see H. Baubigny, Comptes rendus, 1882, 94, pp. 961, 1183; 95, p. 34). Nickel sulphate, NiSO4, is obtained anhydrous as a yellow powder when any of its hydrates are heated. When heated with carbon it is reduced to the metal. It forms hydrates containing one, two, five, six and seven molecules of water. The heptahydrate is obtained by dissolving the metal or its oxide, hydroxide or carbonate in dilute sulphuric acid (preferably in the presence of a small quantity of nitric acid), and allowing the solution to crystallize between 15° and 2o° C. It crystallizes in emerald-green rhombic prisms and is moderately soluble in water. It effloresces gradually on exposure to air and passes into the hexahydrate. It loses four molecules of water of crystallization when heated to too° C. and becomes anhydrous at about 300° C. The hexahydrate is dimorphous, a tetragonal form being obtained by crystallization of a solution of the heptahydrate between 20° and 3o° C., and a monoclinic form between 500 and 7o° C. Nickel sulphate combines with many metallic sulphates to form double salts, and also forms addition compounds with ammonia aniline and hydroxylamine. The nitrate, Ni(NOa)2.6H20, is obtained by dissolving the metal in dilute nitric acid and concentrating the solution between 40° and 5o° C. It crystallizes in green prisms which deliquesce rapidly on exposure to moist air. Nickel carbonyl, Ni(CO)4, is obtained as a colourless mobile liquid by passing carbon monoxide over reduced nickel at a temperature of about 6o° C. (L. Mond, Lanier and Quincke, Jour. Chem. Soc., 1890, 57, p. 749). It boils at 43 C. (751 mm.), and sets at -25° C. to a mass of crystalline needles. It is readily soluble in hydrocarbon solvents, in chloroform and in alcohol. Its critical pressure is 30 atmospheres and its critical temperature is in the neighbourhood of 195° C. (J. Dewar, Proc. Roy. Soc., 1903, 71, p. 427). It decomposes with explosive violence when heated rapidly. Dewar and Jones (Journ. Chem. Soc., 1904, p. 203) have made an exhaustive study of its reactions, and find that it is decomposed by the halogens (dissolved in carbon tetrachloride) with liberation of carbon monoxide and formation of a nickel halide. Cyanogen iodide and iodine mono- and tri-chloride effect similar decompositions with simultaneous liberation of iodine; sulphuric acid reacts slowly, forming nickel sulphate and liberating hydrogen and carbon monoxide. Hydrochloric and hydrobromic acids are without action; hvdriodic acid only reacts slowly. With aromatic hydrocarbons in the presence of anhydrous aluminium chloride, in the cold, there is a large evolution of hydrochloric acid gas, and an aldehyde is formed ; at loo C., on the other hand, anthracene derivatives are produced. Thus by using benzene, benzaldehyde and anthracene are obtained. Dewar and Jones suggest that in the latter reaction it is themetallic nickel which is probably the reducing agent effecting the change, since it is only dissolved in any quantity when the anthracene hydrocarbon is produced. When mesitylene is used, the reaction does not proceed beyond the aldehyde stage since hydrocarbon formation is prevented by the presence of a methyl group in the ortho-position to the -CHO group. Acids and alkalis are in general without action on nickel carbonyl. The vapour of nickel carbonyl burns with a luminous flame, a cold surface depressed in the flame being covered with a black deposit of nickel. It is an extremely powerful poison. Mond and his assistants have discovered several other carbonyls. For example cobalt gives Co(CO)4, as orange crystals which melt at 51°, decomposing at a higher temperature, giving Co(CO)3 and CO at 6o°; Co(CO)3 forms jet black crystals. For iron carbonyls see IRON; also L. Mond, H. Hirtz and M. D. Cowap, Jour. Chem. Soc., 1910, 97, p. 798. Nickel carbonate, NiCOa, is obtained in the anhydrous state by heating nickel chloride with calcium carbonate in a sealed tube to 15o° C. (H. de Senarmont, Ann. Chim. Phys., 185o [31, 30, 138). It crystallizes in microscopic rhombohedra insoluble in cold acids. By precipitation of nickel salts with solutions of the alkaline carbonates, basic carbonates of variable composition are obtained. Numerous determinations of the atomic weight of nickel have been published, the values obtained varying from 58.o to approximately 59.5• The more recent work of T. W. Richards and Cushman (Chem. News, 1899, 79, 163, 1i4, 185) gives for the atomic weight of the metal the values 58.69 and 58.70.
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