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CYANOGEN (Gr. ebavos, blue 'yevvav, t...

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Originally appearing in Volume V07, Page 680 of the 1911 Encyclopedia Britannica.
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CYANOGEN (Gr. ebavos, blue 'yevvav, to produce), C2N2, in chemistry, a gas composed of carbon and nitrogen. The name was suggested by Prussian blue, the earliest known compound of cyanogen. It was first isolated in 1815 by J. Gay-Lussac, who obtained it by heating mercury or silver cyanide; this discovery is of considerable historical importance, since it recorded ' the isolation of a " compound radical." It may also be prepared by heating ammonium oxalate; by passing induction sparks between carbon points inan atmosphere of nitrogen (see H. von Wartenburg, Abs. J.C.S., 1907, i. p. 299), or by the addition of a concentrated solution of potassium cyanide to one of copper sulphate, the mixed solutions being then heated. It also occurs in blast-furnace gases. When cyanogen is prepared by heating mercuric cyanide, a residue known as para-cyanogen, (CN)=, is left; this is to be regarded as a polymer of cyanogen. It is a brownish amorphous solid, which is insoluble in water. Cyanogen is a colourless gas, possessing a peculiar characteristic smell, and is very poisonous. It burns with a purple flame, forming carbon dioxide and nitrogen; and may be condensed (by cooling to -25° C.) to a colourless liquid, and further to a solid, which melts at -34.4 C. (M. Faraday, Ann., 1845, 56, p, 158). It dissolves readily in water and the aqueous solution decomposes on standing; a dark-brown flocculent precipitate of azulmic acid, C4H5Ns0, separating whilst ammonium oxalate, urea and hydrocyanic acid are found in the solution. In many respects it resembles chlorine in its chemical behaviour, a circumstance noted by Gay-Lussac; it combines directly with hydrogen (at sod' to 550 C.) to form hydrocyanic acid, and with chlorine, bromine, iodine and sulphur, to form cyanogen chloride, &c.; it also combines directly with zinc, cadmium and iron to form cyanides of these metals. It combines with sulphuretted hydrogen, in. the presence of water, to form the compound C2N2•H2S, and in the presence of alcohol, to form the compound C2N2.2H2S. Concentrated hydrochloric acid converts it into oxamide. Potash solution converts it into a mixture of potassium cyanide and cyanate. When heated with hydriodic acid (specific gravity 1.96) it forms amino-acetic acid, and with tin and hydrochloric acid it yields ethylene diamine.
End of Article: CYANOGEN (Gr. ebavos, blue 'yevvav, to produce), C2N2
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