CYANOGEN (Gr. ebavos,

See also:

• BLUE (common in different forms to most European languages)

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 .