416 PRINCIPLES OF CHEMISTRY 



cyanogen, carbonic anhydride and nitrogen are formed. The same 

 products are obtained in the eudiometer with oxygen or by. the action, 

 of cyanogen on many oxides at a red heat. 



The relation of cyanogen to the metallic cyanides is seen not only 

 in the fact that it is formed from mercuric cyanide, but also by its 

 forming cyanide of sodium or potassium on being heated with either of 

 those metals, the sodium or potassium taking fire in the cyanogen. 

 On heating a mixture of hydrogen and cyanogen to 500 (Berthelot), 49 

 or under the action of the silent discharge (Boilleau), hydrocyanic 

 acid is formed, so that the reciprocity of the transitions does not 

 leave any doubt in the matter that all the nitriles of the organic acids 

 contain cyanogen, just as all the organic acids contain carboxyl and 

 in it the elements of carbonic anhydride. Besides the amides, 5 - the 

 nitriles (or cyanogen compounds, RON), and nitro-compounds (con- 

 taining the radicle of nitric acid, RN0 2 ), there are a great number 

 of other substances containing at the same time carbon and nitrogen, 

 particulars of which must be sought for in special works on organic 

 chemistry. 



49 Cyanogen (like chlorine) is absorbed by a solution of sodium hydroxide, sodium 

 cyanide and cyanate being produced : C 2 N 2 + 2NaHO = NaCN + CNNaO + H 2 0. But the 

 latter salt decomposes relatively easily, and moreover part of the cyanogen liberated by 

 heat from its compounds undergoes a more complex transformation. 



50 If , in general, compounds containing the radicle NH 2 are called amides, some of the 

 amines ought to be ranked with them ; namely, the hydrocarbons C n H 2W , in which part of 

 the hydrogen is replaced by NH 2 ; for instance, methylamine, CH ? NH 2> aniline, C 6 H 5 NH 2 , 

 &c. In general the amines may be represented as ammonia in which part or all of the 

 hydrogen is replaced by hydrocarbon radicles as, for example, trimethylamine, N(CH 3 ) 5 . 

 They, like ammonia, combine with acids and form crystalline salts. Analogous substances 

 are sometimes met with in nature, and bear the general name of alkaloid$' t such are, 

 for instance, quinine in cinchona bark, nicotine in tobacco, &c. 



