OF CAKDOX WITH OXYGEN AND NITROGEN 405 



volume of nitrogen equal to the volume of the gas taken. As it con- 

 tains carbon it burns, and the colour of the flame is reddish-violet, 

 which is clue to the presence of nitrogen, all compounds of which impart 

 more or less of this reddish-violet hue to the flame. During the com- 

 bustion of cyanogen, carbonic anhydride and nitrogen are formed. 

 This also takes place in the eudiometer with oxygen and during the 

 action of cyanogen 011 many oxides at a red heat. 



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

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

 forming cyanide of sodium or potassium on being heated with sodium 

 or potassium, 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 

 cyanogemA^t as all the organic acids contain carboxyl, and in it the 

 element^^Harbonic anhydride. Besides the amides, 50 the nitriles (or 

 cyanogen compounds, RON), and nitro-compounds (containing the 

 radicle of nitric acid, RNO 2 ), there are a great number of other sub- 

 stances containing, at the same time, carbon and nitrogen, particulars 

 of which must be sought for in special works on organic chemistry. 



4<J Cyanogen (like chlorine) is absorbed by a solution of sodium hydroxide, sodium 

 cyanide and cyanate being produced : C 2 N 2 + 2NaHO = NaCN -f CNNaO + H 2 O. However, 

 the latter salt easily decomposes, just as also part of the cyanogen liberated by heat from 

 its compounds is subjected to a more complex transformation. 



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

 (i))//' ties ought to be ranked with them; that is, the hydrocarbons, C,iH 2m , in which the 

 hydrogen is replaced by NFL ; for instance, methylamine, CH 3 'NH 2 , aniline, C H 5 'NH 2 , 

 &c. In general the amines represent ammonia in which part or all of the hydrogen is 

 replaced by hydrocarbon radicles such as, for instance, trimethylamine N(CH 5 )3. They, 

 like ammonia, combine with acids and form crystalline salts. Related substances are 

 sometimes met with in nature, and bear the general name of alkaloids ; such are, for 

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



