NITKOGEN AND HYDROCARBONS. 227 



tion of the acetylene. But this complication may easily be 

 avoided by adding beforehand to the mixture a suitable volume 

 of hydrogen, for instance, ten times the volume of the acetylene ; 

 no further deposit of carbon is then observed, and the reaction 

 absolutely corresponds to the following equation : 



C 2 H 2 + N 2 = 2CNH. 



The presence of the hydrocyanic acid formed is not, however, 

 completely accomplished under the conditions just described, 

 and the reaction ceases at a certain limit, because the hydro- 

 cyanic acid is inversely decomposed by the spark, into nitrogen 

 and acetylene. But if the hydrocyanic acid be gradually 

 removed by potash, care being taken to dry the gases each time, 

 before renewing the action of the spark, a given volume of 

 nitrogen may be completely transformed into the acid, as has 

 been expressly verified. Hydrocyanic acid is formed solely by 

 the action of the spark or arc, and not of the silent discharge. 



15. Nitrogen and organic compounds. Nevertheless nitrogen 

 is also absorbed by organic matters, when operating with the 

 silent discharge by means of a powerful Euhmkorff coil and 

 the test-tube just described. It is easy to observe (at an 

 ordinary temperature) the absorption of a measurable volume of 

 nitrogen either by hydrocarbons (benzene, essence of turpentine, 

 etc.), or by ternary substances, such as ether, moist dextrine, or 

 paper; 



16. Nitrogen and hydrocarbons. The experiment is very well 

 defined with benzene, a compound devoid of oxygen, 1 grm. 

 of benzene absorbing in a few hours 4 to 5 cub. cms. of 

 nitrogen, the greater part remaining unaltered. The reaction 

 is effected principally between electrified benzene, in vapour, or 

 under the form of very thin liquid layers, and nitrogen gas. It 

 gives rise to a polymeric and condensed compound, a sort of 

 solid resin, which collects on the surface of the glass tubes 

 through which the discharge is effected. This compound, when 

 highly heated, is decomposed, with liberation of ammonia. But 

 free ammonia does not pre-exist, nor is it formed by the silent 

 discharge, either in the dissolved state in the excess of benzene, 

 or in the gases. The latter, moreover, contain a little acetylene, 

 which appears constantly in the reaction of the silent discharge 

 on the hydrocarbons. Essence of turpentine also gave rise to an 

 absorption of nitrogen, in reality slower under the same con- 

 ditions. There was also produced a condensed resinous body, 

 which liberates ammonia on ignition. 



The vapour of ether also x absorbs nitrogen. Methane behaves 

 in the same manner. It yields at once (in a small quantity) a 

 very condensed solid nitrogenous product, which liberates 

 ammonia, by heat, and free ammonia, which remains mixed 

 with the non-condensed gases. With acetylene, the principal 



Q2 



