ACTION OF ELECTRICITY ON NITRIC OXIDE. 193 



Another experiment, lasting six hours, under the same con- 

 ditions, gave sensibly the same results, the proportion of nitric 

 oxide decomposed being the same, and of monoxide rather less, 

 but always very considerable. The action of the electric spark 

 confirms and extends these results. It commences to exert 

 itself with extreme promptitude, and presents several successive 

 terms which deserve attention. 



Operating upon the gas enclosed in sealed tubes with rather 

 weak sparks (two Bunsen elements) a sixth of the gas was 

 already decomposed at the end of one minute. The proportion 

 would certainly have been larger, if the platinum electrodes 

 were situated in the centre of the mass instead of being at the 

 extremity, which retarded the mixture of the gases. About 

 a third of the decomposed product consisted of nitrogen 

 monoxide 



4NO = N 2 + NA, 



the other two-thirds producing nitrogen and nitric peroxide 



N 2 + 2N0 2 . 



At the end of five minutes three-quarters of the nitric oxide 

 was decomposed with formation of nitrogen monoxide and 

 nitrogen trioxide and nitric peroxide. The ratio between the 

 nitrogen monoxide arid the nitrogen, that is, between the two 

 modes of decomposition, was nearly the same as above. It is 

 further necessary to distinguish between the calorific action of 

 the spark, which causes the formation of monoxide (a body not 

 formed by the spark acting on the elements), as well as of a 

 portion of free nitrogen, and the action peculiar to electricity, 

 as shown by an experiment of longer duration. 



In fact, the flow of sparks prolonged for an hour leaves 

 nothing but a mixture of non-decomposed nitric oxide (thirteen 

 per cent, of the initial volume), nitrous vapour (more than forty 

 per cent.), and nitrogen. But no appreciable quantity of 

 monoxide was discovered. This gas therefore disappears before 

 the nitric oxide, doubtless under the influence of the high 

 temperature of the spark. 



This fact, in apparent contradiction to the initial transforma- 

 tion of a part of the nitric oxide into monoxide, seems to show 

 that the nitric oxide commences to undergo decomposition at 

 a lower temperature than the monoxide, and that it nevertheless 

 lasts, in part, longer, or at a higher temperature, in presence of 

 the products of its decomposition. 



However, the still more prolonged action of electricity causes 

 it to disappear in its turn, at the same time that it diminishes 

 the volume of the nitrous vapour produced in the first period. 

 After eighteen minutes only twelve per cent, of nitrous vapour 

 formed, solely of nitric peroxide. The gaseous mixture con- 



o 



