54 Dr Monckman, Action of Copper Zinc Couple [Feb. 24, 



Effect of temperature. It was found that when the liquid 

 was evaporated by heating over a water-bath no ammonia was 

 produced, while the whole of the nitrate was decomposed, nitrite 

 being the only substance left in the liquid. 



Action on KN0 2 . When a solution of KN0 2 was used 

 instead of KN0 3 it was found that after boiling some time it 

 was completely decomposed and the nitrous acid disappeared 

 from the solution without giving any ammonia. 



As no nitrogen compounds could be found in the liquid and 

 no ammonia was given off nor yet any acid compound of nitrogen*, 

 I was driven to the conclusion that it came away as either N or 

 N 2 0, probably the former, and that probably the ammonia acted 

 upon the nitrous acid producing nitrite of ammonia which was 

 again broken up into N and H 2 0. 



During violent ebullition excess of ammonia was produced 

 and driven off, but during gentle evaporation it united with 

 the nitrous acid, which was formed in sufficient quantity to 

 combine with it. 



This appears more probable because, in the first experiments 

 with nitrates, the nitrate was produced by the reducing action 

 of the hydrogen, at the same time as the ammonia, while in the 

 latter case (the nitrites) there was excess of this body from the 

 very beginning of the reaction. In the first ammonia escaped, 

 in the second, not. 



Methods of testing for N. In the experiments described the 

 presence or absence of hydrogen gas was of no importance, but 

 when it becomes a question of testing for nitrogen and estimating 

 its volume, a large quantity of hydrogen becomes inconvenient. 

 I first tried to avoid producing the gas, by using a solution of 

 the nitrite of sufficient strength to absorb the whole of it. I 

 found that it did not work well, the action being very slow 

 and little gas coming away, and as it could not be more than 

 a qualitative method it was abandoned. 



Next it was proposed to sweep out the air from the tubes 

 by a current of gas (C0 2 ) and after boiling the solution to carry 

 the gas produced into a receiver in the same manner. The 

 C0 2 was to be absorbed in the usual way. The danger of 

 producing a compound of NH 3 and C0 2 which might, in presence 

 of the nitrite of potash, produce nitrogen after the manner of 

 AmCl and KN0 2 , formed an obstacle to its use. I was therefore 

 compelled to substitute H. 



* Twice I found a very slight acid reaction produced by the gas evolved and 

 twice considerable quantities of NO were evolved, but after washing the couple 

 until it was perfectly free from acid or acid salt, the dilute solution ceased to give 

 NO. 



