28 REDUCTION OF ALKALI NITRITE BY AN 



silver weighed and calculated into hydroxylamine by the ratio 

 SAgiNHsO, experiments (described in the next paragraph) with 

 solution of hydroxylamine sulphate of similar dilution and 

 alkalinity having shown me that this could be done correctly 

 enough. 



The important observation made by Thum, that hydroxyl- 

 amine when oxidised by suitably alkalised mercuric oxide, 

 silver oxide, or cupric hydroxide, will yield a little hyponitrite, 

 and nitrite, caused me to ascertain whether in my experiments 

 the destruction of sometimes much hydroxylamine in this way 

 might not contribute some of the hyponitrite afterwards found 

 present. To this end I made a blank experiment, closely 

 similar to those made in studying the reduction of sodium 

 nitrite, except that sodium hyponitrite itself was absent. Thus, 

 hydroxylamine sulphate, 1.5 grams (=0.6 gram hydroxylamine) 

 was dissolved along with 32 grams sodium hydroxide in nearly 

 2 litres of water and then a solution was run in with stirring, 

 of silver nitrate 7.5 grams, which constituted a good excess, 

 such as was used in the other experiments. The abundant 

 black precipitate was washed and exhausted with ice-cold dilute 

 nitric acid. This solution, neutralised as usual in my other 

 experiments, gave no silver reaction for silver hyponitrite and 

 nothing more than a slow and very slight action upon per- 

 manganic acid which might be due to a trace of either nitrous 

 or hyponitrous acid. It was easily seen that some nitrous acid 

 was formed by applying the iodide and starch test. Under the 

 circumstances of my experiments, therefore, even when 7 per 

 cent, of the nitrite had been reduced to hydroxylamine, there 

 will have been no perceptible production of hyponitrite during 

 the after-oxidation of the hydroxylamine. The metallic silver 



