CA ]TYPONITRITES ; PROPEr.TIES AND PREPAEATION EY 



the accuracy of his observation. Even when the silver hy2:)0- 

 nitrite has been most carefully precipitated, so as to avoid all 

 sensible precipitation of suli^hite, and has been dissolved in 

 dilute acid and reprecipitated, it has still given a solution of 

 hyponi.trous acid active upon a very little iodine water. But 

 then, though the hyj^onitrous acid remained in solution, iodine 

 was not further taken up, while the acid prepared from silver 

 hyponitrite not derived from oxyamidosülphonate, does not 

 decolourise iodine at all, as Thum first pointed out. 



Hyponitrous acid, according to van der Plaats, liberates 

 iodine from potassium iodide ; according to Thum and my first 

 paper, it does not ; while, according to Hantzsch and Kaufmann, 

 it only does not do so just at first. The last named chemists, 

 therefore, state that the acid does not itself liberate iodine but 

 quickly begins to yield nitrous acid which does liberate it. 

 They also found hyponitrous acid to yield ammonia, but in a 

 later publication, Hantzsch and Sauer state that the ammonia 

 w^as an impurity in the silver hyponitrite which had furnished 

 the acid. Even with the simultaneous formation of the ammonia, 

 it is difficult to understand the generation of nitrous acid. 

 These authors, invoking the aid of tautomery, suppose that the 

 hydrogen leaves oxygen for nitrogen, giving the unknown sub- 

 stance, HN:0, which then becomes NH^+NA» aiid these, again, 

 pass into HNOo + N.-f OH.. In place of this series of improbable 

 — I would say, unnatural — changes, I suggest that, if indeed 

 such change occurs at all, it must be into water, nitric oxide, 

 and nitrogen, the nitric oxide then oxidising into nitrous acid. 

 But I am strongly disposed to deny that hyponitrous acid 

 decomposes of itself into anything but what are certainly its 

 main products, nitrous oxide and water. My reasons are several. 



