SILVER HYPONITRITE. 185 



7. HYPONITROUS ACID AND HYPONITRITES. 



1. In studying the products of the reduction of the nitrates 

 by sodium amalgam, Divers 1 discovered in 1871 a new salt, 

 which he called silver hyponitrite, and of which he determined 

 the composition and the properties. This salt and its derivatives 

 have since been the object of researches by Van der Plaats 2 

 and Zorn. 8 These chemists have attributed to silver hyponitrite 

 the formula AgNO, which would suppose it derived from 

 nitrogen monoxide, associated with silver oxide. But the 

 recent researches which Ogier and the author have made upon 

 this salt from a chemical and thermal point of view have led 

 them to prefer the formula Ag 4 N 4 5 , that is to say 2Ag 2 0,N 2 3 , 

 which makes of the hyponitrous acid a sesquioxide of nitrogen. 



The alkaline hyponitrites are also formed in the electrolysis 

 of the nitrites, and they are formed, though to a very small 

 amount, in the decomposition of the nitrites by heat, especially 

 in presence of iron. It is by means of silver hyponitrite that 

 hyponitrous acid and its salts are prepared ; we shall speak, 

 therefore, first of all, of this compound. 



2. Silver hyponitrite is a yellow amorphous very insoluble body, 

 which is precipitated when silver nitrate is poured into a 

 neutral solution of alkaline nitrite. In order to obtain it pure, 

 it must be re-dissolved in very dilute nitric acid, and re-precipi- 

 tated, by neutralising by ammonia. 



This body undergoes a very sensible decomposition when 

 heated to 100 or a little over. 



Hence the hyponitrite should be dried in vacuo at the ordi- 

 nary temperature, and in the dark. 



Its analysis has supplied the following figures : 



Ag 76-2 76-1 



N 9-7 9-8 



O 14-1 14-1 



These results lead to the formula 



Calculated from Found. 



AgNO(138) iAg 4 N 4 O fl (284) 



Ag 78-3 ... 76-1 ... 76-1 



N 10-1 ... 9-9 ... 9-8 



10-6 ... 14-1 ... 14-1 



Hyponitrous acid has therefore as formula N 4 3 2H 2 0, which 

 constitutes it a sesquioxide of nitrogen, corresponding in the 

 anhydrous state to the formula N 4 3 . 



1 Journal of the Chemical Society," vol. xxiv. p. 484 ; " Proceedings of 

 the Royal Society," vol. xxii. p. 425 ; " Bulletin de la Socie'te' Chimique, 

 torn. xv. p. 176. 



2 " Berichte der Deutsch. Chem. Ges. Ber.," torn. x. p. 1508. 



3 Ibid., torn. x. p. 1306, and torn. xv. p. 1258. 



