12 INTERACTION OF NITRIC OXIDE WITH 



of nitrate {J. Ch. Soc, 1871, 24, 85) fully accounts for its being 

 found only in such small quantity when the temperature is 

 high, and for the production of nitric peroxide and silver in- 

 stead. As determined by Carnelley, the melting point of silver 

 nitrate is 217°. 



The nitric oxide used for the experiments was prepared 

 by the ferrous-sulphate method, stored for two days in a glass 

 gas-holder, and dried in its passage to the silver nitrate by a 

 sulphuric-acid column. At starting, the air in the drying 

 apparatus and in the tube containing the silver nitrate was ex- 

 pelled by carbon dioxide, the silver nitrate being heated in the 

 gas, in order to dry it. Interaction between the silver nitrate 

 and the nitric oxide was recognised by the reddening of the 

 gas. At the end of an experiment the gases were expelled by 

 carbon dioxide before opening the tube. 



Silver nitrate heated in nitric oxide is greatly affected by 

 it, being freely decomposed at much lower temperatures than 

 those at which it decomposes by itself, while the nitric oxide 

 becomes oxidised. The action commences perhaps at 150°, but 

 this is doubtful ; at the melting point of the salt it becomes 

 marked and interaction at the boiling point of mercury consi- 

 derable ; but even at this temperature it is a long time before 

 the decomposition becomes complete, the progress of the change 

 growing slower. For some time the products are silver nitrite 

 and nitric peroxide — AgN03 + NO = AgN02+iS[Oo, with only very 

 little silver, the nitrite being almost wholly preserved for a 

 long time through combination with the undecomposed nitrate. 

 But when by the consumption of the nitrate the nitrite gets 

 unprotected it suffers spontaneous decomposition as usual into 

 silver and nitric peroxide. At last, nothing but silver remains. 



