IMPURITY IN NITRATE OF AMMONIA. 287 



tapours took place, and continued for a considerablt 

 time after the retort had been removed from the fire. 

 The residue in the retort scarcely ever exhibited the same 

 phenomena upon being again subjected to the same treat- 

 ment; but nitrous oxide was always produced without 

 any farther trouble. 



Having frequently procured nitrous oxide without any Suspected Ira- 

 of the phenomena 1 have described, I suspected the ni- ^^^'^ ^* 

 trate of ammonia I had been operating on was impure. 



I made an examination of the salt, and found it contained If was muriate 



.. c • J. f' ' rn J. • 1 of ammouia. 



a portion ot muriate ot ammonia, lo ascertain whe- 

 ther the muriatic acid had been the cause of the rapid 

 disengagement of white vapour, I took a portion of tha 

 same kind of salt I had before made use of, and freed it 

 perfectly from muriatic acid by means of nitravte of silver. 

 Thij purified salt I introduced into a retort, and pro- 

 ceeding in the usual way, obtained pure nitrous oxide 

 without any of the dense white vapour. 



To assure myself the presence of the muriatic acid had Proof by direct 

 been the occasion of the facts I observed, I made some 

 pure nitrate of ammonia by the direct combination of 

 pure nitric acid and carbonate of ammonia. I took two 

 portions of the solution, and to one of them added a so- 

 lution of muriate of ammonia. The two solutions were 

 then crystallised, an equal quantity of each salt was ex- 

 posed to the heat of an Argand lamp, in glass retorts 

 communicating with the pneumatic trough; the retort 

 containing the compound salt gave out very rapidly a 

 dense opake elastic fluid similar to the white vapours 

 first described ; after a short time the evolution of gas 

 became considerably less abundant, and the interior of 

 the retort became clear ; the receiver was then changed ^ 

 upon examination, what came over now was nearly pure 

 nitrous oxide. 



The first portions of the gas evolved, that is the opake p *; f 



gas, had the following properties : the opake gas 



1st. It remained opake after being passed through cold ol^t'ijned from 



° the impure. 



water. salt, 



2nd. A slip of paper coloured blue by tinctu^re of 



turnsole, when immersed in the gas was changed to red. 



3rd. It is not iuflaramabl*. 



4th. A 



