AMMONIUM NITRITE. 165 



from alkaline nitrites, according to the thermal measurements, 

 while in presence of baryta, dilute acetic acid, weaker than 

 hydrochloric acid, gives rise to a division, variable according to 

 the relative propositions. 



This division may be explained by partial dehydration, that 

 is to say, by the state of partial dissociation of the hydrate of 

 nitrous acid in its solution. 



4. Ammonium nitrite. This salt in the solid form has been 

 but little studied. The author having had occasion to prepare 

 it for thermo-chemical researches, several new facts have been 

 observed. It was prepared by decomposing pure barium nitrite 

 by ammonium sulphate in exactly equivalent proportions in 

 the cold. The filtered liquid was evaporated in vacuo over 

 caustic lime, at ordinary temperatures. The operation lasted 

 several weeks, and, owing to decomposition, even then the yield 

 was only thirty to forty per cent, of that required by theory. 

 It is necessary to evaporate, to complete dryness, and to pre- 

 serve the solid salt in vacuo, over caustic lime. The mass is 

 white, crystalline, somewhat elastic and tenacious, so that it 

 may be moulded between the fingers, and adheres to the sides 

 of the containing vessel. It is perfectly neutral, and corre- 

 sponds to the formula (NH 4 ) N0 2 . It is very diliquescent. At 

 the ordinary winter temperature, it decomposes very slowly ; 

 at that of summer more rapidly. Heated to 60 or 70 on the 

 water bath, it detonates violently after a few seconds. It 

 detonates also by a blow from a hammer. Its decomposition 

 disengages weight for weight about three quarters as much heat 

 as nitroglycerin, hence its activity. It cannot be kept in sealed 

 tubes, because they soon explode, from the pressure of the gases 

 generated. It is best kept as above. 



If the decomposition take place with explosion, it yields only 

 nitrogen. When gradually decomposed by progressive heating, 

 the salt loses at first a little ammonia, and afterwards yields, 

 together with free nitrogen, a small amount of the monoxide, 

 nitric oxide, and trioxide vapour. 



Its very slow decomposition, at the ordinary temperature, 

 yields nitrogen and water, without affecting its neutrality. 



Aqueous concentrated solutions decompose more rapidly than 

 the dried salt in the cold, so that when agitated, they evolve 

 gas like champagne. Ammonium nitrite may be formed syn- 

 thetically by mixing together nitric oxide, ammonia, and oxygen. 

 The solid nitrite condenses on the walls of the tube in crystal- 

 line masses, apparently cubical in form. 



The three gases immediately react on each other, but as they 

 do not contain the water necessary for the constitution of 

 ammonium nitrite, nitrogen is formed at the same moment. 

 + 2NH 3 = 2N 2 + 3H 2 0. 



2NO + + 2NH 3 + H 2 = 2NH 4 N0 2 . 



