6 CHEMICAL COMPOSITION. 



41,300 cal. when the solid nitrate is used, and about 37,000 

 when the salt is fused. 



(6) The formation of nitrogen monoxide from ammonium 

 nitrate at a higher temperature, and when the heat is carefully 

 regulated. The reaction : NH 4 N0 3 (solid) = N 2 + 2H 2 (gas) 

 develops + 10,200 cal., the fused salt about + 14,000 cal. 



If the salt be supposed to be previously decomposed into 

 gaseous nitric acid and ammonia, and the action to have really 

 taken place between these two compounds, the formation of 

 nitrogen monoxide, HN0 3 gas + NH 3 = N 2 4- 2H 2 0, would 

 develop + 51,500 cal. 



(c) When rapidly heated, the explosive decompositions, 

 properly so called, of ammonium nitrate take place ; one of 

 them produces nitrogen and oxygen. 



NH 4 N0 3 = N 2 + + 2H 2 (gas). 



This reaction develops from the solid salt + 30,700 cal. ; from 

 the fused salt, about -f 35,000 cal. 



(d) Nitrogen and nitrogen dioxide are also formed 



2NH 4 N0 3 = N 2 2 + N 2 + 4H 2 0, 



and + 9200 cal. are given off when the salt is solid and about 

 + 13,000 cal. when it is fused. 



(e) Heat is also liberated when ammonium nitrate gives rise 

 to nitrogen, water and nitrogen tetroxide 



4KE 4 N0 3 = 3N 2 + N 2 4 + 8H 2 



-f 29,500 caL being set free from the solid salt, and + 33,500 

 cal. from the fused salt. 



(/) The ammonium nitrate may also be conceived as being 

 transformed into nitrogen, water and nitrogen trioxide. 



3HN 4 N0 3 = 2N 2 + N 2 3 + 6H 2 0. 



This reaction liberates + 23,300 cal. from the solid salt, and 

 about 4- 27,000 cal. from the fused ; but never takes place 

 alone, as nitrogen trioxide exists only in the dissociated state in 

 presence of nitrogen dioxide and nitrogen tetroxide. 



(g) Lastly, ammonium nitrate can be resolved into gaseous 

 nitric acid, nitrogen and aqueous vapour under certain influences 

 such as spongy platinum. 



5NH 4 N0 3 = 2HN0 3 + 4T 2 + 9H 2 



yielding + 33,400 cal. from the solid salt, and about + 37,500 

 cal. from the fused. 



These different modes of decomposition of ammonium nitrate, 

 which may be distinct or simultaneous, or more exactly the 

 predominance of any one of them, depend on their relative 

 rapidity and on the temperature at which decomposition is pro- 

 duced. This temperature is not fixed, but is itself subordinate 

 to the rapidity of heating. It has been established by a great 



