206 HEAT OF FORMATION OF THE NITRATES. 



energy than most of the other combinations derived from nitric 

 acid. 



Theory therefore shows that saltpetre is not a favourable 

 agent of combustion ; and in this way it explains the superiority 

 of the organic compounds derived from nitric acid, and especially 

 the nitric ethers, such as nitroglycerin. As a matter of fact, 

 the author's experiments show a much inferior liberation of 

 heat, that is to say, a greater preservation of energy in the 

 formation of these substances. The energy introduced into an 

 explosive compound, formed by the same weight of nitric acid, 

 is in nitroglycerin double that which is found in service powder. 

 Hence it is easy to understand how the abandonment of blast- 

 ing powder for industrial purposes is gradually extending. 

 Perhaps it will be soon the same with service powder, if practice, 

 guided by the new theories, succeeds in discovering more active 

 nitrogenated compounds than powder, which will satisfy the 

 manifold conditions called for in the use of explosive substances 

 in firearms. 



