DIAZOBENZENE NITRATE. 291 



and of nitrous acid. Under certain conditions it takes up the 

 elements of water, reproducing phenol and free nitrogen 



C 6 H 4 N 2 + H 2 = C 6 H 6 + N 2 . 



In this case the nitrogen is produced by the reciprocal reaction 

 of the two nitrogenous components, precisely as in its produc- 

 tion from the direct reaction of ammonia and nitrous acid, the 

 original generators. 



3. The heat disengaged in the formation of a diazo-compound 

 is far below thatfwniciiwould be produced in the formation of 

 nitrogen by the direct reaction of ammonia and nitrous acid. 

 In other words, the water eliminated in the original reaction 

 that engenders the diazo-compound, did not at the time of its 

 formation give off the same quantity of heat as if it had been 

 formed directly by the reaction of the two nitrogenous generators 

 in a free state. Thus, the diazo-compound contains an excess 

 of energy which renders it liable to sudden decomposition. It is 

 a highly explosive body. This theory leads us to foresee the 

 explosive properties of diazo-compounds. Only one of these 

 has, as yet, been studied from this point of view; namely, 

 diazobenzene ; and its properties fully bear out the forecasts 

 of this theory. For purposes of application diazobenzene 

 nitrate is especially worthy of study. It is a crystalline 

 compound, more easily handled than diazobenzene itself, and 

 containing, besides, a greater amount of energy, on account 

 of the additional presence of the nitric acid, which is calculated 

 to exercise an oxidising action upon the carbon. M. Vieille 

 and the author have studied its thermal and mechanical 

 properties. 



2. DIAZOBENZENE NITRATE. 



1. Diazobenzene nitrate is an explosive substance which is 

 solid and crystalline. It answers to the formula 



C 6 H 5 N 2 N0 3 , 



its equivalent being equal to 167. 



It has been proposed to use this body as a priming. In 

 virtue of its various modes of decomposition it is now employed 

 in industry in the manufacture of colouring matters. 



M. Vieille and the author have studied its preparation, 

 stability, density, and also its detonation (both with respect to 

 the heat disengaged and also to the nature of the products), its 

 heat of combustion and of formation from the elements, and 

 lastly, the pressures developed by its detonation in a closed 

 vessel ; but the examination of this last branch of the subject 

 will be reserved for Book III. 



2. Preparation. Aniline is the starting-point in the pre- 



u 2 



