EXPLOSION OF NITEOGEN CHLORIDE. 405 



The quantity of heat liberated in this reaction is considerable, 

 but not well known. Indeed, the experiments of Sainte-Claire, 

 Deville, and Hautefeuille on this point 1 have given two 

 numbers which, calculated with the values actually adopted for 

 the heats of formation of ammonia and its chloride (pp. 237 and 

 243), vary almost from the single to the double. 



8. The permanent pressure may, however, be calculated. For 



' . 1 . , , . 370-4 atm. 3827 kgm. 



a density of charge it would be , or s 



n n n 



per square centimetre, supposing n large enough, in order that 

 the chlorine may not assume the liquid state. 



On the contrary, if the chlorine be liquefied, the density of 

 liquid chlorine being 1*33, 1065 grms. of this body will occupy 

 807 c.c., and hence the pressure developed by the nitrogen, 

 which formed only the fourth of the gaseous volume at the 



normal pressure, will be *> a much lower figure than 



n 0*80 



that yielded by nitrogen sulphide. 



9. The maximum work which can be developed by nitrogen 

 chloride is considerable, but the actual data tend to show that 

 this work is greatly inferior to that of black powder, when an 

 equal weight of both these substances are exploded in any equal 

 capacity. These are results which seem at first sight to contra- 

 dict what is known of the terrible phenomena produced by 

 nitrogen chloride. Nitrogen chloride is, in fact, regarded as the 

 type of these shattering substances, which cannot be employed 

 in firearms to effect the same work of projection wnich powder 

 realises by its progressive expansion. 



10. We shall now try to account for these differences. 



The principal one must doubtless be attributed to the nature 

 of the products of explosion and the complete absence of every 

 compound capable of dissociation. The pressure and the work 

 result from the heat liberated by the decomposition of the 

 nitrogen chloride. Now, the latter gives rise to elementary 

 bodies which have no tendency to recombine, whatever be the 



1 "Comptes rendus des stances de TAcad^mie des Sciences," torn. Jxix. 

 p. 152. The authors employed two reactions that of chlorine on ammonium 

 chloride in presence of water, and that of hypochlorous acid on the same 

 salt, and they believed the results which follow from their measurements 

 were concordant. But the values deduced from the data they adopted, 

 putting aside certain errors in calculation, would be 51'7 and 39'3. By 

 reckoning, still with the aid of their measurements but by means of the heats 

 of formation actually received for ammonia, hydrochloric acid, and ammonium 

 chloride, we find : 57'8 and 37-8. The discordance in these results is prob- 

 ably owing to the reactions not taking place entirely according to the formulae 

 indicated. It would be well to resume these measurements, operating upon 

 pure nitrogen chloride and by the decomposition method, synthesis being 

 here very uncertain. 



