EXPLOSION OF DIAZOBENZENE NITKATE. 293 



carbonic acid to within about 3 J th (less). There was neither 

 carbon monoxide nor any other combustible gas in the residue. 

 Experiments were made with 0'5 grm., suspended by means 

 of a metallic wire, capable of being made red-hot by an electric 

 current, in the centre of a platinum vessel filled with pure 

 oxygen. The average of two experiments gave 0*4296 carbonic 

 acid ; the quantity calculated being 0'43 grm. 



8. Heat of formation from the elements. According to the 

 total heat of combustion, which will be given further on 



C 6 (diamond) + H 6 + N 3 + 3 = C 6 H 5 N 2 N0 3 , absorbs - 47'7 Cal. 



The formation of nitric acid, H + N + 30 = HN0 3 (liquid), 

 gives off + 41*6 Cal. ; we therefore conclude that, taking into 

 account the nitric acid previously existing 



C 6 + H 4 + N 2 + HN0 3 (liquid) = C 6 H^N 2 N0 3 absorbs - 89 Cal. 



This value gives a more exact notion of the heat of formation 

 of diazobenzene itself. But we have to subtract from it the 

 heat disengaged by the combination of the diazobenzene with 

 the nitric acid. But free diazobenzene is itself a liquid body, 

 too imperfectly defined to have enabled one to study it. 



However this may be, these negative values correspond very 

 well with the explosive properties so characteristic of this 

 compound. 



The decomposition of diazobenzene nitrate by means of water, 

 with the reproduction of dissolved phenol and dilute nitric^ 

 acid 



C 6 H 5 N 2 N0 3 + H 2 = C 6 H 6 + N 2 + HN0 3 (diluted), 



gives off + 1081 Cal. 



9. Heat of detonation. This term is used to express the 

 heat given off by the simple explosion of diazobenzene nitrate, 

 an explosion that gives rise to complex products. 



This explosion was effected in an atmosphere of nitrogen, in a 

 steel bomb lined with platinum ; it was ignited by means of 

 the galvanic heating of a fine platinum wire. The nitrate was 

 placed in a little tin cartridge, which was suspended in the 

 centre of the bomb, so as to avoid local actions arising out of 

 contact with the walls. 



The results (in two experiments which were made upon 

 1-6 grms.) were : 688'9 and 686-6 Cal.; the mean being 687*7 Cal. 

 per kgm., or 6877 cal. per grm. This gives for an equi- 

 valent (= 167 grins.) 4- 114*8 Cal., at a constant volume. 



10. The volumes (reduced) of the gases produced were 815*7 

 and 820 litres ; average = 817*8 litres per kgm., or 136*6 

 litres per equivalent (167 grms.). 



11. Under the conditions of the experiments that were made. 



