450 GUN-COTTON AND NITRO-CELLULOSES. 



11. The equivalent of this substance is 1143. 



12. The heat liberated by the formation of gun-cotton from 

 the elements under constant pressure 



24 (diamond) + H^ + N^O*, 



amounts to 624 Cal. for 1143 grins., or 546 Cal. for 1 kgm. 

 The heat of formation of collodion cotton 



C* + H 31 + N 9 + 038 = C at H a (N0 3 H 9 )O u , 



is 696 Cal. for 1053 grms., or 661 Cal. for 1 kgm. 



Soluble gun-cotton made in Norway is very near this com- 

 position. 



13. The heat liberated in the total combustion of gun-cotton 

 by free oxygen 



2[C 24 H 18 (N 2 3 H) 11 9 ] + 0*! = 48C0 2 + 29H 2 + 11N 2 , 



at constant pressure, is 2633 Cal. for 1143 grms. (water liquid), 

 or 2488 Cal. (water gaseous). Say for 1 kgm. of gun-cotton, 

 2302 Cal. (water liquid), or 2177 Cal. (water gaseous). ^~*, / 

 The total heat of combustion of collodion cotton 



2[C 24 H 22 (N0 3 H) 9 11 ]0 51 = 48C0 2 + 31H0 2 + 9N 2 , 



at constant pressure, the water being liquid, -f 2627*5 CaL ; the 

 water being gaseous, + 2474'5 Cal. 



It will be seen that it is nearly the same at equal equivalents 

 as for gun-cotton. 



For 1 kgm. of collodion we should have 2428 Cal. (water 

 liquid), 2351 Cal. (water gaseous). 



14. The heat of decomposition of gun-cotton in a closed 

 vessel, found by experiment at a low density of charge (0'023), 

 amounts to 1071 Cal. for 1 kgm. of the substances, dry and free 

 from ash, or 1225 Cal. for 1143 grms. (water liquid). 



We proceed to compare this result with the heat calculated 

 from the equation for the decomposition. 



15. Equation for the decomposition. From the analysis of the 

 products, the decomposition of the gun-cotton which yielded 

 this quantity of heat practically agreed with the following 

 equation (low densities of charge) : 



(1) 2[C ai H 18 (N0 8 H) 11 9 ] = 30CO = 18C0 2 + 11H 2 + 18H 2 O 



+ 11N 2 . 



But the quantity of heat changes with the equation of decom- 

 position, the latter approximating to 



(2) 24CO + 24C0 2 + 12H 2 + 17H 2 + 11N 2 



for high densities of charge, according to Sarrau and Vieille (p. 

 289). There is, moreover, no nitric oxide under these conditions. 1 



1 Karolyi, Sarrau and Vieille. 



