456 GUN-COTTON AND NITRO- CELLULOSES. 



deviation of the composition employed from the composition in 

 equivalents. 



In a miss-fire, on the contrary, combustion ceases to be total. 

 The authors, for instance, have observed, out of 100 volumes of 



3. The heat liberated by the total and regular reaction 

 amounts, according to the calculation, to 3678 Gal. (water 

 liquid), 3117*5 Cal. (water gaseous) ; or, for 1 kgm., 1321 Cal. 

 (water liquid), or 1120 Cal. (water gaseous). Sarrau and Vieille 

 actually found 1273 Cal. (water liquid) for a composition con- 

 taining only 40 per cent, of gun-cotton instead of 41. The 

 difference between the figure observed (1273) and the calculated 

 figure (about 1288) does not exceed the limits of experimental 

 error. 



4. The reduced volume of the gases = 1116 litres (water liquid), 

 2399 litres (water gaseous) ; or, for 1 kgm., 401 litres (water 

 liquid), and 862 litres (water gaseous). Sarrau and Vieille 

 found 387 litres, with the composition containing 40 per cent, 

 of gun-cotton instead of 41 per cent. 



401 atm. 



5. The permanent pressure = - under the ordinary 



71 U ot) 



reservations. 



a TU ^ . i 14900 atm. 



6. The theoretical pressure = . 



n 



It is somewhat less than for gun-cotton. 

 Sarrau and Vieille actually found, with the composition con- 

 taining 40 per cent, of gun-cotton, and by the crusher method 



Density of charge 0'2, P = 3270 kgm. 

 0-3, P = 5320 kgm. 



which would make for the density 1, 16358 and 17730 ; mean, 

 17000 kgm. approximately, a figure which is rather higher than 

 14900. But it is possible that it ought to be reduced to the 

 half by a more exact estimation of the force of calibration 

 (p. 23). 



6. GUN-COTTON AND POTASSIUM NITRATE. 



1. The total combustion of gun-cotton by potassium nitrate 

 corresponds to the formula 



10[C 24 H 18 (N0 3 H) 11 OJ + 82KN0 3 = 199C0 2 + 41K 2 C0 3 + 

 145H 2 + 96N 2 . 



