NOBLE AND ABEL'S EXPERIMENTS 



31 



solid matter must then be deducted from that of the capacity in 

 which the explosion occurs. 

 We can put, more simply, 



$i being the pressure observed (in kgms.), A the density of 

 charge (ratio between the number of grms. representing the 

 weight of the substance and the number of cub. cms. repre- 

 senting the capacity), a the volume expressed in cub. cms., 

 of the solid or liquid products resulting from the combustion 

 of 1 grm. of explosive substance, measured at the temperature 

 of the explosion. j 



Further, putting = n ; /= s^n - a), n here expressing the 



ratio of the capacity, expressed in cub. cms., to the weight L 

 of the substance expressed in grms. f 



10. The relation thus modified has been verified, at least 

 approximately for dynamite, by Sarrau and Yieille. 



It also represents the experiments of Noble and Abel on 

 the explosion of black powder. In fact, by supposing a = 0'68 

 and / = 2193 kgms., the numbers found by these authorities 

 give for pebble and K.L.G. powders, 



Pressure per sq. cm. 



^ 



Calculated. 



235 kgms. 

 508 

 828 

 1207 

 1666 

 2230 

 2963 

 3869 

 5127 

 6926 



At first sight it appears that these latter results tend to 

 exclude the hypothesis of the total vaporisation of the products 

 yielded by the explosion of black powder. However, the easy 

 vaporisation of potassium sulphide at temperatures lower than 

 1000 tends to encourage the supposition with respect to this 

 body that it assumes the gaseous form at the temperature of the 

 explosion of powder, and the experiments l of Bousingault would 

 also permit of our conceiving the gaseous state of potassium 

 sulphate and carbonate. This point, therefore, remains reserved. 

 There is all the more reason for this, as the co-efficient, a, can be 



1 " Annales de Chime et de Physique," 4' sdrie, torn. xii. p. 428. 



