EXPERIMENTS ON SOLID AND GASEOUS EXPLOSIVES. 



385 



The volume to which the gas will be reduced under infinite pressure may be taken 

 as closely approaching the inverse of the density of the solid explosive. Therefore 



b = 



1-56 



= 0-641, 



whereas v is the inverse of the gravimetric density p. 

 Thus 



c = -0'641. 

 P 



To minimise the error due to cooling we will take the value of p obtained for the 

 smallest cordite in the spherical enclosure. At a gravimetric density of 0'0744 this 

 is 5'137 tons per square inch (see Table VI.), and therefore 



c _ 



0-0744 

 The pressure developed by the explosive is 



o-641 x 5-137 = 6575. 



P = 



cp 



" " 



-bp " 1-0-64 l 



The results calculated from this formula are compared in the following table with 

 NOBLE'S values and with those obtained during the course of the present work* : 



nitally by 

 PKTAVEI.. 



2-87 



7-01 



11-48 



In the above table the pressures are expressed in tons per square inch. 



The experimental results are influenced by many factors, such as the size of the 

 enclosure, the dimensions of the explosive, and the oscillations of pressure, which are 

 doubtless occasionally .set up. On the other hand, the formula we have used does not 



* When the pressure is measured in kilogrammes per square centimetre the constant c becomes 10355, 

 whereas t. = 10021 gives the pressure in atmospheres, the constant b in either case remaining unaltered. 

 A formula similar to the above was used by NOBLE and ABEL in connection with their researches on fired 

 gunpowder. They assumed that the gases strictly followed BOYLE'S law, but introduced a factor (1 -- a.p) 

 to allow for the space occupied by the solid residues left after the explosion. 



VOL. COV. A. 3 D 



