SPECIFIC VELOCITY. 101 



Mixture of cyanogen and oxygen (CN + 2 ) 



Pressure. Velocity. 



0-388 metre ......... 2171-4 metres. 



0-758 ... 



0-878 



Same conclusions. 



Thus, as far as the experiments went, the rate of propagation 

 of the detonation, either with the mixture of hydrogen and 

 oxygen, or with the mixture of carbonic oxide and oxygen, is 

 practically independent of the pressure, like the velocity of 

 sound and the rate of translation of the gaseous molecules, 

 which are analogous phenomena. 



4. SPECIFIC VELOCITY OF THE EXPLOSIVE WAVE. 



1. We have now established the fact that the explosive wave 

 is propagated uniformly and that its velocity is independent 

 of the pressure, and also of the composition and diameter of the 

 tubes, beyond a certain limit. Thus, this velocity constitutes 

 for each inflammable compound, a true specific constant, the 

 knowledge of which is of great interest, from the point of view 

 of the theory of the movements of gases, and also from that of 

 the employment of explosive substances. For this reason it 

 was thought expedient to go more deeply into the study of this 

 question, extending our operations to a large number of mixtures 

 differing greatly in their composition. 



2. Each experiment was repeated two or three times ; it was 

 generally performed in the caoutchouc tube, 40 metres long, 

 with an internal diameter of 5 mms., and of great thickness (as 

 already described, p. 97). The results obtained are shown in 

 five tables, containing the most remarkable cases. In these tables, 

 the first column gives the composition of the initial mixture ; 

 the second, the density of the products of combusition p, as 

 compared with that of air, taken as unit ; the third, the number, 

 N, of molecular volumes of the elements (supposing them to be 

 gaseous) entering into reaction, the volume being 



TT 



N [ 22-32 litres X - X (1 X at)] ; 



the fourth column gives the heat, Q, given off by the reaction, 

 the water being supposed to be in a gaseous form * ; the fifth 

 column gives the square root of this quantity, VQ 5 the sixth 



contains the quotients ' 6*8 being the constant of the 



1 This quantity was measured near zero ; but it would be little different at 

 zero in the cases considered here, especially if the specific heat of the com- 

 pound were estimated as the sum of the specific heats of its elements. 



