CHAKACTEKISTICS OF THE WAVE. 89 



physical constitution of the vibrating medium, this velocity 

 being the same for all kinds of vibrations. But, in the case of 

 the explosive wave, it is the change of chemical constitution 

 which is propagated communicating to the moving system 

 enormous energy and considerable excess of pressure. The 

 velocity of the explosive wave is also much greater than that 

 of sound waves transmitted through the same medium. 



The explosive phenomenon is not reproduced periodically, it 

 gives rise to one single characteristic wave, whereas the 

 phenomenon of sound is generated by a periodical succession of 

 waves resembling one another. 



The characteristics of this new wave are 



(1) It is propagated uniformly, as shown in the experiments 

 made with oxyhydric, oxycarbonic, and oxycyanic mixtures, 

 which were made successively in tubes of lead, gutta-percha 

 and glass, with lengths varying from 40 to 30 and 20 metres. 



It is certain that disturbances are produced near the 

 extremities of the tubes. However, they do not extend far 

 under the conditions of the experiments ; in fact, the experiments 

 made with the tube closed, open at either or both ends, gave 

 the same velocity, which remained the same for a given length. 



(2) The velocity of the explosive wave depends essentially on 

 the nature of the explosive compound, and not on the composi- 

 tion of the tube containing it (lead, gutta-percha). 



(3) The influence of the diameter of the tube on the velocity 

 of the wave is not appreciable between diameters of 5 mms. 

 and 15 mms. It is, however, manifest in a capillary tube, 

 but the diminution, even in this- extreme case (2390 metres 

 instead of 2840 metres), is not excessive. In short, the velocity 

 depends less and less on the diameter in proportion as the 

 increase of the latter leaves more liberty to the individual 

 movements of the gaseous particles and diminishes the friction 

 against the sides of the tube. 



These conclusions are in accordance with those of M. 

 Regnault on the velocity of the sound wave in tubes. 1 



(4) The velocity of the explosive wave is independent of 

 pressure, between the limits 1 and 3, as referred to the pressure 

 of the atmosphere. This is a fundamental property, for it 

 establishes the fact that the rate of propagation of the explosive 

 wave is governed by the same general laws as the velocity of 

 sound. 



(5) The theoretical relation which exists between the velocity 

 of the explosive wave and the chemical nature of the gas which 

 transmits it is more difficult to establish, this velocity depend- 

 ing on the temperatures, and these not being the same in the 

 combustion of two different systems. 



The inequality of the temperatures results from the unequal 



1 " Me*moires de 1'Acade'mie des Sciences," torn, xxxvii. p. 456. 



