SONOKOUS AND EXPLOSIVE WAVES. 87 



of a direct influence of the vibratory movement on chemical 

 transformation. The tests made with gases such as ozone and 

 arseniuretted hydrogen are not subject to this complication; 

 they tend to do away with the hypothesis of a direct influence 

 of sonorous vibrations, even when very rapid, of the gaseous 

 particles on their chemical transformation. 



8. It has been said that there is among the incessant and reci- 

 procal shocks of gaseous particles, when in motion in an enclosed 

 space, a certain number which are susceptible of raising the 

 particles which undergo them to very high temperatures. If it 

 were really so, a mixture of oxygen and hydrogen elements, 

 which combine towards 6500, would become gradually trans- 

 formed into water, ammonia gas, decomposable at about 800, 

 would slowly change into nitrogen and hydrogen, etc. The author 

 never observed anything like this in these gaseous systems 

 preserved for a period of ten years. If this effect does not 

 take place, it is probably due to the loss of energy in each 

 gaseous particle regarded individually, and even its total 

 energy remains comprised within certain limits. 



9. In fine, matter is stable under the influence of sonorous 

 vibrations, whereas it transforms itself under the influence of 

 ethereal vibrations. This diversity in the mode of action of 

 two kinds of vibrations is not surprising if we consider to what 

 extent the sharpest sonorous vibrations are incomparably slower 

 than luminous or calorific vibrations. 



10. Yet there appears little doubt that the propagation of 

 explosion by influence is caused by virtue of an undulatory 

 movement; a complex movement of a chemical and physical 

 order in the explosive substance which is transformed, whereas 

 it is purely physical in intermediate substances whose nature is 

 not changed. What also distinguishes this kind of movement 

 from sonorous vibrations, properly so called, is the extreme 

 intensity, that is to say, the greatness of the energy which it 

 transmits. It is thus that the explosive wave propagates itself 

 in the substance which explodes, not by reason of a single shock, 

 the energy of which would become weaker as it propagates 

 itself, but by reason of a series of similar shocks incessantly 

 reproduced, and which, as they continue, regenerate the energy 

 throughout the wave. On the other hand the propagation by 

 air or by supports is effected solely by reason of the energy of 

 the last shock communicated by the explosive substance, an 

 energy which is no longer regenerated and which rapidly 

 weakens by distance. 



The explosive substance does not detonate because it transmits 

 the movement, but, on the contrary, because it stops it, and 

 because it transforms its mechanical energy on the spot into 

 calorific energy capable of suddenly raising the temperature of 

 the substance up to a degree which causes its decomposition. 



