42 DURATION OF EXPLOSIVE REACTIONS. 



We shall now analyse the phenomena in a more precise 

 manner. 



Second Section. A homogeneous system submitted to uniform 

 conditions and contained in an enclosure to which it cannot yield, 

 and from which it cannot take any heat. 



Let it be a homogeneous system capable of disengaging heat 

 by chemical transformation. 



The case will first be examined where this system is sub- 

 mitted to uniform conditions in all its parts, and contained in an 

 enclosure to which it cannot yield, and from which it cannot take 

 any heat. Under these theoretical conditions, the mass of the 

 matter is of no importance. 



1. The molecular rapidity of reactions in a homogeneous system, 

 everything else being equal, increases with the temperature. 1 

 Indeed, it increases according to a very rapid law, as is proved 

 by the author's experiments on ethers, 2 the rapidity being then 

 represented by an exponential function of the temperature, a 

 function of which the numerical value, in the formation of 

 acetic ether, is 22,000 times greater near 200 than near 7. 



2. The temperature of the system increases, at least up to a 

 certain limit, by the very effect of the reaction. 



The temperature of the system increases, at first incessantly, 

 and does so up to a limit defined by the figure obtained by 

 dividing the heat liberated by unit weight by the specific heat 

 of the system. 



Further, the rapidity with which the system tends towards 

 this limit goes on increasing according as the rise in tempera- 

 ture produced by the reaction itself is more considerable. 



In a gaseous system contained in a fixed enclosure the 

 acceleration will become even greater, at least at the commence- 

 ment, and this owing to. the influence of pressure, which 

 necessarily increases by the fact of the rise in temperature. 

 In short, the author has established that, everything else being 

 equal, and while operating at a fixed temperature, the reactions 

 are affected more rapidly in liquid than in gaseous media. 

 In gaseous media, in particular, he has recognised that the 

 reactions are the more rapid the greater the pressure. 3 



3. The molecular rapidity of the reactions in a homogeneous 

 system, increases with the condensation of the substances, or more 

 simply, the rapidity of the reactions increases with the pressure in 

 gaseous systems* 



Thus, in an enclosure supposed impermeable to heat the 



1 " Essai de Me"canique Chimique," torn. ii. p. 64. 



2 Ibid., p. 93. 3 Ibid., p. 94. 



4 In solid or liquid systems, on the contrary, the pressure exerts little 

 influence according to the author's experiments, which is conceivable because 

 it hardly modifies the state of condensation of the substances. 



