G. F. Becker — A new law of Thermo- Chemistry. 121 



Berthelot's famous thermochemicaHaw,* with extremely satis- 

 factory results. 



This law, the experimental proof of which is very convinc- 

 ing, applies only to the final molecular configuration of given 

 substances, however, and gives no information as to the series 

 of transformations which they undergo before reaching a con- 

 dition of stable chemical equilibrium. But in many of the 

 chemical processes of nature, and in some technical operations, 

 the reactions are interrupted before the final result is attained. 

 In all cases it is a matter of great scientific interest to know the 

 law governing the actual series of transformations from the ini- 

 tial to the final condition of a mixture of substance, between 

 which reaction takes place. 



In the course of the experiments referred to, it appeared to 

 me that the rate at which chemical energy is converted into 

 heat by various possible reactions was an important factor in 

 determining the order of their occurrence. But even the de- 

 termination of the total thermal effects of reactions requires 

 extremely delicate experimentation, elaborate apparatus, and 

 other special facilities. To determine experimentally the rate 

 at which this heat is produced would be a still more serious 

 matter and was quite out of the question with the time and re- 

 sources at my disposal for this purpose. I therefore undertook 

 to inquire whether, by considering chemical energy as a form 

 of motion, any definite results could be reached as to the rate 

 of evolution of heat. This investigation eventually led to a 

 principle embracing that sought. It appears under the title of 

 a theorem of maximum dissipativity in the preceding article. 

 The chemical interpretation of this principle is as follows : The 

 sum of the chemical and physical transformations in any chem- 

 ically active system will be such as to convert higher forms of 

 energy into heat, light, etc., at the greatest possible rate, pro- 

 vided that the interval of time for which the comparison is 

 made is a multiple of a certain fraction of the period of the 

 most rapidly moving particles of the system. For all experi- 

 mental and for most theoretical purposes this is equivalent to 

 the statement that the transformations will be such as to evolve 

 heat, light, etc., at the highest possible rate. 



This law evidently includes M. Berthelot's, of which the 

 principle of maximum dissipativity affords a rigid demonstra- 

 tion. The tendency to the conservation of molecular type 

 which M. Berthelot has observed in complex transformationsf 

 also seems a natural though not rigidly demonstrated conse- 



* Principe du travail maximum. — Tout changement chimique accomple sans 

 intervention d'une energie etrangere tend vers la production du corps ou du sys- 

 teme de corps qui degage le plus de chaleur. Mecanique Chim., vol. i, p. xxix. 



f Mec. Chim., vol. ii, p. 471. 



