Chase.] •->^" [jan. 5 and Feb. 2, 1»77. 



Chemical molecules and atoms are so small that we are unable, at 

 present, to show, so conclusively as in cosmical gravitation, that the 

 "nascent" velocity, or the mean radial velocity at the limit between com- 

 plete dis.s()ciation and incijiient aggregation, is equivalent to the velocity of 

 light. But tlie analogies, whicliare here prcsentwl, are strengthened by the 

 frequent vivid, luminous and thennal accompaniments of chemicsvl change, 

 and by the electric polarity of combining elements. It seems, therefore, 

 reasonably certain that tiie same limiting unity of velocity and cis »2»«^ 

 whicli can be easily traced in light, heat, electricity and gravitation, is also 

 fundamentally efficient in chemical affinity. M. Aymonnet, in his com- 

 munication of a " nouvelle methode pour etudier les spectres calori- 

 fiques,"* says : "Je fcrai rcmarquer. avant de terminer, que I'etude des 

 spectres Ciiiorifiques d'absorption, faite avec des corps portcs a diverses 

 temperatures, peut et doit conduire a la connaissance de lois physiques 

 reliant les phenomenes d'association et de dissociation des corps aiix 

 phenomenes csxlorifiques et lumineux." In another paper reccntlj' pre- 

 sented to the French Academy, "sur le rapport des deux chaleurs spe- 

 cifiques d'un gaz, "f M. Ch. Simon deduces the theoretical ratio C : c : : 1.4 

 : 1. The first attempt at a solution of the problem upon n priori grounds, 

 appears to have been Professor Newcomb's,^: who found from the hypothe- 

 sis of actual collisions, the ratio 5 : 3 if the particles were hard and spheri- 

 cal, or 4 : 3 if they were hard and not spherical ; the second, my own,^ 

 based on the general consideration of all internal motions, which led to the 

 ratio 1.4232 : 1 ; the third, M. Simon's, which took account of rotations 

 and neglected other internal vibrations. 



* Comptes RendiiH, Ixxxlii, 1102—4, Doc. 4, 1876. 



t lb. 7J7, Oct. 16. 1876. J Proc. A. A. S.. v., 112. I AiUe,y.\\,%^l. 



