28 L ARMOR, Physical Aspect of the Atomic Theory. 



atom besides electric inertia ? This is the same as to ask, 

 Is the atom something foreign to the aether and self- 

 existent, which, however, can attract and hold certain 

 aethereal nuclei called electrons, constituting a connexion 

 with the aether through which atoms, which would other- 

 wise be isolated worlds, are in physical relation with one 

 another to form a cosmos ? Such an extension of our 

 conceptions may as we have seen be welcome in 

 biological science, involving as it would that atoms in 

 intimate entanglement may interact differently from the 

 simple and regular methods which obtain when the 

 aether is their only mode of inter-communication. But 

 all who have appreciated the course of evolution of the 

 principles of modern physical explanation through 

 Newton, Lagrange, Young, Fresnel, Faraday, Stokes, 

 Kelvin, Maxwell, Helmholtz, Hertz, to mention only a few 

 names of the past, will still hold that even if the atom 

 itself is intrinsically unfathomed, yet the interaction 

 between atoms separated in space is in its larger features 

 understood and has its seat in their sub-electric connexions 

 with the aethereal medium, 



CJicmical Reaction in Gases. 



The laws of chemical equilibrium in the rarefied state 

 of matter, with free molecules, which belongs to gases, 

 ought to be the most amenable to the direct indications of 

 molecular theory : but in practice it is here that com- 

 plexities show most prominently. 



The earliest and one of the most complete numerical 

 discussions of the facts of the simpler phenomena, those of 

 gaseous dissociation, was made by Willard Gibbs himself 

 in 1879.* In the four cases treated he satisfied himself 



* ' On the vapour densities of peroxide of nitrogen, formic acid, acetic 

 acid, and perchloride of phosphorus.' Silliiiians Journal, (3) vol. 17 : 

 "Scientific Papers," vol. i, pp. 372 — 403. 



