Space occupied by Atoms. 319 



2 i 



the molecular refraction -3 : . -r\ and it has, as a matter of 



w + z a 



fact, been shown by me* that, in accordance with this as- 

 sumption and with the theory of van der Waals, the quantity b 

 is, at the critical temperature, in general about 8*5 or 1 times 

 as great as the molecular refraction. According to this, the 

 refractive index also becomes a simple volume-function. 



The molecular refraction is also dependent in a similar 

 manner on pressure — i. e., is compressible like the quantity b. 

 Although the influence of the internal pressure is only de- 

 monstrable in the case of the quantities b, the considerably 

 stronger affinity pressure acts also on the refraction. From 

 this it follows that we have to consider not only the surrounding 

 cether envelope, but also the atom proper, as elastic. I do not, 

 however, go so far as T. W. Richards, who concludes from this 

 result that the distinction between the internal and external 

 volumes is unjustifiable; but I conclude, from the above com- 

 pressibility, as well as from the multiple relations between 

 the internal volume, the external one and the co-volume (at 

 corresponding temperatures), that ultimately cether and che- 

 mical matter are identical. The consideration of volume 

 thus leads to views similar to those which are developed 

 in the theory of vortex atoms, and even the more modern 

 views regarding electrons are by no means so far removed 

 from those here developed as would at first sight appear 

 to be the case f. It might be specially pointed out> that 

 the doctrine of the three volumes is not only in accordance 

 with the theory of van der Waals, but also with that of 

 Fresnel, who distinguishes the aether bound up with the atoms 

 from free aether. The difference between the external and 

 internal volumes corresponds to the space occupied by the bound 

 cether, while the co-volume is filled with free cether. 



I have pointed out % that the various properties of matter are 

 related to the atomic volumes much more simply and directly 

 than to the atomic weights (e. g. } hardness, elasticity, viscosity, 

 length of free path and velocity of diffusion, boiling-point, 

 melting-point, heat of vaporization, surface-tension, refraction, 

 isomorphic, valency, compressibility, cohesion, affinity, heat 

 of formation, electromotive force, &c.). I have further drawn 

 attention to the fact that the numerical relations among the 

 atomic spaces are likewise simpler than those among the atomic 

 weights, especially when the effects due to intrinsic pressure 



* J. Traube, Ann. der Phys. [4] Bd. v. p. 552 (1904). 



t Cf. J. J. Thomson, 'Electricity and Matter.' 



I J. Traube, Zeitschr. anorg. Chem. Bd. xl. p 372 (1904). 



Phil. Mag. S. 6. Vol. 10. No. 57. Sept. 1905. 2 B 



