of Gases and Molecular Forces. 517 



To get relative values of (2a) 2 for the substances for which 

 we know C and ij 0j we may write our relation (2) thus 



* -064 (273cm)* krri 



[Za) ~ % (1 + 0/273) ~%(1 + 0/273)' 



where k is the same for all bodies. As we do not know the 

 actual masses m, but only the molecular mass M compared 

 to that of the hydrogen atom, we will take 



MV{10 2 7 7o (l + C/273)|- 



as giving relative values of the square of molecular diameters. 

 Subjoined are the data and the results calculated from them ; 

 the values of r} are those given by Obermayer, and the 

 numbers given as (2a) 2 (relative) are the values of 



MV{10 2 77 (l + C/273)}. 



H . N 2 . 2 . CO. C0 2 . N 2 0. 2 H 4 . 

 lO^o 86 166 187 162 138 135 92 



M 2 28 32 28 44 44 28 



C ,... 79 109 127 100 277 260 272 



(2a) 2 (relative) 127 228 206 239 239 261 288 



(2a) 3 (relative) 1440 3440 2963 3698 3686 4230 4884 



Now in the characteristic equations given in my paper on 

 the " Laws of Molecular Force" (Phil. Mag. March 1893), 

 there is a limiting volume in the liquid state denoted by /? 

 and values of ft are given for a gramme of each of the above 

 substances except CO, so that multiplying them by the 

 molecular masses (weights) we get numbers giving other 

 relative values of the volumes of the molecules which should 

 stand in a constant ratio to those already tabulated as 

 (2a) 3 (relative). The following are the values of M/3 and the 

 ratio of (2a) 3 (relative) to M/3 : — 



H 2 . N 2 . 2 . C0 2 . N 2 0. C 2 H 4 . 



Mj3 8-6 22-7 19"3 30-3 29-0 42-8 



(2a) 3 (relative) /M/3 167 153 153 121 137 114 



The value of the ratio is larger for the elements than 

 for the compounds ; but considering that M/3 ranges from 

 8*6 to 42*8, the ratio approaches near enough to constancy 

 to show that the theory is right in its essentials, while it 

 is possible that departure of shape of molecules from the 

 assumed spherical form will have to be taken account of 



