The Molecular Volume of Solids. 



467 



V volume of molecule of substance 



n yg- volume of molecule of water 



Consequently, the numerical value of — would not be altered if we 



n 



took for our definition of molecular volume any volume bearing a fixed 

 proportion to tlie volume first taken as sack definition. The nume- 

 rator and denominator of tke fraction (1) would both be increased or 

 diminished in the same proportion. Now, inasmuch as the molecules 

 of any substance will pack themselves as closely as their mutual 



repulsions will allcw, it follows from geometry that the space — is 



11 



proportional to the sphere of repulsion of the molecule of the sub- 

 stance. 



Hence we may define the volume of a molecule as the volume of 

 its sphere of repulsion without affecting the equation. 



ci . n £ii. weight of molecule 



bpecmc gravity of substance = 2. . 



volume of molecule 



