Residual Valence of Various Molecules 487 



The computation of the total number of valences in a 

 molecule from the cohesion is made from van der Waals' 

 factor "a" by the formula :a = C(Mol. Wt. X Val. number) 2/3 . 

 a was computed by the formula already given, namely 

 a = ((S 2 S + 2)/(S 2))P c V c ,in which S is the critical 

 coefficient and P 6 and V c the critical pressure and volume. 

 The constant C for a single pair of molecules was assumed to 

 be equal to (m 2 k)~ /3 , in which m is the gravitational mass of a 

 molecule of unity molecular weight and k the gravitational 

 constant. From Millikan's recent determination of the number, 

 N, of molecules in a gram mol, the value of this constant was 

 3.2015 X io" 37 expressed in dynes. For a gram mol C is 

 1.177 X io n . 



Owing to various uncertainties and assumptions in the 

 calculations, this method of determination can be regarded 

 only as of the nature of an approximation to the actual amount 

 of residual valence of molecules. 



