(;38 



2"'^ tiie angles 0^ and 6.^, wliirli tlie axes of tlie quadrnplets make 

 vvitli Ihe line whicli joins the centres. For a closer definition of 

 tliese angles we choose in each molecule arbitrarily one of the two 

 equivalent directions on the axis as the positive direction ; we choose 

 further as the positive direction on the line whicli joins the centres 

 the direction from the molecule whose position is determined by 

 the angle considered, towards the other molecule ; Ö, and 6^ are 

 then the angles, from to .t, between the positive directions; 



3"'. the angle (f betweefi two half-planes each of which contains 

 the positive direction of tlie axis of one of the quadruplets and the 

 line joining the centres. This angle is further specified as in Suppl. 

 W. 24A § 6, and goes from to 2rr. 



a 



Fig. 1. 



The method of Suppl. No. 24A § 6 may then be applied imme- 

 diately to the problem dealt with here. It gives for the specific 

 heat at constant volume in the AvoG.VDRO-state, assuming that the 

 spheres are smooth: 



and for the second virial coefficient : 



B = \n{^,ta^ -F) (2) 



where ; 



It = the number of molecules in the quantity of gas for which 

 the equation of state is derived, 



(I =^ the diameter of the molecule and 



"-m^ 



(e '"'61 _l) r" mi 6^ sin &, dr d6 , d&^ d(f . . (3) 







In this formula 



1 

 /( = — (4) 



k is Planck's well known constant, whereas «i, is the potential 

 energy of the pair of quadruplets indicated by the index 1, when 

 the potential energy is put =0 for ?• ^ oo. Its value is given by: 



