268 
employed cf. § 5) gives rise to 
(xuvy') 2 HH Jl —e 
possibilities. 
Let us now place the zj, molecules. Again we may remark that 
one of these molecules can go to form a pair only with another 
molecule of the same group. These pairs can be formed in 
N43) ! 
nlbl 
9 2 116) 1 
2 
different ways (cf. $ 5), 
Let us consider the first pair of molecules in one of these com- 
binations in particular. For the first molecule there are 
4 
— RT 
uvv' 
x |l —nj, 
v, 
places available in the proper space (ef. $ 3). When the first molecule 
has thus been placed and given a definite orientation, there are on 
account of the freedoms d6, dr 
Zar sin 6,dO,dr 
x —_— 
dv 
1 
places in space available for the second molecule. On account of 
the freedoms d6,dp there are 
sin0,dô,dp sin 0,d6,dyp 
do HE 4a 
orientations possible for this second molecule for each of its positions 
in space. 
x and p‚ in addition give rise to the factor vv’. We thus obtain 
on the whole 
r? sin 0, sin 0, dr dO, dO, dp 
dv, 2 dv, 
possibilities for this pair of molecules, to which we affix the factor 
