144 
n, == 4 Ate—hm(c-+e)—2ht da dy de du dv dw da' dy' dz’ du! du' dw' 
Introducing the coordinates of the centre of mass and the relative 
coordinates for a pair, viz: 
X,=} (e+ 2) CIC; X,=a'—«2 etc. 
E=}t(u+u) ele a=u—u etc. 
and putting 
sy est a+ et y= V’ Ke HF 492) ee 
we find for n, 
n, = 4 Ate hm? d5 dy do dX.dY.dZ, e—thmV—2ht da dB dy 4a r? dr 
The number of atoms per unit of volume is found by integration 
of n, over u,v,w and by division by dw dy dz. As always further 
on we think namely of a diluted gas and thus find: 
a) 
The number of molecules per unit of volume is found in the 
same way from 7,, namely 
5 ge | BENS EN ; 
ees a 2hm hm AE 
where w has been written for the volume of the sphere of attraction. 
We thus find for the dissociation constant A the formula 
p 
YP ze 2 
K=— =} we * =} we Ja 
v, 
Passing to the velocity constants we may use the following con- 
siderations. A number of iodine molecules per unit of volume will 
dissociate spontaneously with a velocity proportional to the number 
of molecules, thus 
dv, 
fis 178 
The atoms will associate spontaneously with a velocity proportional 
to the number of pair of atoms. By this the number of molecules 
will increase, thus 
dv, E 
En — ie Vv, 
In the stationary state we must have therefore 
wm, | de 
kvij=kr ae —=——z 
pie ies 
The value of K has been found above. 
Accepting the image of the dissociation we evidently can also 
