( 707 ) 
characteristic of the pure substances. A further confirmation of this 
supposition and characterisation of these quantities can only be given 
by a kinetic theory of the chemical phenomena. Such a theory we 
find already in Boutzmann’s ‘‘Gastheorie’ and we shall see that 
Nerxst’s results are in principle already implied in it.) 
7. In this communication we shall restrict ourselves to the kinetic 
treatment of two simple cases. We shall make use of the statistical 
method of GrBBs, which easily gives both the conditions of equilibrium 
and the entropy of a partially dissociated gas. 
The first case of dissociation which we consider is one of the type 
of the dissociation of lodine vapour (1, S 1 + I). 
For this case BOLTZMANN *) describes the action of the atoms on 
each other in the following way. The atoms are supposed to be 
perfeetly rigid, elastic, and smooth spheres of the diameter o, whieh 
have the mass 77 distributed homogeneously over the volume. The 
chemical forces are not active in all directions round the atoms, 
but are restricted to certain regions at the circumference. They have, 
however, always the direction of the line connecting the centres of 
the bound atoms. The following may serve to describe the action of 
the forces. somewhat more accurately. Let 4 (fig. 1) be the centre 
of an atom; the centre B of a second atom now must lie outside 
the sphere S4, which has been deseribed round A with a radius 
o. If the second atom is to be bound to the atom A, it is necessary 
that B lies in a volume w4, which is firmly connected with 54, 
and adjoins it, while A must lie in the corresponding volume wg 
Rice 
1) This is the more remarkable, because Nernst indeed mentions BoLTZMANN's 
work in his first paper Gott. Nachrichten 1906 p. 7, but adds: “doeh haben sich 
neue praktisch verwendbare Resultate auf diesem Wege bisher nicht ergeben.” 
2) Gastheorie Il. p. 177, 
