896 
therefore, not be applied in case of high temperatures, whereas this 
may be done with Pxranck’s formula: the latter holds (at small 
volumes) both for low and for high temperatures. 
It is, however, remarkable that if (g) were valid for high tempera- 
tures (which is not the case according to us) H=A+3RT is duly 
obtained as limiting value for Z, identical to(/). Our formula, from 
which (f) ensues for high temperatures and (g) for low tempera- 
tures, seems to be more general, and the approach to (f) takes 
place in a somewhat different way than with PLanck’s formula. 
At any rate it will have to be assumed — if p is to be small 
at high temperature, and large at low temperature, and if Ais not 
to become =O at 7'=0 — that with condensed (solid) systems 
(/—o)? changes only comparatively slightly; and that it does so in 
the same degree as the frequency v. Then PLANcx’s quantity 2 would 
be related in a definite way with the constant of the attractive forces 
J (being in its turn again in relation to e°‚ when e represents the 
electric elementary quantum), and in consequence of this also with 
%/,, at the absolute zero. There are very strong indications for this: 
particularly the undeniable connection between the so-called chemical 
constant and also the constant of the vapour-pressure on one side, 
and the quantity “/,2 on the other side, as 1 demonstrated shortly 
ago in a Paper in the Recueil des Tr. Ch. of March and May 1920 
— while it is known that this chemical constant in its turn is again 
in relation with h. 
I hope to return to this special subject later on. 
4. We will now discuss somewhat more fully the nature and 
the way of acting of the forces assumed by us between the molecules. 
In connection with what was already observed above, we might 
assume that the attractive action of M, e.g. rapidly decreases at a 
certain small distance from J/,, and disappears at a certain very 
small distance o, being replaced by a rapidly increasing repulsive 
force, which for «= s, when the moving molecule P would touch 
the molecule M,, would become infinitely great. (Cf. further what 
was already said on this head under a) of Note 2). 
Thus no two separate forces are required, nor two separate Virial- 
parts — an Attractive-Virial part and a Repulsive-Virial part — 
but only one; which point of view was already set forth by me 
some twenty years ago.') The difference with the assumption in the 
first part of this paper lies, therefore, chiefly in this, that then the 
1) See Arch. Teyler (2) T. VII, 3ième Partie, p. 1—34 (1901): „Sur l’influence 
des corrections etc.” (particularly p. 28 et seq.). 
