( 'i43 ) 



a 



Tlie lii'st iHCMulxM- of lliis equation contains the louarithiu of \\w 

 prodiit'l of two ratios, namely the ratio of tiie inwardly directed forces 

 which keei) the molecules — considered as separate systems — 

 inside the vapour and the liquid phase, and the ratio of the inwardly 

 directed forces which keep these systems in both phases intact. In 

 the case that it is a quasi-decrease it is impossible to indicate the 



r dh 



signification of K in such a precise manner; but the quantity J — -y 



ditfering- also in this case from zero, the above considerations show 



with certainty that the quantity K exists also in this case. The 



question whether it will I)e larger or smaller can only be decided 



by a comparison of the course of h with v in the sup[)Osition of a 



quasi decrease with that in the supposition of a real diminishing. 



1 h—h. 

 The term — ~ has been neglected in equation (6). This equa- 



tioH a[>plies oidy for low temperatures, and for those temperatures 



1 



the term in question is equal to — according to the fornuda gi\'en 



for h. It is remarkable that also many other suppositions concerning the 

 nature of the forces which keep the uiolecules intact, different from 

 those suppositions wdiich have led to the form chosen foi- h, yield 

 the same equation (6), every time however onl}' after neglection of 

 a relatively small quantit)' in whose kinetic interpretation I have 

 not yet succeeded. We obtain equation (6) when we assume, 1^*^ that 

 the molecule may be regarded to be a binary system consisting of 

 two atoms or of tw'o closely connected groups of atoms, which w^e shall 

 call radicals, 2"^^ that these parts move relatively to each other, and 

 3'^^ that the amplitudes of these motions are of the same order 

 as the dimensions of the atoms. If the parts are i-adicals, other 

 motions take place inside those radicals, l)ut the amj)litudes of these 

 motions are so small that the^' have no noticeable effect on the 

 N'olume of the radicals. We have represented the forces which the 

 atoms or radicals exercise on one aiiothci- by « (/> — /;J, so in the 

 gaseous stale by ci{l),i — />„). So, as we have <leri\ed the equation: 



and as h,, — /;„ is constant, « must be projxtrtioual with the teuqieratnre, 

 — and I must acknowledge that it is difticidl lo image a mechanism 



JO 

 Proceedings Royal xVcad. Amsterdam. Vol. VI, 



