948 
For hydrogen we have then: 
ice 
Bat ens ede 1,0667 (ho)? + 0,1741 (ho)* …. — 
| 
— 0.1586 hy — 0,1638 (hr) … | … ne fe LD 
For nitrogen the last row of terms is only slightly different, for 
oxygen somewhat more. 
The values of 5 used here being derived from calculations in 
which the induced attraction has not been attended to, this expression 
for B may be regarded as a first step only in a series of succeeding 
approximations. In the Leiden Supplement N°. 39a, the value of 
hv in the Joure-KeLviN point of inversion has been calculated starting 
from eqation (19). When we wished to do this here, we should 
first have to derive still some terms for the “induced part” of 5. 
After this the experimental values of 7%,,(,—0) and Bi, would give 
us corrected values for v and o. We may expect the alteration 
of 6 in consequence of this correction to be rather small, so that also 
the change of equation (19) due to it will be not considerable. 
In this communication we will however confine ourselves to the 
following statement: A comparison of the terms in question shows 
that at least for the mentioned gases, unless the temperature be 
very high, the “qwadrupole attraction” has considerably more in- 
fluence in B than the “induced attraction’. For gases as the above 
the cohesion forces introduced by van pER Waals into the equation 
of state may therefore be ascribed principally to the forces exerted 
by the molecules on each other because of their quadrupole moments 
