ib bey, 
gases at constant pressure, divided by A, i.e. =} -+$— $= # 
and c is the algebraic sum of the heat capacities of the reacting 
a4, «B and arg are the entropy constants of the gases defined in (1) 
By equating (20) and (21) we find: 
Zlogma + Hlogmpg log mag — log (2S) —logh + Hlog (kT) — 4 log (2a)y= 
= = = — a + 4 log T—log k, 
in which mag == mtd mg is the mass of a molecule AD. 
When in this we substitute for a4 and ay the values following 
from (16) and (1), we find : 
aAB a 
Erk =log J + Hlogk — 5louh + Hlogmag +43 log 2 + log, 
corresponding to (18). 
When, however, we assume the two atoms to be of the same 
kind, we shall find a value of half the amount for the dissociation 
AY 
n - . . . . . 
constant = in the kinetic calculation : the probability that two atoms 
ny 
meet that can unite is now namely twice as great as before, all the 
rest remaining the same. 
Thermodynamically we find, however, a four times smaller value : 
; Led 3 De B ; 
in (21) En)’ must then be substituted for > *, the righthand side 
ny n 
1 
remaining unchanged. In this case, just as in the preceding §, we 
should, therefore, find an & log 2 smaller value for a,z. 
As, however, as was said above, it must be generally assumed 
that two similar atoms do not perform the same function in chemical 
combination, we shall have to give a somewhat more general form 
to the suppositions made by van ber Waars Jr. about the chemical 
forces. We suppose every atom to possess two poles, a positive and 
a negative one, and that in a certain combination of two dissimilar 
atoms A and B always e.g. the positive pole of A gets in contact 
with the negative pole of 4. In a combination of two similar atoms 
the positive pole of the one will always be connected with the 
negative pole of the other; in this case it is of no consequence, 
however, which atom is connected through its positive, which through 
its negative pole. This makes the number of possibilities of binding 
still 2 X greater than for dissimilar atoms, and the change of coming 
together becoming already 2 > greater through the mere fact of 
the atoms being equal (see above), it now becomes 4 x greater, 
which is in harmony with the thermodynamic formula, so that also 
in this case we have to assign the value (18) to aap. 
