( 531 ) 
The ‘total contribution to «, from ali the molecules of the layers 
de, and deg, is found by integrating (4) with respect to f from 
vdz to oo. Proceeding in this way we find 
—— de (los Dhr) AB (pds) otten B) 
from which formula the energy per molecule in the layer dz, can 
be calculated by adding up all the values of this expression which 
are such that w (rdz) differs from 0. 
In this way we find 
& = — adz bo (01, + Dep) p(vdz) . . . . (5) 
For the potential energy of the system we have the formula 
k 
k 
pe nee = — ade > Ne Von + nee) p(vdz). . (IIT) 
1 1 5 
§ 3. We may now proceed to the determination of the condition 
for the maximum. Consider therefore the change of log § when we 
give the variation dn, to the numbers n,. These variations are subjected 
to the equation 
k 
Sdn, = 0 Bnn vk Boy pire ne veen AN 
1 
In the following investigation we may replace n,! by n, e ~ 
We find for dlog & 
k 
d log w, 
flog 8= S| tog n, pe +m, zen + 
D 
1 x 
nde 
k 
Ee | DD ital) (Des + Det) + 
1 
k 
J- pak ny, Ae (» d z) (d ny, + d me) os (V) 
; … de, a 
It is easily seen that the two sums, with which @ 8 multiplied 
are equal, both consisting of the same terms, and further that each 
of them is equal to 
1 k 
ae Ex dn. 
adz pas 
36* 
