639 
which cannot be represented by equation 2 that this is owing to 
great inaccuracies in the determinations. I shall then also have an 
opportunity to call attention to a few important reactions, which 
in my opinion have been observed little accurately, and of whieh 
a renewed examination is very desirable. 
2. To begin with I will make clear why equation 2 is applicable 
almost without exception to the material of experimental facts, and 
[ will illustrate this by a gas equilibrium which is one of the most 
accurately investigated equilibria, viz. the carbonic acid dissociation: 
2CO, 22 CO + O,. If we call Zp, the change of energy on conversion 
of two gram-molecules of carbonic acid at the temperature 7’, 
it is represented at another temperature 7’ by: 
Ep Bree) ee Lee (5) 
in which e,‚ represents the mean specifie heat at constant volume 
of two gram-molecules of carbonic acid, and c, of two gram-mole- 
cules of carbonic oxide and one gram-mol. of oxygen between the 
temperatures 7’ and 7’. If the true specifie heats are no functions 
of the temperature, and the mean specific heat is none either, then 
equation 1 yields after substitution of Zp according to 5 on integration 
inde Er, ¢,—-¢, ny ae r, |ar— 
imate aero cer a 
Ep, Ce Cs fis Ct T,—T 
ey ee meee | ee al 
CS RT T R T 
i 
Er, T,--T ' T,—T\? c,—e, T,—T OENE, 
== = ee : A ce ~ +O. € 
Ink RT jane R JE 7 4 r a R 7 in (7) 
The first term of the series disappears, so that equation 7 can be 
OUT lt / TTN 
Wg i (p=) tt ee We eee det 
7 ry. 7 
Nl 
: 3 1 f . 
If we now write In i = In (: + ——— | in a series, we get: 
written : 
ET 2k Je 
The term of the series which has the greatest influence, has 
disappeared; equation 2 is obtained from (8) by neglect of the 
higher terms. And these are generally small. The observations of 
the carbonie acid equilibrium have been carried out between 1300 
