643 
exhibits an appreciable curvature. This is, indeed, also clear from 
table IL, as DBODENSTEIN's observations present a regularly changing 
deviation from expression 10a. This curvature is, however, not 
essential, and must be attributed to errors of observation, which 
appears clearly from this that expression 10d is entirely incompa- 
tible with the observations of Srramüruer. Thus —2,19, —2,17, and 
—2,15 follows from 10d for the first three observations, whereas 
STEGMÜLLER found —2,925, —2,692, and —2,416. Here too we see 
therefore that the straight line 104 and the slightly curved lines 
104 and 10c, represent the observations better than the more decidedly 
curved line 10d. 
4. Of the gas reactions there is no example known to me for 
which the two-constant formula 2 expresses the observations less 
accurately than the more complicated formula; the influence of the 
specific heats is always small, and its influence is always exceeded 
by the errors of observation. This will no doubt be in connection 
with the fact that the algebraic sum of the specifie heats can 
naturally be only small. In the two members of the reaction equa- 
tion the same atoms, namely, always occur and only the different 
way of binding can bring about a difference in specifie heat. If we 
imagine an equilibrium A, = 2A, the specific heat of the di-atomic 
molecule, when there is not yet an appreciable vibration in the 
molecule, will amount to 5X '/, R, corresponding with the three 
degrees of freedom of the translation and two of the rotation (solid 
of revolution). The two free atoms have a specific heat of 6 < 1/, R. 
The algebraic sum, therefore. amounts to */, R. If we are at tempe- 
ratures at which the vibration in the molecule becomes appreciable, 
then a value between zero and 2 XX ‘/, R mast be added for the 
vibration (for the potential and the kinetic energy). The algebraic 
sum will therefore vary between + '/, R and —?/, R. This small 
amount has hardly any influence on the chemical heat, and the 
same thing applies to the other gas equilibria in an analogous way. 
A greater influence of the specific heats may be expected for the 
gas reactions, in which also solid substances take part. For then not 
only the different way of binding of the atoms, but also the difference 
in state of aggregation plays a part. In connection with the above 
I will, therefore, still discuss a few reactions with solid substances. 
In the literature there are described a number of equilibria, which 
would show a maximum or a minimum value for A at a definite 
temperature. It is clear that if this is true, the two-constant formula 
2 cannot be applicable; this, namely, excludes the appearance of 
Jt 
