648 
hexatomic molecule and two tri-atomic ones. It can be directly derived 
from the number of degrees of freedom that a value of 670 cal. 
must be impossible. I think the conclusion must be drawn from this 
that in spite of the care devoted by Prof. Smrrx to these measure- 
ments, the observations cannot be right or that they have been 
wrongly interpreted. The researches are very difficult, and an error 
in the observation passes into the value of the equilibrium constant 
greatly enlarged. The observations with ammonium chloride yield a 
normal behaviour in contrast with the just mentioned observations. 
To prevent misunderstanding it may be pointed out that great 
specific heats can certainly oceur, but that it must then be derived 
from that value that then a chemical reaction plavs a part. Thus 
the specifie heat of nitrogen-tetroxide is for instance very great; if 
can even amount to 100 eal. and more. This, however, is to be 
attributed to the decomposition of N,O, into 2NO,. The specific 
heat of the equilibrium mixture, the composition of which varies 
with the temperature, is then e.g. 100 cal., but by far the greater 
part of this is caused by the shifting of the equilibrium with change 
of temperature and the great reaction energy attending it. If, 
however, we calculate the constant of equilibrium of the dissociation, 
we have no longer to do with the specific heat of the mixture, but 
with the algebraic sum of the specific heats, which is very small, 
also here. This also tallies with the fact that the dissociation constant 
of N,O, in its dependence on the temperature can be represented 
by the two-constant formula 2, in which this sum is put zero. 
If Smiru’s experiments are correct, we should expect a second 
reaction, which has not been taken into account. 
7. The water gas equilibrium. 
The water gas equilibrium is also sometimes found mentioned 
as an example of a reaction with a maximum value of A. This 
conclusion, however, is not derived from direct observation, but 
rests on great extrapolation of data which are partly still little 
accurate. The observations have been carried out between 700° C. 
a he Led _dlog K 
and 1400° C.; caleulated is a reversal of sign of - ae 
2800° C.*). No straight line can be drawn through the observations 
in the graphical representation loy K—=/(7—'); only the points 
which are given as little accurate, however, deviate appreciably 
from the straight line through the other points. Besides, at the 
temperature where this equilibrium would present this peculiarity, 
at about 
1) Hager. Thermodyn. techn. Gasreakt, 
