24°: Messrs. Richardson, Nicol, and Parnell on the 
constant for all temperatures and pressures. A series of 
values of logio oe will be given below. 
To determine g, the heat required to dissociate 1 gm.-mol. 
of hydrogen inside the platinum, we must take two corre- 
sponding values of Q (Q;, Q2) and of @ (9,, @2) and eliminate 
the quantities which are independent of temperature in 
equation (8). We then obtain the formula 
log sQ: —$1og A — logyQo+4 logyo9> 
1/8.—1/6, 
Values of g, for different pressures and different ranges of 
temperature are given in Table VI. The mean value of 
15 determinations yields g, =36,500 small calories. 
Che 
Ai 
numbers in Tables I. to V. have been calculated, and are 
shown in Table VI. The first column gives the pressure 
min cms. of mercury, the second the absolute temperature, 
and the third the values of g, calculated from the values of 
Q given in the earlier tables. The values of g, were calcu- 
lated for approximately constant differences of temperature at 
any one pressure; thus the first value (33,800) corresponds 
to 1129—849, the second (84,600) to 1268—990 and so on. 
The fourth column gives the right-hand side of equation (8) 
for all values-of 7 and 9. The fifth gives the mean of these 
values for each pressure, whilst the sixth gives the corre- 
sponding values of Cy/Ao?. 
Inspection of the numbers in column III. shows that they 
are all fairly constant. The two lowest values correspond to 
the experiments in Tables II].-V. As in these experiments 
the temperatures were not determined so accurately as in the 
others, they cannot be regarded as of equal value in deter- 
mining g, We may also leave out the other value (31,900) 
marked with an asterisk on the ground that it is much less 
than any of the others. The mean of the fifteen remaining 
determinations gives g,=36,500 whilst the mean for the 
whole eighteen was 36,800. 
In obtaining the numbers in column IV. by evaluating the 
right-hand side, the mean value 36,500 cal. was taken for g,. 
It will be seen that the resulting values of log,,>Cu./A,2, although 
very constant at the middle of the range, have a distinct 
tendency to fall off at the lower pressures. This is brought 
out more clearly by the mean values of log;)Cu./A,2 at any 
one pressure given in column V., and by the corresponding 
g= 92 
The values of g and of logo corresponding to the 
