22 
DR. W. A. BONE AND MR. R. V. WHEELER ON THE COMBINATION OF 
chiefly concerned, they do not discriminate between a chemical and a physical 
explanation of the process. If the stimulating effect of hydrogen at 430 is due to a 
chemical reduction of the catalysing material, we should expect a greatly enhanced 
and more permanent effect after long treatment with hydrogen at red heat. But, on 
the other hand, if the stimulus in question is due to a physical change in the 
hydrogen within the cavities of the material, subsequent long exhaustion at red heat 
should materially diminish, if not entirely obliterate it. Phis was the issue we 
attempted to decide in the next two experiments, which were carried out in the 
following manner :—- 
Before each experiment the combustion tube containing the porcelain was trans¬ 
ferred to an ordinary combustion furnace and connected, through fused glass joints, 
at the one end with a supply of pure dry hydrogen, and at the other end with a 
Sprengel pump and manometer. The tube was heated to bright redness in a slow 
current of hydrogen for from 36 to 48 hours, and subsequently exhausted at dull red 
heat for 20 hours. The stop-cocks at each end of the tube were then closed, and it 
was transferred back again to the circulation apparatus, when the rate of combination 
for normal electrolytic gas at 430° was once more determined, the rate of circulation 
being precisely the same as in the preceding experiments of the series. The results 
of the two experiments are tabulated below :— 
Experiment XIX. 
June 3 to 6, 1904. 
Preliminary treatment with hydrogen at red heat 
for 48 hours, followed by exhaustion at red heat 
for 20 hours. Rate of circulation = 1 in 35 
minutes. T = 430“. 
t 
P. 
h. 
hours. 
millims. 
0 
398-8 
— 
1 
364-9 
0-0386 
2 
336-8 
0-0368 
3 
311-3 
0-0359 
6 
246-1 
0-0349 
7 
225-0 
0-0355 
Experiment XX. 
June 8 to 11, 1904. 
Preliminary treatment with hydrogen at red heat 
for 36 hours, followed by exhaustion at red heat 
for 12 hours. Rate of circulation = 1 in 35 
minutes. T = 430°. 
t. 
P. 
k\. 
hours. 
millims. 
0 
383-6 
— 
2 
325-6 
0-0356 
4 
283-3 
0-0329 
6 
243-2 
0-0330 
10 
179-2 
0-0330 
12 
154-2 
0-0330 
These rates show very decisively that the surface had not been stimulated by the 
long exposure to hydrogen at red heat. 1 he values of “ are practically the same 
as the value obtained in Experiment XII., namely 0'0363, with the surface in a 
“ normal ” condition, and with the same rate of circulation. Hence the peculiar action 
of hydrogen in the catalytic process cannot be ascribed to a chemical reduction of the 
surface. 
