HYDROGEN AND OXYGEN IN CONTACT WITH HOT SURFACES. 
47 
Experiment YIII. 
December 4, 1904. 
Original mixture = Ho + 20o nearly, 
circulation = 1 in 45 minutes. T = 
| 
Rate of 
= 250°. 
t. 
P H, 
O* 
lO 
% 
/,: Oo. 
hours. 
minims. 
millims. 
0 
11G ' 6 
244-1 
— 
— 
1 
85-0 
228-4 
0-1374 
0-0289 
2 
65-0 
218-3 
0-1269 
0-0242 
3 
52-3 
212-0 
0-1161 
0-0204 
4 
43-6 
207-6 
0-1068 
0-0176 
5 
37-8 
204-7 
0-0979 
0-0153 
6 
30-8 
201-4 
0-0964 
0-0139 
8 
19-9 
195-7 
0-0960 
0-0120 
10 
14-4 
192-9 
0-0908 
0-0102 
Experiment IX. 
December 8, 1904. 
Original mixture = 3 ID + O 2 nearly, 
circulation = 1 in 45 minutes. T 
Rate of 
= 250°. 
t. 
P H, 
P 0„ 
l 'o,. 
hours. 
millims 
millims. 
0 
295-7 
95-0 
— 
1 
251-1 
72-8 
0-0709 
0-1156 
2 
210-9 
.52-6 
0-0734 
0-1283 
3 
177-8 
36-0 
0-0736 
0•1404 
4 
150-3 
22-4 
0-0735 
0-1569 
5 
127-1 
10-7 
0-0733 
0-1897 
6 
113-7 
3-9 
0-0692 
0-2311 
These experiments prove that the rate of combination is mainly determined by the 
partial pressure of the hydrogen. Throughout Experiment IX, with excess of 
hydrogen, the values of “ ^'pp ” ar e remarkably constant, but in A III., with excess of 
oxygen, they gradually diminish as the combination proceeds. These conclusions 
were afterwards confirmed by the results of Experiments XI. and XIV. It would 
appear that a steadily increasing excess of oxygen has a slight retarding influence. 
The stimulating influence of hydrogen, so well marked in IX., was further proved 
by circulating hydrogen over the gauze at 250° for 4 days, and afterwards 
re-determining the rate of combination for normal electrolytic gas, as follows :— 
Experiment X. 
December 12, 1904. 
Normal electrolytic gas after exposure of the surface to hydrogen at 250° for 4 days. T = 250°. 
t ... . 
0 
1 
1 
n 
2 
H 
3 
4 hours. 
P . . . . 
324-6 
257 • 3 
212-8 
182-0 
157-3 
138-9 
125-9 
103-1 millims 
t’i.... 
— 
0-2018 
0-1834 
0-1674 
0-1573 
0-1474 
0-1371 
0-1245. 
In this experiment ho less than 34 - 5 per cent, of the original gas disappeared within 
the first hour, as compared with 22T> per cent, in Experiments V. and VI. The 
stimulus was, however, very transient and was hardly noticeable after the first 
hour. 
The foregoing conclusions were confirmed by the following group of four experiments, 
