HYDROGEN AND OXYGEN IN CONTACT WITH HOT SURFACES. 
63 
lhe ratio H 2 /0 2 lor the 125‘4 millims. of residual gas was 2*11, a circumstance 
indicative of a slight absorption of oxygen rather than of any permanent reduction of 
the oxide during the experiment. The values “ k” for the whole duration of the 
experiment (third column) indicate, at first sight, a steadily accelerated velocity. 
Reckoning from the end of the first hour, however, the values given in the fourth 
column are obtained. The two series of values, therefore, indicate an accelerated 
velocity during the first hour, after which it varied directly with the pressure of the 
dry gas. 
The most striking feature about the experiment is the extremely slow rate of steam 
formation as compared with that observed in the previous experiment with the 
reduced gauze; to put the matter briefly, no less than 8 hours were required with 
the oxidised gauze to effect the same percentage of change as was observed in 
I), hours with the reduced surface in Experiment I. 
The two following experiments at 214° were next made with mixtures originally 
containing excess of oxygen (H 2 + 20 2 nearly), which proved the rate of change to be 
nearly proportional to the partial pressure of the oxygen. 
Experiment III. 
September 26, 1904. 
“ Oxidised ” gauze at 214°. Original 
mixture = H 2 + 20 2 nearly. Rate of circula¬ 
tion = 1 in 40 minutes. 
Experiment IY. 
September 27, 1904. 
“ Oxidised ” gauze at 214°. Original 
mixture = H 2 + 20 2 nearly. Rate of circula¬ 
tion = 1 in 40 minutes. 
t. 
P H, 
p 0! . 
A Ho. 
*0* 
t. 
P Ho. 
p o«. 
%, 
k o.,. 
hours. 
millims. 
millims. 
hours. 
millims. 
millims. 
0 
144-1 
273-6 
— 
— 
0 
124-5 
259-8 
1 
133-5 
268-3 
0-0332 
0-0085 
1 
112-7 
253-9 
0 • 0433 
0-0101 
l 
124-2 
263 • 7 
0-0323 
0-0080 
2 
100-1 
247-6 
0-0473 
0-0104 
3 
110-0 
256 • 6 
0-0391 
0-0093 
3 
87-0 
241-0 
0-0519 
0-0109 
5 
80-9 
242-1 
0-0501 
0-0106 
5 
62-1 
228-7 
0-0604 
0-0110 
7 
55 • 7 
229-3 
0-0589 
0-0109 
7 
39-5 
217-5 
0-0698 
0-0110 
9 
34-7 
219-0 
0-0687 
0-0107 
9 
19-9 
207-7 
0 • 0885 
0-0108 
11 
18-9 
211-1 
0-0802 
0-0103 
11 
3-9 
199-6 
0-1388 
0-0104 
13 
10-3 
206-7 
0-0881 
0-0094 
• 
i 
finally, in Experiment V., the rate of reduction of the “oxidised” gauze by 
hydrogen at 214° was measured; this proved to be something like ten times as 
fast as the rate of steam formation observed when electrolytic gas was circulated 
over the “oxidised” gauze at the same temperature in Experiment II. So fast 
indeed was the reduction process that a charge of 700 cub. centims. of hydrogen 
introduced into the apparatus almost entirely disappeared within an hour, as the 
following pressure records for two successive charges indicate 
