18 DR. W. A. BONE AND MR. R. V. WHEELER ON THE COMBINATION OR 
In a comparative experiment (VI.) made, three days later, with normal electrolytic 
gas, under precisely the same conditions, [only 21 ’5 per cent, of the oxygen initially 
present disappeared during the first two hours, the values of hi varying between 
0-0572 and 0*0532 as the pressure in the apparatus fell from 429-6 to 116-6 millims. 
in 12 hours .—February 10, 1906.] 
These two experiments bring to light the significant fact that where an excess of 
hydrogen is initially present, the rate of combination does not depend on the partial 
pressure of the oxygen, as the diffusion theory demands, but rather on that of the 
hydrogen. The increasing excess of hydrogen in Experiment A . steadily accelerated 
the disappearance of the oxygen. 
In the next three experiments (VII. to IX. inclusive), the influence of rather a 
large excess of hydrogen or oxygen respectively on the initial rate of change v as 
studied. The rate of circulation was the same in all three experiments, but it was 
purposely made slower than in the two preceding experiments, in order that the 
reaction might be extended over 8 or 10 hours in each case. In Experiment A II. 
(April 7, 1904), the mean value of the reaction constant “ k” for normal electrolytic 
gas was found to be 0 - 0195. 
In Experiments VIII. and IX., original mixtures corresponding nearly to 9H 2 + 0 2 
and H 2 +60 2 , respectively, were employed, with the following results :— 
Experiment VIII. 
April 8, 1904. 
Original mixture = 9H 2 + 0 2 nearly. T = 430°. 
Experiment IX. 
April 15, 1904. 
Original mixture = H 2 + 60 2 nearly. T = 430 . 
t. 
P H, 
p o. 
% 2 . 
*o 2 . 
t. 
P H„ 
p o. 
*0, 
hours. 
0 
2 
4 
6 
8 
millims. 
377-9 
351-1 
328-5 
311-1 
297-7 
millims. 
41-9 
28-5 
12-2 
8-5 
1-8 
0-0159 
0-0152 
0-0141 
0-0129 
0-0837 
0-0960 
0-1154 
0-1708 
hours. 
0 
2 
4 
6 
12 
18 
24 
millims. 
48-7 
44-1 
39-7 
35-5 
26-7 
19-6 
12-9 
millims. 
296-3 
294-6 
291-8 
289-7 
285-3 
281-8 
278-5 
0-0216 
0-0222 
0-0229 
0-0217 
0-0218 
0-0240 
0-0018 
0-0017 
0-0016 
0-0014 
0-0012 
0-0011 
The rates of change observed in the three experiments may be best compared by 
considering the percentage of the original electrolytic gas which disappeared during 
the first two hours in each case. In Experiments VII. and IX., with “normal gas 
and excess of oxygen respectively, these percentages were practically the same, 
namely, 9'1 and 9"4 respectively. The corresponding figure in Experiment A III., 
however, with excess of hydrogen, was no less than 32 per cent., a very clear proof of 
the accelerating influence of excess of hydrogen. 
The conclusion that the rate of change is proportional to the partial pressure of 
