PROFESSOR H. B. DIXON ON THE RATE OF EXPLOSION IN GASES. 115 
The explosion-\vave, rapidly started in this mixture, was communicated to the dilute 
mixture beyond, without break of continuity, before the first bridge was reached. 
A comparison between the few experiments made by Berthelot with diluted 
mixtures and the similar ones made by me will, I think, show the need of these 
precautions. To three volumes of electrolytic gas Berthelot added two volumes of 
nitrogen : the rate of explosion was found to be 2121 metres per second. To three 
volumes of electrolytic gas he added four volumes of nitrogen : the rate of explosion 
was only 1439 metres per second. By interpolation* I find from my own experiments 
with one, three, and five volumes of nitrogen (added to three volumes of electrolytic gas) 
the rates 2200 and 1930, for the explosion of electrolytic gas with two volumes and four 
volumes of nitrogen respectivly. The first agrees fairly with Berthelot’s number, the 
second is far higher than his. I imagine in the second case the interrupter was broken 
before the explosion-wave was established in his experiment. Similarly, in two experi¬ 
ments with cyanogen, Berthelot found a rapid falling off of the rate whicli I did not 
observe. On firing a mixture of cyanogen with twice its volume of oxygen and one 
volume of nitrogen, he found the rate to be 2044 metres; on adding another volume of 
nitrogen the rate fell to 1203 metres. By interpolation I find from my experiments 
2125 and 1960 as the rates of these two mixtures. The first agrees fairly well with, 
the second is far higher than, Berthelot’s number. 
The mean results obtained in a number of experiments on the retarding effect of 
oxygen and nitrogen are given in the following table :— 
Table XIII.—Electrolytic Gas with excess (1) of Oxygen and (2) of Nitrogen. 
( 1 -) 
Mixture. 
2 vols. hydrogen 1 
1 vol. oxygen. J 
+ 0 
With addition of 
1 vol. oxygen. 
Ho + 0 + 0 
With addition of 
3 vols. oxygen. 
Ho - 1 - 0 -|- O 3 
With addition of 
5 vols. oxygen. 
Ho -h 0 + O 5 
With addition of 
7 vols. oxygen. 
Ho + 0 -I O 7 
Mean rate . 
2821 
2328 
1927 
1707 
1281 
( 2 .) 
Mixture. 
2 vols. hydrogen 1 
1 vol. oxygen. J 
H 2 + 0 
With addition of 
1 vol. nitrogen. 
R2 + 0 + N 
With addition of 
3 vols. nitrogen. 
Ho -F 0 + Ng 
With addition of 
.5 vols. nitrogen. 
Ho + 0 -F N5 
With addition of 
7 vols. nitrogen. 
Ho -F 0 + N^ 
Mean rate . 
2821 
2426 
2055 
1822 
— 
These results are shown graphically in fig. 3, Plate 1, where the ordinates are 
volumes of nitrogen (or oxygen) added to three volumes of electrolytic gas, and the 
abscissae are the rates of explosion of the mixtures in metres per second. 
* See fig. 3, Plate 1. 
Q 2 
