PROFESSOR H. B. DIXON ON THE RATE OF EXPLOSION IN GASES. 
IG5 
§ 4. Conclusion. 
The difficulties I have touched on show how far we are from a complete theory of 
explosions. 
The tentative formula which I have proposed must be taken for nothing moi’e tlian 
a “ working hypothesis.” It has been found so far 'purallel to the truth that it may 
be useful to suggest further experiments on the nature of explosions. As Berthelot’s 
formula helped me to interpret the reactions of gaseous carbon, and suggested experi¬ 
ments which led me to modify the hypothesis I was using; so I will venture to hope 
that this modified hypothesis may in turn lead other workers to a truer knowledge of 
explosions. 
In concluding, I wish to thank three former pupils of mine, who have rendered me 
devoted service in the conduct of these experiments—Mr. J. E. Marsh, of Balliol 
College, Oxford, and Messrs. H. W. Smith and J. A. Harker, of Owens College, 
Manchester. 
General Conclusions. 
1. Berthelot's measurements of the rates of explosion of a number of gaseous 
mixtures have been confirmed. The rate of the explosion-v/ave for each mixture is 
constant. It is independent of the diameter of the tube above a certain limit. 
2 . The rate is not absolutely independent of the initial temperature and pressure ot 
the gases. With rise of temperature the rate falls; with rise of pressure the rate 
increases ; but above a certain crucial loressure variations in pressure appear to have 
no effect. 
3. In the explosion of carbonic oxide and oxygen in a long tube the presence of 
steam has a marked influence on the rate. From measurements of the rate of explo¬ 
sion with different quantities of steam the conclusion is drawn that at the high 
temperature of the explosion-wave, as well as in ordinary combustion, the oxidation of 
the carbonic oxide is effected by the interaction of the steam. 
4. Inert gases are found to retard the explosion-wave according to their volume 
and density. Within wide limits an excess of one of the combustible gases has the 
same retarding effect as an inert gas (of the same volume and density) which can take 
no part in the reaction. 
5. Measurements of the rate of explosion can be employed for determining the 
course of some chemical chang-es. 
In the explosion of a volatile carbon-compound with oxygen, the gaseous carbon 
burns first to carbonic oxide, and afterwards, if oxygen is present in excess, the 
carbonic oxide first formed burns to carbonic acid. 
6. The theory proposed by Berthelot —that in the explosion-wave the flame 
travels at the mean velocity of the products of combustion—although in agreement 
with the rates observed in a certain number of cases, does not account for the velocities 
found in other gaseous mixtures. 
