160 PROFESSOR H. B. DIXON ON THE RATE OF EXPLOSION IN GASES. 
there is an explosion without any material change of volume : after passing- a few 
times through lime water, it is reduced a little, manifesting signs of carbonic acid. 
This residue is found to possess the characters of a mixture of equal vmlumes of 
carbonic oxide and hydrogen.” 
John Davy,* * * § in 1832, described some experiments on the explosion of ethylene 
with insufficient oxygen, in which the volume was nearly doubled after detonation. 
In 1861 KERSTENt opposed the view, which he stated was common at that time, 
that in the combustion of hydrocarbons the hydrogen burns before the carbon. He 
describes experiments on the explosion of ethylene and of marsh gas with electrolytic 
gas, and with air. His conclusion is “ that before a portion of hydrogen is burnt, all 
the carbon is burnt to carbonic oxide, and that then the excess of oxvgen divides 
itself between the carbonic oxide and hydrogen.” 
In 1874, Ernst von Meyer^ (who does not refer to the previous work on the sub¬ 
ject) showed that equal volumes of ethylene and oxygen formed carbonic oxide and 
hydrogen when exploded in an eudiometer. Acetylene, diluted with hydrogen to 
diminish the force of the explosion, behaved in the same way. 
On the otlier hand, in many of the text-books of the present day the doctrine is 
taught that in the combustion of hydrocarbons the hydrogen burns before the carbon.§ 
Berthelot comes to the same conclusion from observations of the rate of explosion of 
ethylene mixed with hydrogen, and that of other hydrocarbons rich in hydrogen. 
Measuring the rate of explosion from the point of ignition through a space some 
130 mm. long, Berthelot found that a mixture of hydrogen and ethylene burnt at a 
rate which was quicker than the mean of the rates of hydrogen and of ethylene when 
exploded with oxygen in the same api^aratus : 
jMixtixre. 
CoH, + O, . . 
H. + O . . . 
CgH,. + H. + 0- 
Tirne taken by flame to travel 130 mm. 
2’86 thousandths of second I 
)-1 mean. 
1-04 „ . „ j 
1-37 
He concludes from these experiments tliat the hydrogen burns before the ethylene 
in the mixture. It must again be pointed out that these velocities refer to the 
* ‘Edin. Journal of Science,’ New Ser., vol. 0, p. 50. 
t ‘ Jonrn. Prakt. Cliem.,’ vol. 84, p. 303. 
t ‘.lourn. Prakt. Cliem.’ [IF], vol. 10, ji. 308. 
§ Faraday, lecturing at the Royal Institution, said :—“ The volatile matter raised by combustion 
from the tallow of a caudle is a vapour composed of carbon and hydrogen; and our experiment teaches 
us that the forces which hold these elements together are so nicely balanced that the hydrogen is made 
to combine first, the carbon afterwards” (‘Lectures at Royal Institution,’ p. 280, J. Scoffeen, 1853). 
For a lucid discussion of this question, as far as it affects the liberation of carbon in hydrocarbon 
flames, see Professor A. Sjutiields “On the Ftrncture of Luminous Flames” (‘Journ. Chem. Soc.,’ 
1892, vol. 1, p. 217). 
