120 PROFESSOR H. B. DIXON OX THE RATE OF EXPLOSION IN GASES. 
Ill the case of ethylene, the retarding action of oxygen, which is greater than that 
of nitrogen for the first volume added to the mixture ( 0211 ^^+ 202 ), becomes less and 
less as a large excess of oxygen is added; so that the rate of explosion of ethylene 
and air would be considerably increased by the substitution of oxygen for the nitrogen 
of the air. With a large excess of oxygen the secondary reaction, whereby carbonic 
acid is formed, influences the result, for the conditions are eminently favourable for 
the interaction of the carbonic oxide, steam, and oxygen. 
Table XVII. — The Piate of Explosion of Vcetylene (1) with Oxygen, and (2) with 
Oxygen and Nitrogen.* 
( 1 -) 
Mixture. 
2 vols. acetylene 1 
3 vols. oxygen J 
C 2 H 2 + O 3 
With addition of 2 vols. 
oxygen. 
CoHo + O, 
Mean rate . 
2716 
2391 
( 2 -) 
Mixture. 
2 vols. acetylene 1 
3 vols. oxygen j 
C 2 H 2 +O 3 
With addition of 2 vols. 
nitrogen. 
C 3 H 2 + O 3 + N 3 
Mean rate . 
2716 
2414 
These experiments show that in all the cases examined, viz., the combustion of 
cyanogen, marsh gas, ethylene, and acetylene, the substitution of nitrogen for the 
oxygen required to burn the carbon from carbonic oxide to carbonic acid increases the 
velocity of the explosion. Thtse facts seem only consistent with the view that the 
carJjon burns directly to carbonic oxide, and the formation of carbonic acid is an 
after-occurrence. 
§ 4. Berthelot’s Experiments bearing on the mode of Combustioii of Carbon. 
M. Berthelot found that the pressures produced in the explosion of cyanogen 
were greater for the incomp)lete than for the complete combustions.+ 
* No doubt Avitli a large excess of oxygen tbe explosion of acetylene would be less retai’ded tlian with 
a large excess of nitrogen, as in the case of ethylene. Owing to the expense of preparing the acetylene, 
experiments with a large excess of oxygen Avere not made. 
t ‘ Ann. Chim, et Phys.’ [VI.], Ami. 4, p. 38. 
