PROFESSOR H. B. DIXON ON THE RATE OF EXPLOSION IN GASES. 113 
Cap, V. —The Mode of Burning of Gaseous Carbon. 
§ 1. The fact that carbonic oxide is not acted on directly by oxygen, even in the 
explosion-wave, points to the possibility that the carbon in gaseous hydrocarbons, and 
in other volatile carbon compounds, is not oxidised directly to carbonic acid when 
these gases are burnt with an excess of oxygen. When cyanogen, for instance, is 
exploded with oxygen, the carbon may burn in one or in two stages. Each atom may 
either combine directly with two atoms of oxygen to form carbonic acid, or each atom 
may combine first with a single atom of oxygen to form carbonic oxide, which after¬ 
wards combines with a second atom of oxygen to form carbonic acid. If the 
oxidation is effected in tvm stages, the chemical change first occurring, viz., the 
oxidation of the carbon to carbonic oxide, must take place in the presence of an 
excess of oxygen. Will this excess of oxygen influence the velocity with which the 
initiation of the chemical change is propagated, i.e., the rate of explosion ? The 
interest of tracing the course of any chemical change, and the scientific importance of 
this particular reaction, led me to study the influence of the presence of an excess of 
oxygen, and of an inert gas, on the rate of explosion of gaseous mixtures—with a 
view to obtain evidence on their mode of burning. 
§ 2. The Retardation of the Wave caused hy Inert Gases. 
When electrolytic gas is mixed with oxygen, nitrogen, or steam, the explosion- 
wave is retarded, the oxygen having most effect, the steam least. For instance, the 
addition of one volume of steam to three volumes of electrolytic hydrogen and oxygen 
reduced the rate of explosion to 2494 metres per second in experiments made at 
65° C. At the same temperature the addition of one volume of nitrogen to three of 
electrolytic gas reduced the rate to 2402 metres per second. According to 
Berthelot’s formula a retardation of this order was to be expected—the greater 
specific heat of the steam being more than counterbalanced by the greater density of 
the nitrogen. Experiments made with hydrogen and oxygen at ordinary tem¬ 
peratures, with successive additions of oxygen and of nitrogen respectively, showed 
that, so long as the explosion-wave was propagated in both cases, the retarding 
influence of nitrogen was less than that of an equal volume of oxygen. Three 
volumes of electrolytic gas can be exploded with five volumes of nitrogen, but 
with seven volumes of nitrogen the explosion is not propagated through a long tube ; 
whereas three volumes of electrolytic gas can still be exploded when mixed with 
eight of oxygen. But so long as the volume of nitrogen added is not sufficient to 
stop the explosion, the addition of this inert gas, incapable of taking part in the 
chemical change, produces less effect than the addition of oxygen, one of the reacting 
substances. 
MDCCCXCIII.-A. 
Q 
