620 
MR. H. B. DIXON ON CONDITIONS OF CHEMICAL CHANGE 
these circumstances of slow combustion, is divided between the carbonic oxide and 
the hydrogen in proportions corresponding to the volumes of those two gases. The 
combustible gases being in equal volumes, and the oxygen sufficient to saturate only 
one of them, it was found that the oxygen which had united with the carbonic oxide 
was to that which had combined with the hydrogen as about 5 to 1 in volume. 
Increasing the carbonic oxide, a still larger proportion of oxygen was expended in 
forming carbonic acid. On the contrary, when the hydrogen was increased, a greater 
proportional quantity of oxygen went to the formation of water. 
“ But a similar distribution of oxygen between carbonic oxide and hydrogen does 
not take place when those three gases are fired together by the electric spark. This 
will appear from the following table, in which the three first columns show the 
quantities of gases that were fired, and the two last the quantities of oxygen that 
were found to have united with the carbonic oxide and with the hydrogen. 
Table I. 
Before firing. 
After firing. 
CO. 
H. 
O. 
Oxygen to 00. 
Oxygen to ET. 
Experiment 1 
40 
40 
20 
0 
14 
,, 2 . . 
40 
20 
20 
12 
8 
„ 3 . . 
20 
40 
20 
5 
15 
“ When equal volumes of carbonic oxide and hydrogen gases, mixed with oxygen 
sufficient to saturate only one of them, were exposed in a glass tube to the flame of a 
spirit lamp, without the presence of the sponge, till the tube began to soften, the 
combination of the gases was effected without explosion, and was merely indicated 
by a diminution of volume, and an oscillatory motion of the mercury in the tube. 
At the close of the experiment, out of twenty volumes of oxygen, eight were found 
to have united with the carbonic oxide, and twelve with the hydrogen, proportions 
which do not materially differ from the results of the first experiment in the fore¬ 
going table. At high temperatures, then, the attraction of hydrogen for oxygen 
appears to exceed that of carbonic oxide for oxygen : at lower temperatures, - 
especially when the gases are in contact with the platinum sponge, the reverse 
takes place, and the affinity of carbonic oxide for oxygen prevails.” 
Bunsen’s experiments . 
Bunsen thus states the problem :—* 
“ The proportion in which one body divides itself between two others—present in 
large excess over it—does not depend merely on the relative strength of their 
* Bunsen, ‘Ann. Cliem. Phavm.,’ 85, 137. 
