2 So Dr. Henry on the action of finely divided platinum on 
them, were placed in contact with the sponge, and gradually 
heated in a mercurial bath, the mixture ceased to expand 
between 300° and 31 o° Fahrenheit, and soon began to dimi- 
nish in volume. On raising the temperature to 340°, and 
keeping it some time at that point, no further diminution was 
at length perceptible. From the quantity of carbonic acid, 
remaining at the close of the experiment, it appeared that 
four-fifths of the oxygen had united with the carbonic oxide, 
and only one-fifth with the hydrogen. When four volumes 
of hydrogen, two of carbonic oxide, and one of oxygen, were 
similarly treated, the hydrogen, notwithstanding its greater 
proportional volume, was still found to have taken only one- 
fifth of the oxygen, while four-fifths had combined with the 
carbonic oxide. These facts show that at temperatures be- 
tween 300° and 340° Fahrenheit, the affinity of carbonic 
oxide for oxygen is decidedly superior to that of hydrogen ; 
as, from the experiments before described, appears to be the 
case, also, at common temperatures. 
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 co- 
lumns 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. 
Before firing. 
After firing 
A. 
Exp. 1 
2 
3 
Measure of 
Carb. Oxide. 
• 4® 
. 4 ° - 
. 20 . 
Measure of 
Hydrog. 
. 4 ° • 
, 20 . 
40 . 
Measure of 
Oxygen. 
20 . 
20 . 
Oxygen to 
Carb. Oxide. 
6 . 
12 . 
5 • 
Oxygen to 
Hydrogen. 
14 
8 
20 . 
• 15 
