282 Dr. Henry on the action of finely divided platinum on 
action of the platinum sponge* when they are added to an 
explosive mixture of oxygen and hydrogen, is most remark- 
able in those which possess the strongest attraction for oxy- 
gen ; and it is probably to the degree of this attraction, rather 
than to any agency arising out of their relations to caloric, 
that we are to ascribe the various powers which the gases 
manifest in this respect. This will appear from the following 
Table, the first column of which shows the number of vo- 
lumes of each gas required to render one volume of an 
explosive mixture of hydrogen and oxygen uninflammable 
by the discharge of a Leyden jar ; while the second column 
shows the number of volumes of each gas necessary, in some 
cases, to render one volume of an explosive mixture insensi- 
ble to the action of the sponge, and in other cases indicates 
the number which may be added without preventing imme- 
diate combination. In the first column, the numbers marked 
with an asterisk were determined by Sir Humphry Davy ; 
the remaining numbers in that column, and the whole of the 
second, are derived from my own experiments. 
I vol. of Explosive Mixture was rendered 
incapable of being inflamed by Electri- 
city, when mixed with 
( — — — , 
* About 8 vol. of Hydrogen . . 
6 Nitrogen .... 
* 9 Oxygen .... 
* 1 1 Nitrous Oxide . . 
1.5 Cyanogen . . . 
* 1 Carbonized Hydrogen 
4. Carbonic Oxide . . 
* 0.5 Olefiant Gas . . . 
2 Muriatic Acid . . 
2 Ammonia . . . 
3 Carbonic Acid " . 
Effect of adding the same Gasses to 1 vol. 
of Explosive Mixture on the action of 
the Sponge. 
r~ * > 
not prevented by many vols. 
ditto. 
not prevented by 10 vol. 
ditto. 
prevented by 1 vol. 
not prevented by 10 vol. 
prevented by | a vol. 
prevented by 1.5 vol. 
not prevented by 6 vol. 
not prevented by ho vol. 
ditto. 
