New Quilines of Chemical Philosophy. 25 
‘ duce the most intense heat; but water being thrown upon fire 
extinguishes it: water, therefore, is neither a combustible nor 
a supporter of combustion, and consequently it contains neither 
oxygen ner hydrogen. 
Another experiment, which has been made to prove that wa- 
ter is a compound of oxygen and hydrogen, consists of passing 
steam through a red hot iron tube containing turnings of iron, 
by which means hydrogen gas is produced, and the iron turnings 
become oxidized ; whence it is concluded, that water is a com- 
pound of oxygen and hydrogen. But let the experiment be tried 
with a red hot glass tube containing pieces of broken glass, and 
no hydrogen gas will appear: hence it is evident, that one of the 
component parts of the hydrogen gas, in the former experiment, 
came from the metal. 
Now when the turnings ef iron become red hot, the photogen 
they contain and water produce hydrogen gas: but in this pro- 
cess thermogen must be present, for no combustion nor increase 
of temperature can be generated unless thermogen and pho- 
togen be united. The most condensed rays of the sun do not 
exeite combustion in vacuo, noF in any gas deprived of oxygen, 
even when the most inflammable substance is employed*. Con- 
sequently, the thermogen and water produce oxygen gas, which 
the iron, after being deprived of its photogen, attracts, and be- 
comes an oxide of that metal. 
This experiment may be illustrated by the burning of iron, 
wire in oxygen gas. In this beautiful exhibition the most bril- 
liant light and the most intense heat are generated, by thevunion 
of the photogen of the metal and the thermogen of the oxygen 
gas. The metal, having lust its photogen, attracts oxygen gas, 
and becomes an oxide of iron intensely heated. 
The photogen or generator of light in the metal cannot be 
hydrogen, for “no combinations of iron with hydrogen or azote 
are known }.” If this assertion be correct, we have combustion 
without hydrogen. 
Sir H. Davy observes, that “ the nature of water may be shown 
synthetically as well as analytically.” 
«¢ When ten grains of the metal called potassium are added to 
about two grains of water in a glass tube, there is a violent ac- 
tion, much hydrogen is disengaged, and by heating the results 
the operation is completed. The same effect is produced upon 
the potassium, as would be produced by heating it strongly in 
contact with a small quantity of oxygen; it becomes united to 
oxygen, and its increase of weight is in proportion to the weight 
of the hydrogen as 15 to 2 f.” 
* See Phil. Mag. vol. xlii. p. 370, t Davy’s Elements, p, 388. 
} Davy’s Elements, p. 247. 
But 
