New Outlines of Chemical Philosophy. 23 
exists combined or uncombined with matter ; by thermogen is 
to be understood the imponderable element of ail supporters of 
combustion, whether it exists combined with matter, or in a 
free and uncombined state. 
Thermogen and Photogen. 
When a Leyden jar is receiving a charge from an electric ma- 
chine, one side receives thermogen from the atmosphere, and the 
other side receives photogen from the earth. When a commu- 
nication is made between the inside and the outside of the jar, 
by some conductor of these elements, the element from the in- 
side attracting the element from the outside, a spark is produced, 
consisting of a double current exhibiting both light and heat, 
and the equilibrium which was destroyed by the action of the 
machine is restored. But it cannot be supposed that these ele- 
ments are annihilated by their union: such a supposition would 
be absurd: they only enter into new combinations, and return 
again into those receptacles from whence they were withdrawn, 
For while the element of one side of the jar goes to the earth, 
the element of the other side is gommunicated to the air. 
When two portions of the same element are nearly equal they 
repel each other, but when they are very unequal they attract 
each other. This is known from an infinite number of experi- 
ments: consequently, the immense attraction of the photogen in 
the earth attracts any small portion ef the same element, which 
may be disengaged from its base, with an infinite force; and the 
thermogen in the atmosphere attracts every small portion of the 
same element the instant that it is disengaged from matter. 
But why does not the thermogen in the atmosphere unite with 
the photogen of the earth, as they have’a very strong attraction . 
foreach other? This question will be easily solved as ‘soon as it 
is understood that they are kept asunder by their bases. Oxygen 
aud hydrogen gases mixed together in a proper vessel, would re- 
main for ages without producing any effect upon one another ; 
but let their elements be brought into contact, either by pressure 
or increase of temperature, and combustion will instantly take 
place. 
If the attraction between these elements of combustion aud 
their bases were not proportioned to a mathematical exactness, 
the whole ceconomy of our globe would be deranged. For, if 
this attraction were greater than it is at present, we should have 
perpetual frost ; and if this attraction were much less than it is, 
_all combustibles would be reduced to ashes in a moment: but, 
in the present state of things, it is impossible that either of these 
events should happen. 
It is not to be understood that photogen is light, or that 
thermogen 
