432 A Comparison of the Old and New Theories (June, 
and as long as we do not know this, it is impossible for us to say 
whether it can take place or not by a separation of electricities. But 
whether an increase of temperature, or the appearance of fire, in 
reality takes place in such cases, we may determine by experiment. 
The question, then, comes to this: do we know any example of 
two combined bodies, whose simplicity is undisputed, that separate 
from each other with an increase of temperature produced by the 
separation itself, and which assumes a state of complete disunion ? 
For my part, I am acquainted with no such example; for that in 
the present case neither euchlorine, nor chloride of azote, nor 
iodide of azote, can be admitted, is obvious. 
None of the easily reducible metallic oxides gives the least sen- 
sible increase of temperature when it is reduced by means of heat, 
and the reduction ceases as soon as the temperature is lowered ; 
which would not be the case if the process of separation occasioned 
an increase of heat, which, at least in some cases, would be able 
to complete the process without the aid of external warmth. If 
such an evolution took place, the red oxide of mercury, when 
heated to the decompesing point, must explode; for example, 
when it is thrown into a platinum crucible at a white heat. But, 
though both the oxygen and mercury at that temperature are 
gaseous, the oxide is only slowly reduced as it comes in contact 
with the crucible. Hence we may say that in this case, as well as 
in that of boiling water, heat becomes latent ; and that, of conse- 
quence, in chemical decompositions, heat is rather absorbed than 
evolved. 
When the affinity between two bodies is destroyed by an increase 
of temperature, we cannot suppose that this takes place in conse- 
quence of an annihilation of the affinity, so that the united bodies 
are instantaneously separated from each other, just as a body hang- 
ing by astring falls to the ground when we cut the string. The 
actions of the affinity and of the temperature are to be considered 
as two powers acting in opposition to each ether, in consequence of 
which the affinity, when overcome, is instantaneously prevented 
from acting sensibly. We see from this that an increase of tempe- 
rature can produce no instantaneous decomposition in a large mass, 
especially when we take into view the slowness of the propagation, 
of heat. But as it is certain that each electrical neutralization and’ 
chemical combination is accompanied by an increase of tempera- 
ture, it is obvious that, if electro-chemical decomposition were 
accompanied by the same increase, this would not be confined to a 
few rare examples, but would be a necessary and constant con- 
comitant of every decomposition. But as it has been observed only 
in a few rare cases, we may conclude it follows with tolerable certainty 
that an increase of temperature is not produced by decomposition. 
From what has been said, it follows that an explosion, which 
cannot take place without an evident increase of temperature pro- 
duced by itself, cannot well accompany the separation of two ele- 
mentary bodies, which by the separation are reduced each to a state 
