Affinity and Fleat. aa 
may give rise to a vicious circle in the minds of young 
chemists or of persons who have not maturely reflected on 
these definitions. 
It is seen from the explanations I have given, that a 
more or less dilute solution really contains a certain 
quantity of heat, arising either from gain by contraction 
or by cooling by expansion. Hence most of the combina- 
tions which are due to the nascent state ought to take 
place in solutions, especially those which take place under 
cooling, those which give explosive substances. 
From what has been adduced in this chapter, it will be 
seen how great in their origin are the differences between 
the calorific effects produced when gases combine with each 
other and the calorific effects developed by the combina- 
tion or solution of liquids with each other. In the latter 
case, the heat of contraction has almost always been suffi- 
cient and more than sufficient to account for all. As to 
gases, this heat of contraction which may be calculated by 
formule given above, is always very small as compared 
with the heat disengaged during combination ; it may in- 
deed be zero, as in the case of hydrogen and chlorine and 
indeed, whenever gases combine in equal volumes, and 
hence without condensation. Therefore we must admit 
that gases contain of themselves and in the latent state, 
the principle of motion or of heat which is manifested at 
the moment of combination. 
Lavoisier considered oxygen to be composed ofa cer- 
tain unknown radical and of this principle which he 
materialized under the name caloric. This point of view 
I shall develope in a following chapter. | 
In direct combinations, the motion is destroyed and con- 
verted into heat. Just asa finite velocity can only be im- 
parted to a body in a finite time, or combination will always 
require for its production a greater or less time, but always 
a definite one. 
On the phenomena of indirect combination (or that pro- 
duced by the nascent state) require (1), a volution; (2), an 
absorption of heat, or a cooling. The time necessary for 
their development will be greater, (1) as the solubility of the 
substances acting in the menstrua is smaller, (2) as the © 
absorption of heat is greater. . 
The action of time need not be mysterious; we must 
always either explain it simply or wait for facts to account 
for it. 
