616 On. the Maiteriality of Caloric. 
of effecting.Thus a most intense fire does not 
expel, entirely, the carbonic acid from alkalis. 
But when the affinity ofan acid for an alkali 
concurs with that of carbonic acid for caloric, 
a decomposition ensues.——Again— Water may.be 
submitted to the highest temperature, without 
imparting a gaseous form to the hydrogen which 
it contains; but the conspiring affinity of a metal 
for oxygen occasions the production of hydro- 
genous gas... On.this principle, many chemical 
facts are resolved into the law of double affinity, 
which. are, at present, explained by that of sin- 
gle elective attraction. 524 
4. Caloric acts, sometimes, as an intere 
medium in .combining. bodies, which, without 
its aid, are not susceptible of combination. 
Thus carbon and oxygen do. not evince’ any 
tendency to combination, at the ordinary tem- 
perature of the atmosphere; but caloric brings 
them into union, and constitutes, itself, part of 
the resulting compound, This, and a variety 
of other instances, have a striking resemblance 
to what is called intermediate affinity. 
In the theory of Dr. Crawford, no influence 
- is allowed to chemical affinity over the pheno- 
mena of heat;~ and indeed. hat. philosopher 
expresses a decided opinion, that elementary 
heat is not capable of uniting chemically with 
bodies. Hence it appears, that the difference - 
