On the Materiality of Caloric. 607 
to the communication of heat, from an external 
source, €xists, also, in thus explaining Mr. 
Davy’s‘ experiment: but I cannot admit that 
the argument is demonstrative, in proving the 
evolved caloric not to be derived from external 
substances; for no absurdity is implied in sup- 
posing, that a body may be receiving caloric in 
One state, and giving it out im another. We 
have an examplé of the simultaneous admission 
and extrication of a subtile fluid, the materiality 
of which is admitted by Mr. Davy, in an excited 
electric, which, at the very same instant, receives 
the electric fluid from without, and transfers it 
to the neighbouring conductors. In an ignited 
body, also, the two processes of absorption and 
irradiation of light, are, perhaps, taking place at 
the amse moment. 
II. Another cause of the increase of tem- 
perature in bodies, is the liberation of their 
combined caloric; and, if this be a source of 
temperature, the absolute quantity of caloric in 
a body must be diminished by friction. That 
no such diminution really takes placé, we Have 
the evidence of two experiments+thé one of 
Mr. Davy, the other of Count Rumford. Mr, 
Davy, by tubbing together two pieces of ice 
converted them into water. Now water, ex hy- 
. pothesi, contains more caloric, than the ice, from ° 
VOL. Vv, oie) 
