3 o 73^ 
Steam Engine. 21 
ni. Yet ic€j during liquefaction^ must absorb much ca- 
loric , — Expose a pound of water at 32 and a pound of 
ice at 32®, in a room, the temperature of which is several 
degrees above the freezing point, and uniformly the same 
during the experiment. The water will arrive at the tem- 
perature of the room, several hours before the ice is melt- 
ed ; and the melted ice will have, as before its liquefac- 
tion, the temperature of 32®. Yet the ice must, during 
the whole of this time, have been imbibing caloric, be- 
cause (according to Experiment IV. \ 1.) a colder body 
can never be in contact with a warmer one, without re- 
ceiving caloric from it. The caloric, therefore, which 
has entered the ice, but is not to be found in it by the 
thermometer, is said to have become latent. As it is the 
cause of the liquefaction of the ice, it is sometimes called 
caloric of fluidity, 
IV. The quantity of caloric that enters into a pound of 
ice, and becomes latent, during liquefaction, may be learn- 
ed by experiment.— T q a pound of water, at 172' ’, add 
a pound of ice at 32®. The temperature will not be the 
arithmetical mean (102®), but much below it, viz. 32®. 
All the excess of caloric in the hot water has therefore 
disappeared. From 172® take 32® ; the remainder, 
140®, shows the quantity of caloric that enters into a 
pound of ice during liquefaction ; that is, as much calo- 
ric is absorbed by a pound of ice, during its conversion 
into water, as would raise a pound of water from 32® to 
172o. 
It is from the property of its uniformly absorbing the 
same quantity of caloric for conversion into water, that 
ice has been ingeniously applied, by Lavoisier and La- 
place, to the admeasurement of the heat, evolved in certain 
operations. Let us suppose the body (from which the 
caloric, evolved either by simple cooling or combustion, 
is to be measured) to be inclosed in a hollow sphere of ice, 
