22 
Steam Engine. 
with an opening atthe bottom. When thus placed, the heat, 
which is given out, will be all employed in melting the 
ice ; and w ill produce this effect in direct proportion to 
its quantity. Hence the quantity of ice, which is convert- 
ed into winter, woll be an accurate measure of the caloric, 
that is separated from the body submitted to experiment. 
In this way, Lavoisier ascertained that equal weights of 
difeent combustible bodies melt, by burning, very differ- 
ent w’eights of ice. The appciratus ’^vhich he employed 
for this purpose, he has called the calorimeter. Its con- 
struction can scarcely be understood without the plate, 
which accompanies the description in his “ Elements of 
Chemistry.’’ 
V. Other examples of the absorption of caloric^ during 
the liquefaction of bodies^ are furnished by the mixture of 
snow and nitric acid, or of snow’ and common salt, both 
of wdiich, in common language, produce intense cold.^' 
1, Dilute a portion of nitric acid with an equal w^eight' 
of w^atcr ; and, when the mixture has cooled, add to it a 
quantity of light fresh-fallen snown On immersing the 
thermometer in the mixture, a very considerable reduction 
of temperature will be observed. This is owing to the 
absorption, and intimate fixation, of the free caloric of 
the mixture, by the liquefying snowx 
2. Mix quickly together equal weights of fresh-fallen 
snow at 32*^, and of common salt cooled, by exposure to 
a freezing atmosphere, dowm to 32"^. The two solid bo- 
dies, on admixture, wall rapidly liquefy ; and the thermo- 
meter will sink 32°, or to 0 ; or, according to Sir C. Blag- 
den, to 4° low^r. (Philosophical Transactions, Ixxviii. 
281.) To understand this experiment, it must be recol- 
lected, that the snow' and salt, though at the freezing tern- 
The extraordinary powers of muriate of lime and snow, in ge? 
aerating cold, rvill be described hereafter. 
