31 
Steam Engine, 
led to receive an addition of heat equal to 10,35®, that 
is, water saturated with common salt boils at 222,35, 
when it would otherwise boil at 212. If saturated with 
“ sal ammoniac, it boils at 221,79. Borax, sulphat of 
magnesia, and sulphat of lime, lowered the boiling point. 
“ These are facts important to the theory of a steam en- 
gine.” 
V. The absorption of caloric ^ during evaporation^ shown 
by experiment. — Moisten a thermometer with alcohol, or 
with ether, and expose it to the air, repeating these opera- 
tions alternately. The mercury of the thermometer will 
sink at each e> posure, because the volatile liquor, during 
evaporation, robs it of its heat. In this way (especially 
with the aid of an apparatus described by Mr. Cavallo, in 
the Philosophical transactions, 1781, p. 50' ), v^ater m.ay 
be frozen in a thin and small glass ball, by means of ether. 
The same effect may be obtained, also, by immersing a 
tube, containing water at the bottom, in a glass of ether, 
which is to be placed under the receiver of an air pump ; 
or the ether may be allowed to float on the surface of the 
water. During the exhaustion of the vessel, the ether 
will evaporate rapidly ; and, robbing the water of heat, 
will completely freeze it ; thus exhibiting the singular 
spectacle of two fluids in contact with e<^ch other, one of 
which is in the act of boiling, and the other of freezing, 
at the same moment. 
VI. The fixation of caloric in water ^ by its conversion 
into steam^ may he shewn by the following experiments : 
—1. Let a pound of water at 212^^, and eight pounds of 
iron filings at 306®, be suddenly mixed togetlier. A large 
quantity of vapour wdli be instantly generated ; and the 
temperature of the mixture will be only 212® ; but that 
of the vapour produced, is also not more than 212® ; and 
the steam must therefore contain, in a latent or combined 
