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conflicting principles in physics having been assumed, to 
explain calorific phenomena, render it desirable to obtain, 
if we can, some reliable tests of the several grounds on 
which the opposing theories are based. — On the one side it 
is affirmed that, “ Heat is a material element pervading the 
universe.” On the other, “that it is, in fact, a nonentity, 
and merely the result, or consequent effect, of the exertion 
or expenditure of moving forces.”— In purely physical en- 
quiries we must be guided by ascertained facts, rather than 
by authority, even of the most eminent physicists ; where- 
fore I shall adduce some of the well-known facts bearing 
upon the points at issue. The materiality of heat cannot 
be sustained, except upon the admission of Dr. Black’s 
doctrine of latent or specific heat in bodies ; on this assump- 
tion, then, I shall cite some of the cases that go to prove 
the existence of heat in bodies, beyond what is sensible or 
thermometric in them; and, therefore, in a neutral or latent 
state. And first, I take the results of the carefully con- 
ducted experiments of Dr. Fairbairn, showing the relations 
of heat and water in their different forms of union. The 
following passage is from his valuable work: — “Useful in- 
formation for Engineers,” London, Longman & Co., 1866. 
pp. 3-4. “When water attains the temperature of 212° 
Fahr. under the atmospheric pressure, it boils and gives off 
steam, which, when slowly formed, contains about 934’6° of 
latent heat, or heat not indicated by the thermometer ; if to 
this be added the sensible heat of 212°, we have 1146 , 6° of 
heat required to raise, say one pound of water into steam, 
under the atmosphere of 14*71bs. pressure. But at a pres- 
sure of 251bs. per inch, the boiling point rises to 240°, at 
501bs. to 281°, and at lOOlbs. it is of 327J° of temperature.” 
The temperature or sensible heat in steam is thus gradually 
raised by the increasing pressure or density of the steam, 
