188 New experimental Researches 
crease of temperature. Admitting the force of these arguments, 
it follows that when water of 32° and 212° are mixed, and give 
a temperature denoted by 119° of the common thermometer, we 
must conclude that the true mean temperature is somewhere be- 
low that degree. I have already assigned the reason why I place 
the mean at 110.” Now the only reason I can elsewhere find, 
is derived from his general law, ‘‘ that all homogeneous liquids 
expand, as the square of the temperature, from the point of 
greatest density or congelation.” In p. 7, he ventures to assert 
nothing more than, * that it is not improbable that the true mean 
temperature between 32° and 212°, may be as low as 110° 
Fahrenheit.” 
Satisfied from my pyrometrical experiments, that his general 
hypothesis of the expansion of liquids being as the square of their 
temperature, is totally inapplicable to mercury, the inference re- 
lative to the thermometric mean between 32° and 212° cannot 
be allowed. But let us examine, on their own merits, the pre- 
ceding arguments against Dr. Crawford and De Luc’s verifica- 
tion of the mean temperature between that of freezing and boil- 
ing water. 
The reasoning derives its sole force from the assumption, that 
the capacity of water for heat, increases as its temperature is 
raised. There is adduced, however, no fact in the least decisive 
on this main point. What analogy is there between the entire 
change of form and constitution suffered by an incondensible li- 
quid, on becoming an elastic vapour, and the progressive heating 
of the liquid itself? Or, although dilute sulphuric acid and other 
liquids should increase in their specific caloric on being heated, 
which however has not been satisfactorily demonstrated, are we 
to assert that water must do so too? It is a matter of surprise to 
me, that a philosopher of Mr. Dalton’s judgement and acuteness 
should have pressed such inconclusive analogies into his service. 
He knew well that water is endowed with some curious peculia- 
rities, when compared with other liquids, or anomalies, as we 
idly style them; for they constitute no anomaly in nature, but 
wisely fit water fur performing the important functions assigned 
to it in the ceconomy of our. globe. 
In a series of experiments, carefully conducted on the relative 
capacities for heat, of water, sulphuric acid, oil of turpentine, 
and spermaceti oil, published in my Essay on hydrochloric acid 
and the chlorides; it seems to be directly demonstrated that 
the specific heat of water does not increase, but actually dimz- 
nishes, and that very conspicuously, as its temperature rises. It 
is there proved, that from 210° to 150° Fahr. the specific heat 
of oil is to that of water as 597 to 1000; and from 150° to 90° 
as 513 to 1000. ‘The same proportional difference of relation is 
exhibited 
