Quantity of Heat evolved from Atmospheric Air, 225 
oe ee 
In corroboration of the general accuracy of the experiments 
it may be further mentioned, that the converse of the result,here 
sought, viz., the quantity of. heat which the condensed air in its . 
7 expansion is capable of absorbing, or, in other words, the quantity . 
of ice it is capable of ‘edi was, after making due allow- 
ances, sufficiently nearly equal to the quantities as set down in 
columns eight and nine, to prove ‘that there has been no material 
error of observation or calculation 
; The chief object of Table V. is to present in a form obvious at 
| a glance, the changes of temperature which correspond to propor-: 
tional changes in the density of air. Philosophers have so often 
found the phenomena of nature conforming, in all their cireum- | 
stances, to uniform laws, that they seem to have supposed the 
evolution of heat, from the mechanical condensation of air, must 
follow some course of regular progression. The convenience to “ 
experimenters which has resahted from the establishment of that 
aw by which aerial bodies adjust their volume and pressure ex- ..- 
actly a each other, has induced them to hope that one equally «© | 
simple would be discovered for measuring the proportion of heat 
| set free from air by condensation. And, under the impression 
that such a law must exist, equal proportions of heat have been » ;. 
considered to be set free, under regular diminutions of volume, 
or increase in pcan of air. Thus, Dalton, finding, on experi ft 
E 
