Quantity of Heat evolved from Atmospheric Air. 217 
‘ 
enter into the minute examination of this subject. A few exper- 
iments are recorded in scientific works which show that the spe- 
cific heat of air, at different densities, diminishes at a much slower 
umes, at temperatures from 32° to 140°, and barometric aie 
from 3 74 to 39-6, increased in a ratio as follows, viz. ; a 
B tric Specific heat. ac * 
at “39-6 ‘ : ‘ 1-215 f 
- 29°84 : ‘ i) FOO 
. 14-92 , ‘693 \ . 
’ ss 7-44 540 ; 
” 374 368 “at 
oe 4 
From this table it is apparent that the specific heat of atmos- , 
pheric air, considered in the ratio of its weight or mass, diminishes — 4 
as the density i increases ; and it may be calculated, that when air ‘ 
‘ 
in the same volume is condensed to double its density, its specific. ° . ° 
heat is increased from 1-000 to 1-467; when its density isquad-  - 
rupled it becomes 1-883; and when its density is ttimesin- =, . #4 
creased its specific heat i is 2-717. The densities i inercea inthe og # 
geometrical progression 1, 2, 4, 8, correspond near ly to the ae ie 
cific heats in the arithmetical tee , 4, 3, 2. i. 4 
If the view I have taken of this law be correct, ian it be appli- > 
cable to an explanation of thé heating Operation of airinthecen-. — .. 
dition referred to, we are prepared to examine the extenof ifs ~ # 
influence. Before, however, this can be determined, we amiust ; 
phe 
form an estimate of the whole amount of heat evolved b 
the specific heat of air, under a. gl 
pounds 
or, that. one pound of. air heats * one, po 
As the s ‘$peciti heat of rat oto 3 
is 2669; on one pound of it volving. heat eflong 
uan 
