OF GASES AT CONSTANT VOLUME. 
959 
of liquid, at tlie initial temperature, above tbis density. Nor had I sufficient data to 
calculate out the latent heat effect, &c., due to presence of liquid at higher densities. 
The former expression for the dependence of specific heat on density, p, was 
Cy = OT6577 + 0-2064p. 
A more accurate formula embracing all the experiments up to p = 0T50 may now 
be obtained :— 
Cy = 0T650 + 0-2125p + 0-M0p\ 
This accurately interprets the line carrying the mean results of the observations. 
At zero density, the specific heat at constant volume is thus 0T650. 
The expression must only be considered as applying over the interval 12° to 100° C., 
and not beyond the density 0T50. As observed, the presence of liquid renders it 
inaccurate at higher densities. It is needful to define the initial temperature, seeing 
that the results of the observations recorded in Part III. show that at densities lying 
even much below 0T50 the rate of variation of the specific heat with change of 
density is dependent upon the range of temperature obtaining. 
It is convenient to indicate these results upon the plate. Accordingly, a dotted 
line below the full curve conveys the specific heat over the range 35° to 100°, and 
one below this the specific heat between 56° and 100°. A third range of tempera¬ 
ture is dealt with in Part III., but its data are insufficient for plotting upon the 
plate; the results for this range, 78° to 100°, would appear to lie still lower. 
It is to be observed that the curvature almost dies out for the higher ranges of 
temperatare. In fact, the gas behaves then more nearly as a perfect gas. Thus, 
from 35° to 100°, the specific heat is given, closely, by 
Cy = 0-1650 + 0-2300/>. 
I 
> 
, 
1 
^anation of cne Mean dpecific Hear of 
Carbon Dioxide wich Density 
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QDensiCt/OOZO 0040 0 060 0-080 O-IOO 0-120 0-140 0160 0130 0-200 
