01ST THE THERMAL PROPERTIES OF ALCOHOL. 
151 
T. 
Volume. 
Sp. vol. 
P. 
P. V. 
Vapour density. 
90 
0-84487 
483-5 
993 
839-7 
23-47 
0-77117 
441-4 
1085 
837-3 
23-54 
0-73470 
420-5 
1135 
834-4 
23-62 
0-71638 
410-0 
1163 
833-7 
23-65 
100 
0-84509 
483-7 
1026 
867-7 
23-34 
0-62423 
357-3 
1385 
865-0 
23-43 
0-53019 
304-1 
1598 
849-9 
23-83 
0-51280 
293-5 
1650 
846-7 
23-92 
110 
0-84532 
483-8 
1062 
898-4 
2315 
0-62440 
357-4 
1429 
892-6 
23-30 
0-43828 
250-8 
1996 
875-2 
23-76 
0-38213 
218-7 
2259 
863-7 
24-08 
JJ 
— 
0-36330 
207-9 
2342 
851-2 
24-43 
35 . The results of all these determinations of vapour-density are represented, so 
far as it is possible without introducing confusion, on Plate 4 ; the ordinates represent 
pressures, and the abscissae vapour-densities compared with hydrogen under similar 
conditions of temperature and pressure; the smaller curve represents the results of 
the experiments at lower temperatures on a larger scale. The lines are isothermals; 
and the curve connecting their terminal points gives the densities of the saturated 
vapour at the corresponding temperatures and pressures. From inspection of this curve 
it is evident that these results for densities of saturated vapour confirm those obtained 
by direct measurement at temperatures above ISO 0 ; but the previous results are 
incorrect, below that temperature, for reasons already given. So far as can be judged 
from these results, the density of the saturated vapour of alcohol decreases with fall 
of temperature, and corresponding fall of pressure. 
36. But from experiments with acetic acid, this is found not to be the case with that 
substance. On the contrary, the density of its saturated vapour increases rapidly 
with fall of temperature and pressure. Hence, it appeared necessary to carry out 
experiments on the density of saturated alcohol-vapour at still lower temperatures, 
for it was deemed possible that after reaching a minimum density, fall of temperature 
would produce an increase. The apparatus, which will be fully described in an account 
of the experiments with ether, consisted of a Hofmann’s vapour-density apparatus, 
so modified as to admit of alteration of pressure. The desired temperature was 
produced by jacketing with running water. 
The following results were obtained at 13‘0 o :— 
Volume. 
Pressure. 
P. V. 
CCS. 
mms. 
106 
15-55 
1648 
86-7 
18-85 
1634 
77-5 
20-85 
1616 
69-0 
23-6 
1628 
64-0 
25-7 
1645 
62-2 
26-35 
1639 
