ON THE THERMAL PROPERTIES OF ALCOHOL, 
139 
would imply the probable formation of complex molecular groups ; that this is the 
case with acetic acid vapour will be shown in a subsequent memoir. 
25. In concluding this part of the subject we give a table taken from the curves, 
showing specific volumes, specific gravities, and vapour-densities at definite intervals 
of temperature. 
Specific Gravity, Specific Volume, and Density of Saturated Vapour at definite 
Intervals of Temperature. 
T. 
Sp. gr. 
Sp. vol. 
V. dens. 
T. 
Sp. gr. 
Sp. vol. 
1 
Y. dens. 
110 
120 
130 
140 
150 
160 
170 
180 
190 
/ 0-00577 
1 0-00650 
/ 0-00800 
10-00850 
/ 0-0105 
10-0108 
f 0-0135 
10-0136 
0-0170 
0-0208 
0-0253 
0-0310 
0-0388 
cub. centime. 
/ 173 
\154 
1 125 
1118 
/ 95-2 
1 92-6 
f 741 
1 73-5 
58-8 
48-1 
39-5 
32-3 
25-8 
J29-5 
1 32-8 
/ 29-5 
132-1 
/ 29-5 
131-4 
J29-5 
130-7 
/ 29-45 
130-05 
/ 29-45 
129-6 
29-4 
29 - 7 
30- 85 
200 
210 
220 
225 
230 
232 
234 
236 
237 
238 
239 
240 
241 
242 
242-5 
0-0495 
0-0651 
0-0854 
0-0976 
0-1135 
0-1209 
0-1296 
0-1401 
0-1463 
0-1532 
0-1615 
0-1715 
0-1835 
0-1990 
0-2164 
cub. centims. 
20-2 
15-4 
317 
10-25 
8-81 
8-27 
7-72 
7-14 
6-83 
6-53 
6-19 
5-83 
5-45 
5-02 
4-62 
33-1 
36-4 
40-75 
43-4 
46-7 
48-3 
50-15 
52- 5 
53- 9 
55-65 
57-7 
60-2 
63-5 
67-3 
74-25 
The bracketed numbers express the limits between which these constants appeared 
to fall. 
26. Heats of Vaporisation of Alcohol. 
From the foregoing data it is possible to calculate the heats of vaporisation of 
alcohol by means of the formula 
t / \t dp 
L=( Sl — 
L= Heat of vaporisation. 
s 1 and s 2 = Volumes of saturated vapour and liquid respectively. 
t= Absolute temperature. 
J= Mechanical equivalent of heat. =42500. 
Rate of change of pressure, measured in grammes per square centimetre. 
27. This rate of change was ascertained from the vapour-pressures of alcohol, 
calculated by Biot’s formula, two points being chosen, 0T° above and 0 - l° below the 
temperature required, and the difference between these pressures was multiplied by 5. 
From 231° to 239° inclusive the values were read from a curve constructed to show 
relations of ~ to temperature; the number at 240° is calculated, but at 241°, 242 c , 
(XJj 
and 242’5° the curve was again employed. The results are given in the following 
table 
