ON THE THERMAL PROPERTIES OP ALCOHOL. 
15 
o 
o 
be seen that above 180° the agreement is close, but that, as was expected, the results 
diverge widely at lower temperatures ; above 210 ° the agreement was perfect. 
The values at 0 °, and between 13° and 90° are obtained by interpolation on curve 2 , 
Plate 5. 
40. Heats of Vaporisation of Alcohol. 
From these numbers the heats of vaporisation were calculated by the method 
already mentioned. They are given in the table which follows 
T. (cent.) 
T. (Alis.) 
t. 
jT 
dp* 
dt 
S\ — s 2 . 
L in calorics. 
O 
0 
273 
0-00642 
1-142 
30136 
220-9 
10 
283 
0-00666 
2-061 
16113 
221 2 
20 
293 
0-00689 
3-557 
9003 
220-6 
30 
303 
0-00713 
5-890 
5240 
220-1 
40 
313 
0-00736 
9-378 
3169 
218-7 
50 
323 
000760 
14-38 
1976 
216-0 
60 
333 
0-00783 
21-41 
1273 
213-4 
70 
343 
0-00807 
30-93 
840-9 
209-9 
80 
353 
0-00831 
43-30 
573-7 
206-4 
90 
363 
0-00854 
59-29 
398-1 
201-6 
100 
373 
0-00878 
79-09 
283-8 
197-1 
110 
383 
0-00901 
103-26 
204-5 
190-3 
120 
393 
0-00925 
132-33 
150-5 
184-2 
130 
403 
0-00948 
166-48 
112-5 
177-6 
140 
413 
0-00972 
206-32 
85-3 
171-1 
150 
423 
0-00995 
252-08 
65-66 
164-7 
160 
433 
0-01019 
304-17 
50-61 
1569 
170 
443 
0-01042 
362-67 
39-26 
148-4 
180 
453 
0-01066 
A28-9 
30-44 
139-2 
190 
463 
0-01089 
502-65 
23-45 
128-4 
200 
473 
0-01113 
585-7 
17-89 
116-6 
210 
483 
0-01136 
678-85 
13-38 
103 2 
(For temperatures above 210 ° reference must be made to § 28.) 
41. The relations between temperature and heats of vaporisation are graphically 
represented in the two curves on Plate 5, fig. 1 , curve No. 2 , represents this 
relation for vapour-density. The points experimentally determined are indicated by 
circles. Between 90° and 13° the dotted line shows the probable course of the curve. 
It is obvious that the error must be extremely small, and it is probable that the 
vapour-density attains its minimum at a temperature somewhat below 50°. 
42. The curve representing latent heats is similarly indicated by circles and dots. 
That part of it deduced from the interpolated portion of our observations of vapour- 
density seems to point to a constant value for heat of vaporisation below about 20 °, 
the temperature at which vapour-density becomes normal being about 40°. This 
would imply that below that temperature the difference between the specific heats of 
the saturated liquid and saturated vapour is inversely proportional to the absolute 
temperature; for in the equation y—c'- b“~y —7 the expression ^vanishes. 
* In grams, per square centimetre. 
MDCCCLXXXVI, 
X 
