ON EVAPORATION AND DISSOCIATION. 
327 
It will be remarked that Regnault’s vapour-pressures are in every case much lower 
than ours. On reference to his memoir (‘ Memoires de l’Academie des Sciences/ 
vol. 26, p. 456), it is evident that his low results are to be accounted for by insuffi¬ 
cient drying of his specimen ; it was only rectified several times over quicklime. He 
states, also, that the fluctuations of his thermometer when the dynamical method was 
employed were so great as to interfere with the accuracy of his results. Regnault, 
moreover, did not think it worth while to convert the readings of his mercury thermo¬ 
meter into those of an air thermometer. 
The orthobaric volumes of 1 gramme of methyl-alcohol were read from a curve 
drawn so as to pass through the experimental points. We have not constructed a 
formula to represent these relations. They are given in the Table .which follows :— 
Orthobaric Volumes of 1 gramme of Liquid. 
Tempera¬ 
ture. 
Volume. 
Specific 
gravity. 
Tempera¬ 
ture. 
Volume. 
Specific 
gravity. 
Tempera¬ 
ture. 
Volume. 
Specific 
gravity. 
O 
20 
1-265 
0-7905 
O 
120 
1-449 
0-690 
O 
220 
2-041 
0-490 
30 
1-2765 
0-783 
130 
1-477 
0-677 
225 
2-139 
0-4675 
40 
1-291 
0-7745 
140 
1-506 
0"664 
230 
2-268 
0-441 
50 
1-307 
0-765 
150 
1-540 
0-6495 
232 
2-328 
0-4295 
60 
1-324 
0-7555 
160 
1-577 
0-634 
234 
2-413 
0-4145 
70 
1-3405 
0-746 
170 
1-623 
0-616 
236 
2-528 
0-3955 
80 
1-360 
0-7355 
180 
1-672 
0-598 
237 
2-'59 7 
0-385 
90 
1-379 
0-725 
190 
1-733 
0-577 
238 
2-699 
0-3705 
100 
1-401 
0-714 
200 
1-808 
0-553 
238-5 
2-751 
0-3635 
110 
1-4245 
0-702 
210 
1-903 
0-5255 
Orthobaric Volumes of 1 gramme of Vapour. 
The following Table gives the volume of 1 gramme of saturated vapour at even 
temperatures :—- 
Tempera¬ 
ture. 
Volume. 
Specific 
gravity. 
V apour- 
density. 
Tempera¬ 
ture. 
V olume. 
Specific 
gravity. 
Vapour- 
density. 
O 
0 
c.cs. 
17,803 
0-0000562 
16-10 
O 
160 
C.CS. 
50-16 
0-01994 
20-64 
10 
10,044 
0-0000996 
16-15 
170 
39-59 
0-02526 
21-45 
20 
5,899 
0-0001695 
16-23 
180 
31-40 
0-03186 
22-40 
30 
3,608 
0-0002772 
1630 
190 
24-94 
0-04010 
23-57 
40 
2,276 
0-0004394 
16-41 
200 
19-70 
0'05075 
25-13 
50 
1,484 
0-0006739 
16-52 
210 
15-33 
0-06521 
27-40 
60 
993-8 
0-001006 
16-66 
220 
11-58 
0-08635 
31-00 
70 
682-7 
0-001465 
16-85 
225 
9-97 
0-1003 
33-50 
80 
479-8 
0-002084 
17-06 
230 
8-42 
0-1187 
36-80 
90 
344-0 
0-002907 
17-31 
232 
7-83 
0-1277 
38-40 
100 
251-0 
0-003984 
17-61 
234 
7-24 
0-1381 
40-30 
110 
186-0 
0-005376 
17-97 
236 
6-64 
0-1505 
42-75 
120 
140-0 
0-007142 
18-36 
238 
5-95 
0-1681 
46-25 
130 
106-6 
0-009379 
18-81 
238-5 
5'59 
0-1789 
48-70 
140 
82-25 
0-01216 
19-33 
239 
5-33 
0-1878 
50-80 
150 
64-00 
0-01562 
19-93 
