ON EVAPORATION AND DISSOCIATION. 
321 
No meniscus was visible at 240°. On lowering the temperature to 239'9° the 
meniscus appeared after a short time. The apparent critical temperature, therefore, 
lies between 239'9° and 240°. 
Only one reading is given at high pressures. The reason for this is that the altera¬ 
tion of level of the mercury in the volume tube altered the level of the mercury in the 
gauge by only 0T mm. 
B. The weight of this portion was ascertained by a comparison of its volumes in 
the gaseous state with those of C under similar conditions of temperature and 
pressure. It was found to be 0‘02565 gramme. With this portion vapour-densities 
at high temperatures, and vapour-pressures, were determined. 
For this series the jacketing vapour was brornonaphthalene boiling under various 
pressures. 
Pressure of bromo- 
naphthalene. 
Temperature. 
Volume of 1 gramme. 
Pressure. 
V apour-density. 
mms. 
O 
c.cs. 
mms. 
181-75 
220 
39-934 
20,645 
18-58 
29-304 
26,109 
19-98 
23-462 
30,510 
21-40 
17-610 
36.058 
24-18 
14-713 
39,016 
26-68 
13-271 
40,590 
28-43 
12-554 
41,397 
29-48 
12-125 
41,829 
30-21 
11 -8-10 
42,178 
30-68 
11-696 
42,231 
31-02 
V apour- pressu re 
= 42,319 
207-35 
225 
39938 
20,999 
18-45 
29-368 
26,647 
19-77 
23-466 
31,282 
21 08 
17-614 
37,146 
23-65 
14-717 
40,536 
25-94 
13-275 
42,269 
27-58 
11-844 
44,165 
29-59 
11-123 
45,168 
30-80 
10-410 
45,907 
32-38 
10-269 
46,012 
32-75 
10-125 
46,118 
3314 
V apour-pressure 
= 46,222 
235-95 
230 
39-94 
21,337 
18-34 
29-37 
27,192 
19-57 
23-47 
31,980 
20-83 
17-62 
38,191 
23-23 
14-72 
41,914 
25-34 
13-28 
43,918 
26-81 
11-84 
46,011 
28-69 
11-13 
46,894 
29-96 
10-41 
47,801 
31-40 
9-696 
48,756 
33 06 
8-982 
49,737 
34-99 
8-674 
49,884 
36-12 
V apour-pressure 
= 50,262 
2 T 
MDCCCLXXXVII.-A, 
