PRESSURE ON THE TEMPERATURE OP VOLATILIZATION OF SOLIDS. 
45 
freezing mixture; but at higher pressures condensation took place in the tube con¬ 
necting: the condenser with the heated tube. 
O 
Pressure. 
Temperature of 
camphor. 
Pressure. 
Temperature of 
camphor. 
millims. 
millims. 
17 
4P2 
92-8 
136 0 -3 
7-2 
48'9 
105-0 
140-3 
15-4 
92-4 
109-4 
141-7 
27’2 
101-0 
1557 
147-0 
35-0 
109-4 
197-6 
154-3 
46'0 
116-7 
218-5 
157-9 
66-3 
127-4 
240-7 
160-1 
88-6 
134-2 
297-8 
168-0 
14. When pressure was gradually increased to 370 millims. the camphor melted, 
and a drop hung from the end of the solid camphor coating the thermometer. By 
lowering the pressure to 358 millims. this drop solidified. The pressure of the solidi¬ 
fication point was confirmed by a second experiment, but the pressure of melting 
seemed to vary. 
15. The tension of camphor vapour in a barometer tube was next determined. 
When carried out with only ordinary precautions it was found impossible to exclude 
moisture, which rendered the results false. Correct results were obtained in the 
following manner. The upper end of the barometer-tube was drawn into a capillary, 
and connected with a Sprengel’s pump ; the whole tube was then jacketed, and sur¬ 
rounded with the vapour of boiling aniline, while a current of dry air was drawn 
through it. Some camphor was then introduced by the lower end, which was imme¬ 
diately dipped under hot mercury. The mercury was then pumped up the inclined 
tube; after it had reached a certain level, the camphor solidified, and adhered to the 
side of the tube. While the mercury rose further, bubbles of camphor vapour rushed 
up the tube, carrying with them all air and water vapour. After the mercury had 
entered the capillary portion of the tube the jacketing tube was slipped down, and 
the capillary tube was sealed through the mercury. We think it right to give details 
of the method of operation, as we found it a matter of extreme difficulty to expel all 
moisture and air. The temperatures given were obtained by jacketing the barometer- 
tube with the vapours of various pure liquids. 
Temperature. 
Pressure. 
Temperature. 
Pressure. 
millims. 
millims. 
20-0 
1-0 
132-0 
78-1 
35-0 
1-8 
154-0 
188-8 
62-4 
6-4 
175-0* 
354-0 
78-4 
9-5 
184-5 
4310 
100-0 
22-6 
* Melting-point of camphor (Gay-Lussac, Ann. Cliim. Phys., ix., 78). 
