CHANGE FROM THE LIQUID TO THE SOLID STATE ON VAPOUR-PRESSURE. 465 
degrees was employed, and for series VII. and VIII. the barometer was refilled and 
again boiled out. It was easy to know when the acetic acid was solid and when 
liquid; for on lowering the pressure with liquid acid the temperature fell steadily 
and readings were taken, the pressure being kept constant for some time before each 
reading. As soon as the acid solidified, however, the temperature rose suddenly 
nearly to the melting-point, and then quickly fell to below its starting-point. Air 
was then carefully admitted to raise the temperature of the acid to near its melting- 
point, readings being taken from time to time ; and on pressure being reduced by 
means of the pump, readings of the vapour-pressure of the solid acid were again taken, 
during fall of temperature. 
12. VAPOUR-pressures of solid and liquid acetic acid. 
Series I. 
Temperature. 
Pressure. 
State. 
millims. 
27-2 
16-8 
Liquid 
22-4 
12-9 
16'6 
8-7 
13-2 
6-9 
Solid 
5-4 
3-5 
3-7 
2-8 
11 
-0-6 
1 95 
11 
Series II. 
Temperature. 
Pressure. 
Sfate. 
millims. 
27'3 
17-45 
Liquid 
21-4 
12-65 
16-75 
10-45 
15-6 
9-15 
Solid 
15-4 
8-75 
Series III. 
Temperature. 
Pressure. 
State. 
millims. 
14-2 
8-3 
Liquid 
12-2 
6-05 
Solid 
8-4 
4-25 
11 
7-2 
4-05 
11 
6-3 
3-70 
11 
1-85 
2 "35 
11 
-5-6 
1-30 
” 
3 o 
MDCCCLXXXIV. 
