42 
DRS. W. RAMSAY AND S. YOUNG ON THE INFLUENCE OF 
9. In Section 7 it was stated that the alteration of the temperature of the condenser 
influenced the pressure in the apparatus. Indeed, any alteration in the temperature 
of the apparatus must influence the pressure due to air ; hence it follows that if the 
temperature of the bath is altered, the pressure in the apparatus must also be altered. 
When the temperature of the bath is kept constant the pressure due to ah’ alters 
only with alteration in the temperature of the condenser, and its change is therefore 
very small. To ascertain the effect of changing the temperature of the bath, the 
following experiment was made :— 
Temperature 
of bath. 
Temperature of 
condenser. 
Temperature 
of ice. 
Pressure. 
Difference 
found. 
Difference 
calculated. 
O 
millim. 
75 
-11 
-6-3 
0-890 
4-7 
4-7 
85 
-10-8 
-6-1 
0-905 
4-7 
4-8 
100 
- 9-5 
-5-0 
0-930 
4'5 
4-4 
110 
- 9'1 
-4-7 
0-948 
4"4 
4-4 
120 
- 8-8 
-4-3 
0-962 
4-5 
4-35 
140 
- 8-2 
-3-7 
0-990 
4-5 
4-25 
In this experiment the capacities of the condenser, of the bulb, and of the whole 
apparatus were known ; the pressure (0‘89 millim.) was calculated from the lowest 
reading, and the difference in pressure was calculated from the observed temperatures 
and volumes of the various parts of the apparatus. 
The agreement between the observed and calculated results is sufficient to give 
probability to the above hypothesis. 
10. These results, although fairly conclusive, are all deduced from the behaviour of 
one substance, ice, which on account of its low melting-point and vapour-tension offers 
considerable difficulties in manipulation. Acetic acid was chosen, and the following- 
series of results were obtained, the method of experiment being precisely similar to 
that followed with ice. Acetic acid melts at 16 0, 4. 
