152 
PROFESSOR W. RAMSAY AND DR. S. YOUNG 
At a volume of 59 cub. centims. liquid was present. 
37. This method involves three readings of heights of mercury, and calculation of 
a fourth; and as an error of O'l mm. makes an alteration in the value of P. Y. of 
6 to 10 units, the results, although irregular, are well within the limits of experi¬ 
mental error. They show that the product of pressure into volume remained 
practically constant up to a very small distance from the volume at which con¬ 
densation began to occur. 
38. From measurements at the boiling-point of alcohol under atmospheric pressure, 
an attempt was made to ascertain the weight of the extremely minute amount of 
alcohol present. 
Volume. 
Pressure. 
P. V. 
CCS. 
mms. 
125-9 
15-75 
1983 
123-5 
15-85 
1958 
118-8 
16-80 
1996 
114-9 
17-10 
1965 
From the mean of these results, 1976, the weight of alcohol was calculated to be 
0 - 004166 grm. 
Using this weight to calculate the vapour-density at 13°, the number 22'65 was 
obtained. This result is not unsatisfactory, considering the experimental difficulties; 
and, in our opinion, it proves that the density of the saturated vapour is practically 
normal at low temperatures. 
39. The densities of the saturated vapour can be deduced from the curves showing 
the densities of unsaturated vapour; they are represented by the points of inter¬ 
section of these curves with the horizontal lines which exhibit change of volume of 
gas in presence of liquid, while pressure remains constant. They were read from the 
smoothed curve given in Plate 4, and they are as follows :— 
T. 
Sp. gr. 
Sp. vol. 
V. D. 
T. 
Sp. gr. 
Sp. vol. 
V. D. 
O 
0 
0-000033 
30137 
23-00 
O 
110 
0-00486 
205-9 
24-50 
13 
0-000073 
13655 
23-00 
120 
0-00658 
151-9 
24-95 
20 
o-oooin 
9004 
23-00 
130 
0-00877 
114-0 
25-43 
30 
0000191 
5241 
23-00 
140 
0-01152 
86-8 
25-99 
40 
0-000315 
3170 
23-00 
150 
0-01488 
67-2 
26-55 
50 
0-000506 
1977 
23-10 
160 
0-01916 
52-19 
27-40 
60 
0-00079 
1274 
23-20 
170 
0-02446 
40-88 
28-40 
70 
0-00119 
842-2 
23-40 
180 
0-03115 
3211 
29-70 
80 
0-00174 
575-0 
23-50 
190 
0-0397 
25-18 
31-43 
90 
0-00250 
399-5 
23-80 
200 
0-0508 
19-69 
33-65 
100 
0-00351 
285-2 
24-02 
210 
0-0655 
15-27 
36-65 
On comparing the results of this table with that previously given in § 22, it will 
