128 
DRS. W. RAMSAY AND S. YOUNG ON SOME OF 
II. Low Temperatures. 
(a.) Weight of water in the modified Hofmann’s apparatus (described with a 
wood-cut in ‘ Phil. Trans./ 1887 A., p. 59). 
0-20087 grm. 
Readings commenced at largest volume, and vapour then compressed. 
Tempei-a- 
ture. 
Pressure. 
Volume. 
V apour 
Density 
Tempe ra- 
ture. 
Pressure. 
Volume. 
Vapour 
Density 
(H = 1). 
(H = 1). 
O 
millims. 
c.c. 
O 
millims. 
c.c. 
75 
23-35 
150'5 
8-83 
40 
19-15 
149-1 
9-78 
23-40 
148-5 
8-93 
21-2 
135-7 
9-71 
23-65 
146-3 
8-97 
23-15 
122-3 
9-86 
25-80 
134-9 
8-92 
26-0 
109-0 
9-85 
27-4 
125-9 
8-99 
29-2 
96-54 
9-90 
29-6 
116-4 
9-01 
33-75 
83-07 
9-96 
32-2 
106-2 
9-08 
39-3 
71-10 
9-99 
35-3 
96-36 
9-13 
48-45 
55-90 
10-31 
39-95 
86-52 
8-98 
52-2 
49-66 
10-77 
45-7 
74-78 
9-08 
54-1 
42-05 
12-27 
30 
18-05 
154-9 
9-66 
75 
(repeated) 
236 
24-1 
30-3 
47-65 
146-9 
141-2 
111-9 
72-17 
8- 96 
9- 12 
9-16 
9-03 
18-9 
20-1 
22-1 
24-45 
145 - 2 
134-5 
122-0 
109-0 
9-85 
10-00 
10-03 
10-14 
57-7 
79-2 
58-12 
42-76 
9-26 
9-17 
26-7 
29-9 
31-05 
96-72 
84-50 
68-61 
lO"46 
10-70 
(12-69) 
31-35 
55-0 
Condensed 
31-45 
43-0 
50 
20-35 
153-0 
9-25 
21-8 
140-5 
9-40 
25 
17-25 
154-2 
9-99 
23-4 
130-5 
9-43 
18-0 
144-8 
10-20 
26-95 
113-2 
9-45 
19-25 
134-4 
10-27 
33-25 
v 91-35 
9-49 
20-35 
123-1 
10-62 
42-1 
71-82 
9-53 
21-8 
111-6 
10-93 
54-75 
54-49 
9-66 
22-4 
99-32 
11-95 
70-75 
42-52 
9-58 
23-35 
86'5 
„ (13-16) 
It is to be noticed that four readings are required for each pressure, so that at the 
lowest pressure an error of 1 per cent., or say 0‘2 millim., is not excessive. 
In considering these results it is seen that, as a ride, the density increases on 
diminishing volume. This, however, cannot be ascribed to real increase of density, 
but to diminution of the actual weight of the water present in the state of vapour 
through adhesion of water to the surface of the tube. That this explanation is the 
correct one is seen from the following considerations. 
At 75° very little rise of vapour-density is to be observed, although there is a 
slight tendency towards a higher value at the smallest volumes. The pressure was 
never near the vapour-pressure, which at this temperature is 288 ‘5 millims. 
