OSMOTIC PRESSURES OF SOME CONCENTRATED AQUEOUS SOLUTIONS. 
501 
Table VIII. 
I. II. 
III. 
IV. 
V. 
VI. 
VII. 
VIII. 
IX. 
X. 
1 
Name 
Date. of 
tube. 
Apparent 
turning- 
point 
pressure 
in atmo¬ 
spheres. 
Rate of 
movement 
of water- 
level due 
to guard¬ 
ring leak. 
Turning- 
point 
pressure 
in atmo¬ 
spheres. 
Time. 
Solution 
leak. 
Rate of 
movement 
of water- 
level due 
to solution 
leak. 
The 
increment 
of pressure 
used in 
the experi¬ 
ment. 
Rate of 
movement 
of water- 
level 
caused by 
increment 
of 
pressure. 
' 
li. in. 
atmospheres 
100 Grammes Mannite. 
Jan. 18 | X 
13-3 
0-3 
*13 • 3 
2 10 
0-0014 
5-0 
0-34 
1-9 
„ 26 | X 
— 
0-5 
*12-9 
2 10 
0■0008 
2-8 
0-34 
— 
110 Grammes Mannite. 
Jan. 9 1 X 
14-7 
0 - 5 
*14-6 
2 0 
0-0017 
6-2 
0-34 
4-1 
125 Grammes Mannite. 
Dec. 5 1 X 
16-71 
0-5 
*16-64 
3 45 
0-0009 
1-5 
0-34 
2-4 
7 G 
— 
0-5 
15-9 
2 30 
0-0066 
— 
0-34 
— 
„ 14 ! X 
16-82 
0-8 
*16-71 
2 0 
0-0014 
4-4 
0-34 
2*6 
Remarks .—The experiments with mannite are not satisfactory; there seems to be 
no doubt that the membranes are slightly more permeable to this substance than to 
the sugars. The numbers under the heading “solution leak” are not reliable; they 
were obtained by evaporating down the contents of the tube and weighing the 
residue. Small quantities of copper sulphate left in the tube from the previous 
electrolytic “remaking” would help to produce higher and erratic results. No 
higher osmotic pressures are obtainable with mannite, as 125 grammes in the litre is 
about the limit of solubilitv. 
»/ 
