506 
THE EARL OF BERKELEY AND MR. E. G. J. HARTLEY ON THE 
APPENDIX A. 
[August 15.—An empirical method of making the correction for “solution leak" 
(see p. 498, explanation of Column VIII. ; also p. 503) can be applied by assuming that 
during the passage of the solution through the minute holes in the membrane the 
solute has been partially filtered off from the solvent, and that this action is 
proportional to the concentration; if so, the rates tabulated in Column VIII. of 
Tables VI. and VII. must be multiplied by a factor which is proportional to the 
concentration. * 
In the case of cane sugar, it is easy to see that this factor, for a solution of 
300 o-rammes in the litre, is 3, and therefore for the other concentrations it will be 
4‘2, 5*4, 6*6, and 7 ‘5 respectively. Then, proceeding in a manner similar to that 
explained at the top of p. 495, but adding the resulting pressure correction, we 
get, for the observations (marked f) done with the dead-weight pressure gauge, the 
following table, of which the results are to be compared with the numbers in 
Table X., where no “ solution leak" is present:—- 
Date of 
experiment. 
Turning- 
point 
pressure 
in atmo¬ 
spheres. 
Solution- 
leak 
correction 
in atmo¬ 
spheres. 
Final 
corrected 
turning- 
point 
in atmo¬ 
spheres. 
Date of 
experiment. 
Turning- 
point 
pressure 
in atmo¬ 
spheres. 
Solution- 
leak 
correction 
in atmo¬ 
spheres. 
Final 
corrected 
turning- 
point 
in atmo¬ 
spheres. 
300 
Grammes ( 
Iane Sugar 
660 
Grammes ( 
lANE SUGAIi 
. 
(Equilibrium 
pressure from Table X. 
= 26-77 
(Equilibrium pressure = 100-78 atmospheres, see 
atmospheres.) 
Table X.) 
Oct. 4 . . . 
26-28 
0-27 
26-55 
Nov. 3 . . 
100-19 
0-45 
100-64 
„ 6. . . 
26-07 
0-24 
26-31 
Jam 30 
99-42 
1-12 
100-54 
Nov. 14 . . 
26-32 
0-51 
26-83 
Feb. 14 . . 
100-22 
0-56 
100-78 
420 
Grammes Cane Sugar. 
750 
Grammes Cane Sugar. 
(Equilibrium 
pressure = 43-97 atmospheres, see 
(Equilibrium pressure = 133-74 atmospheres, see 
Table X.) 
Table X.) 
Sept 12 . . 
43-42 
0-57 
43-99 
Nov. 17 . . 
133-44 
0-76 
134-20 
„ 20 . . 
42-46 
1-95 
44-41 
March 28. . 
133-28 
0-63 
133-91 
Nov. 23 . . 
43-32 
0-74 
44-06 
540 
Grammes Cane Sugar. 
(Equilibrium 
pressure = 67-51 atmospheres, see 
Table X.) 
Oct. 19 . . 
67-22 
0-31 
67-53 
We propose to investigate this matter more closely. It may throw some light on 
the molecular structure of solutions.] 
* Almost as good an agreement is obtained if we assume that this factor is proportional to the pressure 
on the solution. Unfortunately the experiments with dextrose (Table VII.) are not numerous enough to- 
differentiate between the two. 
