198 
PROFESSOR GRAHAM ON OSMOTIC FORCE. 
late about the general result first stated ; the mean diffusates of sugar and amounts of 
replacing water were in the different solutions : — 
In 1 per cent, solution, 0T45 grm. sugar to 0*756 grm. water . . 1 to 5*21 
In 2 per cent, solution, 0180 grm. sugar to 1*054 grm. water . . 1 to 5*85 
In 5 per cent, solution, 0*459 grm. sugar to 2*405 grm. water . . 1 to 5*22 
In 10 per cent, solution, 0*934 grm. sugar to 4*158 grm. water . . 1 to 4*43 
In 20 per cent, solution, 1*430 grm. sugar to 6*672 grm. water . . 1 to 4*66 
The mean of the various solutions is 1 part of sugar replaced by 5*07 water. 
The phenomenon of the osmose of sugar partakes very much of a physical charac- 
ter, and may possibly prove to be nothing more than the exchange of sugar for water 
by the purely mechanical operation of diffusion. 
A third series of observations on sugar were made in an osmometer of albuminated 
calico. The results, it will be seen, are quite in accordance with those of the mem- 
brane osmometers. 
Table V. — Sugar in Osmometer F of Albuminated Calico for five hours. 
I. 
II. 
ill. 
IV. 
V. 
VI. 
VII. 
Sugar in 
solution. 
Rise in 
millimeter 
degrees. 
Same in 
grammes of 
water. 
Diffusate of 
sugar in 
grammes. 
Previous 
maceration. 
Hydrostatic 
resistance. 
Temperature, 
Fahr. 
per cent. 
1 
16 
0-684 
0-124 
day. 
1 
min. 
2 
Q 
59 
1 
22 
0-912 
0-156 
1 
10 
60 
4 
31 
1-311 
0-476 
1 
1 
61 
4 
42 
1*767 
0-505 
1 
1 
63 
4 
34 
1425 
0-542 
1 
1 
63 
10 
92 
3-876 
1-283 
1 
0-50 
63 
10 
106 
4-389 
1-179 
1 
0-66 
64 
10 
90 
3-762 
M93 
1 
1 
63 
This osmometer is remarkable for the variable but generally very small amount of 
its hydrostatic resistance, a condition of the septum which is apt to increase the 
diffusate, owing to the expulsion of a portion of the solution by the pressure of the 
dense solution. The diffusates of sugar (Column IV.) may be considered as nearly 
proportional to the per-centage of sugar in the osmometer. The osmose of the 4 and 
10 per cent, solutions are also nearly proportional, the means being 36 and 96 ms. ; 
but the osmose of the 1 per cent, solution is sensibly in excess. A slight excess in 
the early experiments with an albumen osmometer is, it may be remarked, not un- 
usual, and appears to be due to the considerable quantity of soluble matter, with an 
alkaline reaction, which the fresh albumen affords to the water in the osmometer, 
this soluble matter then acting as an osmotic body. 
Sulphate of Magnesia . — This salt was selected to illustrate the osmose of neutral 
salts. The sulphate of magnesia is neutral to test-paper. It appears, further, to be 
