188 
PROFESSOR GRAHAM ON OSMOTIC FORCE. 
Or the rise in the same time with another membrane which had been previously 
exposed to a steam heat of 212° for ten minutes without impairing its activity. 
With 1 per cent, carbonate of potash at 60° Fahr., a rise of 402 ms. 
With 0*1 per cent, carbonate of potash at 60° Fahr., a rise of 196 ms. 
With 0*1 per cent, carbonate of potash at 60° Fahr., a rise of 153 ms. 
With 2 per cent, carbonate of potash at 60° Fahr., a rise of 511 ms. 
With 4 per cent, carbonate of potash at 60° Fahr., a rise of 781 ms. 
With 10 per cent, carbonate of potash at 60° Fahr., a rise of 863 ms. 
In the last experiment a rise of fluid in the tube of upwards of 30 inches occurs in 
five hours, and so much water is impelled through the membrane as would cover 
its whole surface to a depth of 8*6 millimeters, or one-third of an inch. Both mem- 
branes, but particularly the first, show the comparatively great activity of small pro- 
portions of salt, the average osmose of 0’1 per cent, of carbonate of potash in the first 
osmometer being 167 millimeter degrees, and of 1 per cent. 206 millimeter degrees. 
Now the quantity of carbonate of potash which diffuses out of the osmometer into 
the water-jar, was determined by the alkalimetrical method in the second and third 
of the 0*1 per cent, observations first related, and found to be in both cases 
0*018 gramme (0*28 grain) ; the quantity of water also which entered in return can 
be calculated from the known capacity of the tube of the osmometer, of which each 
millimeter division represented 0*060 gramme of water; and consequently 167 divi- 
sions represent 10*020 grammes (155 grains) of water. We have, in 0*1 percent, 
solution, 
Mean diffusate of carbonate of potash . . . 0‘018 gramme = 1 
Mean osmose (of water) 10*020 grammes =556 
The conclusion is, that while the membrane was traversed during the five hours of 
an experiment by 1 part of carbonate of potash passing outwards, it was traversed by 
556 parts of water passing inwards. 
In the two experiments with 1 per cent, solution of carbonate of potash in the 
same osmometer, the diffusates were 0*192 and 0*198 gramme of carbonate of potash, 
which are sensibly ten times greater than the diffusates of the 0*1 per cent, solution. 
But the mean osmose of the 1 per cent, solutions is greater than that of the 0*1 per 
cent, solutions only in the proportion of 206 to 167, or as 1 to 0*81. The ratio in 
question however varies greatly in different membranes. We have, consequently, in 
1 per cent, solution, — 
Mean diffusate of carbonate of potash . . . 0*195 gramme = 1 
Mean osmose (of water) 12*360 grammes =63*4 
Whatever, therefore, be the nature of the chemical action occurring in the mem- 
brane which influences osmose, a minute amount of that action appears to be capable 
of producing a great mechanical effect. 
All idea of contractility or organic structure being the foundation of the osmotic 
