224 Wisconsin Academy of Sciences, Aids and Letters. 
tion touched the rubber, for the reason that there is no affinity 
between these liquids and rubber. Thus .'the first condition 
necessary for osmosis to take place was lacking, namely, that 
the membrane must be able to dissolve (i. e. imbibe or take up) 
one of the liquids that bathe it. When in the second part of 
experiment 2 the water was replaced by toluene, the latter was 
taken up by the membrane; but osmosis did not take place 
because the liquid on the other side, the brine, having no af¬ 
finity for toluene to speak of was unable to extract toluene from 
the rubber. 
3) The inside liquid was water, the outside liquid 99.5 per 
cent alcohol, the membrane rubber. The liquid rose in the 
osmometer showing the main current to be from the alcohol 
through the rubber to the water. This is what one would ex¬ 
pect for the alcohol is taken up by the rubber and then the 
water by virtue of its affinity for alcohol extracts the latter 
from the rubber. 
4) This experiment was like No. 3 except that a 20 per cent 
aqueous cane sugar solution was used as the inner liquid. 
Again the liquid rose in the osmometer, alcohol passing through 
the rubber into the sugar solution. No sugar, however, was 
found in the alcohol on the outside. The rise in the osmometer 
tube was slow, being about five centimeters in five days. The 
inside diameter of the stem of the thistle tube was about 3.5mm. 
The main direction of the current was, of course, such as 
was to have been expected from what was said in connection 
with the preceding experiment. No sugar was found in the 
alcohol outside for sugar has so little affinity for alcohol, for 
rubber and for rubber soaked with alcohol that it is not taken 
up by any of these. 
5) The inner liquid was pyridine, the outer liquid water 
and the membrane parchment. The liquid rose in the osmo¬ 
meter showing the main current to be from the water through 
the parchment to the pyridine. Some pyridine was also found 
in the water. 
6 ) The experiment was like No. 5, except that a rubber 
membrane was used instead of parchment and the water was the 
inner liquid and the pyridine the outer. The liquid again rose 
