Kohlenberg—Osmosis and Osmotic Pressure. 233 
pyridine,, is yet not soluble in hydrocarbons and consequently 
has practically no affinity for rubber. Further, recalling that 
water is readily taken up by parchment, and pyridine and 
toluene not, and considering these facts in connection with 
those already mentioned, the data obtained in Nos. 15, 17 and 
18 are readily explained. 
23) The inside liquid was a 7.06 per cent cane sugar solu¬ 
tion in pyridine, the outer liquid pyridine and the membrane 
rubber, supported by muslin tied over it. The liquid rose in 
the osmometer to a height of 22.7 cm. in 4 days, the height 
after the second day being 21.8 cm. Sugar had not passed into 
the outer liquid except in mere traces. 
24) This experiment was like No. 23 except that xylene was 
used as the outer liquid instead of pyridine. The liquid rose 
to a height of 16.4 cm. in 4 days. Sugar was not present in 
the outer liquid in appreciable quantities, but pyridine was. 
25) The inside liquid was a 1.2 per cent solution of sugar 
in pyridine, the outer liquid pyridine and the membrane rub¬ 
ber supported by muslin. The temperature was kept at 22.5° 
C. A rise of the liquid in the osmometer tube was noted after 
five minutes. After 3 hrs. the column measured 4 cm.; after 
12 hrs. about 5 cm. Sugar did not pass through the septum 
in appreciable amounts. The experiment shows that the solu¬ 
tion used is able to produce but a very feeble osmotic pressure. 
26) The inner liquid was a 0.125 normal solution of sugar 
in pyridine, the outer liquid pyridine and the septum rubber 
supported by muslin. The whole was kept at 0° C. After 3 
days the liquid had risen only 0.5 cm. in the osmometer tube; 
after 5 days, the rise was but 1.9 cm. The membrane was in¬ 
tact, and practically no sugar had passed into the pyridine 
without. 
27) This experiment was like No. 26 except that a 0.25 nor¬ 
mal solution of sugar was used as the inner liquid. The tem¬ 
perature was kept at very nearly —16° C. During the first 
day the liquid rose to 9.5 cm. in the osmometer; on the second 
day the column measured 13.5 cm.: and on the fourth day 17.5 
cm. The membrane was intact and only very slight amounts 
of sugar were present in the outer liquid. The same experi- 
