Kohlenberg—Osmosis and Osmotic Pressure. 239 
the rubber, though paraffine passed through into the toluene 
on the outside. After 24 hours only about one-eighth of the 
paraffine was left undissolved and the liquid on the inside was 
practically on a level with that on the outside. Much paraffine 
was found in the outer liquid. 
50) In this case the cube of paraffine was separated from 
pyridine by means of rubber, the arrangement being as de¬ 
scribed in connection with No. 42. The observations were 
practically the same as when alcohol was employed, No. 48. 
51) The experiment was identical with the preceding one, 
No. 50, .except that CC1 4 was used instead of pyridine. After 
24 hours about three-fourths of the paraffine was still left in 
the solid state, it floated on the layer of liquid which had formed 
on the upper side of the rubber. Considerable paraffine had 
gone through the septum into the CC1 4 below. The membrane 
was much enlarged and bulged downward. After two days, 
all the paraffine had dissolved and the liquids in and outside 
were nearly on a level. 
52) About two grams of dry powdered A.gN0 3 was placed 
on the upper side of a rubber membrane the lower side being 
bathed by pyridine. The arrangement was as pictured in Fig. 
5, the powdered AgN0 3 , which was spread out over the sur¬ 
face of the membrane,, taking the pla.ce of the block represented 
in the figure. The experiment then was the same as No. 45 ex¬ 
cept that the AgN0 3 was used in place of camphor. After 7 
hours no liquid was visible on the upper side of the membrane. 
Pyridine had, however, passed into the silver nitrate and formed 
a solid addition product with it. No appreciable amount of 
AgN0 3 had passed into the pyridine without. After 24 hours 
all the AgNG 3 had dissolved and the liquid in the osmometer 
had risen to a height of about 1.5 cm. and continued to rise. 
After four days the experiment was stopped and the outer 
liquid examined for AgN0 3 . It was, however, found to be 
present only in mere traces. This shows that vulcanized caout¬ 
chouc is indeed a good “semi-permeable” membrane in this 
case. 
Considering experiments Nos. 42 to 52 in which solids were 
separated from liquids by means of rubber septa, it is evident 
