Kohlenberg—Osmosis and Osmotic Pressure. 253 
€.; while at 5 in the afternoon of the fifteenth day it measured 
166.7 cm. at 16.0° C. As in the previous case, care was taken 
not to jar the apparatus during the experiment. In this case, 
too, traces of sugar were found in the outer liquid, c) In a 
third similar experiment the pressure also increased but little 
after the second day. The experiment was stopped at the end 
of four days in this case, when the mercury column was 107.4 
cm. high, the temperature being 17.5° 0. Only traces of sugar 
were found by testing the outer liquid. 
It will be noted that the highest pressure was observed in (a). 
In this experiment the pressure came up more rapidly than in 
the other tw r o cases, accomplishing 115 cm. in the first twenty- 
four hours. The discussion of the causes of the discrepancies 
in the results of (a), (b) and (c) will be left until a little 
later. 
54) This experiment was performed in duplicate. The ar¬ 
rangement was exactly like that in No. 53 except that the 
liquid in the osmometer consisted of a solution of cane sugar in 
pyridine containing one-eighth of a gram-molecule per liter of 
the solution, a) The pressure rose slowTy increasing but 
slightly after forty-eight hours. On the sixth day the mercury 
column measured 62.4 cm., the temperature being 17.5° C. 
The whole was then surrounded with melting ice, and after two 
hours the mercury column measured 0.2 cm.; at the end of ten 
hours the pressure was 0.6 cm. The temperature then gradu¬ 
ally rose during the night as the ice disappeared. At 14.5° C. 
the column measured 48.8 cm. and at 17.5° C. it again came up 
to 62.0 cm., nearly where it was before the chilling process. 
In this case the experiment was left set up for five days longer, 
when the column measured but 43.6 cm. at 18° C. Sugar was 
found to be present in the outer liquid in small amount, b) 
This was a duplicate of (a). The observations made were prac¬ 
tically the same as in (a) except that the pressures were differ¬ 
ent. The chilling process with ice was omitted in this case. 
After two days the pressure increased but slightly. On the 
third day it was measured carefully and found to be 52.8 cm. 
at 17.5° C. During the next two clays the temperature fell 
very' gradually to 14.5° C. and the column then measured 12.5 
