252 Wisconsin Academy of Sciences, Arts and Letters. 
found to be quite needless to measure more closely than this, 
for the results of separate duplicate experiments showed as a 
rule greater variation. 
I will first give the results of the experiments performed by 
using the method just described, which method, though it is the 
usual one, had to be modified later in one important particular 
in order to secure reliable results. The individual experiments 
are numbered consecutively with those preceding so as to 
facilitate future reference to them. 
53) The liquid in the osmometer was a solution of cane 
sugar in pyridine containing one-fourth of a gram-molecule 
per liter of the solution. The outer liquid was pure pyridine. 
The experiment was run in triplicate, that is three separate in¬ 
dividual tests were made with the same solution. The temper¬ 
ature in each case was 17.5° C. a) In the first of these ex¬ 
periments the pressure came up slowly, remaining nearly con¬ 
stant after the second day. The experiment was nevertheless 
allowed to go on for nine days when the pressure was finally 
measured and found to be 186.2 cm. at 17.5° C. Before discon¬ 
tinuing the experiment, the whole of the outer vessel was 
packed in melting ice for ten hours. The mercury column be¬ 
came constant at 125 cm. after three hours and remained there 
for the remaining seven hours:. The temperature was then per¬ 
mitted to rise slowly and after three days the mercury column 
was 159.5 cm. high, the tempreature being 16.4°. When the 
whole had finally reached the temperature 17.5°, the mercury 
column was again 186.0 cm. high. This then would seem to be 
pretty good evidence that the maximum pressure had indeed 
been reached. During the operation care was taken not to dis¬ 
turb the apparatus by jarring it in any way. The outer liquid 
was found to contain traces of sugar, but the exact amount 
was not determined, b) In the second independent yet per¬ 
fectly similar experiment, the pressure also rose gradually, 
changing but slightly after the second day. The temperature 
was kept at 17.5° C., and at the end of eleven days the column 
of mercury measured 155.6 cm. This experiment was then al¬ 
lowed to run for four days longer. At 8 in the morning of the 
fourteenth day the mercury column measured 166.4 cm. at 16.4° 
