MEASUREMENT OF OSMOTIC PRESSURE 549 



osmosis under different conditions and on the maximum pressure 

 that could be set up by the osmotic flow. The most important 

 experiments were those in which this maximum osmotic pressure 

 was measured, using as a "semi-permeable" membrane the 

 precipitated films of copper ferrocyanide first described by 



Fig. i. 



Traube in 1865. These measurements were carried out with 

 the cells shown in fig. 1. 



Rigidity was conferred upon Traube's floating membranes 

 by depositing them first upon linen or silk but finally in the 

 walls of a porous battery-jar, a method that has been in use 

 through thirty-five years of subsequent work and has been proved 

 to be capable of furnishing membranes strong enough to resist 



