Mr Vegard, On the Free Pressure in Osmosis. 



17 



tration, however, the velocity after the sudden bend of the curve 

 continues to fall. 



The condition for a steady state and the time taken for 

 reaching it depend on several circumstances. A nearer study 

 of this question would require a special research. I shall here 

 only call attention to some circumstances which seem to have an 

 effect. 



>l 



Fig. 1. 



The time depends to some extent on the dryness of the mem- 

 brane at the moment when the solution is brought into contact 

 with it. Thus the membrane in the second experiment, Table II, 

 was dried with filter paper while in the third the membrane was 

 just so wet as to give a regular reflection of light. The result 

 was that the steady state occurred much sooner in the third 

 experiment and that in spite of the fact that the concentration 

 was greater. 



The steady state sets in more suddenly and is better marked 

 for dilute solutions than for more concentrated. We shall later 

 come back to this question. Further the steady state is better 

 marked and more suddenly obtained when the membrane is more 

 perfect. So e.g. in the measurements described in the earlier 

 paper, where the maximum resistance was much greater, the 

 stationary state in all cases was reached within half-an-hour. For 



VOL. XV. PT. I. 2 



