700 



DONNAN EQUILIBRIUM AND OSMOTIC PRESSURE 



added, a point which will be discussed in the next chapter. What is 

 of importance here is the following. The curves for osmotic pres- 

 sure calculated on the basis of the Donnan equilibrium and plotted 



450 



425 



400 



375 



350 



^325 



^ 300 



^275 



^ 250 



I 225 



g 200 



1 ^^° 



^ 100 

 75 

 50 

 25 



pH 14 1.6 IB ZO 22 2.4 2.6 2.8 aO 3.2 3.4 a6 3.8 4.0 42 44 4j6 4fl 



Fig. 2. Calculated curves of osmotic pressure taken from the data of the experi- 

 ments represented in Fig. 1. The calculation is made on the basis of the validity 

 of Donnan's theory of membrane equihbrium. The calculations lead to curves 

 resembling the curves in Fig. 1 in all essential points, in regard to valency effect 

 of the anion, as well as in regard to influence of pH. (See legend in Fig. 1.) 



in Fig. 2 resemble the curves for the osmotic pressure observed in 

 the same experiments represented in Fig. 1 in the following 

 essential points. 



