ELECTRICAL CHARGES OF COLLOIDAL PARTICLES AND 

 ANOMALOUS OSMOSIS. 



By JACQUES LOEB. 



{From the Laboratories of The Rockefeller Institute for Medical Research.) 

 (Received for publication, January 26, 1922.) 



/. The Transport Curves on the Acid Side of the Isoelectric Point of the 



Membrane. 



The experiments described in a preceding paper^ leave no doubt 

 that the Donnan equilibrium is the main source of the potential 

 differences between solid gelatin particles and the surrounding liquid. 

 On the other hand, experiments on the influence of salts on electrical 

 endosmose, cataphoresis, anomalous osmosis, and Quincke's current 

 potentials suggest in certain cases at least a second source which is 

 generally designated as adsorption potentials. The difference be- 

 tween the two kinds of potentials should be that while the potential 

 differences due to the Donnan equilibrium depend on the ionization 

 of the protein, the adsorption potentials should occur regardless of 

 whether or not the solid colloid is ionized. Adsorption potentials 

 should, therefore, be found just as well in the case of isoelectric pro- 

 tein where the protein is practically non-ionized as in the case of 

 metal proteinates or protein-acid salts, while the p.d. due to the 

 Donnan equilibrium should be restricted to the latter two forms of 

 protein.2 



It is intended to investigate on the basis of this idea whether or not 

 there exist at the surface of solid gelatin adsorption potentials in 

 addition to potentials due to the Donnan equilibrium. It will be 

 necessary to use for this purpose either electrical endosmose or anomal- 

 ous osmosis or Quincke's current potentials or cataphoresis. We 

 shall select in this paper anomalous osmosis. By anomalous osmosis 



1 Loeb, J., /. Gen. Physiol, 1921-22, iv, 351. 



^Loeb, J., J. Gen. Physiol., 1920-21, iii, 667; 1921-22, iv, 351. 



463 



