710 DONNAN EQUILIBRIUM AND OSMOTIC PRESSURE 



VII. Theoretical Remarks. 



It is of interest to compare the colloidal speculations with the 

 almost quantitative results at which we arrived. All colloidal 

 theories would agree in ascribing the efJfect of the hydrogen ion con- 

 centration or of the valency of the ions with which the protein is in 

 combination to a modification in the state of the protein particles, 

 such as hydratation or degree of dispersion. The hydratation theory 



12 







pH 2.0 22 2.4 2.6 2.8 3.0 32 3.4 3.6 38 4.0 42 44 4.6 



Fig. 7. Curves for the specific conductivity of 2.4 per cent solutions of gelatin 

 chloride, sulfate, and oxalate, showing the entirely different character of these 

 curves from that of the osmotic pressure curves in Figs. 1 and 5 in the preceding 

 paper. 



is advocated by Pauli^ who assumes that the ionized protein particle 

 is strongly hydrated while the non-ionized protein particle is not 

 hydrated. If this were the correct explanation of the peculiar type 

 of curves, such as those reported in Fig. 1 of this paper, we should 

 expect the curves for the specific conductivity of the protein in solu- 

 tion to show a close similarity to the curves in Fig. 1. But such is 



^ Pauli, W., Kolloidchemie der Eiweisskorper, Dresden and Leipsic, 1920. 



