JACQUES LOEB 269 



ing is considerably higher than that caused by Ca(0H)2 and Ba(0H)2 

 for the same pH. This agrees with the results of the titration experi- 

 ments which prove that Ca(0H)2 and Ba(0H)2 combine with gelatin 

 in equivalent proportions and that hence the cation in combination 

 with the gelatin salt with these two latter bases is bivalent. 



3. The fact that proteins combine with acids and alkalies on the 

 basis of the forces of primary valency is therefore not only in full 

 agreement with the influence of ions on the physical properties of 

 proteins but allows us to predict this influence qualitatively and 

 quantitatively. 



4. What has been stated in regard to the influence of ions on the 

 swelling of the different gelatin salts is also true in regard to the influ- 

 ence of ions on the relative solubility of gelatin in alcohol-water 

 mixtures. 



5. Conductivity measurements of solutions of gelatin salts do not 

 support the theory that the drop in the curves for swelling, osmotic 

 pressure, or viscosity, which occurs at a pH 3.3 or a little less, is due 

 to a drop in the concentration of ionized protein in the solution; 

 nor do they suggest that the difference between the physical proper- 

 ties of gelatin sulfate and gelatin chloride is due to differences in the 

 degree of ionization of these two salts. 



