JACQUES LOEB 87 



experiments on casein solutions, that the increase in the viscosity of 

 the protein caused by the addition of acid (or of alkah) is due to an 

 increase in the ionization of proteins, as a consequence of the salt for- 

 mation betweenproteinandacidor alkali, the protein salt being capable 

 of a greater degree of ionization than the protein not treated with acid 

 or alkali. In order to explain the relative differences in the effect of 

 various acids on the viscosity, Pauli assumes that the protein salts 

 formed with different acids differ in their degree of electrolytic dis- 

 sociation. He states; e.g., that "the strong trichloracetic acid and 

 the slightly weaker sulfuric acid furnish few protein ions."^ He also 

 states that the relative efficiency of different anions on the other 

 properties of proteins, as osmotic pressure, precipitation by alcohol, 

 is the same as that found for viscosity. 



In his experiments on the influence of acids and alkalies on the 

 osmotic pressure of gelatin solutions the writer had arrived at the con- 

 clusion that the results he obtained cannot be expressed in terms of 

 ion series.^ These experiments showed only an influence of the val- 

 ency of the anion or cation in combination with the gelatin, but no 

 other influence. Solutions of Li, Na, K, and NH4 gelatinate of the 

 same pH and the same concentration of originally isoelectric gelatin 

 had the same osmotic pressure. The same was true for Ca and Ba 

 gelatinate; but the osmotic pressure of Ba and Ca gelatinate was only 

 one-half or less than that of Li, Na, K, or NH4 gelatinate of the same 

 pH and the same concentration of originally isoelectric gelatin. The 

 influence of acids on the physical properties of proteins was still more 

 interesting. Solutions of gelatin chloride, bromide, nitrate, acetate, 

 phosphate, citrate, tartrate, succinate, of the same pH and the same 

 concentration of originally isoelectric gelatin, had approximately the 

 same osmotic pressure, while the osmotic pressure of solutions of 

 gelatin sulfate was only half or less than half of that of gelatin 

 chloride, etc. The osmotic pressure of solutions of gelatin oxalate 

 was almost but as a rule not quite as high as that of gelatin chloride.^ 



This peculiarity found its explanation in an investigation of the 

 combining ratios of these acids with gelatin. The writer was able to 



^ Pauli, W., Fortschr. naturwiss. Forschung, 1912, iv, 243. 

 8 Loeb, J., /. Gen. Physiol., 1918-19, i, 483, 559. 



