OSMOTIC PRESSURE 



187 



The experiment just described for gelatin phosphate was repeated 

 for gelatin chloride, with similar results. 



According to DakhYs 1 recent analyses gelatin contains 1.4 

 per cent phenylalanine. Since one molecule of gelatin cannot 

 contain less than one molecule of phenylalanine and since the 

 molecular weight of this amino-acid is 165 the lowest possible 

 weight of gelatin is 11,800. If a molecule of gelatin contains 

 two molecules of phenylalanine, the molecular weight should be 

 about 23,600. This would be approximately the figure we might 

 expect from the data of Table XXXVI on the assumption that 

 the differences in the last two rows may be considered to be the 

 values of the osmotic pressure of the protein particles. 



TABLE XXXVII. INFLUENCE OF CONCENTRATION OF ALBUMIN CHLORIDE 

 OF pH OF ABOUT 3.4 on THE OSMOTIC PRESSURE 



A similar experiment was made with different concentrations of 

 solutions of the chloride of crystalline egg albumin. The original 

 pH of the albumin chloride solution was 3.5 and that of the outside 

 solution 3.0. After equilibrium was established the pH both 

 inside and outside was slightly changed as is shown in Table 

 XXXVII. The osmotic pressures for 0.25 to 4 per cent solutions 



1 DAKIN, H. D., J. Biol. Chem., vol. 44, p. 499, 1920. 



