JACQUES LOEB 



573 



treated with different quantities of H3PO.-. In the case of HNO-, 

 and oxahc acid we determined the amount of acid in combination 

 with the same amount of gelatin by titration with NaOH for pH = 7.0, 



70 

 60 

 50 

 40 

 30 

 20 

 10 



pH Z3 Z.5 Z7 2.9 31 33 3.5 3,7. 3.9 4.1 4.3 4.5 4,7 



H2,504 • 

 HBr o 



Fig. 5. Relative influence of HBr and H2SO4 upon swelling. 



130 

 120 

 1 10 

 100 



90 



80 



70 



60 



pH 23 2.5 27 2.9 31 33 3.5 37 3.9 4.1 4.3 45 47 



H^504 ® 

 HBr o 



Fig. 6. Relative influence of HBr and H2SO4 upon viscosity. 



and making the two corrections discussed before. Table IV gives 

 the equivalents of these three acids in combination with 0.1 gm. of 

 gelatin for different pH in terms of cc. of 0.01 N NaOH used for 

 titration. 



