JACQUES LOEB 



577 



130 

 120 



■ no 



100 



90 



80 



70 



60 



pH 2.3 25 Z7 29 . 3.1 33 3.5 37 39 4.1 43 45 47 



OAalic acid • 

 Tartaric acid o 



HBr + 



Fig. 9. Viscosity curves of gelatin treated with HBr, tartaric, and oxalic acids 

 are identical when plotted over pH as abscissae. 



70 



60 

 50 

 40 

 30 

 20 



10 



pH Z.3 25 27 29 3.1 33 35 37 39 4! 43 45 47 

 Oxalic acid ® 

 HCl o 



Fig. 10. Curves showing the influence of HCl and oxaKc acid upon swelling 

 of gelatin. The curves are identical when plotted over pH. 



Antagonism Experiments between HCl and Phosphoric and Oxalic Acids. 



It was to be expected that when H3PO4 or oxahc add is added to 

 HCl or HBr it can produce no or only a shght antagonistic effect. 

 The results of actual experiments support this expectation. The 

 same experiment as that with HCl and H2SO4 (represented in Fig. 

 4) was made by mixing different proportions of HCl and H3PO4. 



