248 



AMPHOTERIC COLLOIDS. II 



jionof Qelatin-Br 

 and Gelatin-U 



Isoelectric 



point 

 Pure gelatin 



Region of 

 Na-Gelatinate 



70 



60 



50 



40 



30 



20 



20.0 



175 



15.0 



12.5 



10.5 



7.5 



5.0 



25 







250 



225 



200 



175 



150 



125 



100 



75 



50 



25 



4 



3 



2 



1 



HCl _Mj;[]lM_M_M__n_Mji__M_M__M_0 



conc.used 4 6 16 32 64 128 256 512 1024 2M6 4096 9192 

 pH 3.5 3.5 3.6 37 37 4.1 4.6 5.Z 5.5 64 6.& 70 7Z 



Fig. 6. Gelatin treated first with varying concentrations of HCl, washed, 

 then treated with m/8 NaBr, and washed again. Curves for conductivity, osmotic 

 pressure, alcohol number, and swelling. On the right side from the isoelectric 

 point gelatin exists as sodium gelatinate, on the left side a's gelatin chloride or 

 bromide, at the isoelectric point as pure, sparingly soluble gelatin. 



