204 



SOLUTION AND PRECIPITATION OF PROTEINS 



at a concentration above m/8, while both NaCl and CaCl2 increase 

 the solubility of Na gelatinate, NaCl in concentrations above m/2, 

 and CaCl2 in concentrations above m/16. 



In all three cases, therefore, is the solubility of gelatin diminished 

 by sulfates, but only exceptionally by chlorides. This explains the 



140 

 130 



c 



a 

 .1-t 



o 



.1-4 

 I 1 



o 



120 



110 



100 



90 



80 



70 



60 



50 



40 



30 



20 



10 







M 

 2 



IN 2M 



n j-^ i-i 11 11 11 II 1.1 11 

 '^ iOM 512 256 128 64 32 16 ~B 4 



Concentration of salts 



Fig. 6. Influence of salts on the time required to dissolve 0.8 gm. of powdered 

 Na gelatinate of pH 10.5 at 35°C. 



results contained in Table III. 



We have seen that addition of little acid to isoelectric gelatin in- 

 creases the osmotic pressure, viscosity, p.d., and swelling with in- 

 creasing concentration, while beyond a certain pH the addition of 

 more acid has a depressing effect. This is characteristic of the 



