JACQUES LOEB 



569 



that 1 gm. of isoelectric gelatin should* be melted and added to 15 

 cc. of 0.01 N HBr or H2SO4 and that the volume be made up to 100 

 cc. by adding distilled water. By mixing HBr and H2SO4 in variou? 



30 



28 



26 



2A 



22 



20 



18 



!& 



14 



12 



10 



8 



6 



A 



pH2.3 25 27 2.9 3.1 33 3.5 37 3.9 4.1 43 45 47 

 HBr o 



Fig. 3. Conductivity curves for gelatin sulfate and gelatin bromide. Ab- 

 scissae represent pH; ordinates, conductivity of gelatin sulfate and gelatin bro- 

 mide, showing that aside from a few irregular values the curves are practically 

 identical for the two acids. This disproves the assumption that the differences 

 in osmotic pressure, as shown in Fig. 2, can be attributed to differences in ioni- 

 zation and "hydratation" of the two gelatin salts. 



proportions but always adding 15 cc. of 0.01 N acid to 1 gm. of iso- 

 electric gelatin, melting the latter, and making up the volume to 

 100 cc. by the addition of water, the amount of gelatin salt formed 

 and its degree of ionization, i.e. the conductivity, should remain the 



