JOHN H. NORTHROP 



793 



be the case with the suspensions already discussed. If, however, the concentration of 

 salt required to lower the potential to this value was o.oi m or more, this was no longer 

 true and no complete agglutination occurred, even though the potential was reduced 



Fig. 4 

 typhosus. 



Acid concentrafion,equivalentsper liter 

 , — Effect of acid concentration on the potential and agglutination of suspension of B. 



10-5 "io^l \0^ 10^2 10^1 



5al+ Conccntration^cquivalents per liter 



Fig. 5. — Effect of salt concentration on the potential and agglutination of suspension of B. 

 typhosus. 



to zero. It is evident that either (i) the potential measurements are wrong, or (2) 

 some other factor has to be considered besides the potential, since with this suspension 

 it is no longer possible to predict the flocculation from the potential alone. The fact 



