652 



STABILITY OF BACTERIAL SUSPENSIONS, U 



0.01 N salt decreases the potential and broadens the agglutination 

 zone slightly. More concentrated salts, however, although it reduces 

 the potential still more, decreases the agglutination, since the cohesive 

 force is now being reduced. In concentrations of more than 1.0 N 

 no agglutination occurs. The salt also shifts the zone of agglutination 

 to the acid side. This result has been obtained by Michaelis and 

 Rona^^ with proteins. 



+1.0 +13 



S 



-2.0 -26 



4.6 

 3 



3.3 



3.9 

 pH 

 4 5 6 7 8 9 

 Concentmtion of HCl x 10^ 



3.0 

 10 



Fig. 10. Effect of NaCl concentration on the potential and agglutination of 

 B. typhosus at the acid agglutination zone. 



Effect of the Salts on the Potential. — The experiments show the famil- 

 iar result that the effect is due to the oppositely charged ion and in- 

 creases in general with the valence of the ion. The effect is not purely 

 due to the valence since the hydrogen ion is far more active than the 

 other monovalent ions. The result also depends on the nature of the 



^® Michaelis, L., and Rona, P., Biochem. Z., 1919, xciv, 225. 



