160 



ANTISEPTICS 



TABLE 33 



Inhibition of growth by sodium sulfite. (From Rahn and Conn, 

 1944. Courtesy of "Industrial and Engineering Chemistry.") 



PH 



Fractions of 



SO3 

 ions 



HSO, 



Undiss. 



Inhibitory concentration, 

 in mg. per 100 cc. 



Na.SOo 



Undissoci- 

 ated 



Bacterium coli 



Saccharomyces ellipsoideus 



efficient tlian the sodium or calcium salts. Olson and 

 Macy (1940) point out that ''the final pH is an extreme- 

 ly important factor in restraining mold growth". While 

 2% sodium propionate had no effect at pH 7.0, it suf- 

 ficed to prevent mold growth for 5 days at pH 6.1; These 

 authors advance the theory that inhibition may be due 

 to the undissociated acid. 



