Experiment 9. The mortality of Bad. coli at different temperatures in M/500 



buffer at pH 7.1 



Note: The buffer consisted of 50 ec. M /5 KHjPO, plus 29.63 cc. M /5 NaOH in 

 5000 cc. distilled water. The original pH of 7.0 shifted to 7.1 during sterilization. 



Experiment 10. The mortality of Bad. coli at different temperatures in M/SOO 



buffer at pH 8.0 



Note: The buffer consisted of 50 cc. of M /5 ICHoPO, plus 46.80 cc. M /5 NaOH 

 in 5000 cc. distilled water. After sterilization, the pH remained at 8.0. Toward 

 the end of the experiment, the pH gradually shifted to 7.7, apparently because 

 of the low concentration of the buffer and the nearness to the limit of its zone 

 of effectiveness. 



228 



