158 



TABLE III— Continued. 



'Precipitation occurred in all aliquots of this series. 



(1) Figures in this column are difference between the media without and with added salt. 



(2) Figures in this column are difference between corresponding media containing no gelatin. 



(3) These salts were used because they are typical of classes of salts that vary in hydrolysis. 



Table III brings out the following: 



(1) The temperature of the media affect.s the titration. 



(2) The effect of temperature on titration varies with the ba.se.s of 

 the media and the chemicals used in making' the media. 



(3) Increasing length of time of autoclaving does not appreciably 

 change the acidity of the media. 



(4) Potassium nitrate did not appreciably change the acidity of the 

 agar or the agar plus gelatin media. 



