232 BERTHA VAN H. ANTHONY AND C. V. EKROTH 



a further depression of ionization, especially when these sub- 

 stances are decomposed by boihng. 



The meagre results from the few investigations conducted 

 in this field lead us to suspect that the presence of sugars in 

 media may have a considerable influence on the effective acidity, 

 that is, the dissociated acid principles (Hildebrand 1913). Work 

 in these lines is to be continued. 



SUMMARY 



Marked and continued hydrolysis, resulting in the formation 

 of acid principles, occurred on successive heatings of meat in- 

 fusions in the autoclave. The state of complete hydrolysis, 

 i.e., the point at which no further acidity is produced, was not 

 reached with these meat infusions (which had been subjected 

 previously to boiling over the open flame for one to two hours) 

 even after prolonged autoclaving at fifteen pounds pressure 

 for eight^^ hours. 



Hydrolysis did not occur in solutions of Liebig's beef ex- 

 tract subjected to similar heatings. In the portion which had 

 been adjusted to the neutral point, however, shght hydrolysis 

 did take place. 



Those portions of meat infusion in which the natural acidity 

 had been adjusted with normal sodium hydroxid to plus one 

 (phenolphthalein) showed that hydrolysis occurred on applica- 

 tion of heat and continued to do so after successive adjustments 

 and autoclavings. There was produced in these portions as 

 much acidity, approximately, as was developed on heating the 

 corresponding uncorrected portions. 



The further production of acidity after the addition of sodium 

 hydroxid is due to the hydrolytic effect of heat in the presence 

 of water, upon these portions of the medium unbound by alkali. 



The fact that hydrolysis is promoted by heat makes inaccurate 

 the estimation of acid ions in a batch of medium when there is 



** With three of the meat infusions the time was extended from eight to four- 

 teen hours. 



