Chittenden and Smith — Diastatlc Action of Saliva. 365 



tioti and that the maximutn of the diastatic action of j)arotid saliva 

 corresponds with the strongest acid reaction ; but in these observa- 

 tions doubtless the acid reaction was in every case due to acid-pro- 

 teids and not to free acid. Again it was found by one of us* that the 

 presence of O'OOo per cent. HCl decidedly increased the diastatic 

 action of saliva, but while the observation was correct the result was 

 wrongfully attributed to 0*005 per cent, free acid when it should have 

 been attributed to the same percentage of combined acid, where 

 doubtless the proteid matter was not wholly saturated. Likewise 

 Watson'sf oft-quoted result, whei-e the addition of a drop of strong 

 acid to saliva gave him an increased diastatic action, was doubtless 

 due to the acid-proteid matter formed and not to free acid, though it 

 may have been due to partial or complete neutralization. 



We endeavored to ascertain whether the acid-proteid matter 

 formed by the addition of acid to undiluted saliva would have any 

 destructive action on the diastatic ferment when warmed at 40° C. 

 Of course only a slight action, if any could be expected, still it seemed 

 of sufficient importance to warrant the experiment. Accordingly two 

 mixtures were prepared as follows : 



A. . B. 



Saliva, 20 c.c. 20 c.c. 



HCl 0-2^ to neutralize, 6-8 6-8 



" " combine with proteids, 3-2 



H2O, 13-2 10 



40 c.c. 40-0 C.C. 



Neutral. 0-016^ HCl combined 



These two solutions were warmed at 40° C. for 1 hour, then neu- 

 tralizing and equalizing! niixtures were added, after which starch 

 and water to 100 c.c. The results were in ^ a conversion of 38-68 

 per cent, of the starch into sugar, and in J5 a conversion of 38*26 

 per cent., so that while there may have been some little destruction 

 of the ferment, it is plain that the diminished action noticed in the 

 two preceding cases in the presence of the larger percentages of acid- 

 proteid matter was probably due to simple retardation, since the 

 percentage of combined acid was not more than half that in the 

 above experiment. 



We have studied the influence of acid-proteid matter on salivary 



* Chittenden and Griswold, Amer. Chem. Jour., vol. iii, 312. 

 f Jour. Chem. Soc, 1879, 543. 



X Equivalent amo"unts of standard acid and sodium carbonate solutions, so that 

 A for example might contain the same amount of sodium chloride as B. 



