Chittenden arid Smith — Diastatic Action of Saliva. 371 



Series XXI. 



20 c.c. filtered saliva wei'e neutralized and the proteids exactly- 

 saturated with HCl, then diluted to 100 c.c. The solution contained 

 0"0073 per cent, combined HCl, but no free acid. A. 



20 c.c. of the same saliva neutralized and the proteids saturated 

 by the addition of the same amount of acid as in A^ 1*2 c.c. 0*1 

 per cent. HCl were then added, so that a distinct tropaeolin reaction 

 could be obtained in the 41 c.c. of fluid. The fluid was diluted to 

 100 c.c! and then contained 0*0012 per cent, free HCl. B. 



20 c.c. of the same saliva, neutralized and the proteids exactly 

 saturated with acid ; then enough more acid added to give a distinct 

 tropaeolin reaction, after which the solution was diluted to 1 00 c.c. 

 The 100 c.c. of fluid contained exactly 0'003 gram HCl. C. 



A drop of the latter fluid on being tested gave a distinct violet with 

 tropaeolin 00. 



Following are the results of digestions made with the foregoing 

 solutions of saliva. 



Here it is seen, as before, that the smaller percentages of free acid 

 arising from the use of 5 and 10 c.c. of saliva, show a distinctly 

 increased diastatic activity, while with 20 c.c. the results are very 

 nearly identical; too large an amount of free acid to increase the 

 action and yet not enough to materially diminish it. 



We next tried the influence o^ increased percentages of free acid on 



the action of ptyalin. 



Series XXII. 



30 C.c. filtered saliva were neutralized and the proteids just satu- 

 rated with acid, then diluted to 150 c.c; 10 c.c. of this diluted 

 saliva equal to 2 c.c. of the original saliva were used in each diges- 

 tion. Following are the results, after warming with starch at 40° 

 C. for 30 minutes in the presence of the percentages of free acid 

 specified. The acid solutions were mixed with the starch previous 

 to the addition of the saliva. 



