370 Chittenden and Smith — Diastatic Action of Saliva. 



to the small amount of acid-proteid matter present, certainly could 

 not have been due wholly to free acid. 



We have tried a large number of experiments on this point in a 

 variety of ways, all of which tend to show that a very small trace 

 of free acid, when the amount of acid-proteids is not large, does, 

 seemingly, slightly increase the diastatic action of the ferment. It is, 

 perhaps, questionable, however, whether in the use of such small 

 percentages of acid, the results are to be strictly depended upon. 

 The presence of a small amount of phosphate in the starch or a 

 trace of alkali, not to be detected by litmus, might easily neutralize 

 the small amount of acid added. Again, non-saturation of the 

 proteids to only a very slight extent might effect the result. We 

 subjoin two or three of our experiments. 



Series XX. 



20 c.c. filtered saliva were neutralized and then sufficient 

 acid added to combine with the proteids present ; the mixture then 

 diluted to 100 c.c. The solution contained 0-0114 gram combined 

 HCl, but no free acid. A. 



20 c.c. of the same filtered saliva neutralized, and the proteids just 

 saturated with acid. 3-1 c.c. O'l per cent. HCl were then added and 

 the mixture diluted to 100 c.c. The solution contained 0*0114 gram 

 combined HCl, and in addition 0-0031 gram free HCl. The solution 

 gave a distinct violet with tropaeolin 00. B. 



l^igestions were made, using 1 gram starch in a volume of 100 

 c.c. Time, 30 minutes. Following are the results. 



Here there can be no question but that there was free acid in B. 

 The saliva gave a distinct reacion with tropaeolin 00 and the starch 

 used was apparently neutral. In this instance 0*0006 per cent, free 

 acid slightly diminished the diastatic action, while 0-0003 per cent, 

 slightly increased it. 



A second experiment of like nature gave the following results : 



