Chittenden and Cummins—Action of Diastase of Malt. 45 
plying that the ferment acts more vigorously in the naturally acid 
extract than in a neutral fluid. The same investigators found that 
making the extract faintly alkaline with sodium carbonate also 
diminished somewhat the activity of the ferment, while sodium 
hydroxide completely stopped the action of the ferment. A like re- 
sult was also obtained on the addition of 0°05 per cent. salicylic acid. 
Such are the recorded statements bearing on this question. Few 
quantitative results are given, and the influence of proteid matter, 
aside from its connection with dilute acid, has not been considered. 
Method employed. 
A fresh malt extract was prepared for each series of experiments, 
since the fluid tends rapidly to become acid, owing to the develop- 
ment of schizomycetes. The extract was prepared from coarsely 
ground malted barley, by simply extracting it with water at 40° C. 
for two to three hours (5 grams barley to 100 ¢. c. water), then filter- 
ing, neutralizing and diluting to 500 ¢. ¢. 
Owing to the great difficulty of obtaining perfectly neutral starch, 
that used in the present work was prepared from potatoes, thoroughly 
washed and dried, making a starch perfectly neutral to the most 
delicate test papers. The volume of each digestive mixture in the 
various experiments was 100 ¢c.¢., containing 1 gram of starch pre- 
viously boiled with a portion of the water, a definite quantity of the 
malt extract and a given amount of acid, alkali, or proteid matter, 
except in the control, which was naturally free from the latter. In 
determining amylolytic power the digestive mixtures were warmed 
at 40° C. for thirty minutes, after which further ferment action was 
stopped by boiling the fluid. The extent of amylolytic action was 
then ascertained by determining in one-fourth of the fluid, made up 
to 100 ¢.¢., the amount of reducing bodies by means of Allihn’s* 
gravimetric method; the reducing bodies being then calculated, for 
the sake of convenience, to dextrose, from which in turn, was calcu- 
lated the percentage of starch converted. 
Influence of sodium carbonate on the amylolytic action of diastase. 
Previous experimentst with saliva have shown that the percentage 
of alkaline carbonate which absolutely or to a certain extent hinders 
its amylolytic action can be designated only for a definite mixture 
and not in a general sense, owing to variations in the amount of pro- 
* Zeitschrift fiir Analytische Chemie, vol. xxii, p. 448. + Chittenden and Smith. 
