Bitlev Pit in Applet. 197 



These wfiv kept in a water bath at :^80— 4()0('. 



In 2 houis a hue. dispersed eoafjuliim liad appeared in about 

 equal amounts in a and h. 



This had sli<rhtly increased and settled out at the end of 23 

 hours, and l)y tliis time a slijjfht precipitate had appeared in the 

 control c. a and }> were also darker in colour than r. 



a. />. and c were shaken thoroughly, and 1 c.c of each was tested 

 on 5 c.c. of starch solution (1%). 



The control finished in 1\ minutes, a in 4 minutes, and h in 5i 

 minutes. 



Although a had been in contact with a greater percentage of 

 tannic acid, yet its action was quicker -than that of h. 



This may be explained by supposing that the formation of a 

 coagulum was the sole inhibiting factoi-, and that the acceleration 

 was caused by the presence of .04% of tannic acid in the final 

 starch-diastase mixture, in the case of «, whereas only .01% was 

 present when testing h. [No acid being present in control.] 



Experiment 6. (Tubes each contained 10 c.c. of mixture.) 



Starcli (1%). 



Tannic Acid 



(final concentration). 

 a - 8 c.c. - .2% 



h - 8 c.c. - .05% 



c (control) - 8 c.c. - 



In testing these, it was obviously necessary to compare them with 

 the control in the presence of a corresponding amount of acid, 

 hence the control was divided into two. 



The following tubes were made up (each containing 5 c.c. of 

 mixture). 



starch. Diastase. 



(1 3 C.c. of a 1 c.c. 1% Taka diastase 



a J ' 



'-2 3 c.c. of c (control) ., 



, ^ 3 3 c.c. of h „ 



' 4 3 c.c. of c (control) ,, 



1 and 2 then contained .12% of Tannic Acid 

 and 3 and 4 „ „ .03% 



It was found that 1 and 2 went neck and neck (6 minutes), and 

 at a faster rate than 3 and /f, which also went neck and neck (10 

 minutes). 



This experiment shows that the prolonged action of .2% tannic 

 acid on .8% filtered staixh solution does not materially affect its 

 subsequent hydrolyses by taka diastase. 



