236 



Alfred J. Ewart : 



Tannic 

 Acid Solution added. 



TABLE A. 



Iodine Test After 



Stroni 



Hours. 

 ; blue. 



5 e.c. of b%- 



5 c.c. of 1% 



5 c.c. of 0.2% 

 5 c.c. of 0.4% 

 5 c.c. of 0.008% 

 5 c.c. of 0.0016% 

 5 c.c. of 0.0010% • 

 5 c.c. of distilled 



water 

 5 c.c. of 1% starch • 



and 

 10 c.c. of 2.5% tan-- 



nic acid 



*Equallingr in the total 15 e.c. of solution, 

 centration of the 5 c.c. added in each case. 



Strong^ blue. 



Strong blue. 



Paler blue. 



Purple. 



Purple. 



Nil, all dissolved. 



Nil, all dissolved. 



Strong blue. 



26 Hours. 



- Starch in dense 



ppt., liquid 

 starchless. 



- Nearly all starch 



pptd. 



- Strong blue. 



- Violet. 



- Nil. 



16 Hours. 

 Strong blue. 



- Strong blue. 



- Strong blue. 



- Paler blue. 



- Purple. 



- Nil. 



- Nil. 



Dense residue of 

 starch ; liquid, 

 starch free. 



, concentration of 1.6°, of tannic acid (J of the con- 



Similar results were obtained with Taka diastase, except that 

 it appeared to be a little less sensitive than the samples of malt 

 diastase used. Possibly on this account the retarding action of 

 the 0.02 per cent, solution was not so pronounced, and it required 

 ivowx 0.2 to 0.08 per cent, solutions to practically arrest the dias- 

 tatic action. At least much undissolved and condensed starch was 

 still present in the latter case after 30 hours. A portion of the 

 difference was due to the higher temperature, and with malt dias- 

 tase at 350 C, 0.2 to 0.08 per cent, tannic acid was also necessary 

 to prevent the complete solution of the starch in 30 hours. 



To each 5 c.c. of 1 per cent. Taka diastase, and 5 c.c. of 1 per 

 cent, solution, 5 c.c. of tannic acid were added, and the mixture 



