58 



' DIASTASIMETRY.' 



[BOOK II. 



an illustration of the way in which the experiments are cfarried out, 

 noted and expressed. 



10 c.c. of standard starch mucilage + 90 c.c. of water 

 + 0-1 c.c. of pancreatic extract, at 40 C. 



Mode of cal- 

 culating the 

 value D, from 

 the results of 

 the above ex- 

 periments. 



In the method of experiment which has just been 

 described, the temperature and the volume of starch 

 paste, are maintained constant, the volume of diastatic 

 solution, and the time occupied by it in effecting the 

 reaction are, however, varied. To obtain the value of 

 D we must calculate, from the data obtained, what 

 number of cubic centimetres of the standard mucilage would have 

 been required, if the volume of diastatic solution had been 1 c.c. and 

 the time five minutes. 



Let v= volume in cubic centimetres of the diastatic solution, 

 n= time expressed in minutes, 

 D=diastatic value according to definition; then 



D 



10 5 

 - x -. 



v n 



Example. In the experiment previously cited to shew the usual 

 course of events, 01 c.c. of pancreatic extract induced the achromic 

 point in six minutes, 



n 10 5 

 then JJ x ^ 



D = 83-3, 



that is to say, 1 cubic centimetre of the pancreatic extract used, 

 would at the temperature of the experiment (40 C.), in the period of 

 five minutes, convert 83 cubic centimetres of standard mucilage to 

 the achromic point. Now, as the proportion of starch in the standard 

 mucilage is always the same and known, viz. 1 grm. per 100 c.c., it is 



