W. A. Davis and G. C. Sawyer 365 



If a; = dextrose in 50 cc. ; y = maltose in 50 cc, 

 2-58a; + l-38y = 0-0770 



4-22X+ n-oiy = o-idr. 



Solving, X = 0-02587 grm. in 50 cc. 

 y = 0-00746 grm. in 50 cc. 

 Total dextrose in 500 cc. = 0-2587 grm. = 0-2328 grm. starch. 

 Total maltose in 500 cc. = 0-0746 grm. = 0-0707 „ 



.-. Total starch = 0-3035 grm. 



Percentage of starch in the vacuum-dried extracted leaf 



0-3035 X 100 



= ^^^^05~ = ^'^^- 



Percentage of starch in the total vacuum-dried matter 

 3-08 X 102-42 



161-67 



1-95. 



Summary of Analysis ^ 



Rotation of aqueous extract calculated on 100 grms. t.v.d.m. 



in 100 cc =5-76° 



This represents as "soluble starch" ... ... ... = 1-43 % 



Actual "soluble starch" found by diastase ... ... = 0-41 % 



True starch found by diastase ... ... ... ... = 1-95 



JFi 0/ 



' A duplicate analysis of this sample, gave : Rotation of aqueous extract per 100 grms. 

 T.V.D.M. = 5'58'; calculated as soluble starch this = 1-38 per cent. "Soluble starch" by 

 diastase = 0-30 per cent.; true stanch = 1-24 per cent. The duplicates here given 

 for the true starch are not so close as is usually the case in these analyses ; a more 

 typical case (4 a.m.) gave 1-24 and 1-43 per cent. The greatest difficulty is encountered 

 in the sampUng, as was pointed out in a former paper; for each analysis the whole of the 

 powdered leaf material, especially that at the bottom of the bottle, where the heavy 

 starch grains tend to collect, should be turned out on a sheet of paper and 10 grms. 

 sampled so as to represent a fair average of the whole of the material. 



