598 Philippine Journal of Science 1920 
Table 6. — Analysis of starch and flour by the Munson and Walker and 
the alkaline potassium permanganate methods. 
Sam- 
ple 
No. 
Name of sample. 
1 
Munson and Walker 
method. 
lAlkaline potassium 
permanganate 
method. 
Direct 
acid hy- 
drolysis 
method. 
Saliva 
method. 
Direct 
acid hy- 
drolysis 
method. 
Saliva 
method. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
J 
Corn starch 
79.79 
80. 35 
2 
Do 
79. 98 
80. 89 
Do 
83. 71 
82.96 
4 
Do 
78.89 
79. 18 
5 
Ca.Ksa.va staroh ^ 
79. 52 
78.76 ! 
Do 
79.43 
80. 43 
7 
Do 
78. 70 
78. 01 
Do 
78.20 
77.72 
g 
Do 
78. 70 
77. 88 
10 
Do . 
78. 90 
78.03 
11 
Arrowroot flour - 
77. 79 
84.00 
12 
Do 
78. 90 
68. 83 
84.04 
70. 39 
13 
Rice flour 
70. 94 
76. 58 
14 
Ranana flrmr 
56. 88 
66. 75 
16 
Dioscorea doemona flour 
66.88 1 
45.21 
68.28 
45.32 
16 
Dioscorea alata HovlT,.' 
66.49 
60. 13 
72.86 
59. 89 
permanganate in a volume of 100 cubic centimeters, 0.2 N alkali 
is found to be the concentration most favorable for the oxida- 
tion of glucose, the extent to which this sugar is oxidized declin- 
ing when the concentration of alkali is changed from this point. 
In the case of 0.1 N potassium permanganate, there are two 
concentrations of alkali most favorable for the oxidation of 
glucose; these are 0.6 N and 0.2 N. The results obtained in 
these experiments on the concentration of alkali most favorable 
■for the oxidation of glucose by potassium permanganate agree 
with those of the previous work on the subject. The amount 
of potassium permanganate used increases uniformly with in- 
creasing amount of glucose from 1 to 40 milligrams only when 
the concentration of alkali is 0.04 N. This is the main reason 
for choosing this concentration of alkali, for with it more ac- 
curate and consistent results and a wider range of concentration 
of glucose can be obtained. One-tenth N potassium permanga- 
nate was chosen in preference to 0.2 N because it was thought 
that the former concentration would have less power to oxidize 
organic substances other than glucose when the method is ap- 
plied to agricultural products, and it will surely give more ac- 
curate results. 
