584 
Philippine Journal of Science 
1920 
meters of sugar solution is placed in an Erlenmeyer flask and 
definite volumes of 0.2 N potassium permanganate and of 10 
per cent potassium hydroxide solutions are added, and the whole 
mixture is boiled for ten minutes. After this lapse of time 
the mixture is cooled to 70° and 20 per cent sulphuric acid and 
0.2 N oxalic acid solutions are added. The excess oxalic acid 
is titrated by standard potassium permanganate solution until 
the pink color can be detected. Their work was principally on 
the oxidation of lactose, sucrose, glucose, raffinose, mannite, 
maltose, and hydrolyzed starch. They determined the number 
of grams of carbon dioxide produced in each case. In the 
determination of starch, a sample of the air-dry material is 
dried at 40° C. and the ash, water, protein, pentosans, and fat 
are determined in this dried matter. The hydrolyzed starch so- 
lution obtained by inversion is oxidized as described above. The 
percentage of starch is calculated on the basis of potassium per- 
manganate used in oxidation. Their results with tapioca and 
rice give percentages of starch higher by 1 per cent than when 
determined by difference; that is, by subtracting the sum of 
the percentages of the other constituents (ash, water, protein, 
fat, pentosans, etc.) from 100. 
EXPERIMENTAL 
The experimental part of this paper is discussed under the 
following heads : 
A. Determination of the proper concentration of alkali and potassium 
permanganate solutions in which to carry on oxidation of glucose. 
B. Determination of the optimum temperature and time of heating. 
C. Application of the method to glucose determination. 
D. Application of the method to starch analysis. 
E. Comparison of the Munson and Walker method with the one proposed. 
A. DETERMINATION OF THE PROPER CONCENTRATION OF ALKALI 
AND POTASSIUM PERMANGANATE SOLUTIONS IN WHICH TO 
CARRY ON OXIDATION OF GLUCOSE 
To find the effect of oxidizing known amounts of pure glucose 
in different concentrations of alkali by 0.2 N, 0.1 N, and 0.05 N 
potassium permanganate solutions, respectively, experiments 
were conducted following a procedure similar to that described 
under C, and using a final volume of 60 cubic centimeters for 
the mixture. 
DISCUSSION OF RESULTS 
Table 1 is self-explanatory. The results can be visualized and 
discussed clearly with the aid of the curves in figs. 1, 2, and 3. 
