216 
The Philippine Journal of Science - 
1920 
vacuum in an apparatus similar to that described by Browne, (l) 
Its purity was determined, as follows : 
1.6450 grams of the pure lactose were weighed and dis- 
solved to 100 cubic centimeters. Twenty-five cubic centimeters 
of this solution were analyzed by the Soxhlet method for the 
lactose content, and a portion was polarized after having been 
allowed to stand for twenty-four hours. 
Table 1 . — Determination of the purity of lactose. 
Lactose. 
Method of analysis. Per cent. 
Optical method 100.00 
Soxhlet method 99.98 
Average 99.99 
Table 2. — Determination of lactose by the alkaline potassium perman- 
ganate method. 
Lactose. 
0.1 N 
KMnOi. 
Lactose. 
0.1 N 
KMn04. 
Lactose. 
0.1 N 
KMnOi. 
Lactose 
0.1 N 
KMn04. 
mgs. 
1 
cc. 
2. 51 
3.21 
4.04 
4.39 
5. 47 
6.52 
7. 69 
9.13 
9. 98 
11.37 
mgs. 
11 
cc. 
12.30 
13.80 
16.41 
16. 72 
17.85 
19.04 
20.16 
20. 96 
21. 50 
22.89 
mgs. 
21 
cc. 
23.63 
24. 87 
25.92 
26.67 
28. 10 
28.39 
29.50 
30.60 
31. 49 
32.55 
mgs. 
31 
cc. 
34.66 
35.69 
36. 16 
37.26 
38.26 
38. 64 
39.28 
40.16 
40.66 
41.47 
2 
12 
22 
32 
3 
13 
23 
33 
4 
14 
24 
34 
6 _ 
15 . 
25 ___ 
35 
6 
16 
26- 
36 
7 
17 
27 
37 
8 
18 
28 
38 
9 
19 
29 
39 
10 
20 
30 
40 
APPLICATION OF THE NEW METHOD TO THE ANALYSIS OF 
LACTOSE IN MILK 
The milk under examination was analyzed for its lactose 
content by means of the optical method, the gravimetric method, 
and the new method, thus making possible a comparison of the 
results of the three methods. That the milk samples should 
all be of equal concentration, the evaporated canned milk was 
diluted by mixing equal parts of the milk and water before 
proceeding with the analysis. To determine which of the meth- 
ods is the most accurate, similar analyses were made on 
“synthetic” milk prepared as indicated below. The prepara- 
tion of the solution used for the gravimetric method and the 
new method is as follows: (8) 
Dilute 25 cubic centimeters of milk of known weight with 
400 cubic centimeters of distilled water in a 500 cubic centi- 
meter graduated flask. Add 10 cubic centimeters of the cop- 
