220 The Philippine Journal of Science 
that the mercuric nitrate, the ash, or the nitric acid, or all three, 
affect also the specific rotation of lactose. The influence of the 
factors seems to be cumulative in the case of the evaporated 
milk and compensating in the case of the sterilized milk. 
SUMMARY AND CONCLUSIONS 
The attempt to apply the alkaline potassium permanganate 
method to the determination of lactose in milk has met with 
success. This method has advantages over’ the older methods 
in rapidity and accuracy. Lactose determinations run with 
the new method give consistently lower results than with the 
Soxhlet method. 
The results obtained by the polariscopic method are very 
unreliable and cannot be used for accurate work, especially in 
the analysis of canned milk. Where a high degree of accuracy 
in the results is required the Quisumbing or Soxhlet method 
should be given preference. 
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