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464 Philippine Journal of Science mo 
may continue indefinitely. The rate of this process depends upon the 
amount of surface exposed to the air, compared with the total volume 
of oil, and may in extreme cases cause an exceedingly rapid deterioration. 
It may be entirely prevented by storing the 'oil in completely filled recep- 
tacles, impervious to air. 
Along with the two above-mentioned processes, a slight hydrolysis due 
to heat, moisture and free acids already present is constantly taking place. 
It may be reduced considerably by filtration, which removes most of the 
water, together with the organic impurities. 
There is reason to believe that some hydrolysis is brought about by 
enzymes produced by the molds, as unheated oils which have been filtered and 
rendered antiseptic increase in acidity somewhat more rapidly than do 
heated ones under the same condtions. However, this distinction is not 
so apparent after the first year. 
Light has apparently no effect on the oxidation by air of coconut oil. 
The third and latest paper 5 from the Bureau of Science 
laboratory on the storage of coconut oil deals chiefly with methods 
of measuring rancidity. On the subject of the cause of ran- 
cidity the authors, besides quoting from Walker and others, 
make the following observation : 6 
We believe that the nonfatty material in coconut oil has a profound 
influence on its character, and experiments are now in progress to test 
this out. 
Regarding the nature of rancidity they state : 7 8 
If the formation of rancidity is caused or accompanied by an oxidation, 
one of the first changes to take place would be the breaking down of the 
unsaturated acids into simpler acids * * *. 
On the same subject Lewkowitsch s comes to the following 
conclusion : 
I therefore define as rancid those oils and fats, the free fatty acids 
of which have been acted on by the oxygen of the air, in the presence 
of light. Similar explanations have been given before and the only new 
element I can claim here would consist in ascribing more emphatically 
than has been done hitherto the initial phase of rancidity, namely, the 
hydrolysis, to the accelerating action of enzymes. 
The view that light is a necessary condition for rancidity, 
which Lewkowitsch insists upon, and which he apparently bor- 
5 Brill, H. C., and Parker, H. O., The rancidity of Philippine coconut oil, 
Philip. Journ. Sci. § A 12 (1917) 95-110. 
0 Op. cit. 96. 
7 Op. cit. 108. 
8 Lewkowitsch, J., Chemical Technology and Analysis of Oils, Fats, and 
Waxes. London, Macmillan & Co. 1 (191-3) 52. 
A more recent text, Edible Oils and Fats, by C. A. Mitchell, London, 
Longmans, Green & Co. (1918), presents no new data on this subject. 
