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taste or odor. Such an oil very slowly increases in acidity, and, even 
after standing for one year under ordinary conditions, may still be edible 
without further purification.t Commercial oils, on the other hand, which 
contain from 5 to 10 per cent of free acid when freshly prepared, deterio- 
rate much more rapidly, even though they have been filtered and are free 
from impurities. For example, No. 32, which, on first examination, had 
6.8 per cent of free acid, increased in two months to 7.5 per cent. This 
oil is very clear, bright, and dry, being entirely free from sediment or 
turbidity of any kind. The samples prepared by us from fresh copra 
ranged from 0.06 to 0.16 per cent, the increase in two months being so 
small as to be almost negligible. Samples Nos. 1, 2, and 38, which 
contained a little over 1 per cent of free acid when fresh, increased from 
0.1 to 0.3 per cent in the same time. 
In fact, the increase in free acid to be expected in an oil when it is 
standing under ordinary conditions may almost be considered as being 
roughly proportional to its initial acidity. There are also indications 
that an oil from which albuminoids, ete., have been removed by filtration 
will retain its original condition better than one containing the above 
impurities. No. 6, for instance, which has been filtered once but which 
contained a considerable sediment, increased in four months from 0.10 
per cent to 0.19 per cent, while Nos. 7, 8, and 9, oils prepared in a 
similar manner but filtered more thoroughly, only showed an increase in 
the same time of from 0.16 per cent to 0.19 per cent of free acid.° This 
fact. was a little more noticeable among oils prepared from sun-dried 
copra. Samples Nos. 11, 12, and 13 were taken from the same lot of oil, 
the only difference being that No. 11 was left unfiltered, while the 
impurities were removed as completely as possible from Nos. 12 and 13. 
It will be noticed that No. 11, in six months, shows a total increase of 0.15 
per cent free acid, having a little more than double its original acid value. 
Nos. 12 and 13 have in the same time increased only 0.01 and 0.02 per 
cent, respectively. . 
The oils prepared from commercial copra likewise show this distinction 
to a greater or less extent. No. 25, an unfiltered oil, increased from 2.6 
to 3.4 per cent in two months, while No. 26, which is the same oil filtered, 
shows no change at all. However, contrary to expectations, the difference 
‘The sudden increase of acidity in samples “A” and “B” between the fourth 
and the sixth months is due to the abnormal conditions under which they were 
kept at this time. The two samples when originally prepared were kept in 
500-cubie centimeter bottles which were nearly full, but during the fourth and 
fifth months they were opened so frequently for the purpose of taking samples 
for aldehyde and peroxide tests that only about 25 cubic centimeters remained 
in each bottle. The increase in acidity is probably due to a continuation of the 
surface oxidation which is discussed in a later part of this paper. A portion 
of sample “B” which had previously been removed to a smaller bottle showed 
practically no change at the end of six months. 
°>On further standing, however, the difference in this case is not so marked. 
