130 WALKER. 



bottles. The sliglit, but regular, increase in acidity of G-a is probaljly 

 due to the hydrolj'tie action of a trace of water not removed by filtra- 

 tion, comliined with the free fatty acids already present. Some slight 

 oxidation also may have taken place, as the bottle was not absolutely free 

 from air. 



Numbers 7 and 8, sterilized and kept under antiseptic conditions in 

 Erlenmeyer flasks, with a large oil surface exposed and free access of 

 air through the cotton plugs, practically doubled their percentage of free 

 acid in two years. The filtered samples of number 8 show considerably 

 more increase than the unfiltered oils numbered 7, a fact which tends to 

 confinn my belief tliat as a general rule the freer an oil is from moisture 

 and impurities the more cpiickly is it subject to oxidation when exposed 

 to the air. The samples kept in the light have not increased in acidity 

 any more than those kept in the dark, in fact, 8-b at the end of one 

 year contains 0.6 per cent more free acid than 8-a. 

 • In view of this latter work, indicating the considerable variation in 

 acid content of the same oil which may be brought about by different sized 

 containers with consequently varying amounts of oil exposed to the air, 

 it was decided to bring to a close the series of oils described in a previous 

 paper '^ and which were set aside to determine the amount of free acid 

 which might be produced on standing, since after the first year, most of 

 the further increase in acidity would be dependent to a very large extent 

 uj)on the amount of oil surface exposed to air in the bottles. No 

 attempt was made at the time when these samples were prepared to 

 exclude oxidation by keeping them in filled bottles, and with few ex- 

 ceptions no record was kejjt of the quantity of oil in a bottle, so that 

 wide variations in acidity after the first year were to be expected. For 

 convenience, a description of the oils as first made is reprinted here, 

 together with a table giving their increase in free fatty acid from the 

 time of their j)reparation up to the present date. 



DESCRIPTION OF OILS USED AND DESCKIEED IN TABLE IV. 



(A) Expressed oil from vacuum-dried copra. Has been heated for two hours 

 at 100° and filtered twice through paper. A light-colored, clear oil with the 

 characteristic coconut taste and odor. 



(B) An oil similar in every respect to "A" except that it was prepared from 

 copra dried at 80° to 90°, without vacuum. 



(1) Fresh coconut meat grated and dried at 80° to 90° on August 16, 1904; 

 was allowed to stand in a covered specimen jar until March 11, 1905. At that 

 time it was still of a pleasant odor and taste, although both odor and taste 

 were not quite as good as when the specimen was freshly prepared. No mold 



^Ihid., 118. 



