106 The Philippine Journal of Science 1917 



The oxidizability value for the coconut oils exceeded 15 (the 

 maximum value given by sweet olive oils according to Issoglio) 

 in samples 4, 11, 14, 32, 35, and 44. All of these samples were 

 rancid, but samples 15, 30, 31, and 37, which were rancid, gave 

 values lower than 15. It is possible that a limiting value of 

 15 for coconut oil may be too high, but the limit cannot be 

 brought low enough to include all the rancid oils examined by 

 us and still exclude the sweet oils. The test appears to be a 

 good confirmatory one, since no sweet oils gave high results. 



The acetyl values of several oils were determined in an endeav- 

 or to ascertain if any relationship exists between them and the 

 rancidity. The lowest value, 7.0, was given by No. 31, a rancid 

 oil, while the highest value, 21.7, was shown by No. 11, also a 

 rancid oil. The value of the acetyl number is dependent on 

 the presence of the hydroxyl group. Lewkowitsch makes no 

 mention of the presence of hydroxy acids in coconut oil. The 

 only unsaturated acid generally accepted as present in coconut 

 oil is oleic, which exists in comparatively small quantities. It 

 is possible that when rancidity takes place one of the reactions 

 occurring is the formation of oxy or dioxy stearic acid from 

 oleic acid, but this would not account for an acetyl number of 

 a magnitude of 21.7 for coconut oil. The residue of the increase 

 must arise from the freeing of the hydroxyl groups of the 

 glyceryl radical. A high acetyl number should be, therefore, 

 associated with a high acid value in the case of coconut oil. A 

 study of the contents of Table IV proves that this relationship 

 does not exist in all instances. It is possible that where the 

 hydrolysis of the oil takes place in the copra itself much or all 

 of the free glycerol remains in the press cake or is further de- 

 composed, resulting in a low acetyl number along with a high 

 acid number. 



The iodine number of an oil with a high acetyl number should 

 be correspondingly low if the increased value of the acetyl nunv 

 ber arises from the oxidation of the unsaturated acids. The data 

 in Table IV do not prove the validity of this assumption, since 

 no definite relationship appears to exist between the values of 

 these two chemical constants. 



Further tests were made on four oils. These data are re- 

 corded in Table V. 



