10 BULLETIN 350, U. S. DEPARTMENT OF AGRICULTURE. 



cold-pressed oil from the kernels of the domestic cherries, although 

 examined immediately after extraction, contained considerable free 

 acidity. This was doubtless due to the fact that the kernels were 

 taken from pits which had been kept in the laboratory for about a 

 year. As a general rule, oil from old seeds is high in acid content. 



The acidity of the oil from the kernels of the imported cherries 

 was considerably lower, due possibly to freshness of the kernels. 



With two exceptions, the related oils included in Table II are low 

 in acidity, due to the fresh condition of the oil when examined. Of 

 the two exceptions, one of the oils was a year old before the deter- 

 mination of the free acidity was made, and the other was a market 

 sample, the age of which was not known. 



The saponification and iodin values of the cherry oils, which values 

 are a criterion of the composition, agree quite closely with each other 

 and compare favorably with the other oils, only an occasional vari- 

 ation occurring. 



From the standpoint of general chemical composition, therefore, 

 the refined oil from the cherry pits and the expressed oil from the 

 kernels are very similar to almond oils and to the oils from peach, 

 apricot, and prune kernels. 



CHEMICAL EXAMINATION OF THE FIXED OIL. 



The general nature of the fixed oil having been determined, a more 

 detailed analysis was made in order to obtain information bearing 

 on the composition of the oil and to note the effect of refining on the 

 more important properties. 



Besides the acid, saponification, and iodin values, the following 

 additional constants were determined, according to the method rec- 

 ommended by the Association of Official Agricultural Chemists : x 



The volatile acids, consisting of the glycerids of such acids as butyric, valeri- 

 anic, caproic, etc., were determined and expressed as the Reichert-Meissl num- 

 ber, which is a measure of the volatile acids expressed in cubic centimeters of 

 decinormal alkali required to neutralize the volatile acids contained in 5 grams 

 of oil. 2 



The soluble and insoluble acids were determined, the former representing the 

 percentage of soluble acids calculated as butyric acid and the latter the per- 

 centage of insoluble fatty acids (Hehner value). 3 



The acetyl value, which is a measure of the glycerids of hydroxy fatty acids, 

 was determined largely for comparative purposes. 4 



Likewise the unsaponifiable matter, which is a variable characteristic, was de- 

 termined. 5 The percentage of unsaponifiable matter in a fixed oil is regulated 

 largely by the presence of variable quantities of an alcoholic substance, phytos- 

 terol, and other substances, such as coloring matter and waxlike compounds. 



1 Wiley, II. W., ed. Official and provisional methods of analysis, Association of Official 

 Agricultural Chemists. As compiled by the committee on revision of methods. U. S. 

 Dept. Agr., Bur. Chem. Bui. 107 (rev.), 272 p., 13 fig., 1908. 



2 Wiley, H. W., op. cit., p. 139. 



3 Wiley, H. W., op. cit., p. 138, 139. 

 1 Wiley, II. W., op. cit., p. 142. 



5 Wiley, H. W., op. cit., p. 144. 



