THE UTILIZATION OF CIIKKKY BY-PRODUCTS. 9 



The refractive index appears likewise to be affected by the pres- 

 ence of free fatty acids as impurities. The crude oils are seen to 

 possess a lower refractive index than those which have been refined 

 and which therefore contain less impurities. The refractive prop- 

 erty of the refined oils corresponds very closely with that of the 

 other oils included in Table I. 



The congealing point is a property which is affected by differences 

 in composition. Oils of the same kind, whether crude or refined, 

 often differ in the congealing point, as is shown by the oils from the 

 pits of both the domestic and the imported cherries. The refined 

 cherry oil compares favorably in this respect with the other oils 

 tested. 



No marked difference is observed in the color, odor, or taste of the 

 various oils except that the crude oils are slightly darker and have 

 a less agreeable odor and taste than the other oils. 



For the purpose of making a further comparison it was deemed 

 advisable to determine the so-called chemical constants (the acid, 

 saponification, and iodin values), which are shown in Table II. 



Table II. — Chemical constants of cherry oils compared with various other fruit- 

 kernel oils. 



Source of oil 



Cherry pits (red sour 

 cherries): 



Crude 



Refined 



Cherry kernels (red sour 

 cherries) cold pressed 2 

 Cherry pits (imported 

 cherries): 



Crude 



Refined 



Free fatty 

 acids. 



Acid 



value. 



21.5 

 15.1 



6.2 



22.1 



18.4 



Cal- 

 cu- 

 lated 



oleic 

 acid. 



P.ct. 



10.90 



2.58 



11.10 

 4.10 



Sa- 

 poni- 

 fica- 

 tion 



value. 



189. 2 

 186. 4 



185.2 

 189. 8 



Iodin 

 value. 



101.7 

 102.4 



110.3 

 111.4 



Source of oil. 



Cherry kernels (import- 

 ed cherries) 



Peach kernels 3 



Apricot, kernels 3 



Apricot kernels (same as 

 above, 1 year old) 



Prune kernels 3 



Sweet almonds (market 

 sample) 3 



Bitter almonds 3 



Free fatty 

 acids. 



Acid 

 value, 



3.5 



.83 

 .75 



13.3 

 1.9 



3.5 

 1.7 



Cal- 

 cu- 

 lated 



oleic 

 acid. 



P.ct. 



1.76 

 .41 

 .38 



6.68 

 .95 



1.76 

 .86 



Sa- 

 poni- 

 flca- 

 tion 

 value. 



188.5 



187 



203 



180 

 160 



193 



188 



Iodin 

 value. 



108.2 



110 



107 



118 

 105 



107.3 

 106.3 



1 Acid number determined after standing 6 months. 



2 Kernels obtained from pits about 1 year old. 



3 Rabak, Frank. Peach, apricot, and prune kernels as by-products of the fruit industrv of the United 

 States. U. S. Dept. Agr., Bur. Plant. Indus. Bui. 133, p. 16, 1908. 



Before discussing the data in Table II it should be mentioned that 

 the amount of free fatty acids in an oil is wholty dependent upon the 

 age of the oil or of the material from which it is extracted. Freshly 

 expressed or extracted oils from fresh material show but a trace of 

 free acids, often less than 1 per cent. Most fatty oils are unstable 

 as regards the liberation of free fatty acids, the quantity increasing 

 with the age of the oil. 



The crude oils from the cherry pits show a high acid content, 

 which, however, was largely reduced in the process of refining. The 

 1934S — Bull. 3.">0— 1G 2 



