THE UTILIZATION OF CHERRY 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 tcith 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 
1 5.1 
6.2 
22.1 
18.4 
Cal- 
cu- 
lated 
as 
oleic 
acid. 
P.ct. 
10.90 
2.58 
3.13 
11.10 
4.10 
Sa- 
poni- 
rica- 
tion 
value. 
189.2 
186.4 
187. i 
185.2 
189.8 
Iodin 
value. 
101.7 
102.4 
106.9 
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 
13.3 
1.9 
■3.5 
1.7 
Cal- 
cu- 
lated 
as 
oleic 
acid. 
P.ct. 
1.76 
.41 
.38 
6.68 
.95 
Sa- 
poni- 
fica- 
tion 
-alue. 
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 wholly dependent upon the 
nge 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 
19348°— Bull. 350—16 2 
