128 
Journal of Agricultural Research 
Vol. II, No. 3 
ration of each of the constituents of the oil. In the fractionation of the 
various hop oils, a flask of this sort having a capacity of 200 cubic centi¬ 
meters was employed. The bulb of the thermometer was placed directly 
opposite the outlet tube in all the experiments. The rapidity of dis¬ 
tillation was also regulated so that about the same amount of oil dis¬ 
tilled during a given period of time. Fractions were collected between 
different temperatures, the same range of temperature being main¬ 
tained in the distillation of each oil. Even with all these precautions it 
was impossible to make the separation of the compounds entirely complete. 
Vacuum distillation would possibly have effected the separation with 
less decomposition, but the difficulty of keeping conditions alike in each 
case would hardly compensate for the partial decomposition which is 
unavoidable by direct distillation. With the conditions of distillation 
practically alike in each fractionation, approximately the same amount 
of decomposition should result in the high-boiling fractions in each oil. 
For purposes of comparison, fractionation by direct distillation was. 
employed with each sample of oil from the various kinds of hops, seven 
fractions being collected from the oil of the 1906 crop, as follows: Frac¬ 
tion 1, 165° to 185° C.; fraction 2, 185° to 205° C.; fraction 3, 205° to 
225 0 C.; fraction 4, 225 0 to 245 0 C.; fraction 5, 245 0 to 260° C.; fraction 
6, 260° to 275 0 C.; fraction 7, 275 0 to 290° C.; and finally the residue 
290° C. +. Seven fractions were also collected from the oils of the 1907, 
1908, and 1909 crops between somewhat different temperatures, as will be 
seen in the tables. The percentage of oil distilled was calculated for each 
fraction of the various oils of the crops of 1906, 1907, 1908, and 1909. 
In order to facilitate comparisons and to bring out more forcibly the 
differences in the approximate composition of the oils, as manifested 
by the fractionation, tabulations were made of the oils distilled each 
season. The figures in Table IV express the percentage of oil dis¬ 
tilled at the temperatures indicated. Curves were also made of each 
fractionation in order that the comparison could be seen at a glance (see 
figs. 2, 3, 4, and 5). 
Table IV.— Fractionation of hop oils, showing the percentage distilled at different tem¬ 
peratures for the years IQ06 to IQOQ, inclusive . 
1906 CROP. 
Source of hops. 
Fraction 
I. 165° to 
185* C. 
Fraction 
2, 185° to 
205*0. 
Fraction 
3, 205° to 
225* C. 
Fraction 
4, 225 0 to 
245 *C. 
Fraction 
5, 24s 0 to 
260* C. 
Fraction 
6, 260° to 
*75 # C. 
Fraction 
7 » 275 ’C.+ 
Residue, 
290* C.+ 
Oregon. 
26. 9 
13 - 1 
ii- 55 
14-7 
9.2 
10.3 
14 - 25 
Do. a . 
33-5 
II. 4 
6.4 
5-7 
7-9 
6.4 
12. 4 
16. 0 
New York... 
I m ported 
24-S 
J 7 - 5 
2 -5 
3-5 
IS- 2 
19. 2 
17. 6 
(Saaz)... 
9.0 
9. 1 
2-5 
8.4 
25.6 
00 
<N 
17.6 
Do.«. 
10. 0 
9.2 
8.5 
10. 0 
30.0 
18. 6 
5-7 
8.0 
a In cold storage one year before distillation of the oil. 
