154 
Journal of Agricultural Research 
Vol. II, N9* a 
The reason that it was impossible to quantitatively acetylize the oil 
was either because there was no free myrcenol present in the oil or be¬ 
cause this alcohol would not acetylize without partial decomposition. 
The latter is probably the case, since in the experiments it was observed 
that the fractions containing the alcohol and esters were very unstable 
and readily polymerized to a viscous liquid. Furthermore, these frac¬ 
tions invariably gave negative results when acetylization was attempted. 
IDENTIFICATION OF HUMUEENE 
Combustion of fractions 9 to 16 gave from 84 to 87.6 per cent of carbon 
and 11.2 to 11.8 per cent of hydrogen. The theoretical requirement of 
a sesquiterpene is 88.1 per cent of carbon and 11.8 per cent of 
hydrogen. It is probable, therefore, that the fractions consisted of a 
sesquiterpene with inseparable quantity of alcohols, probably sesqui¬ 
terpene alcohols which would have a tendency to lower the percentage 
of carbon. The hydrogen content would remain practically the same 
for the four classes of compounds—the terpenes, alcohols, sesquiter¬ 
penes, and sesquiterpene alcohols. Since the sesquiterpene humulene 
has been mentioned as a constituent of hop oil, a comparison was made 
between the physical properties of the high-boiling fractions of the 
saponified oil and the humulene obtained from different sources, the 
results being given in Table XII. 
Table XII.— Comparison of the physical properties of high-boiling fractions of hop oil 
with those of humulene . 
Properties. 
Fractions of saponified hop oil. 
Humulene. 
Boiling points of fractions 
and humulene. 
255“ to 
265 C. 
265° to 
275° C. 
275 0 to 
285° C. 
285° to 
295 ° C. 
295° to 
305 ° C. 
From 
hop oil.® 
261° to 
265° C. 
From 
oil of 
poplar 
buds. b 
263° to 
269° C. 
Specific gravity at 
22° C... .. 
Rotation d . 
Refraction at 22 0 C.. 
O. 8740 
— 2. I 
1.4871 
O. 8850 
+ IO.3 
I. 4947 
O. 8870 
+ 6-9 
I. 4948 
O. 8930 
+ 7-6 
4973 
O. 8940 
4-8. 2 / 
I. 5000 
c O. 8987 
+ I 0 2' 
I. 4978 
c 0. 8926 
*+io° 4 8' 
0 Chapman (1893). 
Fichter and Katz (1899). 
c At is® C. 
d Rotation of hop oil fractions determined in 50 mm. tubes. 
e 200-mm. tube. 
Close relationship exists between the physical properties of the frac¬ 
tions of hop oil and those of humulene obtained from both oil of hops 
and oil of poplar buds. It is possible that traces of sesquiterpene alco¬ 
hols occur in the fractions of the highest boiling points, since the boiling 
