Journal of Agricultural Research 
Vol. II, No. 2 
ISO 
Preparation of the nitrosochlorid and other crystalline terpene deriv¬ 
atives with bromin and halogen acids failed in all cases. This, together 
with the unusually low specific gravity, pointed to another class of 
related hydrocarbons belonging to the aliphatic series. Aliphatic hydro¬ 
carbons with the same empirical formula, C 10 H 16 , are termed the “olefinic 
terpenes.” The presence of olefinic terpenes in volatile oils was first 
observed by Power and Kleber (1895), who isolated a hydrocarbon from 
oil of bay, which was termed “myrcen.” Chapman (1903) mentioned 
this hydrocarbon as a constituent of oil of hops. 
In order to compare the hydrocarbon myrcene of bay oil with the 
hydrocarbon from hop oil, the properties of the respective compounds 
were tabulated as given in Table IX. 
Table IX.— Comparison of the properties of hydrocarbon from oil of hops with the olefinic 
hydrocarbon myrcene. 
Properties. 
Hydrocarbon from oil of hops. 
Myrcene. 
Boiling point. 
Specific gravity. 
Index of refraction. 
165° to 170° C. 
0.8093 22 ° c. 
1 . 470 '?. 
171 0 C. 
0.8023 at 15 0 C. 
1.4673. 
Inactive. 
Colorless, becoming yel¬ 
low and resinifying. 
Rotation (50-mm. tube). . 
Color and behavior on 
standing. 
^ . 
-23-9' . 
Colorless, becoming slightly 
yellow and changing to a 
viscous mass. 
A very close relationship is observed between the boiling point and 
the specific gravity of the two compounds. The slight discrepancies 
which exist, especially in the rotation, are probably due to some impurity 
of the fraction. The most striking characteristic of the hydrocarbon is 
its instability. The tendency to polymerize was most marked, the 
respective fractions in the large number of oils fractionated becoming 
viscous and almost solid in a comparatively short time. This peculiar 
property was observed by Power and Kleber (1895) in their experiments 
with the hydrocarbon from bay oil. It was also exhibited in oil of hops, 
which became viscous, even when the usual precautions were taken 
against light and air. 
Since the properties of the hydrocarbon from the oil of hops show such 
a close resemblance to those of myrcene, it can be stated with compara¬ 
tive certainty that the terpene hydrocarbon, which represents the large 
proportion of the lower-boiling constituents, is identical with the olefinic 
terpene myrcene. By reference to the curves of fractionation of the 
various oils (figs. 2, 3, 4, and 5) it will be observed that in practically all 
cases myrcene constitutes the largest portion of the oils. 
