I5« 
Journal of Agricultural Research 
Vol. II, No. a 
distilled commercial lupulin and obtained an oil. By experimenting with the 
oxidation of the oil he identified acetic and isovalerianic acids. Octoic, or caprylic, 
acid was identified in the aqueous distillate from the oil by means of the silver salt. 
In the aqueous distillate from the lupttlin he also identified butyric and valerianic 
acids (1886). 
It was not until 1893 that Chapman (1893) undertook the study of hop oil and 
obtained some insight regarding its actual composition. He found in his first experi¬ 
ments that an oil which had been standing for n months boiled considerably higher 
than freshly distilled oil and contained a sesquiterpene as its chief constituent. 
Continuing his work on the composition of the oil, he concluded after careful frac¬ 
tionation that the sesquiterpene which he had found as the chief constituent was 
humulene (1894; 1895a). The highest boiling fraction (263° to 266° C.), which con¬ 
sisted chiefly of humulene, represented in most cases about 40 per cent of the oil. 
The lowest boiling fraction (about 170° C.) also represented a large proportion of 
the oil and was considered to be a terpene hydrocarbon. The middle fractions had 
a pleasant odor and consisted of oxygenated compounds. The humulene from the 
highest boiling fraction of the oil was subsequently investigated by Chapman (1895b) 
and several crystalline derivatives of this compound were prepared. In a later 
report (1898) he stated that the oil contained no phenols, aldehydes, or ketones; 
that it was sparingly soluble in water, but sufficiently so to impart a characteristic 
odor to the water; also that the oil changed in the air to a viscous mass. In 1903 
the investigation was continued (Chapman, 1903), and the lowest boiling fraction 
(166 0 to 168° C.) was found to have properties similar to myrcene from oil of bay. 
One of the higher boiling fractions had a strong odor, which fraction, it was stated, 
probably contained linalool or esters of linalool. The acids obtained by saponifi¬ 
cation of the oil were identified by means of their silver salts as valerianic and iso- 
nonoic acids. In all freshly distilled samples of the oil, myrcene and humulene 
were said to be present to the extent of 80 to 90 per cent. 
Semmler and Mayer (1911) by the preparation of a number of characteristic deriv¬ 
atives established the identity of the terpene from hop oil with the terpene myrcene. 
According to Deussen (1911) the humulene of hop oil is very similar in general 
properties and crystalline derivatives to the sesquiterpene caryophyllene. 
LITERATURE CITED 
Barbier, Ph. 
1901. Sur le myrcenol et sa constitution. In Compt. Rend. Acad. Sci. [Paris], 
t. 132, no. 17, p. 1048-1050. 
Bonnier, Gaston. 
1894. Recherches experimentales sur Tadaptation des plantes au climat Alpin. 
In Ann. Sci. Nat. Bot., s. 7, t. 20, no. 4/5/6, p. 217-223. 
Briant, Lawrence, and Meacham, C. S. 
1896. Hops.—The influence of climate, ripeness, soil, drying, and general manipu¬ 
lation on the value of hops. In Jour. Fed. Inst. Brewing, v. 2, p. 423. 
Chapman, A. C. 
1893. The essential oil of hops. Preliminary notice. Proc. Chem. Soc. [London], 
v. 9, no. 127, p. 177. 
1894. Essential oil of hops. In Proc. Chem. Soc. [London], v. 10, p. 227-229. 
1895a. Essential oil of hops. In Jour. Chem. Soc. [London], Trans., v. 67, p. 54-63. 
1895b. Some derivatives of humulene. In Jour. Chem. Soc. [London], Trans., 
v. 67, p. 780-784. 
1898. Essential oil of hops. In Jour. Fed. Inst. Brewing, v. 4, p. 224-233. 
1903. Essential oil of hops. In Jour. Chem. Soc. [London], Trans., v. 83, p. 
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