1094 Wisconsin Academy of Sciences, Arts, and Letters. 
following constituents of pharmaceutical interests has been re¬ 
ported: Volatile oil, resin, wax, alkaloids and inorganic sub¬ 
stances. Chapman 3 gives the composition of the ethereal ex¬ 
tract as follows: 
a-resin .. 18.06 per cent. 
i 8 -resin .67.74 “ “ 
Wax . 0.28 11 “ 
Other constituents (fat, oil, 7 -resin, etc.).13.64 “ “ 
Ash . 0.27 “ “ 
Occurrence and Description of Individual Constituents. 
Volatile Oil . 4 The volatile oil obtained by distillation with 
steam is a pale vellow, or colorless, mobile liquid possessing a 
fragrant and characteristic odor, and a slightly burning taste. 
It is almost insoluble in water, to which, however, it imparts its 
odor, and only slightly soluble in dilute alcohol. It is soluble 
in ether, petroleum ether, chloroform and the other volatile oil 
solvents. The specific gravity at 20°C is 0.8357 to 0.8776, and 
the specific rotatory power, [a] D 20 , is 0.20 to 0.58. 5 
According to Chapman, 6 the oil is composed of the terpene, 
myrcene, (C 10 H 16 ), 40 to 50 per cent; inactive linalool, a fraction 
of 1 per cent; linalyl isononoate, a fraction of 1 per cent; the 
sesquiterpene, humulene 7 (C 15 H 24 ), about 40 per cent; and 
probably some ether of geraniol with a small amount of a diter- 
pene. Rabak, 8 who has more recently completed an investiga¬ 
tion of the constituents of the oil, states that, in addition to 
myrcene and humulene, the oil contains the heptoic, octoic and 
nonoic acid esters of myrcenol with traces of free fatty acids and 
probably some free alcohols. 
As much as 2 per cent of volatile oil has been obtained from 
lupulin by steam distillation. 9 
Resin. The chemical constitution of the so-called “hop 
resins” is still an unsolved problem, the literature being replete 
3 Ibid, p. 81. The hop and its constituents. The Brewing Review, Lon¬ 
don (1905). 
4 The following references are to the earlier literature on the volatile oil: 
Payen, Felletan and Chevalier and Personne, 1. c. ; Wagner, Journ. f. prakt. 
Chem. (1853), 58, p. 351; Ossipon, Ibid. (1886), 142, p. 238. 
5 Chapman, l. c. 
6 Ibid. 
7 E. Deussen, who has determined the constitution of humulene, finds it to 
be 1-caryophyllene. Journ. f. prakt. Chem. (1911), 83, p. 483. 
8 Journ. Agric. Research (1914), 2, p. 115. 
9 Payen, Pelletan and Chevalier, l. c. See also Semmler, l. c. 
