AND CHEMISTRY 



have a powerful agreeable odour and bitterlasto j they^appear 

 to consist of an acid, ethereal oil, an aromatic resin, wax, ex- 

 tractive, and a bitter principle called lupuline. By pressure, 

 hop heads yield a green, light, acrid oil, called oil of hops. 



The aggregate fruits of this plant are botanically known 

 under the name of strobiles, in common parlance as hops. 

 These fruitfr consist of scales (bracts) and achaenia, the latter 

 of which are surroundedby yellowish aromatic glands. They 

 are usually termed lupulinic gknds, and are the most active 

 part of hops. They contain a volatile oil, and a bitter prin- 

 ciple called lupuline, or lupulite, to the presence of which 

 hops owe their properties. The bracts also contain some 

 lupuline, and are therefore not devoid altogether of active 

 principles. . 



The female flowers, growing on a separate plant, are in 

 the form of a catkin, having each pair of flowers supported 

 by a bract, which is ovate, acute, tubular at base. Sepal 

 solitary, obtuse, smaller than the bract, and enfolding the 

 ovary. Ovary roundish, compressed; stigmas two, long, 

 subulate, downy. The bracts enlarge into a persistent catkin, 

 each bract enclosing a nut enveloped in its permanent bractlet, 

 and several grains of yellow lupuline. 



To the folioles or scales of the flower of the hop adhere 

 a certain quantity of yellow powder or dust. Ives attributes 

 to this powder alone the active principle of hops. But Payen 

 and Chevallier are of opinion that the entire flower contains 

 the same active principles which are found in the yellow 

 dust. If this were not so, the hops, which in transport lose 

 a great quantity of this yellow powder, would have but a 

 feeble effect in the manufacture of beer. 



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