83 



The great differences between the individual analyses may, no 

 doubt, be ascribed to actual variations in the material examined. 

 Lupulin, obtained by carefully brushing out the hop cones, contains 

 far less ash than the rough lupulin collected as by-product during 

 the preparation and handling of hops. 



As regards the sub-division of the resins and decomposition pro- 

 ducts of the crystalline bitter principles into "hard" and " soft" resin, 

 numerous observations have been communicated by BRIANT and 

 MEACHAM, 1 who examined hops of diverse origins. REMY S investi- 

 gated the same subject, and for separating the hard and soft resins 

 proceeded as under : 



" Twenty-five grms. of hops were completely extracted with ether, 

 and the ether residue treated with 90 per cent, alcohol to separate 

 the wax. The alcohol soluble portion after evaporation to dryness, 

 was again dissolved in ether, the solution repeatedly shaken out with 

 dilute sulphuric acid (0.5 per cent.) in order to remove certain basic 

 substances, evaporated, and the ether residue finally divided into 

 hard and soft resins by treatment with petroleum ether (b.p, up to 

 60 C.)." 



BRIANT and MEACHAM'S* process is a good deal simpler than the 

 preceding. 



" Five grms. of hops are placed in a Soxhlet extracter, and 

 completely exhausted with petroleum ether. The ether residue is 

 freed from wax in the way already described, the alcohol evapo- 

 rated, heated for six hours to 90 C, and weighed as " soft " resin. 

 The hard resin is then determined by exhausting the hops a second 

 time with ordinary ether." 



The analytical error in these methods is, as a rule, as much as 

 i per cent. Nevertheless, the results serve to show that the better 

 kind of hops, as a general rule, exhibit a higher proportion of soft resin, 

 and a correspondingly higher percentage of total resins. According to 

 RE MY, the hops of the 1896 harvest were characterised by notably 



31 Journal of the Federated Institutes of Brewing, 1897, 2 33- 



32 Wochenschrift fur Brauerei, 1898. 530. 



G 2 



