THE HOP. 



More recently Aubry analyzed nine samples of conti- 

 nental and English hops, the results showing less 

 variation than might be expected, as follows: 



The conclusion drawn from these results is that 

 the tannic acid effects of hops are accomplished mostly 

 after they have been deprived of their resin, and that 

 but a very small proportion of the nitrogenous constit- 

 uents of the hops being taken up by the water extract, 

 they are of but little importance in the wort. 



THE CHEMISTRY OF HOPS 



is treated in further detail for this work 

 by E. E. Ewell, of the Division of Chem- 

 istry, United States Department of Agriculture, as fol- 

 lows: 'That our knowledge of the chemistry of hops is 

 still deficient in many points is shown by this quota- 

 tion from Moritz and Morris's Text Book of the Sci- 

 ence of Brewing/ published in 1891: 



"Although it must be granted that in recent years 

 we have got to know something precise as to many of 

 the constituents of the hop, yet its chemistry, like all 

 botanical chemistry, is surrounded by difficulties in 

 regard to the isolation and investigation of the various 

 constituents, difficulties far exceeding those of the 

 study of other materials used in brewing." 



According to these authors, "Hops are added to the 

 beer for the following reasons: (i) To give the beer 

 the distinctive bitter flavor and aroma; (2) to precipi- 

 tate certain nitrogenous constituents of the wort; (3) 

 to clarify the wort, not only by the separation of the 

 above constituents, but by the mechanical clarifying 



