63 



may be of interest to give briefly their histories and their physical 

 constants : 



Sp.Gr. Sp.Gr. [a] 20 



i5/i5 2o/2o D 



No. i 0-8802 0-8776 + 0-41 



No. 2 0-8662 0-8636 +0-58 



No. 3 0-8771 0-8739 + 0-50 



No. 4 0-8743 0-8716 



No. 5 0-8676 0-8645 + 0-30 



No. 6 0-8639 0-8610 0-20 



No. 7 0-8403 ...... 0-8357 0-08 



No. i sample I prepared myself by the steam distillation of about 

 80 kilograms of mixed hops, some grown in Burgundy, some in Alsace, 

 and the remainder in Kent and Sussex. 



No. 4 was also prepared by me and was obtained from mixed hops 

 of English and foreign growth. 



The remaining five samples were distilled for me by Messrs* 

 SCHIMMEL & Co., of Miltitz, near Leipzig four from fine quality 

 Bavarian hops of different years, and one from Californian hops grown 

 in 1899, which I had purchased in this country, and sent to the above- 

 mentioned firm for distillation. It will be seen, therefore, that the 

 oils which have passed through my hands represented the produce of 

 different countries and of different years, and that their genuineness 

 was in all cases entirely above suspicion. 



These samples were then submitted to prolonged fractional dis- 

 tillation under greatly reduced pressure for the purpose of separating 

 their constituents as completely as the differences in their boiling 

 points would allow. Without going into details in regard to the 

 methods employed (full particulars of which may be found in the 

 Transactions and Proceedings of the Chemical Society), I may say 

 that practically the same results were obtained in the case of all the 

 samples of oil dealt with, and one account of the constituents will 

 therefore suffice. 



The Fraction of Lowest Boiling Point. This was found to consist 

 of a hydrocarbon having the formula C 10 H 16 . Although this is the 



