202 EXPERIMENT STATION KECOED. 



The oils from the American hops were all strongly aromatic, and in most 

 cases agreeable. " The oils from the foreign hops seemed to be distinctly dif- 

 ferent from the American oils, possessing a A-ery pronounced flowery odor, 

 combined with a fatty odor, the effect being most agreeable," All of the oils 

 had a decidedly aromatic taste, and in some bitterness, fattiness, and acidity 

 were pronounced. All of the California oils were characterized by bitterness 

 and pungency with slight fattiness, while the oils from the imported hops were 

 fatty and only slightly pungent and bitter. 



The oils having the highest specific gravities were from New York State hops 

 and averaged 0.S554 at 24° C. " The refractive property of the Oregon, New 

 York, and Washington oils, as compared with the California oils, was not 

 greatly different. However, the oils from the imported hops showed a higher 

 refractive index than any of the other oils." The oils most soluble in alcohol 

 come from the Oregon hops, one volume of the oil dissolving completely in three 

 volumes of 94 per cent alcohol. The solubility varied with the seasons. 



In the chemical examination the following average constants were determined : 

 Acid number (for California hop oil 1,45, Oregon hop oil 2.7, New York 3.25, Wash- 

 ington 1.25, and Saaz 2.02), ester number (California hop oil 45.56, Oregon 

 58.8, New York 50.9, Washington 52.8, and Saaz 2.3.5), and saponification num- 

 ber (California hop oil 47, Oregon G1.5, New York .54.2. Washington 54. and 

 Saaz 21), "The high and low acid numbers were significant of nothing im- 

 portant as far as the aroma was concerned, as the free acidity did not percepti- 

 bly affect the odor of the oil. The ester numbers revealed most striking simi- 

 larities and dissimilarities, not only during one season but for several succes- 

 sive seasons. The oils from the imported hoi)s were conspicuous because of the 

 fact that the data for the sevei'al seasons showed the ester content to be only 

 about one-half as great as the ester content of the oils from the California, 

 Oregon, Washington, and New York hops." That the low ester content is re- 

 sponsible for the generally acknowledged superior aroma of imported hops could 

 not be positively stated, but it is thought probable since other oils, like lav- 

 ender and peppermint, are more, fragrant than oils with a high ester content. 



In the fractionation of the various oils, the data show that as a general thing, 

 the oils from the California, Oregon, and Washington hops during the several 

 seasons had a high content of low-boiling constituents, while the oils from 

 the imported hops were invariably poorer in the low-boiling constituents. On 

 the other hand, the oils from the imported hops seemed, generally speaking, 

 to contain much higher percentages of the high-boiling compounds. The oil 

 of the 1908 crop, however, was unique in that it appeared to be similar to the 

 other oils during that particular season. The curves of the imported oils fol- 

 lowed those of the New York oils the most closely, the general direction being 

 similar. The California oils also followed very similar directions, as did the 

 Oregon and Washington oils. 



The fractions having the lowest specific gravities in all cases were those 

 boiling below 185° C. This portion of the oil is usually supposed to contain 

 most of the terpene constituents. The optical rotation of the various fractions 

 of hop oil was very low. " The most noticeable feature was the tendency of the 

 New York oil to follow the same course as the imported oil during each sea- 

 son. The curves of rotation, as well as the curves of fractionation, show some 

 differences in the various oils, though ijerhaps in a lesser degree," The acid, 

 ester, and saponification numbers of the fractions during each year were very 

 variable. 



From the results it is obvious that the oils which, in their original condi- 

 tions, posse.ss free acids (as indicated by the high acid numbers) show much 

 more decomposition of ester with the liberation of free acids than do the oila 



