526 Pflanzenchemie. — Angewandte Botanik. 



is most significant, since the quality o( tlie odor is probably most 

 greatly influenced by them. 



Important differences in the oils are apparent not only durino- 

 any particular season but for several seasons. These constani 

 diöerences are shown most forcibly in the curves of the physical 

 and Chemical properties of the oils. The curves of fractional distil- 

 lation, which may be said to represent a partial quantitative 

 Separation ot the chief constituents, bring out strongly the rela- 

 tionship which exists between the hops from any source durino- 

 one season and several seasons. The optical rotation curves also 

 Show this relationship. In general the physical properties of the 

 oils — the fractionation, specific gravity, and optical rotation — 

 Show strong similarities which may exist among related oils or 

 strong dissimilarities among unrelated oils. The esters bemg re^arded 

 as the constituents of most importance in affectino; the odor'^of the 

 hops from which the oils were distilled are com^Dared by means 

 of the ester numbers. The curves of the ester content of the various 

 oils and fractions of the oil show at a glance the remarkable 

 differences in the oils from the several geographical sources The 

 courses followed by the imported oils ^re most conspicuous because 

 of their constantly lower ester content. More remarkable is the fact 

 that the ester content of the imported oils remains lower from year 

 to year, practically every sample under Observation possessin^ an 

 exceedmgly low ester value. The oils from the California hops 

 are both physically and chemically very similar from season to 

 season. Those trom the various sections show no important differences 

 in their properties during any particular season, the curves showino- 

 considerable parallelism. The Oregon and Washington oiis are very 

 similar in their properties, but differ somewhat from the California 

 oils. The New York oils seem to be the most closelv related to 

 the foreign oils in all properties, with the exception of the ester 

 content, which is considerably higher. From the Standpoint of the 

 increasing ester content the various oils arrange themselves in the 

 following Order. Imported. California, Washington. New York, 

 and Oregon, the three latter being very closely related. 



No general conclusions can be drawn regarding the possible 

 superiority of any particular oil as compared with any of the other 

 oils. Whether high or low ester content denotes richne'ss or poorness 

 in the quality of the hops, or vice versa, can not be detinitely 

 stated. Sufifice it to say that from the results obtained it is clear 

 that the geographical source of hops mav be indicated by the 

 ester numbers of the oil distilled from the hop, since the experim.ents 

 show that the ester numbers of the oils from hops of anv particular 

 source or season are very similar. Jongmans. 



Kelley, W. P., The lime-magnesia ratio: I — IL The effects 

 of calcium and magnesium carbonates on ammonifi- 

 cation. (Cbl. Bakt. 2. XLII. p. 519—526, 577—582. 1914.) 



Versuche über die Bedeutung des Kalkfaktors für die N-Um- 

 setzungen in Böden von Hawai. 



I. Ammonisationsversuche. Benützt wurde Blulmehl und 

 gemahlener Sojakuchen (20^ des an der Luft getrockneten Bodens). 

 Die zur Verfügung stehenden Böden waren Lateritböden, entstan- 

 den aus basaltischer Lava. Wo Mg C0.> eine Reizwirkung hervor- 

 brachte, blieb der spätere Zusatz von Ca CO3 wirkungslos; ^dort, wo 



