AGRICULTURAL CHEMISTRY AGROTECHNY. 203 



with less acidity or with none. With the acid values tlie ester numbers wore 

 very regular from 3' ear to year. 



The approximate composition of hop oil is considered to be as follows: " Free 

 acids. — Chietly valerianic, with traces of formic, butyric, and heptoic acids: 

 combined acids (in form of esters), chiefly heptoic (oenanthylic) and nonoic 

 (pelargonic) and somewhat smaller quantities of octoic (caprylic). some decylic 

 (caprinic) and undecylic acids, with traces of formic and acetic acids; alde- 

 hydes, formaldeliyde in the lowest boiling fi'action: hydrocarbons, myrceue 

 (olefinic terpene). 30 to r»o jjer cent, humulene (sesquiterpene), 15 to 25 per 

 cent ; esters, chiefly heptoic, octoic, and nonoic acid esters of the alcolutl 

 myrcenol, to the extent of 20 to 40 per cent (from the ester number (44) of the 

 oil in question the amount of esters calculated as the heptoic-acid ester of 

 myrcenol was found to be 21 per cent) ; . . . alcohols, probably myrcenol and a 

 small proportion of sesquiterpene alcohols." 



" From the data presented it is clearly evident that tbe geographical sourr-e 

 of hops has a pronounced effect upon the volatile oil and hence also upon the 

 odor of the hops." The ester content Is thought to be the most influential factor 

 in modifying the odor of the oils and consequently that of the hops. 



A review of previous chemical investigations is followed by a bibliograiihy of 

 cited literature. 



About the occurrence of adenin and asparaginic acid in mulberry leaves, 

 Z. MiMUROTO (Jour. Vol. Afrr. Imp. Vniv. Tokyo, 5 (1912), No. 1, pp. 63-65).— 

 Adenin and asparaginic acid were obtained from young air-dried mulberry 

 leaves. In all probability the asparaginic acid is present as asparagin, a.s 

 ammonia was evolved during the working up of the free ester. A peptone-lilte 

 substance was obtained from the phosphotungstic acid precipitate. 



About the occurrence of histidin betain in Boletus edulis, E. Winterstein 

 and C. Reuter (Iloppe-Hcylct'.s Ztschr. Physiol. Chew., 86 {1918), Xo. 3, pp. 

 234-237). — In work previously noted (E. S. R., 28, p. 501), a base having the 

 formula CsHisXiOj and found in the arginin fraction of B. edulis was discussed. 

 The dipicrate of the histidin betain was conipared with another dipicrate ob- 

 tained by Barger and Ewins from ergothionin, and a study was also made of 

 the monopicrate and gold salts of this compound. The two compounds are 

 identical and represent histidin betain. 



On some conditions affecting the activity and stability of certain fer- 

 ments, J. H. Long and W. A. Johnson (Jour. Amer. Chem. 80c., 35 (1913), No. 

 7, pp. 895-913). — It is suggested in this paper that starch paste for diastatic 

 comparisons should be made fi'om laboratorj'-prepared potato starch, sound and 

 fully ripe potatoes being employed. Long washing and boiling of commercial 

 starch will not always be sufficient to secure a suitable product. The amylo- 

 lytic activity of pancreas preparations is best exhibited in a mixture con- 

 taining about 25 mg. of sodium bicarbonate to 100 cc. of paste and ferment 

 solution. Larger amounts of bicarbonate retard the reaction somewhat but 

 do not appear to destroy the ferment, since the full I'apidity of conversion may 

 be recovered by the partial neutralization of the soda by weak hydrochloric 

 acid. The addition of enough acid to convert all the soda to salt at once de- 

 stroys the ferment, however. 



" Glycerol extracts of the pancreas retain their amylolytic power through 

 many months, but by dilution with water this activity is speedily lost. The 

 loss of digesting power is very marked after a short incubui.i'^n of the diluted 

 extract at 40°, but if salt is present the destructive effect of incubation is 

 much diminished. The effect of incubation of commercial preparations is much 

 the same as with the glycerol extracts, and the presence of salt lessens the dis- 

 turbing action of alkalis here, also, 



