CHEMISTRY. 375 



i. e., amandin, corylin, excelsin, avenalin, edestin, and conglutin. The 

 composition and distinguisliiug cliaracteristics of these proteids are 

 brought together in a table. 



The chemistry of honey, O. Kiinnmann and A. IIilger (Fortick. n. 

 Jjebciismfl. loid llyij. Chem., 3 [1S!H))^ p.211 ; ahs. in CIteiii. (Untbl., ISOd^ 

 II, No. 9, p. 470, and Cliem. Ztg., 20 {1896), No. 72, ReperUp. 229).— 'Mha 

 statements concerning the dextrinons bodies present in dextrorotatory 

 honeys and the fermentation of lioney by yeast are very variable. The 

 authors have conducted extended investigations with pure yeasts and 

 have attempted to disclose the chemical nature of the dextrin. 



Fermentation experiments. — All levorotatory honeys contain only 

 traces of dextrin, and the amounts i)resent in tlie dextrorotatoiy forest 

 honeys have a direct relation to this dextrorotation. If, therefore, 

 large amounts of yeast are used with the former, inactive residues are 

 easily obtained. Von Raumer and jMader showed that press yeast acts 

 more strongly on the honey dextrin than Iteer yeast. To obtain an 

 exact measure of the fermentative energy of various yeasts, the authors 

 started with accurately determined amounts of a dextrin which had 

 been isolated from dextrorotatory honeys. The artificial solutions used 

 had the following composition : Honey dextrin 1 gm., levulose 5.5 gm., 

 dextrose 4.5 gm., and the concentrated aqueous extract (pre])ared by 

 boiling) of 10 gm. beer yeast. The solution was then made up to 100 cc. 

 with water. The yeast extract was added for the purpose of producing 

 a smoother fermentation. One hundred and lifty cubic centimeters of 

 this solution was mixed with 10 gm. of yeast and fermented at 25° C. 

 for 140 hours. The beer yeasts were previously deprived of most of the 

 water pi-esent by squeezing in a cloth, and were carefully washed with 

 water to remove wort. 



Three beer yeasts from different sources gave slight dextrorotatory 

 residues. Two press yeasts gav^e inactive residues, but as such yeasts 

 are never pure, it was thought best to prepare a pure culture of one 

 of the species i)resent. This showed much less energy and left a 

 I)lainly dextrorotatory residue. This i^roved plainly that all the pre- 

 vious work was inexact, and that to obtain good results all materials 

 must be sterilized, the fermentation carried on with well-characterized, 

 easily controlled j)ure cultures of yeast, and all extraneous infection 

 avoided during the fermentation. 



Wine yeasts were unable to ferment the dextrin. During a period of 

 IG to liO days only 8.7 to 13.1 per cent of the dextrin present was fer- 

 mented. 



Beer yeasts showed more energy than wine yeasts, but only the 

 variety Saccharoinyces-rombe was able to ferment all the dextrin, 

 while with the others the amounts varied from 40 to 25 ])er cent. It 

 was further found that only extended fermentation would remove the 

 last portions of invert sugar. 



The honey dextrin was isolated by fractional i)recipitatiou with 



