19 



Polarization of honeys after fermentation. 

 [Concentration, 20 grams honey in 100 cubic centimeters.] 



Sample 



17., 



1. 



2 



27. 



14. 



Polarization (degrees) 



+30.4 



+28.6 



+24.0 



+11 



+6 



When the fermentation residue of a honey gives a right-handed 

 rotation it is generally considered to be an adulterated honey. How- 

 ever, normal honeys have been found whose unfermentable residues 

 give a right-handed polarization when the beer or wine yeast has 

 been used. Raumer a found that a 10 per cent fermentation residue 

 of a normal honey might give a dextrorotation of value of -f- 11.86 to 

 +13.77 (Laurent). So, although the honeydew honey gives after fer 

 mentation a right-handed polarization, it should not. therefore, be 

 classed as a glucose honey. However, by the fermentation method, 

 it is certainly not to be distinguished from a glucose honey. 



The unfermentable carbohydrates determined as dextrose found 

 in the fermentation residue were as follows: 



Unfermentcd carbohydrates calculated as dextrose in fermentation residues of 



different honeys. 



Sample. 



Before in- 

 version. 



After in- 

 version. 



Differ- 

 ence.'' 





Per cent. 



Per cent. 



Per cent. 



17 _ _ 



7.25 



17.47 



10.22 



1 _ _ _. 



7.49 



18.94 



11.45 



2 



6.57 



16.14 



10.57 



27 . 



2.67 



7.98 



5.31 



14 _ _ 



1.02 



3.91 



2.89 



6 Difference due to dextrinous matter. 



The results show that the honeys rotating to the right before fer- 

 mentation contain the greatest amounts of unfermentable carbo- 

 hydrates. 



Precipitation with alcohol. — Methyl alcohol causes in honeydew 

 honey a somewhat stringy, but not gummy, precipitate, part of which 

 does not dissolve in water. 



Twenty grams of honey, samples 17 and 3, were made up to 250 

 cubic centimeters with methyl alcohol and allowed to stand. The 

 precipitates obtained amounted to 0.339 per cent and 0.27 per cent, 

 respectively, and were optically inactive. 



One hundred cubic centimeters of the honey filtrate (sample Xo. 3) 

 were placed on the water bath to remove alcohol and made up again 



Bui. 17 



0 Ztschr. Angew. Cliem., 18S9, p. 608. 



