MANNANE AS AN ARTICLE OF HUMAN FOOD. 105 
ing at 205°C. The characteristic mannose-oxime was also ob¬ 
tained by slow evaporation of a portion of the syrup with a mix¬ 
ture of hydrochlorate of hydroxylamine with sodium carbonate 
and purified by recrystallization from absolute alcohol. A por¬ 
tion of the sugar-syrup was also repeatedly oxidized with nitric 
acid to see whether mucic acid could be obtained, but none was 
found ; therefore no galactan was present in the konniaku root- 
stock. Also, as no pentose reaction with hydrochloric acid 
and phloroglucin could be observed, there could not be present 
in the konniaku-root xylan or araban to any considerable extent. 
If all the sugar obtained was mannose, as is very probable, 
then the konniaku powder mentioned yielded 55.86% of mannose. 
This konniaku root is evidently very well suited for the 
preparation of the polyanhydride of mannose called mannane 
in a pure state. As this mannane is used as food, it must 
evidently be digested by the enzymes in the intestines and 
transformed into mannose or a dimannose corresponding to 
the maltose made from starch, but my attempts to convert the 
mannane of konniaku by diastase made from malt into a sugar, 
were not successful. The more interesting then is it that the 
human intestines can digest mannane. 
