FORMATION OF MANNAN IN AMORPHOPHALLUS KONJAK. 407 
of this precipitate had a slimy consistency, and showed the in¬ 
teresting property of losing its slimy character on prolonged 
boiling, whereby the slimy compound separated as insoluble floc- 
culi. The freshly prepared solution of the mucilage yields a 
white flocculent precipitate with basic lead acetate upon the ad¬ 
dition of some ammonia, and a thick blue precipitate with either 
Fehling' s solution or copper sulphate solution in presence of 
sodium hydrate. On boiling with dilute sulphuric acid of 3 °/ 0 
the mucilage was, after a few hours, transformed into a sugar, 
which, after the removal of the sulphuric acid by barium carbon¬ 
ate and evaporation of the filtrate, at once yielded, on the addition 
of phenyl-hydrazine acetate, the characteristic precipitate of 
mannose-phenylhydrazone. (1) To test whether galactans or 
pentosans were present in stalk and blade, the residue, which 
remained after the extraction of several hundred grams with 
alcohol and warm water, was boiled for several hours with dilute 
sulphuric acid of 4 °/ 0 . The syrup obtained after neutralizing 
with barium carbonate and evaporating, was tested for the 
presence of pentose with phloroglucin and hydrochloric acid, and 
for galactose by evaporation with nitric acid, but neither a pentose 
reaction nor mucic acid were obtained ; therefore neither pentos¬ 
ans nor galactans were present. Only a little mannose was 
obtained from this insoluble part. 
The question whether mannose as such is present in the 
stalk and blade I tried to answer by extracting these objects 
with alcohol of 50 °/ 0 whereby the mannans would remain in¬ 
soluble, while the sugar would be dissolved. These extracts were 
evaporated, (2) dissolved in a little water, and basic lead acetate 
added to remove tannin and other impurities. The filtrate freed 
from lead with hydrogen sulphide was evaporated after neutrali¬ 
zation with sodium carbonate. Upon the addition of phenylhydra- 
zine acetate, only the extract of the stalk yielded a sufficient quan¬ 
tity of the precipitate of mannose-phenylhydrazone, while there 
was a doubtful trace in the case of the extract of the blade. The 
filtrate of the above precipitate yielded, upon further addition of 
phenylhydrazine acetate and heating on the water bath, such a 
(1) This mucilage of the stalk and blade agrees therefore in its essential properties 
with the soluble mannan which Kinoshita obtained from the tuber (loc. cit.). 
(2) Since in the case of the stalk an acid reaction of the extract was noticed, it was 
neutralised with sodium carbonate. 
