ON THE CARBOHYDRATE GROUP IN YAM MUCIN. 
247 
brown liquid was fillered and the filtrate was decolorized with animal char- 
coal. The clear yellowish liquid thus obtained reduced Fehling’s solution 
very strongly. The amount of free hydrobromic acid in the solution was then 
determined by titration against decinormal alkali solution and about 4/5 of 
the calculated amount of lead carbonate necessary to neutralize it were added, 
under strong agitation. After 2 hours standing, the lead bromide was sucked 
out and the filtrate was concentrated in vacuum under 40°, until nearly all 
of the remaining hydrobromic acid was driven out. The brownish syrup 
obtained was boiled with 100 c.c. of 96^ alcohol and filtered; the residue 
was moistened with a little warm water and again extracted with alcohol. 
This process was repeated several times, until the reducing substance could 
no longer be detected in the alcoholic extract. The extracts were united, the 
precipitates formed on standing (chiefly lead bromide) filtered off and then 
concentrated to a syrup. The syrup w T as dissolved in 30 c.c. of nitric acid, 
sp. gr. 1.2. and heated on a water bath until red fumes came off. It was 
then allowed to cool, 10 c.c. of nitric acid were added and concentrated to 
a small volume, with constant stirring. About 50 c.c. of water were then 
added and again evaporated to drive out the nitric acid. Finally the syrup 
was dissolved in 100 c.c. of water, decolorized with animal charcoal and freed 
from the remaining hydrobromic acid by the careful use of silver nitrate. 
The filtrate from silver bromide was exactly neutralized with ammonia and 
then acidified with a few drops of very dilute acetic acid. Calcium acetate 
was then added drop by drop to precipitate oxalic acid, neutralized again 
with ammonia and boiled with concentrated lead acetate solution. When cold 
the lead precipitates were separated by filtration with suction and washed 
well with cold water. The precipitates were suspended in 120 c.c. of water 
and decomposed thoroughly with hydrogen sulphide. The excess of hydrogen 
sulphide was driven off by boiling the solution, and the filtrate was concent- 
rated on a water bath. The solution thus obtained should contain noriso- 
saccharic acid produced by oxidation of glucosamin, if it were present. To the 
hot aqueous solution of norisosaccharic acid, an excess of cinchonin was added 
until its reaction was distinctly alkaline. When cold it was filtered and the 
filtrate treated in a separating funnel with acetic ether to extract the free 
