BULLETIN OF THE BUSSEY INSTITUTION. 61 
In another trial half as much potash was used as before: 0.5 
orm. of the pure dextrose was dissolved in a small quantity of 
water and to it were added 1.25 cc. of the normal solution of 
potash (7.e., 0.07 grm. KOH). The mixed solution was made 
up to 5 cc. and heated on a water-bath for an hour and a half at 
a temperature of about 70°. Hydrochloric acid of 5 percent. was 
added to slight acidity and then a few drops of potash solution, 
enough, that is to say, to make the liquid very faintly alkaline. 
The solution was evaporated to soft dryness, the residue was 
taken up with 1 cc. of water and the solution mixed with 16 drops 
of the phenylhydrazin acetate reagent. After a few hours many 
mannose-hydrazone balls were visible in the precipitate, and 
excellent crystals of this substance were obtained on recrystalliz- 
ing the balls from diluted alcohol. 
Another test was made using half as much potash as in the last 
trial: To 0.5 grm. of the pure dextrose, dissolved in a small 
quantity of water, there was added 0.625 cc. of a normal solution 
of potash (7.e., 0.035 grm. of KOH): The mixed liquor amount- 
ing to about 5 cc. was heated on a water-bath during an hour and 
a half at a temperature of 70°C. The liquid was acidified with a 
few drops of hydrochloric acid of 5 percent., then made very 
faintly alkaline with potash and evaporated to soft dryness. The 
residue was taken up with 1 cc. of water, and there was added to 
it 16 drops of the phenylhydrazin acetate reagent. A brownish 
precipitate formed slowly, and there was seen in it after a few 
hours many large mannose-hydrazone balls, the number of which 
increased on longer standing. On recrystallizing from diluted 
alcohol excellent crystals of mannose-hydrazone were obtained. 
A test in which half as much potash was used as in the last 
case was as follows: To 0.5 grm. of the pure dextrose, dissolved 
in a small quantity of water, 0.31 cc. of the normal potash solution 
was added (7.e., 0.017 grm. of KOH). The liquid was made 
up to the volume of 5 cc. and heated on a water-bath at 70° 
during an hour and a half. A few drops of hydrochloric acid of 
5 percent. were then added, but not enough to fully neutralize the 
solution which was left very faintly alkaline. In this condition 
it was evaporated to soft dryness. The residue was taken up 
with 1 cc. of water and the solution mixed with 16 drops of the 
phenylhydrazin acetate reagent. A reddish-brown precipitate 
