62 BULLETIN OF THE BUSSEY INSTITUTION. 
formed slowly. After four hours there were seen in it some spiny 
crystals of dextrose osazone and a very few large, yellowish 
globules which may have been mannose-hydrazone. Next day 
numerous mannose-hydrazone balls, both large and small, were 
visible, and excellent crystals of this substance were obtained by 
recrystallizing from diluted alcohol. 
Yet another trial was made, using half as much potash as in 
the preceding instance: To 0.5 grm. of the pure dextrose, dis- 
solved in a small quantity of water, 0.15 cc. of normal potash 
solution was added (7.e., 0.008 grm. of KOH). The liquid, 
amounting to about 5 cc., was heated on a water-bath at the tem- 
perature of 70° C. during an hour and a half. It was then found 
to have an alkaline reaction and was made slightly acid by adding 
a few drops of hydrochloric acid of 5 percent. Next it was made 
slightly alkaline by the addition of a drop or two of the normal 
potash solution and was evaporated to soft dryness. The residue 
was taken up with 1 cc. of water and 16 drops of the phenyl- 
hydrazin acetate solution were added. A reddish-brown precipi- 
tate formed slowly and some spiny crystals of dextrose osazone 
were seen in it. There were a few yellowish balls also which 
may perhaps have been mannose-hydrazone, but this point was 
uncertain, and only dextrose osazone crystals were obtained on 
recrystallizing from diluted alcohol. 
It was argued that the quantity of potash used in the last but 
one of the above trials probably corresponded somewhat nearly to 
the quantity of soda that might be present in the ordinary method 
of testing for mannose in woods in case the acid product of 
the hydrolysis had been decidedly over-neutralized with sodium 
hydroxide. To test this idea, 0.4 grm. of the pure dextrose was 
dissolved in 20 cc. of water, a few drops of strong hydrochloric 
acid were added, and the mixture was left at rest during forty- 
eight hours. Enough of a solution of sodium hydroxide was then 
added to make the solution decidedly alkaline. A part of the 
solution was examined without having been concentrated by evap- 
oration, while the remainder was evaporated to soft dryness. 
The residue was taken up with 4 cc. of water. As regards the 
unevaporated liquor, 12 drops of the phenylhydrazin acetate 
reagent, added to 1 ec. of the liquor, gave a small yellowish pre- 
cipitate in which some spiny crystals of dextrose-osazone appeared, 
