37 2 Maugham.—Observations on the Osazone Method 
the effect of glycerine on the production of osazones from the four principal 
plant sugars, dextrose, levulose, maltose, and cane sugar. 
As is well known, aqueous solutions of dextrose and levulose give with 
phenylhydrazine acetate long, fine, yellow, acicular crystals after a few 
minutes’ heating at ioo° C. As a rule levulose deposits crystals before 
dextrose, the latter coming down on cooling. Microscopically the two 
osazones are usually indistinguishable. They are both fairly insoluble in 
cold water, but readily dissolve in alcohol. 
Maltose, after being heated for an hour or more, produces a yellow 
syrup which crystallizes after standing for a longer or shorter period. 
Frequently these crystals look much like those given by dextrose and 
levulose, but more often they have a broader and flatter form, much like 
that of a sword blade, and they may be paler in colour. 
Cane sugar, if pure, gives osazones only after becoming hydrolysed by 
prolonged heating. 1 The resulting crystals are like those of dextrose and 
levulose. 
A glycerine solution of the reagents is, however, used in Senft’s method, 
and it has been found that the glycerine tends to hinder or prevent crystal 
formation to an extent which varies with the different sugars. This follows 
from the experiments now to be described. 
Experiment I. Thirteen pairs of test-tubes were set up. Of these, 
ten pairs contained small and approximately equal amounts of one or other 
of the four sugars powdered and moistened. To each was added about 
o*75 c.c. of the mixed reagent. The tubes were then completed by adding 
2 c.c. of water to one set (a), and 2 c.c. of glycerine to the other set (b). 
The other three pairs of tubes contained the reagent together with (a) water, 
and (b) glycerine, to serve as controls. 
Tubes 1-5, i. e. a control pair + one pair of each kind of sugar, were 
then heated for 35 minutes at 98° C. 
Tubes 6-10, i. e. a similar set, were heated for 60 minutes. 
Tubes n-13, i. e. a control pair-}-a pair containing cane sugar-fa pair 
containing maltose, were heated for 75 minutes, after which the gas was 
turned off and the tubes were allowed to cool slowly in the bath. 
The tubes were then examined periodically and gave results indicated 
in the table below. 
Neutral aqueous solutions of cane sugar are slowly inverted on boiling. Watts, iv, p. 550. 
