206 Proceedings of the Royal Society of Edinburgh. [Sess. 
the statement that mutarotation is a reversible process represented by 
the equation 
a- form 7 —^ /3- form. 
EXPERIMENTAL. 
/3-d-GLUcosE. 
Ten grams of pure a-d-glucose were dissolved by boiling in 38 c.c. of 
freshly distilled pyridine (B.P. 114-115° C.) previously treated with 
potassium hydroxide and the solution filtered. The solution was cooled 
in ice water, and, on scratching the sides of the vessel, crystals came out 
after about an hour. The solution was filtered off and the crystals washed 
with some pyridine and then with ether. On drying at 105° C. to constant 
weight pure /3-glucose in a very fine state of division was obtained. The 
yield was about 3*4 grams. The melting-point of the substance was 
146-148° C. and the specific gravity at 13° C. (determined by the method 
of flotation) 1547. 
The cryoscopic measurements in water were not repeated. The figures 
for formamide solution were as follows : — 
Concentration per 
Mol. weight 
Mol. weight 
100 grams of solvent. 
found. 
calculated. 
035 
181-4 
180 
0-68 
181-4 
33 
0*98 
183-5 
The polarimetric figures (cf. figs. 1 and 2, in which the data for both 
a- and /3-(i-glucose are graphed) were as follows : — 
