45 
1914-15.] The Optical Eotation of Sugars. 
{Cf. figs. 14 and 15). [ajc in water decreases 0-08° for each 1° rise in 
temperature from 10° to 25°; hence [ 0 ]^*^ = 54*99°. 
The corresponding values in formamide solution are 0*07° ; 4-50*98°. 
It will be observed that the equilibrium solution in both the water and 
the formamide solution is the same starting from either the a- or the /3- 
modification of lactose. 
The results obtained prove conclusively that mutarotation takes place 
in non-aqueous solutions of sugars with a velocity comparable with, though 
not so great as, that in aqueous solutions. This is seen most readily on 
inspection of the curves, though it must be noted that the curves in the 
case of pyridine solutions as given by Grossmann and Bloch are for red 
light and not for the sodium flame. The velocity of mutarotation for the 
two kinds of light does not apparently differ to any great extent, so that 
for comparison the curves for red light have only to be moved parallel to 
themselves (G. and B., loc. cit). 
It is the pleasant duty of the first-named author to acknowledge grate- 
fully a grant from the Moray Bequest Fund for the purchase of the polari- 
meter used in the above experiments. 
Chemistry Department, 
Univeksity of Edinburgh. 
(Issued separately February 2 , 1915 .) 
