1915-16.] The Optical Eotation of Sugars. 215 
In the following table a summary of the values of K for the various 
K 
— lo <*&- 
t 2 -t x 
where t x and t 2 are times from moment of solution till polarimetric readings 
were made, /5 X and /3 2 are the actual polarimetric readings at times t x and t 2 , 
and <p is the actual reading when constant. 
It will be observed that in the case of the three sugars — (Aglucose 
c£-galactose, and lactose — in which measurements from both modifications 
were made, the values for the constant in each solvent are in close 
agreement. Attention may also be called to the much smaller value of K 
in formamide solution than in water solution. 
K in water. 
K in formamide. 
Sugar. 
a ->/3. 
/?— >a. 
a ->/?. 
/3~> a 
Temp. 
Temp. 
Temp. 
Temp. 
Z-arabinose 
. 
0*0134 
12° 
0*00154 
13° 
Z-xylose 
0-0188 ! 20° 
0*00306 
20° 
fZ-glucose . 
0*00627 20 
0*00690 
20 
0*00109 
20 
0*000996 
20 
cZ-galactose 
0*00960 20 
0*00722 
20 
0*001988 
20 
0*00157 
20 
*eZ-mannose . 
0*0273 20 
0*00326 
20 
oZ-fructose . 
0*00839 
20 
maltose . 
0*00503 20 
0*00163 
20 
lactose 
0*00378 ; 14° 
0*00297 
17° 
0*000387 
15° 
0 0004 
17° 
* Erratum. — Proc. Roy. Soc. Edin ., 1914-15, xxxv, 37, the value of K in. formamide 
is given as 0*000326 instead of 0*00326. 
The authors desire to express their gratitude for a grant from the 
Moray Bequest Fund towards the expenses incurred in the above 
experiments. 
Chemistry Department, 
University of Edinburgh. 
{ Issued separately November 29, 1916.) 
