1914-15.] 
The Optical Rotation of Sugars. 
37 
(i-MANNOSE. 
The mannose was finely powdered and heated to 105° till of constant 
weight. It was perfectly colourless and melted at 129-132°. 
The cryoscopic measurements, using formamide as solvent, were as 
follows : — 
Concentration per 
' 100 grains of solvent. 
Mol. weight 
found. 
Mol. weight 
calculated. 
0-706 
187-5 
180-0 
1-42 
191-8 
?? 
2-25 
182-7 
5? 
The following polarirnetric results (cf. figs. 9 and 10) were obtained 
Solvent 
Water. 
Formamide. 
Graph 
X 
+ 
Concentration 
grams in 100 
> 2-8128. 
2-02 
72. 
c.c. solution. 
Time. 
r i 2 o 
Hd. 
Time. 
r 120 
Wd. 
10 min. 
- 3-91° 
7 min. 
- 25-16° 
22 „ 
+ 2-13 
11 „ 
22-70 
28 „ 
+ 7-64 
18 „ 
21-43 
32 „ 
10-84 
24 „ 
20-22 
38 „ 
11-02 
35 „ 
18-24 
71 „ 
13-83 
45 „ 
15-30 
80 ., 
14-22 
2 hr. 6 „ 
5-42 
93 „ 
14 22 
2 „ 12 „ 
2-46 
19 hr. 30 „ 
+ 14-40 
2 „ 33 „ ! 
1-72 
19 „ 45 ,, 
Constant 
2 „ 49 „ 1 
- 0-49 
20 „ 
3 „ 1 
+ *0-98 
3 „ 13 „ 1 
+ 1-97 
K = 0-0273. 
3 „ 32 „ 
2-95 
Calc, initial 
[»]!?= 
4 „ 3 „ ! 
5-67 
-19-9°. 
21 „ 52 „ 
+ 11-84 
Extrapolated 
- 20-0°. 
[»]!?= 
23 „ 
Constant 
K = 0-000326. 
Calc, initial 
■ [“]”= 
- 26-9°. 
Extrapolated 
- 26-0°. 
