14 The Estimation of Carlmhydrates 



Series II. A fresh approximately 1 % solution of laevulose was 

 used. (Solution 2.) 



25c.c. gave (1) 0-2960 grm., (2) 0-2960 grm., (3) 0-2966 grm. 

 Average = 0-2962 grm. CuO. 



Hence concentration of laevulose = 1-028 grms. per 100 c.c. 

 Rotation observed in 400 mm. tube af = — 3-808° 

 Specific rotation of the laevulose [a]^f = — 92-7°. 

 50 c.c. of solution 2 were mixed with 5 c.c. of basic lead acetate 

 and the mixture left 24 hours. Sodium carbonate was then added 

 and the solution diluted to 100 c.c. 



Table IV. 



Reduction values Polarisation values 



c.c. of CuO from Laevulose calc. % of a„ in % of 



basic lead 25 c.c. on 100 c.c. of laevulose 400 mm. laevulose 



Time acetate grms. original solution remaining tube remaining 



24 hours 5 0-2580 0-8820 86-5 - 1-496° 78-6 



Series III. A fresh solution of laevulose was used (solution 3). 

 25 c.c. gave 0-3164 grm. CuO (average of three values). 

 Hence laevulose = 1-1025 grms. in 100 c.c. 

 Rotation observed in 400 mm. tube = — 4-060°. 

 [a]f - - 92-0°. 

 50 c.c. of solution 3 were mixed with 5 c.c. of basic lead acetate. 

 After 6 days the solution had become decidedly yellow. It was preci- 

 pitated with sodium carbonate and treated as shown in column 3. 



Table V. 



Reduction values Polarisation values 



As in the earlier experiments, there is the same wide difference for 

 apparent laevulose remaining by the reduction and polarisation methods. 

 As the time is considerably greater (6 days) so that the amount of 



