318 The Carbohydrates oj the Manf/old Leaf 



Proportions of Dextrose and Laevulose. 



(A) Pentoses as arabinose. If a; = gnus, of dextrose in 25 cc. B, 



y = grms. of laevulose in 25 cc. B, 



we havei 4-22x - 7-'iQy = - 0-097°, 



2-56x + 2-My = 0-2047. 

 Solving for x and y, 



X = 0-04457 grm. dextrose in 25 cc. J5 (= 15 cc. A), 

 y = 0-03872 grm. laovnloso in 25 or. 5(=15cc. A). 



^ ■ r.^,.--, -IJOO 500 100 ^ ^^ „, 



.•. Dextrose in t.v.d.m. = 0-044.j7 x -ir^- x -r-— x rirr^f, 5-01 %. 



15 440 134-79 ^° 



,>r.oo-o 2000 500 100 . oc o/ 



Laevulose in T.V.U..M. = 0-038/2 x -j— x ^^^ x ^^^ ..^ = 4-35 %. 



.-. D + L = 9-36l/o. 



? = "?- 1-151. 

 L 4-3.) 



(B) Pentoses as xylose. 4-22x - 7-36y = - 0-056°, 



2-56a; + 2-34?/ = 0-2047. 



Hence as in (A), "^ of dextrose = 5-39 % 



% of laevulose = 3-94 % 



D + L -9^33% 



D._,5-39 

 L~3^"^**^- 



Calculating Reducing Sugars as Invert Sugar. 



Invert sugar in 25 cc. B = cf-AAW ^ 0"08351 grm. 



rw.aQr.1 2000 500 100 . .. „ , 



= 0-'^8351 x ^^ X ^ X ^^^^^ = 9-39 % on t.v.d.m. 



If the rotation in B wore due to invert sugar, in 200 mm. tube at 20°, 

 rotation 



0-08351 X 4 X 200 x - 19-6 



10 



- 0-131°. 



' Tlie constants 4-22 and 7-36 for dextrose and laevulose arc calculated from the specific 

 rotatory powers [a]^^ =52-7 and [a]'^ = - 92-0° for 1 per cent, solutions of the sugars. The 

 constants 2-.5() and 2 34. corrcspondinf.' with the 0'2210 gmi. CuO actually weighed, are 

 taken from Brown, Jlorris and .Millar's Tables for dextrose and laevulose. 



