112 EXPERIMENT STATION RECOED. 



more than 1 per cent of reducing sugars. Very often no difference is noted 

 between the figures obtained by polarization and those obtained from the total 

 sugar determination. In fact, in some instances the polarization gives higher 

 figures than the total sugar determination despite the fact that an invert sugar 

 content of from 0.5 to 0.8 per cent is present 



In growing beets for a high sugar content one is justified in selecting on 

 the basis of the polarization test, providing this is done before spring. Although 

 invert sugar possesses as high a feeding value as saccharose, it might be well 

 to throw out those roots which show strong inverting properties when growing 

 beets for a high sugar content. Such varieties use up a greater amount of 

 sugar during the winter storage period. In growing feed beets with a high 

 yield per acre, and which contain much water, it is proper to polarize in the 

 fall because in such beets inversion takes place very rapidly during storage, 

 and in many cases shows no rotation, or may show a levorotation even though 

 the total sugar content may be appreciable. As there is no rapid and simple 

 method for determining the total amount of sugar present the polarization 

 method must form the basis for judging mangels. 



Organic dry matter instead of total dry matter should be used as the basis 

 for selecting beets grown for a high, dry substance content. 



Method for the direct polarimetric determination of sucrose in the pres- 

 ence of certain reducing sug'ars, P. Lemeland (Jour. Pharm. et Chim., 7. ser., 

 2 (1910), No. 2, pp. 298-302; Bui. Assoc. Chim. Suci: et Distill., 28 (1911), 

 No. 5, pp. 275-278; Ztschr. Ver. Deut. Zuckerinckis., 1912, No. 681, II, pp. 1192- 

 1196; abs. in Jour. Soc. Chem. Indm., 31 (1912), No. 21, pp. 10Jt6, 10!,7 ; Chem. 

 Zentm., 1912, II, No. 21, p. j:78S).— Continuing previous work (E. S. R., 24, 

 p. 611), the author finds that if hydrogen peroxid and a little mangaijese 

 dioxid are added to a solution containing either arabinose, dextrose, levulose, 

 galactose, or lactose, and heat applied, the optical and cupric reducing proper- 

 ties of these carbohydrates are destroyed. Sucrose or dextrins are not affected 

 by this treatment. 



" For the determination of sucrose in presence of any of the reducing sugars 

 mentioned above, a solution of the sugars is heated, in a boiling water bath 

 with 0.5 gm. of manganese dioxid, or with 2 gm. if the quantity of reducing 

 sugar present exceeds 10 gm. For every gram of reducing sugars present, a 

 mixture of 2 cc. of 36 per cent sodium hydroxid solution and 30 cc. of hydrogen 

 peroxid (German official preparation) is added little by little to the hot 

 liquid ; this operation may be completed in from 35 to 45 minutes. The solu- 

 tion is then cooled, neutralized exactly with dilute acetic acid, decolorized 

 with charcoal or basic lead acetate, made up to a convenient volume, and 

 polarized. . . . 



" In analyzing mixtures containing a high proportion of reducing sugars to 

 sucrose, advantage may be taken of the solubility of sucrose in 91 per cent 

 alcohol, as in the following example: A mixture of 1 gm. of sucrose with 

 25 gm. of dextrose was left for 24 hours in contact with 100 cc. of 91 per cent 

 alcohol, and shaken frequently. The undissolved portion was separated by 

 centrifuging, and washed twice with 50 cc. of 91 per cent alcohol. The com- 

 bined alcoholic solutions were distilled, after addition of a trace of calcium 

 carbonate, and the residual liquid was treated with the oxidizing mixture as 

 prescribed above. A polarimetric reading of +1° 14' was obtained instead of 

 -fl" 18' (control solution of pure sucrose). The new method can not be 

 applied to mixtures containing maltose, for this sugar is not completely decom- 

 posed by the oxidizing mixture. Dextrins can be determined in presence of 

 sugars other than maltose, any sucrose present being first inverted." 



