18 ANALYSES OF SUGAR BEETS, 1905 TO 1910. 



of the ordinary round, ball-shaped one in general use, so that the 

 entrained air bubbles may seek the surface and not remain on the 

 sides of the vessel. This method has been much criticized because a 

 finely divided pulp is necessary to prevent an imperfect extraction of 

 the sugar, and also because ordinary shaking will not disengage all 

 of the air bubbles from the pulp, thereby causing the use of a smaller 

 quantity of water to fill the flask to the mark, and thus giving too 

 high results for sugar in the beet. 



COLD-WATER DIGESTION METHOD OF SACHS LE DOCTE. 



This is a modification of Pellet's method for the purpose of removing 

 the error resulting from the entrained air. Weigh 26 grams of the 

 fine beet pulp into a tin-lined copper vessel (Z>, frontispiece), add 5 

 cc of basic lead-acetate solution and 172 cc of water. Put the cover 

 E in place and shake the whole vigorously, then allow it to stand for 

 three minutes, remove the cover, filter, and polarize the solution in a 

 200 mm tube after adding a drop of acetic acid and double the reading, 

 or polarize in a 400 mm tube, in which case the reading gives the per 

 cent of sugar in the beet. 



In this method it is assumed that beets contain 95 per cent of 

 juice with an average specific gravity of 1.07. The volume of the 

 juice contained in a normal weight would then be 



and (200-23.08 cc) 176.92 cc of water would be necessary to complete 

 the volume to 200 cc. A special pipette (F, frontispiece) has been 

 designed to deliver this amount. A quarter turn of the stopcock 

 opens the entrance G for the lead acetate, so that 5 cc can be meas- 

 ured, then another quarter turn opens the water entrance H to fill 

 the burette to the overflow, and a half turn delivers the whole into 

 the dish. 



As in the preceding method, the beet pulp must be very fine, 

 otherwise an imperfect extraction will occur. This method is also 

 open to criticism in that all beets do not contain 95 per cent of juice 

 and all beet juice does not possess a specific gravity of 1.07. It is 

 rightly claimed, however, that the errors introduced by the use of 

 these constants are so small that they will fall within the limits of 

 accuracy of the readings. 



HOT-WATER DIGESTION METHOD. 



Weigh 52 grams of the beet cuttings and transfer them with water 

 to a large-mouth flask (C, frontispiece) of 201.2 cc content; add from 

 5 to 10 cc of lead subacetate solution, fill the flask to the mark with 



