14 ANALYSES OF SUGAR BEETS, 1905 TO 1910. 



of litharge with normal lead acetate. These are 3PbAc2PbO the 

 one usually prescribed for clarification, PbAcPbO the monobasic, and 

 PbAc2PbO the diabasic." l Variations in time of digestion, in 

 quantities of litharge used, and in temperature of digestion will result 

 in solutions containing mixtures of all of these. 



To prepare this reagent boil 3 parts (by weight) of neutral lead 

 acetate and 1 part of yellow litharge with 10 parts of water until 

 the reaction is completed or the material is practically all dissolved. 

 This generally takes not over half an hour. Cool and dilute the 

 solution with water to a specific gravity of 1.25 or 53.7 Brix. The 

 solution is filtered or allowed to stand until clear. The bottle should 

 be kept tightly corked, as the composition of the solution changes. 

 It may also be prepared by dissolving dry lead subacetate (contain- 

 ing 72.81 per cent of lead) in water until the specific gravity of the 

 solution is 1.25 or 53.7 Brix. 



METHODS FOR DETERMINING SUGAR. 



Methods for the determination of sugar in the beet may be divided 

 into two general classes, namely, direct and indirect. The former 

 may be subdivided again according to the solvent used and the 

 temperature of extraction. There is only one indirect method and this 

 will be considered first. 



INDIRECT METHOD. 



The indirect method depends on pressing the juice from the beets, 

 determining the sugar in the juice, and then by a factor calculating 

 the per cent of sugar in the beet. In practice this is accomplished 

 by inclosing the beet cuttings in a jute or cotton cloth, placing the 

 whole in a press, and catching the juice in a vessel large enough to 

 hold it all. The juice is thoroughly mixed, poured into a cylinder, 

 and allowed to stand until the air bubbles have collected at the sur- 

 face; generally from 20 to 30 minutes is necessary. This foam is 

 brushed aside when the Brix hydrometer is placed in the liquid to 

 obtain a reading on the content of solids. The hydrometer is al- 

 lowed to come to rest before a reading is made, and should float free 

 of the sides during the reading. After observing the reading and 

 noting the temperature of the solution, the normal or double normal 

 amount of the juice is either drawn up in a sucrose pipette (Spencer's 

 method, A, frontispiece) or is weighed. This portion is run into a 

 100 cc flask with water, and a solution of basic lead acetate added 

 in a sufficient quantity to produce a complete precipitation, but an 

 excess is to be avoided. The flask shown at B, frontispiece, is an 

 excellent shape for sugar analysis, because the slanting sides prevent 



i U. S. Dept. Agr., Bureau of Chemistry But 122, p. 223. 



