76 METHODS OF ANALYSIS. 



order to compensate for the volume of the marc and the lead precipitate. Add 

 from 3 to 5 cc of lead subacetate solution of 54.3 Brix for the clarification. This 

 reagent should be run into the flask in advance of the beet pulp. Add a few 

 drops of ether to break the foam, then sufficient water to increase the volume of 

 the solution to about 190 cc. Heat to 80 C. in a water bath and maintain this 

 temperature about thirty minutes, occasionally giving the flask a circular 

 movement to facilitate the escape of the air from the pulp. Increase the volume 

 of the solution from time to time during the heating, so that when the opera- 

 tion is completed only a few drops of water will be required to complete the 

 volume of the solution to the mark. After approximately thirty minutes' heat- 

 ing, cool the flask and contents, acidify with strong acetic acid, dilute to the 

 mark, mix, and filter. The state of division of the pulp will govern the time of 

 heating. In polarizing the filtrate use a 400 mm observation tube, thus directly 

 obtaining the per cent of sucrose in the beet. 



