472 SORGHUM. 



by which they could be distiuguished during the remainder of the ex- 

 amination. After being cut and brought to the laboratory, the 

 length of the stalk from butt to the extremity of the head, its entire 

 weight, and diameter at the butt, were taken. It was then stripped 

 and topped, as in the usual way of preparation for the mill, and again 

 weighed. The "stripped stalk" was then expressed in a three-roll 

 mill, and the juice collected in a weighed flask and weighed to deter- 

 mine " per cent of juice" in the stripped stalk. The specific gravity 

 Avas determined witli a piknometer, after an interval of an hour to al- 

 low the escape of air bubbles and the subsidence of suspended starch. 

 For the determination of the " total solids" in the juice 2'='"^- were ac- 

 curately measured into a weighed porcelain dish 6 to 7^'^- Avide and 1. 5 

 to 2'=™- deep, the bottom of Avhich was previously co\'ered with coarse 

 sand to a depth of .75'^'"- to insure complete desiccation. After twelve 

 to fourteen hours' drying at 85° to 90° C, there was no further loss 

 of water. The Aveight of the residue in grams, divided by twice the 

 specific gravity, gaA'e the per cent of " total solids." 



For the determination of glucose and sucrose, lOO*^'"^- of the juice 

 were taken and defecated by the addition of 25'''""- of solution of basic 

 acetate of lead in Avater. The filtrate from the lead precipitate, 

 which was perfectly clear, Avas, in many instances, polarized, and then 

 devoted to the methods of volumetric analysis. OAviug to the degree 

 of dilution, cA^ery lO*^'"^- of filtrate represented S*^"''^- of juice. 



For the determination of glucose lO*"'"^- of the filtrate Avere taken ; 

 for sucrose, 5^'™"-. The portion for glucose was diluted with about 50 

 to 75*^'"^- of water, and about the same amount of Fehliug's solution 

 added. The porcelain dish containing the Avhole Avas placed upon a 

 water bath kept at such a- temperature by steam, that the liquid in the 

 dish rose to about 75° C. , but no higher. After an interval of thirty 

 minutes, the dish Avas removed and allowed to cool. The portion for su- 

 crose Avas diluted with lOO*^'"'^- of Avater, 5''"'''- of hydrochloric acid (sp. 

 gr. 1.05) added, and the mixture heated iu a porcelain dish on a steam 

 bath for a half hour, the temperature not rising above 90° C The in- 

 version being complete, an excess of Fehliug's solution Avas added, de- 

 pending in amount on the maturity of the cane, and the liquid allowed 

 to remain thirty minutes longer on the bath, after Avhich it Avas re- 

 moved. When the suboxide of copper had completely settled, in the 

 case of both sucrose and glucose, the supernatant liquid jvas decanted 

 into a beaker placed iu front of each disii, and hot Avater Avas poured 

 over the suboxide. This process was repeated, pouring the first liquid 

 decanted into a second beaker, and so on until it could be poured away 

 free from any oxide, and the original dish Avas nearly free from alkali. 



