50 



log are the notes made by my assistant, Mr. W. L. Hutchlnson, up to 

 September 1, at which time he resigned to accept the professorship of 

 chemistry in the Agricultural and Mechanical College of Mississippi. 

 His leaving put an end to his interesting investigations. 



June 21. Iodine shows no starch in Minnesota White Amber, just headed. Single 

 polarization gives no sucrose. 



The following were found: Glucose, 3.65 per cent. ; solids, 6.66 per cent. ; albumin- 

 oids, .17 per cent. 



The precipitate produced by subacetate of lead, after being freed from the lead, 

 gave no trace of oxalic acid, but a quantity of tartaric acid. So great was the latter 

 that every attempt at its entire removal failed, so that no positive conclusions as to 

 the other acids present were drawn. 



On July 16 fully matured samples of Early Amber were obtained, the juice extracted 

 and subjected to analysis. The sucrose was determined by single and double polari- 

 zation and by Fehling's solution. The following are the results: 

 . Sucrose: Total solids, 16.58; single polarization, 12.31; double, 12.28; Fehling's, 

 12.22. This juice was concentrated to sirup, and the latter gave, by single polariza- 

 tion, sucrose, 52.41 ; double polarization, 53.58. 



STARCH IN SORGHUM. 



With green canes just heading no indications of starch are given by 

 iodine. If there were any blue it was completely obscured by the in- 

 tensely brown coloration. This brown coloration indicated dextrine and 

 other forms of soluble starch. 



With well-matured canes iodine gives an intensely blue color to- 

 wards the top, decreasing in intensity towards the "butt. Canes occu- 

 pying an intermediate condition between these extremes, or in that 

 stage of growth when maturity begins to appear, as indicated by the 

 presence of sucrose in the lower part of the stalkj starch will be found 

 in the butt but not in the top. 



The above conclusions of Mr. Hutchinson have been fully confirmed 

 by subsequent experiments ; and it is not unusual in our laboratory now 

 to prognosticate the amount of sucrose in a cane by the presence of 

 starch, so intimately are they associated. Both sucrose and starch 

 seem to be formed simultaneously the former from glucose and per- 

 haps other bodies, and the latter from dextrine and other soluble 

 forms. 



Glucose occurs in largest quantities when the polariscope gives no 

 indication of sucrose by single polarization. In a sample of green cane, 

 in which there was no starch and by single polarization no sucrose, but 

 by double polarization 1.53 per cent., as high as 7 per cent, of glucose 

 was found. As the cane from which the above sample was selected, 

 matured, repeated analyses made at short intervals showed that the 

 glucose decreased, until at maturity it reached as low as 0.8 per cent. 



SINGLE VS. DOUBLE POLARIZATION. 



In juices from matured canes there is a very close agreement between 

 the sucrose obtained by single and double polarization. Not so with 



