K. Mn-.vKK : On the Nature of the Sugars found in the Tubers of Arrowhead. 27 



reaction and mannose phenylhydrazonp could lie formed as above mentioned. 



b. Isolation of sucrose. 



When the syrup was left untouch(>d nearly twenty four hours, it was found 

 tliickly laden with fine crystals. A small amount of 9^>% alcohol was added to 

 the syrup, mixed, filtered with suction, and washed with absolute alcohol and ether. 

 The sugar thus obtained was slightly yellowish in colour, but upon recrystallization 

 from alcohol it became perfectly white and left no ash on ignition. After drying over 

 sulphuric acid in a vacuum, its melting ]X)int was determined and found to be 159°C 



0.5 gi'am of the dried sugar was dissolved in water and made up into 25 cc., 

 and polarized in 200 mm. tube in Schmidt and Haensch half shadow polariscope. 

 The rotation was found to be 7.7 on the scale toward the right. The specific 

 rotatory jxiwer of this sugar is 



. s-r, 7.7 X 0.346 X 25 , rr r / t- onc\ 



i"^^ = K7-^ = +6G.() at 20) 



0.5 X 2 



The melting point and specific rotatory power indicates that the sugar at 

 hand is uo other than sucrose. 



c. Osazone tests. 



The mother-liquor filtered ofi' from the crystals of sucrose was evaporated 

 again into a syrup. After standing for about two days, a small amount of sucrose 

 crystals was again formed in it. The crystals were removed as in the aljove 

 experiment, and the filtrate was conccnti'ated once more to a syi'U]^. It did not 

 show any sign f)f forming new crystals even after one week standing. An attempt 

 was then made to separate and detect the sugars as osazone. 



]. 1 gram of the syi-up, 2 grams of phenylhydrazinhydrochloride, 3 grams 

 of sodium acetate and 20 cc. of water were mixed and heated in a boiling water 

 bath. After 15 minutes j-ellowish crystals had been produced. At the end of 

 one hour and a half, the heat was removed, and the crystals were examined under 

 a microscope. None of the other forms, besides the stellate form of the yellow 

 needle shajied crystals, which coincides with that of phenylglucosazone, were 

 observed. When cooled, it was filtered and washed with a little water. The 

 yellow crystals thus obtained M'ere recrystaUized from G0% alcohol and dried over 

 sulphuric acid in a vacuum. The melting ])oint was determined and found to be 

 204°, which coincides with that of phenylglucosazone. Consequently, the osazone 

 under question is phenylglucosazone. 



