SACCHAROSE. MALTOSE. LACTOSE. 126 



IL SACCHAROSES. 



CANE SUGAR GROUP. 



Cane Sugar. Apply the following tests to a solution of 2 cm 

 crystals in a tube full of water. 



1. Solutions do not reduce (Fehling, Trommer). 



2. Easily inverted = Heat with dilute H 2 SO 4 to 100 C., very 



soon a reducing sugar is produced : 



C 12 H 22 O n + H 2 O = C 6 H 12 O 6 (dextrose) + C 6 H 12 O 6 (levulose). 



Levulose is the more strongly levorotary, therefore the 

 mixture exhibits left-hand rotation to the extent of the 

 difference between the two. 



3. Barfoeds Reagent is not reduced by cane sugar. 

 Maltose is a reducing sugar. 



Differs from dextrose because rotary power, nearly three times as great maltose, 

 150 ; dextrose, 56 (10 P-C. solution at 20). Its reducing power is one-third less. 

 60 parts dextrose reduce as much as 100 parts maltose. Maltose can be trans- 

 formed into dextrose easily by acids and ferments, but dextrose not into maltose. 

 Maltose must first be transformed into dextrose before its absorption into the 

 blood. One molecule of maltose decomposes into two molecules of dextrose. 



1. Barfoeds Reagent is not reduced. 



2. Phenyl-hydrazin test, see dextrose. Requires several hours 



boiling. Yields fine yellow needles of phenyl-maltosazone, 

 shorter, but in well-shaped crystals thicker than those of 

 phenyl-glucosazone. 



Lactose is a reducing sugar. 



Less soluble in H,O than dextrose. Rotary power same as dextrose. Insoluble 

 in alcohol. Non-fermentable by yeast. Lactose must be transformed into dextrose 

 before it can be assimilated. If injected into the veins it appears in the urine. 



1. Barfoeds Reagent is not reduced. 



2. Phenyl-hydrazin reaction. See Dextrose. Requires longer 



boiling. Yields fine and shorter needles than the other 

 two sugars mentioned, usually in heavy clusters. 



