96 THE CARBOHYDRATES 



The inversion of cane sugar may be represented thus : 

 C w H n O u + H 2 = C 6 H 12 6 + C 6 H 12 6 



The molecular weight of cane sugar is 342, and the amount 

 of invert sugar this will give on inversion is, from the equation, 

 360. In other words, I gram of glucose corresponds to f| 

 = -95 gram of cane sugar. The titration result must therefore 

 be multiplied by *95 ; otherwise stated : 



10 c.c. Fehling's = -0475 gram sucrose. 



Estimation of Maltose. 



Three points must here be remembered : firstly, that 

 maltose will reduce Fehling's solution ; secondly, that this 

 reduction may not be complete, and therefore the maltose 

 must be inverted before it is titrated ; thirdly, that the re- 

 ducing power of maltose is not the ^ame as glucose, I gram 

 of maltose having the same reducing power as '62 gram of 

 glucose. From the equation representing the inversion of 

 maltose, it may be found that I gram of maltose gives I -05 

 gram of glucose; and, as I gram of maltose has the same 

 reducing power as "62 gram of glucose, it follows that I 

 gram of maltose after inversion gives an increased reducing 

 power, viz. : 



1*05 - "62 = '43 gram glucose, 

 " '43 gram glucose = i gram maltose, 



and i gram glucose = . gram maltose, 

 = 2*32 grams maltose. 



The titration result, which represents glucose, must therefore 

 be multiplied by 2-32. 



Estimation of Mixtures of Sugars. 



In many cases it is possible to isolate the different sugars 

 in solution, and estimate them separately by means of 

 Fehling's solution or by some other method, and this separa- 

 tion must be accomplished when their action on Fehling's 

 solution is similar. For example, it may be desired to esti- 

 mate the amount of levulose and dextrose in a solution. Add 

 to the dilute solution some ammoniacal lead acetate ; both 



