284 SUGARS. [CH. XIII 



several hours. Filter off the glucosazone (which is nearly 

 insoluble in cold water) and evaporate the solution to a 

 small bulk on the water-bath and allow it to cool ; maltos- 

 azone (which is soluble in water) should [separate out if 

 maltose was present in the original solution. 



[The maltosazone obtained in this way will not be 

 pure, for satisfactory identification it should be recrystal- 

 lised from alcohol and the melting point determined.] 



This reaction in connection with the evidence obtained 

 by an increase of reducing power on complete inversion, 

 as compared with the reducing power after inversion 

 with citric acid, will show satisfactorily whether maltose 

 is present or not. 



(c) Mannite and Pentoses. 



Mannite. 



A portion of solution is completely fermented with 

 yeast, filtered, evaporated to dryness, and the residue is 

 taken up with absolute alcohol. Addition of ether causes 

 a precipitate if mannite is present. 



If ether causes a precipitate, the precipitate should be 

 collected and recrystallised from alcohol. Mannite crystal- 

 lises well and may be recognised by the appearance of the 

 crystals. 



[Dulcite gives the same reactions, but can be easily 

 distinguished from mannite by giving mucic acid when 

 oxidised with nitric acid. Dulcite is of rare occurrence.] 



Pentoses. 



A portion of aqueous solution is distilled with hydro- 



