48 MALTOSE ; ITS PROPERTIES. [BOOK II. 



Its higher optical activity and smaller reducing power as com- 

 pared with glucose is exhibited below. 



Reducing Power. Optical Activity. 

 ()J 



Glucose 100 53 x 



Maltose 65 + 150 



Maltose is easily and completely fermented by yeast. When a 

 mixture of maltose and sucro-dextrose or glucose is fermented, the 

 whole of the former is said to disappear before the latter is touched 2 . 

 When heated for 3 hours with very dilute sulphuric acid, maltose 

 yields 98'3 98*9 of its weight of dextrose. 



By the action of dilute sulphuric acid upon maltose at tempera- 

 tures between 80 and 90 C., there is obtained, as the only product, 

 a dextrose having the specific rotation (a)j=58'65, and a cupric 

 reducing power of 100 3 . 



When boiled with a solution of potassium or sodium hydrate, 

 solutions of maltose react as solutions of dextrose, assuming a yellow 

 amber colour which gradually deepens into a dark yellowish brown as 

 the process of boiling is continued. 



Similarly, maltose resembles dextrose in its behaviour when boiled 

 with a solution of sodium carbonate and basic bismuth nitrate, or 

 bismuth carbonate ; the bismuth is reduced and the powder suspended 

 in the liquid becomes brown. 



W T ith Phenyl-hydrazin NH 2 - NH (C 6 H 5 ) maltose, like the other 

 true sugars, forms a compound ; a so-called phenyl-maltosazon, which 

 separates in clusters of yellow crystals ; the compound which consists 

 of two molecules of maltose and two molecules of phenyl-hydrazin, 

 has the composition C 24 H 32 N 4 9 : is soluble in about 75 parts of hot 

 water and melts at about 206 4 . Whilst in its melting point this 

 compound resembles the analogous glucosazon, C 18 H 22 N 4 O 4 (which 

 melts at 205 C.), which is formed by the action of phenyl-hydrazin 

 on grape sugar, it is distinguished from it by the fact that the 

 latter compound is almost insoluble in water. 



In order to obtain this interesting compound of Phenyl-hydrazin and 

 maltose the general process employed in the preparation of all the osazones 

 is followed. Dissolve 2 grammes of phenyl-hydrazin hydrochloride with 

 twice its weight of sodium acetate in 20 c. c. of distilled water. 



To a fairly concentrated solution of maltose add an equal volume of 

 this solution and place the mixture in a water bath, keeping it at 100 C. 

 for half-an-hour. The liquid assumes a yellow colour and if sufficiently 

 concentrated commences to deposit the crystalline maltosazone; on allow- 



1 The rotatory power of glucose solutions varies with their concentration and tem- 

 perature, diminishing as the concentration is less and vice versa (Tollens). 



2 Miller's Chemistry, Vol. in. p. 613. 



3 Brown and Heron, Op. cit., p. 620. 



4 Emil Fischer, 'Synthesen in der Zuckergruppe.' Berichte d. deutsch. chem. 

 Gesellschaft. Berlin, 1890 (No. 12), S. 2119. 



