ISOMALTOSE. 219 



but insoluble in ether. Its solutions are dextrorotatory; and the specific 

 rotation is variable, depending upon the concentration and temperature, 

 but is considerably stronger than dextrose, 1 and is generally given as 

 ( a ) D =-f 137 to 138. Maltose ferments readily and completely with 

 yeast, and acts like dextrose in regard to the reduction tests. It yields 

 phenylmaltosazone on warming with phenylhydrazine for 1J hours. 

 This phenylmaltosazone melts at 205 C., and is more soluble in hot water 

 than the glucosazone. Maltose differs from dextrose chiefly in the fol- 

 lowing: It does not dissolve as readily in alcohol, has a stronger dextrorota- 

 tory power, and has a feebler reducing action on FEHLING'S solution; 10 

 cc. FEHLING'S solution are, according to SoxHLET, 2 reduced by 77.8 milli- 

 grams anhydrous maltose in approximately 1-per cent solution. 



Isomaltose. This variety of sugar, as has been shown by FiscHER, 3 

 is produced, as are dextrin-like products, by reversion, and by the. action 

 of fuming hydrochloric acid on dextrose. A re-formation of isomaltose 

 and other sugars from dextrose can also be brought about by means of 

 yeast maltase (HILL and EMMERLiNG 4 ). It is also formed, besides 

 ordinary maltose, in the action of diastase on starch paste, and occurs 

 in beer and in commercial starch-sugar. The formation of isomaltose 

 in the hydrolysis of starch by malt diastase has been denied by many 

 investigators because they considered isomaltose as contaminated mal- 

 tose. 5 It is produced, with maltose, by the action of saliva or pancreatic 

 juice (KULZ and VOGEL) or blood-serum (ROHMANN 6 ) on starch. 



Isomaltose dissolves very readily in water, has a pronounced sweetish 

 taste, and does not ferment, or, according to some, only very slowly. 

 It is dextrorotatory, and has very nearly the same power of rotation as 

 maltose. Isomaltose is characterized by its osazone. This forms fine 

 yellow needles, which begin to form drops at 140 C. and melt at 150- 

 153 C. These are rather easily soluble in hot water and dissolve in hot 

 absolute alcohol much more readily than the maltosazone. Isomaltose 

 reduces copper as well as bismuth solutions. 



Lactose (MILK-SUGAR) . As this sugar occurs exclusively in the animal 

 world, in the milk of human beings and animals, it will be treated in a 

 following chapter (on milk) . 



1 See Hoppe-Seyler-Thierf elder's Handbuch, 8. Aufl. 



2 Cited from Tollens' Handbuch der Kohlehydrate, 2. Aufl. 1, 154. 



3 Ber. d. deutsch. chem. Gesellsch., 23 and 28. 



4 Emmerling, ibid., 34; Hill, ibid., 34, and 1. c., foot-notes 1 and 2, p. 65. 



5 Brown and Morris, Journ. of Chem. Soc., 1895; Chem. News, 72. See also Ost. 

 Ulrich, and Jalowetz, Ref. in Ber. d. deutsch. chem. Gesellsch., 28; Ling and Baker, 

 Journ. of Chem. Soc., 1895; Pottevin, Chem. Centralbl., 1899, II, 1023. 



8 Kulz and Vogel, Zeitschr. f. Biologic, 31; Rohmanh, Centralbl. f. d. med. Wis- 

 sensch., 1893, 849. 



