ISOMALTOSE 117 



resembling sword blades ; alcoholic solutions of maltosazone 

 are dextro-rotatory. (Distinction from glucosazone.) 



4. On hydrolysis, by boiling with dilute mineral acid, 

 maltose breaks up into two molecules of glucose — 



C12H22O,, + H,0 - aQHiPe 



the rotatory power of the solution being thereby diminished. 



5. Maltose is fermentable by ordinary yeast, but not by 

 S. Marxianus * and S. Ludwigii. As yeast ordinarily contains 

 maltase, it was generally thought that hydrolysis by this 

 enzyme was a preliminary to fermentation by zymase. Ac- 

 cording to Willstatter,t however, a distillery yeast free from 

 maltase is able to ferment sucrose at V^ 4-6, which is a 

 degree of acidity at which maltase is unable to act. 



The constitutional formula assigned by Haworth and Peat % 

 to maltose is — 



I ° 1 



CHOH— (CHOH)2— CH— CH— CH2OH 



. O . 



O— CH— (CH0H)3— CH— CHjOH 



from which it appears that the union between the two glucose 

 molecules is through the fourth carbon atom of one and the 

 aldehydic carbon atom of the other ; it can therefore be de- 

 scribed as a-glucosido-4-glucose. 



ISO-MALTOSE. CiaH^^Oi,. 



Not a little confusion exists with regard to the use of the 

 term iso-maltose ; the name was first given to a sugar obtained 

 by Fischer § by the action of concentrated hydrochloric acid 

 upon glucose, and this same substance has since been shown 

 to be formed also by the action of dilute hydrochloric acid 

 upon strong solutions of glucose. Subsequent workers, || 



* Croft Hill : " Proc. Chem. Soc," 1901, 17, 45. 



t Willstatter : " Zeit. physiol. Chem.," 150, 287. 



X Haworth and Peat : " J. Chem. Soc," 1927, 844. 



§ Fischer : " Ber. deut. chem. Gesells.," 1890, 23, 36S7 ; 1895, 28, 

 3024. 



II Georg and Pictet : " Helv. chira. Acta.," 1926, 9, 444. Berlin : 

 " J. Amer. Chem. Soc," 1926, 48, 1107. 



