32 PHYSIOLOGICAL CHEMISTRY. 



is an unimportant aldose of artificial origin. 



SORBINOSE is a ketone sugar obtained from the juice of the 

 mountain ash berry. It is levorotatory and non-fermentable 

 with yeast. 



INVERT SUGAR. This name is given technically to the mix- 

 ture of glucose and fructose, equal molecules, produced by the 

 action of weak acids on cane sugar, as described below. 



THE CANE SUGAR GROUP. 



The Saccharobioses or Disaccharides. These are sugars 

 of the formula C 12 H 22 O 11 and are important substances. 

 The best known representatives of the class are cane sugar, 

 milk sugar and malt sugar, all of which are natural products, 

 with cane sugar'the most abundant. These bodies are closely 

 related to the hexoses, two molecules of the latter being in 

 some manner condensed or united to produce one of the 

 former. The disaccharides, on the other hand, by treatment 

 with weak acids or certain ferments break up easily into two 

 molecules of a hexose, water being added in the reaction : 



GiHaOii + H 2 = C 6 H 12 Oe + C 6 H 12 6 . 



The hexose molecules formed may be alike or different, and 

 the process of converting the disaccharides into monosaccha- 

 rides in this manner is called " inversion." By this inversion 

 the following changes should be noted : 



Saccharose or cane sugar yields glucose and fructose. 



Lactose or milk sugar yields glucose and galactose. 



Maltose or malt sugar yields glucose and glucose. 



SACCHAROSE. This sugar has been known from earliest 

 times to some peoples, but did not become an article of com- 

 merce until after the discovery of the Americas. It is found 

 in the juices of various canes, several kinds of beets, the saps 

 of many trees and in many seeds and nuts. On the com- 

 mercial scale it is produced from the beet and canes and in 

 smaller amount from maple sap. 



Cane sugar does not undergo fermentation directly with 



