56 THE THEORY OF IONS 



The di-saccharides or Cane-sugar group are 

 products of an aldose or alcoholic aldehyde and a 

 ketose in such a way that there is a loss of a molecule 

 of water. Thus : 



(C 6 H 12 6 - H) + (C 6 H 12 6 - OH) - C 12 H 22 O n + H 2 0. 



Dextrose Laevulose Cane-sugar 



Maltose consists of two molecules of dextrose 

 linked together, with loss of water ; and lactose of a 

 molecule of dextrose and a molecule of galactose, 

 also linked together with loss of (H + OH) a molecule 

 of water. 



The poly-saccharides, amyloses, or cellulose group 

 are likewise formed by linking together more than 

 three molecules of hexoses or glucoses in the sugar- 

 cane fashion. 



Glucosides are formed from dextrose or other 

 glucoses and a phenol, by junction of their alcoholic 

 hydroxyls in regular ether-fashion ; that is, by one 

 of the molecules dropping an H and the other an 

 OH to form a molecule of water. They can also be 

 split into their components by enzymes or by dilute 

 alkalies and acids. 



Combinations of C and H alone are called hydro- 

 carbons. The simplest compound is that in which 

 each of the four valencies or poles of the carbon 

 atom is joined to a hydrogen atom. It is marsh gas 

 or methane, CH 4 . The organic world is constructed 

 out of this combination by repeatedly removing one 

 or more atoms of hydrogen, and placing some 

 equivalent in their stead. This is done by substitu- 

 tion or replacement. The carbon atom may drop one 



