GUM. 147 



of pectine. The same form of gum is found in the 

 carrot, parsnip, and many similar roots. 



337. A solution of gum in water is called mu- 

 cilage ; comparatively a small quantity of gum ren- 

 ders water thick and slimy : such a solution feels 

 sticky to the fingers ; it dries slowly, and leaves a 

 small quantity of gum on the surface of any sub- 

 stance over which it has been spread. Gum is inso- 

 luble in spirit of wine ; hence mucilage is precipi- 

 tated, and the gum it contains thrown down as an 

 insoluble curd when mixed with spirit. The juices 

 of many plants are sticky from the quantity of gum 

 which they contain. 



338. Gum consists of the same elements as starch, 

 namely, oxygen, hydrogen, and carbon; but it coil- 

 tains a rather larger proportion of oxygen than 

 starch does. Gum consists of — 



Carbon 4268 



Oxygen 5059 



Hydrogen 637 



10,000 



339. Associated with gum in many plants, there 

 is found a substance which dissolves easily in water, 

 and like gum, forms a sticky thick solution; it is 

 distinguished readily from gum, however, by possess- 

 ing a sweet taste, whilst gum is insipid or tasteless ; 

 it is called sugar or saccharine matter, under which 

 names a considerable variety of different substances 

 are included. 



