STARCH. 357 



the syrup. The former object is effected by the addi- 

 tion of chalk and subsequent nitration, and the latter, 

 as usual, by boiling 



TT 899. WOOD CONVERTED INTO GUM. 



How is wood 



converted into If the boiling be omitted in the above pro- 

 cess, the woody film takes the form of a 

 gum, called dextrine, of the same composition as the. 

 wood itself, but soluble in water. Linen, or cotton 

 rags, or paper, may be converted into sugar, or gum, 

 by the same process. The sugar obtained is the same 

 as that contained in grapes, and is therefore called 

 grape sugar, and also glucose. It differs, somewhat, 

 from ordinary cane sugar, as will be hereafter explained. 



STARCH. 



WJiatissaid ^00. DESCRIPTION. Starch is identical 



of the compo- i n composition with wood and gum. It 



sitlon and i -i 



structure of consists of minute enveloped grains, which 

 burst and discharge their contents when 

 swollen by warm water. 



Where is 901. OCCURRENCE. Starch isfoiuid 



starch found? j n abundance in most grains and other 

 seeds ; in the tubers of the potatoe plant ; in many 

 fruits, and in the pith of certain trees. In greater or 

 less quantity, it is contained in all substances of vege- 

 table origin which are used as food. Horse chestnuts 

 contain 12 per cent, of starch, and have been used in 

 Europe for the production of flour. 



902. STARCH FROM POTATOES. Starch 



How is starch . 



prepared from is prepared from rasped potatoes, by wash- 

 potass/ ing them Qn a seiye> Th water becomes 



