74 



POPULAR ECONOMIC BOTANY. 



and properties^ being a fine white^ silky^ or glistening-look- 

 ing powder^ which will not bind together by pressure be- 

 tween the fingers. By mixture with other matters belonging 

 to the various plants from which it is procured^ it however 

 assumes other characteristics^ which are permanent in many 

 species in so complete a degree that the starch-granules ofi'er 

 an indication of the species of the plant. 



All kinds of grain yield starch in abundance. Wheat 

 starch is manufactured in very large quantities^ but rarely 

 to serve for food^ its principal use being as a stiffening ma- 

 terial for textile fabrics ; its mode of manufacture is as fol- 

 lows : — wheaten flour is steeped in cold water for two or 

 three weeks ; this causes acetous fermentation^ w^hich dis- 

 solves a large portion of the gluten by which the starch was 

 held combined ; the residue is washed thoroughly with clean 

 cold water upon fine sieves ; here the starch and water pass 

 through^ while the bran and a further portion of the gluten 

 remain behind to be rejected. "When the starch is thus 

 washed thoroughly pure, it is placed in wooden boxes with 

 perforated bottoms, lined with canvas, through which the 

 moisture drains; when nearly dry, it is cut into square 

 masses and placed on porous tiles to absorb any remain- 

 ing moisture, after which it is finally dried in a stove; 



