328 



CHEMISTRY. 



ingredients in all cereal grains and other seeds, and in the 

 tubers and roots of various plants. It is also in the bark 

 and pith of many trees. It is abundant in all unripe fruits, 

 and some of it changes into sugar as they ripen. All vege- 

 table substances which are used as food contain more or 

 less of starch. Thus in bread, so prominent an article of 

 food as to be called the staff of life, about four fifths of the 

 substance (that is, exclusive of the water) is starch. Arrow- 

 root is a starchy meal which is prepared in the West and 

 East Indies from the roots of marshy plants. Sago is pre- 

 pared by heat and water from starch extracted from the 

 pith of palm-trees. 



449. How Starch is Obtained. Make some dough by 



moistening flour, 

 and work it with 

 the hand on a sieve 

 or on muslin (Fig. 

 Ill), pouring some 

 water continually 

 upon it, until it 

 ceases to pass 

 through milky. 

 There will be a 

 substance left on 

 the muslin which 

 we will speak of 

 soon. That which 

 is in the water be- 

 low, giving it a 

 milky appearance, 

 is starch, which will settle in a little while as a white pow- 

 der. In a similar way it can be obtained from rasped po- 

 tato, and from other substances that contain it. 



450. The Grains of Starch. Starch appears to the naked 



Fig. 111. 



