STARCH. 145 



chestnut, and many other plants. They all agree in 

 general chemical characters with wheat-starch, and, 

 like it, consist of carbon, oxygen, and hydrogen, 

 rather less than one-half of their weight consisting of 

 oxygen. Starch consists of — 



Carbon 4425 



Oxygen 4908 



Hydrogen 667 



10,000 



332. When starch is examined by the help of a 

 magnifying glass, it is found to consist of variously 

 shaped transparent little grains, marked in a very 

 peculiar manner. These grains vary in shape and 

 size according to the plant from which they are ob- 

 tained; this fact renders it possible to ascertain 

 whether any particular sample of starch is arrow- 

 root, potato starch, wheat starch, or a mixture of 

 several kinds. 



333. The quantity of starch obtained from differ- 

 ent plants varies very much. Good wheat generally 

 yields from 70 to 75 per cent. ; barley contains nearly 

 80; oats and rye, 60 to 65; beans 40 to 45; peas 

 about 50; potatoes 15 to 20; arrowroot, 20 to 25. 

 Almost all the seeds and grain used as articles of 

 food, such as wheat, barley, oats, rye, maize, rice, 

 millet, &c., contain a large quantity of starch. Semo- 

 lina is prepared from hard Italian wheat; it is the 

 hard granular particles which escape the action of 

 the mill-stones. Macaroni is the dried paste of hard 



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