156 CHYMISTRY APPLIED TO AGRICULTURE. 



Gluten appears to exist more extensively than albumen 

 in the vegetable kingdom ; it may be extracted from 

 acorns, chestnuts, horse-chestnuts, apples, quinces, wheat, 

 barley, rye, peas, and beans; from the leaves of the cab- 

 bage, cress, hemlock, borage, and saffron ; from the ber- 

 ries of the elder, the juice of the grape, &c. ; it is, how- 

 ever, contained in the greatest quantity in the grain of 

 wheat, and it is from this that it is usually procured. 



In order to extract gluten, the flour of wheat must be 

 kneaded into a paste with water ; this paste must be after- 

 wards worked by the hand under a stream of water from a 

 spout, till the liquid flows off clear ; the starch, sugar, and 

 all the other principles contained in wheat, which are solu- 

 ble in water, are thus carried off, and there remains in the 

 hands only a soft, elastic, glutinous, ductile, semi-transpa- 

 rent substance, adhering to the fingers after it has lost its 

 moisture, and exhaling an animal odor ; this substance is 

 called gluten or the vegeto-animal principle. 



Gluten is destitute of taste, turns brown in the air, and 

 putrefies in the same manner as animal substances do ; it 

 is insoluble in alcohol, and but slightly soluble in water. 

 Combustion and distillation disengage from it the same 

 products as those furnished by animal matter. 



Wheat is composed almost entirely of starch and gluten. 

 The results of the analyses made by Davy, of the wheat of 

 different countries is as follows : 



100 parts of fall wheat of excellent quality gave of 

 starch. ... 77 

 gluten. . . .19 



100 parts of spring wheat 



starch. ... 70 

 gluten. ... 24 . 



100 parts of Barbary wheat 



starch .... 74 

 . gluten. ... 23 



100 parts of Sicily wheat 



starch .... 75 

 gluten. ... 21 



The wheat of southern countries contains more gluten 

 than that of the northern countries ; and the hard-grained 

 wheat more than the soft-grained wheat of the same coun- 

 try. That wheat which contains the most gluten, ferments 



