THE VOLATILE PAET OF PLANTS. 101 



Exp. 53. — Prepare a solution of vegetable casein from crualiod peas, 

 oats, almonds, or pea-nuts, by soaking them for some hours in warm 

 ■water, and allowing the liquid to settle dear. Coagulate the casein by 

 addition of- an acid to the solution. It may be coagulated by rennet, 

 and by salts of magnesia and lime, in the same mauner as animal casein. 



The Chinese prepare a vegetable cheese by boiling peas 

 to a pap, straining the liquor, adding gypsum until coagu- 

 lation occurs, and treating the curd thus obtained in the 

 same manner as practiced with milk-cheese, viz.: salt- 

 ing, pressing, and keeping until the odor and taste of 

 cheese are developed. It is cheaply sold in the streets of 

 Canton under the name of Tao-foo. Vegetable casein 

 occurs in small quantity in oats, the potato, and, many 

 plants ; and may be exhibited by adding a few drops of 

 acetic acid to turnip juice, for instance, which has been 

 freed from albumin by boiling and filtering. The casein 

 from peas and leguminous seeds has been designated 

 legumin, that of the oat has been named avenin. Almonds 

 yield a casein, which has been termed emulsin. As al- 

 ready mentioned, casein (Ritthausen's gluten-casein) exists 

 in wheat-gluten, and in rye. Each of these sources yields 

 a casein of somewhat peculiar characters ; the causes of 

 these diiferences are not yet ascertained, but probably lie 

 in impurities, or result from mixture of other albuminoids. 



In crude wheat-gluten two other albuminoids exist, viz. : 



Gliadin, or vegetable glue, is very soluble in water and 

 alcohol. It strongly resembles animal glue. 



Mucidin resembles gliadin, but is less soluble in strong 

 alcohol, and is insoluble in water. When moist, it is yel- 

 lowish-white in color, has a silky luster, and slimy consist- 

 ence. It exists also in rye grain. (Ritthausen, Jour, fur 

 Prakt. Chem., 88, 141 ; and 99, 463.) 



Composition of the Albuminoids. — There are various 

 reasons why the exact composition of the bodies just de- 

 scribed is a subject of uncertainty. They are, in the first 

 place, naturally mixed and associated with other matters 

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