ALBUMEN. ' 151 



has a dark brown color, and is used to give color to 

 brandy and other similar spirits. 



346. Albumen and gluten in many respects are 

 very similar ; they exist in plants in smaller quantities 

 than the three substances already described ; but they 

 are nevertheless most important, and of especial in- 

 terest, as their presence in vegetables is essential to 

 their value as food (597). 



. 347. When the clear juice of any plant is boiled, 

 there usually collects on the surface a thick green 

 scum, which may easily be separated by straining 

 the liquor through linen. This scum consists almost 

 entirely of albumen and gluten, the former being a 

 distinct proximate vegetable principle, the latter a 

 mixture of two separate principles, fibrin and glia- 

 dine, with oil ; they are associated together, and 

 exist in greater or less quantity in almost all plants. 

 In general, the seeds of plants contain even a larger 

 relative proportion of these substances than the plants 

 themselves. A modification of these substances, which 

 is found in many plants, is called legumine or vege- 

 table caseine, because it is almost identical with the 

 peculiar principle of milk, called caseine (568). 



348. The flour of wheat contains a considerable 

 proportion of gluten; it maybe readily separated 

 from flour by tying a portion of thick paste in a 

 piece of linen, and then kneading the paste thus in- 

 closed in linen under a stream of cold water ; by this 

 process all the starch will gradually be washed out, 



