58 The Feeding of Animals 



following explanations will clothe them with practical 

 meaning. 



(1) The albumins. There are several albumins. 

 They are found in the juice of plants, in certain liquids 

 of the animal body such as the serous fluids, in muscle, 

 blood and milk, and abundantly in eggs. Unlike other 

 proteids, these compounds are soluble in pure cold 

 water, and when such a solution is heated to the boil- 

 ing point, they separate from the liquid by coagulation 

 and become insoluble unless acted upon by some strong 

 chemical. 



When macerated beef is treated with cold w^ater 

 the albumin in it goes into solution, and if this ex- 

 tract is boiled to make beef tea, it is a matter of com- 

 mon observation that the albumin separates in clotted 

 masses. None remains in the tea. It is well for the 

 housewife to know that all lean meat contains this 

 substance, which by prolonged treatment with cold water 

 may be removed to the detriment of the residue, and 

 which, if the exterior surface of the meat is brought 

 in contact with boiling w^ater at once, coagulates in the 

 outer laj'Crs of the meat and thus prevents an exten- 

 sive loss of soluble matter. 



The clear serous fluid which is left after removing 

 the clot from blood contains albumin which may also be 

 coagulated hy heat. After the casein is removed from 

 milk by acid or rennet, the albumin of the milk remains 

 in the whey. It is this which in part causes milk to 

 clot if brought to the boiling point. One of the most 

 familiar examples of this class of proteids is the white 

 of an Qgg, which, when cooking in boiling water, be- 



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