EGGS. 107 



the albuminous parts may be thus coagulated as the temperature 

 of the inner parts rises to boiling point. In treating meat to 

 obtain "stock" ("bouillon") for the foundation of soups, the op- 

 posite procedure is adopted. Cold water is used, and the tem- 

 perature slowly and gradually raised, but not quite to boiling 

 point, in order that as much as possible of the soluble materials 

 may be extracted, and a tasteless, friable muscle tissue remains 

 (" bouilli "). As the fluid is generally allowed to boil in order 

 to clear it, much of the proteid material which was dissolved in 

 the earlier stage, is coagulated and removed with the scum. Al- 

 though " stock " cannot contain any great proportion of the most 

 important constituents of meat, it is of much value as a nutri- 

 ment in medical practice, possibly on account of some stimulating 

 action of its ingredients upon the motions of the intestines and 

 heart. A strongly albuminous extract of meat, " beef-tea," may 

 be made by digesting flesh in a small quantity of water, and keep- 

 ing the temperature below that at which albumin coagulates, and 

 adding vinegar and salt to facilitate the formation of syntonin 

 and the solution of myosin. The salt can be then removed by 

 dialysis. 



Eggs. Eggs consist of two parts, one the white, composed of 

 albumin, and the other, the yelk, chiefly made up of fat. 



The white is a concentrated watery solution of albumin, held 

 together by delicate structureless membranous mesh-works. Be- 

 sides the albumin it contains traces of fat, sugar, extractives, and 

 salts. 



The yellow fat emulsion of the yelk contains a peculiar proteid, 

 vitellin, some grape sugar, and some inorganic salts, in which 

 combinations of phosphoric acid and potassium are conspicuous. 

 Hard-boiled eggs, if not finely divided by mastication, are also 

 very difficult to digest, for the gastric juice cannot penetrate the 

 hard masses of coagulated albumin which are so easily and com- 

 monly swallowed. Eggs, when lightly cooked, are easily digested, 

 as the albumin is already coagulated, and cannot be introduced 

 into the stomach in large masses. Eggs are of very great nutri- 

 tive value, as they contain so large a percentage of proteid, fats 

 and salts. 



