CHEMISTRY OF A HEN'S EGG. 25 



moment's consideration. Great as is the physical 

 and chemical difference between a fully cooked and 

 an uncooked egg, it is no less remarkable in the 

 degree of digestibility conferred upon it by the 

 process. Uncooked, it passes by the most simple 

 processes of assimilation from the digestive to the 

 nutritive and circulatory organs, and is at once 

 employed in nourishing or sustaining the bodily 

 functions. Unduly cooked, the egg resists the ac- 

 tion of the gastric juices for a long time, and be- 

 comes unsuited to the stomachs of the weak and 

 dyspeptic. A raw or soft-boiled egg is of all va- 

 rieties of food the most concentrated and nourish- 

 ing ; a hard-boiled egg is apt to trouble the diges- 

 tion of the strong and healthful, and its nutrient 

 properties are sensibly impaired. 



The yolk contains water and albumen, but associ- 

 ated with these is quite a large number of mineral 

 and other substances which render it very complex 

 in composition. The bright yellow color is due to a 

 peculiar fat or oil, which is capable of reflecting the 

 yellow rays of light, and this oil holds the sulphur 

 and phosphorus which abound in the egg. If the 

 yolk be removed and dried, and the yellow oil sepa- 

 rated, it will be found to form two thirds of the 

 substance. The whole weight in its natural state 

 is about 300 grains, of which three fifths are water ; 

 of the white, more than three quarters are water. 



