VITELLIIS O'VI, or the yelk of the egg of the domestic fowl, is employed in phar macy for the purpose of administering substances insoluble in water (the oils and resins, for example) in the form of emulsions. The white is employed as an antidote, in cases of poisoning by corrosive sublimate or with salts of copper. As a dietetic article in the' sick-room, eggs, either lightly boiled or poached, or as inzredients of puddings, are invaluable; the stomach, after an acute disease, being often able to digest an egg, when any more solid article of animal food would set up gastric irritation.
The article EGG, CHEMISTRY OF, requires a few supplementary remarks. The albumen, occurring in the white, is for the most part in combination with soda; in addition to this principal ingredient, the white contains fats (chiefly margarin). grape sugar 5 per cent of the dried residue), and soluble salts, in which the chlorides preponderate, with a 'little silica (for the formation of feathers) and fluorine. The yelk consists of casein (fOrming 14 per cent), albumen (about 3 per cent), fats, some of which contain phosphorus (about 30 per cent), a little grape-sugar, and mineral constituents (about 1.5 per cent), in which there is a great preponderance of potassium
compounds and phosphates. Of the pigments of the yelk we only know that there is both a yellow and red pigment, and that one at least of them contains iron. It is,difti cult to conceive a more concentrated form of nourishment than a food thus composed of casein, albumen, fat, sugar, potassium salts, phosphates, and iron; and its resem blance in composition to milk is very remarkable.
The shell of the egg consists almost folely of carbonate of lime (about 97 per cent), with a little phosphate of lime. and traces of magnesia and organic matter. The variety of color in the eggs of different birds is supposed to be due to certain modifica tions of bile-pigment with which they come in contact in the cloaca.