619. Ovum.—Gallinaceum, N.F. Fresh hen's egg.
619. OVUM.—Gallinaceum, N. F. Fresh hen's egg.
SOURCE.—The egg of the common domesticated hen (probably from India originally) is well known as an article of food throughout the country.
DESCRIPTION.—A thin, calcareous shell incloses an albuminous substance known as white of egg, which in turn incloses the vitellus or yolk.
CONSTITUENTS.—The three parts of an egg are entirely separate and distinctive in composition.
(a) Testa Ovi, Egg-shell.—Almost pure calcium carbonate (90 to 97 per cent.), the remainder being made up of magnesium and calcium phosphates, together with about equal quantities of organic matter.
(b) Albumen Ovi, White of Egg.—Made up mostly of a solution of albumen and water (albumen 15 per cent., water about 85 per cent.), with slight traces of fat and sugar, as well as KCl and NaCl, which are the chief components of the ash. Ovi Albumen Recens, N.F. Fresh egg albumen.
(c) Vitellus, U.S.P. 1890.—Egg Yolk, or Yelk. Compounded of water (about 52 per cent.), fat (30 per cent.), vitellin (16 per cent.), and inorganic salts (1.5 per cent.), such as chloride of sodium, sulphates and phosphates of magnesium, etc., together with coloring matter and traces of lactic acid and sugar. Ovi Vitellum Recens, N.F. Fresh egg yolk,
ACTION AND USES.—Shell sometimes used as antacid. The white, besides its nutriment, is valuable as an antidote when corrosive sublimate, sulphate of copper, or other metallic poisons have been taken into the stomach. The yolk is even more nutritious than the white, having a greater amount of digestible solids. It is used in preparing emulsions of oils and applied as a dressing for burns.