IMK'f II.

Materia Medica.

205

dysentery, and other disorders of the bowels. After they avea year old, their flesh becomes less and less digestible; but thecapon and poulard retain their tenderness longer.

The egg consists of two distinct fluid matters, the white andthe yolk; the membranes which inclose these, and the shell. *

Qualities. — The white is inodorous and insipid, of a glaryviscid nature, readily dissolving in water, coagulable by a heatof 165° Fahrenheit, and also by acids and alcohol. Whencoagulated it becomes sapid, and is no longer soluble either incold or hot water. From the experiments of Dr. Bostock, itappears to be composed of water 85*0, albumen l - 2, in 100parts; and besides shows traces of uncoagulable matter 2*7,and salts 0'3, sulphureted hydrogen gas, and benzoic acid.The yolk is also inodorous, but has a bland oily taste; andwhen agitated with water forms a milky emulsion. Whenboiled it becomes a granular solid, and yields by expressiona yellow insipid fixed oil. It consists of four constituents,water, oil, albumen, and gelatine; on the presence of the al-bumen depends the hardness of the boiled yolk. The shell con-sists of carbonate of lime, phosphate of lime, and animal mucus.When it is burnt, the carbonic acid is dissipated, the animalcement destroyed, and pure lime, with phosphate of lime,obtained. As long as the yolk remains suspended in thecentre of the albumen, an egg is supposed to be good; but itspoils as soon as the yolk touches the shell. The preventingthe admission of air, through the pores of the shell, preserveseggs for a longer period than they otherwise could be keptgood. This is effected by covering the egg with grease, ordipping it into lime water. A fresh or good egg appearssemi-transparent, when placed between the eye and the light:but when it is opaque or irregularly cloudy, it must be rejected.

Medical properties and uses. — The yolks of raw eggs aregently laxative, and have been thought serviceable in jaundiceand other hepatic obstructions. Beaten up with sugar andwine, they are extremely nutritive, and are consequently usefulin convalescencies, and other cases of debility. In pharma-ceutical operations the yolks are used for rendering oil andbalsams miscible with water ; and the whites for clarification.'The shells are antacid; but possess no advantages over chalkwhen unburned, or lime when they are burned.

PHYSETER. Syst. Nat. Gmelin. i.227.

1 Hens have been known to lay eggs when twenty years old. Supplement lo Latham, 207.

1 Owing to peculiar Idiosyncrasy, the smallest portion of the white of egg cannotbe eaten by some persons without otcasioning pain, sickness, and an erysipetalous'rnption on the skin.

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