The following observations refer to the eggs of the domestic chicken. The egg is composed of four distinct parts: the shell; the membranous envelope of the albumen; the white; the vitellus, or the yellow. The envelope of the albumen contains nitrogen and sulphur, and phosphate of lime remains after incineration. The white or the albumen contains in 100 parts :

Albumen................................................ 12 to 15

Matter not coagulable..................................... 5

Water................................................... 80

The residue after incineration of the albumen is composed of phosphates and sulphates of lime and magnesia, and alkaline carbonates. The yellow is a phosphorated fatty matter suspended in water by means of an albuminous substance known as vitellin. The yellow contains 53·78 parts of water, 17·47 of albumen, and 28·75 of fatty matter. According to Gobley (Fonssagrives, from whom most of these details have been obtained), the yellow has the following chemical constitution :

Water....................................................  51·486

Vitellin...................................................   15·760

Margarin and olein..........................................  21·304

Cholesterin................................................    0·438

Margaric and oleic acids.....................................    7·226

Phospho-glyceric acids......................................    1·200

Sal-ammoniac..............................................    0'034

Salts.....................................................    7·299

Extracts........... ......................................    0400

Ammonia, nitrogenized matters, coloring matter, lactic acid.......    0·833

Eggs consumed by the sick should be fresh and sound. The average weight is about two ounces avoirdupois. According to Parkes, the following are tests of the freshness and soundness of eggs:

"Fresh eggs are more transparent in the center; old ones at the top. Dissolve one ounce of salt in ten ounces of water: good eggs sink, indifferent swim. Bad eggs will float even in pure water." Fonssagrives recommends the same tests. Eggs coated with beeswax dissolved in warm olive-oil (one third beeswax, two thirds olive-oil) it is said may be preserved for two years.

Eggs raw, or better, whipped, are the most digestible of alimentary substances, and, as their composition indicates, possess a very high degree of nutritive value.