EFFLORESCENCE. Some salts, like car bonate of soda or soda ash, by exposure to air lose their transparericy, and become white, crum bling into powder. This is termed efflorescence. In geology the appearance of crystals upon earthy, rocky,or other mineral surfaces, is termed efflorescence.
EGG. Birds and most insects and fishes and some other animals, are generated from globular-formed bodies called eggs, produced -within the mother. -These, after being deposited by the parent in fa'vorable situations, and ex posed to the proper influences of temperature, etc., undergo a succession of changes, which at last result in a fully developed living creature. (See Embryology.) This, breaking through the outer crust that has confined it, enters upon its new existence. The eggs of the lower orders of animals are collected and held together in great numbers by a viscous membrane, and are called spawn. Those of the birds are deposited singly.' They consist of a calcareous shell, white or colored, formed almost wholly of carbonate of lime; the other constituents are minute quan • tities of animal matter, phosphate of lime, car - bonate of magnesia, oxide of iron, and sulphur. Lining this hollow shell is a thin and tough membrane, composed principally of albumen. At the larger end of the egg is a space between the outer shell and this membrane, which, very small when the egg is first laid, gradually in creases with its age. It is called the macula aeris, and is filled with air, in which the pro portion of oxygen is larger than in the atmos phere. This, it is said, is for the respiration of the unhatched chick. Within the membrane is the white of the egg, or the albumen, a viscid liquid, in membranous cells, which encloses the yolk and the real germ of the animal. As this germ left the place of its production in the body of the female, and passed into the egg-discharg ing canal, the albumen gathered around it in Successive layers, a portion in very delicate mem branes, called the chalazcs, which are attached to 'the poles of the yolk, and serve to suspend it in such a manner that the smaller and lighter half must always be uppermost. The outer layer of the albumen, is less thick and viscid than that next the yolk. Around it the lining membrane and calcareous shell are successively added before the egg is laid. The composition of the albumen is: water, 85 parts; pure albumen, 12; mucus, 2.7; and saline matter, 0.3, including soda with traces of sulphur. The yolk, called vitellus ovi, is also a glairy fluid, commonly of a yellow color, enclosed in its own membrane, and consists of a great variety of constituents, viz. • water, 41.486; a form of albumen called vitel line, 15.76; margarine and oleine, 21 304; cho lesterine, 0.438; oleic and margaric acids, 7.226; acid, 1.2; muriate of ammonia, .034; chlorides of sodium and potassium and sulphate of potassium, 0.277; phosphates of lime and magnesia, 1.022: animal extracts, 0 4; and 0.553 of coloring matter, traces of iron, lactic acid, etc. Upon one side of the yolk is a round spot, yellowish white, called the cicatrieuta, the germ of the ovum, which by the arrangement of the chalazte, already referred to, is always kept uppermost, and next to the source of heat supplied by the animal in sitting. As that is into nto the foetus, the albumen first furnishes nourishment to it, and when this is consumed more is supplied by the yolk. Eggs of the hen are hatched by being kept at a tem perature of 104° for three weeks. Their has been retained after they have been exposed to a temperature of 10° Fahr. ; and it is a remark able fact that the freezing point of new-laid egga is much lower than that of the water and aft men of which they principally consist, and both of which congeal at about the same temperature.
Eggs, too, that have been once frozen, or have been long kept, freeze at the point their con stituents would seem to require. The specific gravity of new laid eggs is from 1.08 to 1.09. By keeping they diminish in weight from evap oration of water, and the substitution of air through the pores of the shell. This diminution has been observed to continue for two years; an egg weighing originally 907i grains being re duced, as remarked by Dr. Thomson, to 883.2 grains. When they have lost so much weight as to float upon water, they are generally un sound. The preventing of this evaporation by covering their surface with a coating of varnish, wax, gum arable, or lard, checks their putre faction. It is said that if every new-laid ,egg was at once rubbed over with sweet butter it would he a rare thing to see one unsound. The Scotch sometimes drop them in boiling wafer for two minutes, by which the membrane within the shell is partially coagulated and rendered impervious to air. Hen's eggs vary so much in gravity, that it is a wonder they continue to be sold by numbers instead of weight. A dozen of the largest have been found to weigh twenty four ounces, while the same number of smaller ones of the same stock weighed only fourteen and a half ounces. The fair average weight is said to be about twenty-two and a half ounces to the dozen. The relative weights of the por tions of the egg as given by Dr. Thomson are: shell and membrane, 106.9; albumen, 804.2; yolk, 288.9. About one-third of the entire weight may he regarded as nitrogenous and nutritious matter, a greater proportion than that of meat, whiph is rated at only from twenty five to twenty-eight per cent., while the nutritive portion of the oyster is only about twelve per cent. The white of the egg, from its tendency to coagulate into a hard and indigestible sub stance, is likely to disagree with the stomach of invalids, when the yolk may prove perfectly harmless. Raw eggs are more wholesome than boiled, or even than those lightly poa,ched,which are very digestible. Eggs betome more, difficult of digestion by being kept. In medicine the shell is used as an antacid, its animal composi tion seeming to adapt it better for the stomach than chalk, the mineral form of carbonate of lime. The white is employed for clarifying liquors and syrups. which it accomplishes by entanglingNthe small particles floating in them as it coagulates, and either rising with them to the surface, or sinking to the bottom An astringent poultice is formed by causing it to coagulate with a piece of alum briskly stirred with it. This, wider the name of alum curd, is used as an application to the eye in some forms of ophthalmia. The white is also used as an antidote to corrosive sublimate and salts of copper. The yolk is sometimes given in jaun dice, and forms an excellent diet in dyspepsia., It is preferable to the white in making emul sions. The largest sized eggs of which we have any account are some found in 1850 in alluvium in Madagascar. They belong to a bird which it is supposed has recently become extinct, to which M. Saint Hilaire has given the name of Affpfornis maximus. Two of ithe eggs are pre served in the French academy. One of them measures thirteen and a half inches on its longest diameter, and eight and a half inches on the shortest. The thickness of the shell is about onezeighth of an inch. The capacity of the egg is about eight and a half quarts, six times that of the ostrich's egg—equal to 148 hen's eggs, or 50,000 eggs of the humming bird. From some of the bones of the bird which have been pre served, its height is calculated to be about twelve feet.—New American Cyclopedia.