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Page:Popular Science Monthly Volume 35.djvu/107

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EGGS IN CHEMISTRY AND COMMERCE.

chiefly those of sea-birds, or those which live in moist localities. This glutinous coating is doubtless intended to preserve the eggs from the water, or to maintain the degree of heat necessary to preserve life. There are soft eggs laid entirely without shells, or with only the albuminous inner membrane. This occurs chiefly in hens that are too fat; and this failing can be remedied by supplying calcareous substances with their food.

Egg-shell is much used in medical prescriptions. When calcined at a low red heat the shells afford a very pure form of carbonate of lime. The principal use of egg-shells is, however, when blown, for the cabinets of private ornithological collections and those of public museums. The eggs of the ostrich are often mounted in silver, and form elegant drinking-cups; so are the handsome green eggs of the Australian emeu, which look as if made of dark morocco-leather. Ostrich egg-shells serve as water vessels among the African women; necklaces made of pieces of egg-shells punched out in a circular form are worn by some African natives.

Eggs blown are sometimes used in shooting-galleries, strung as a mark or target. The smooth surface of the egg-shell can even be used for artistic purposes, and we often see ostrich-eggs and hens' eggs painted or engraved with fanciful designs.

The employment of egg-shells for ornamental purposes is extremely ancient. A MS. in the Harleian collection represents a number of egg-shells ornamented in the most elegant and costly manner; miniatures were often painted upon them with extreme care, and egg-shells thus curiously decorated became valuable and highly esteemed presents. In Venice young noblemen frequently lavished large sums of money upon portraits painted within egg-shells, intended as presents.

Those who have only seen the ordinary fowl's eggs of our shops and poultry-yards would suppose that eggs were always white. But, on examining a large collection of birds' eggs, it will be found that they are of all colors. Except, perhaps, some very clear shades, the yellow for instance, none are wanting. There are blue eggs, yellowish, green, reddish, and olive. When we consider the eggs of some nine thousand different birds known, we find that not one fifth of those of the European birds are white, and among the exotic birds the number of white is much less. The white color is not always pure; there are gray and yellow shades, more or less of a dirty hue. In colored eggs, there are uniform colors and spotted colors. Although the larger number of the races of domestic fowls lay white eggs, there are some which have a yellow or nankeen tint; these are principally Asiatic birds. Birds which build open nests seem uniformly to have