EGGS IN CHEMISTRY AND COMMERCE. 95 



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 sup- 

 plying calcareous substances with their food. 



Egg-shell is much used in medical prescriptions. When cal- 

 cined at a low red heat the shells afford a very pure form of car- 

 bonate 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 Af- 

 rican 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 os- 

 trich-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 fre- 

 quently 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 yel- 

 low shades, more or less of a dirty hue. In colored eggs, there 

 are uniform colors and spotted colors. Although the larger num- 

 ber of the races of domestic fowls lay white eggs, there are some 

 which have a yellow or nankeen tint ; these are principally Asi- 

 atic birds. Birds which build open nests seem uniformly to have 



