"Earth (Animal) is the earth of shells of animals; or that which is obtained by , or putrefaction of animal substances. 1. The earths of the shells of Sea Fishes have the general properties of calcareous earths. It is said to differ from the mineral calcareous earths in being more difficultly soluble by vitriolic acid, and in being less disposed to vitrify along with salts and metallic glasses. The shells of eggs are also calcareous, but are somewhat fusible by fire. 2. The earths of calcined bones and horns are soluble by nitrous, marine, and vegetable acids, and with difficulty by vitriolic acid; but are not capable of being converted into quicklime by . They are said to be unfusible, even when mixed with salt, metallic glasses, and other fusible mixtures. They are therefore used in the composition of enamels and opake white glasses. Nevertheless, Wallerius affirms, that the earth of calcined bones, by intense heat, was changed, without addition, to a green glass. The same author says, that the earth of the whites and yolks of eggs was easily fusible, and that in general the fusibility of animal earths is in proportion to the softness of the parts from which they were obtained. 3. The earth of blood, flesh and skins of animals, is soluble by all acids, and is fusible by fire; that of blood and of other animal fluids being most fusible. This earth, like that of burnt bones and horns, is not calcareous; but both these kinds of earth are said to be rendered calcareous by being dissolved in acids, precipitated by fixed alkali from those acids, and afterwards calcined. They probably contain some mucilaginous substance, from which they cannot be entirely divested by fire without a previous solution in acids."