among ancient philosophers, one of the four elements of which the whole system of nature was thought to be composed. See ELEMENT.

EARTHS, in Chemistry, are such substances as have neither taste nor smell, are incombustible, are nearly insoluble in water, and have a specific gravity under 5. Such are lime, barytes, &c. See CHEMISTRY INDEX.

in Astronomy and Geography, one of the primary planets; being this terraqueous globe which we inhabit.

For the astronomical facts with regard to the earth, see ASTRONOMY; for its geographical history, see GEOGRAPHY; and for the opinions or theories of its Earthquake formation and changes, see GEOLOGY INDEX.