Domestic Encyclopædia (1802)/Earth

EARTH, in general, signifies that solid, incombustible substance which forms the basis of the globe we inhabit.

Chemists have, hitherto, made us acquainted with eight different species of simple earths, namely, 1. The siliceous, or flint; 2. calcareous, or lime; 3. magnesian, or talc; 4. argillaceous, or clay; 5. ponderous, or barytes (Derbyshire spar); 6. Strontian (from a place of that name in Scotland); 7. Circon, or jargon of Ceylon; and 8. glucine earth, very lately discovered by Vauquelin, and also called sweet earth of beryl.—We cannot enter into an analysis of the different earths here enumerated, and shall, therefore, content ourselves with stating, that simple earths are rarely found in a state of purity; that all the strata of rocks (which compose in a manner "the shell of this globe," on the surface of which the vegetable mould is immediately incumbent) principally consist of siliceous, argillaceous, calcareous, or other compound earths derived from the primitive kinds before specified; that stones are only earths in an indurated state; that the characteristic difference between earths and alkalis arises from the insolubility of the former, while the latter may be dissolved in water or other fluids; and, lastly, that most of these earths unite with acids, and neutralise them, like alkalis.

As we treat of those species of earth, which may be usefully employed in domestic economy, under their respective heads of the alphabet (see Clay, Flint, Lime, &c.), we cannot in this place enlarge upon the subject.