"Whatever may be the revolutions of chemical nomenclature, mankind will never cease to consider as Earths those solid bodies, composing the mineral strata, which are incombustible, colourless, not convertible into metals by all the ordinary methods of reduction, or, when reduced by scientific refinements, possessing but an evanescent metallic existence, and which either alone, or at least when combined with , are insipid and insoluble in water."