EARTHS

In chemistry , a group of metallic oxides. The principal earths are baryta strontia, lime, magnesia, alumina, berylla or glucina, yttria, zirconia, and thoria. The first four are termed ALKALINE EARTHS ; the remainder, together with the oxides of the very rare metals erbium, terbium, norium, cerium, lanthanum, and didymium, constitute the EARTHS PROPER . The term earth was very loosely applied by the older chemical and pharmaceutical writers, and the practice is still common among the vulgar at the present day. Thus, ABSORBENT EARTH (chalk); ALUMINOUS E. , ARGILLACEOUS E. (alumina); BOLAR E. (bole); BONE-E. (phosphate of lime); FULLER’S E. (an absorbent clay); HEAVY E. (baryta); Japan e. , or terra Japonica (catechu); SEALED E. (bole), ., are names even now frequently encountered both in trade and in books.