EARTHS

a term applied in geology to certain loosely aggregated siliceous, 38 EARTH-SHINE and aluminous materials, the detritus of pre-existing rocks. In chemistry the term earth is given to certain metallic oxides, such as the ‘alkaline earths’ lime, baryta, and strontia; also to alumina and a series known as the “rare earths.” The earths were regarded as simple bodies until Sir H. Davy proved them to be compounds of oxygen with metals.