ALUMINA

ALU'MINA, n. An earth or earthy substance, which has been considered to be elementary, and called pure clay; but recently, chimical experiments have given reason to believe it to be a metallic oxyd, to the base of which has been given the name aluminum. This metallic base however has not been obtained in such a state as to make its properties susceptible of examination. Alumina is destitute of taste and smell. When moistened with water, it forms a cohesive and ductile mass, susceptible of being kneaded into regular forms.

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A‐lu″mi‐na (�), n. [[L. alumen, aluminis. See Alum.]] (Chem.) One of the earths, consisting of two parts of aluminium and three of oxygen, Al2O3. ☞ It is the oxide of the metal aluminium, the base of aluminous salts, a constituent of a large part of the earthy siliceous minerals, as the feldspars, micas, scapolites, etc., and the characterizing ingredient of common clay, in which it exists as an impure silicate with water, resulting from the decomposition of other aluminous minerals. In its natural state, it is the mineral corundum.