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Native alumina or aluminium sesquioxide, Al2O3; corundum; esp., the blue transparent variety of corundum, highly prized as a gem. of rubies, sapphires, and of pearlés white. Chaucer.

he free state as a reducer, and as a means of obtaining other metals (as magnesium and aluminium) is an important commercial product. Symbol Na (Natrium). Atomic weight 23. Specific gravity 0.97. Sodium amalgam, an alloy of sodium and mercury, usually produced as a gray metallic crystalline substance, which is used as…

., white earth] (Com.), a white amorphous earthy substance consisting of burnt gypsum, aluminium silicate (kaolin), or some similar ingredient, as magnesia. It is sometimes used to adulterate certain foods, spices, candies, paints, etc. -- Terra cotta. Etym: [It., fr. terra earth + cotta, fem. of cotto cooked, L. coct…

A rare metallic element of the aluminium group found in some minerals, as certain pyrites, and also in the lead-chamber deposit in the manufacture of sulphuric acid. It is isolated as a heavy, soft, bluish white metal, easily oxidized in moist air, but preserved by keeping under water. Symbol Tl. Atomic weight 203.7.…

of thiophene obtained as a white crystalline substance, (C4H3S)2.CO, by the action of aluminium chloride and carbonyl chloride on thiophene.

A fluoride of aluminium, calcium, and sodium occurring with the cryolite of Greenland.

A rare metallic element of the boron-aluminium group, found in gadolinite and other rare minerals, and extracted as a dark gray powder. Symbol Y. Atomic weight, 89. [Written also ittrium.]

(Min.), a mineral, related to spinel, consisting essentially of the oxides of zinc and aluminium; gahnite. -- Zinc vitriol (Chem.), zinc sulphate. See White vitriol, under Vitriol. -- Zinc white, a white powder consisting of zinc oxide, used as a pigment.