A purer form is made from the mineral bauxite by driving off its
combined water. Bauxite is the ore from which is made the pure aluminum
oxide used in the electric furnace for the production of metallic
aluminum. Formerly we imported a large part of our bauxite from France,
but when the war shut off this source we developed our domestic fields
in Arkansas, Alabama and Georgia, and these are now producing half a
million tons a year. Bauxite simply fused in the electric furnace makes
a better abrasive than the natural emery or corundum, and it is sold for
this purpose under the name of "aloxite," "alundum," "exolon," "lionite"
or "coralox." When the fused bauxite is worked up with a bonding
material into crucibles or muffles and baked in a kiln it forms the
alundum refractory ware. Since alundum is porous and not attacked by
acids it is used for filtering hot and corrosive liquids that would eat
up filter-paper. Carborundum or crystolon is also made up into
refractory ware for high temperature work. When the fused mass of the
carborundum furnace is broken up there is found surrounding the
carborundum core a similar substance though not quite so hard and
infusible, known as "carborundum sand" or "siloxicon.
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