The garnet is but as hard as quartz, and is a silicate of alumina with lime and a little iron.
It is composed of silica, alumina, carbonate of lime, magnesia and oxide of iron.
Alizarin only stains the untreated woollen, whilst the piece treated with alumina is dyed red, and that with iron, purple.
At the end of this time it must be washed, to extract the sulphate of alumina.
The electricity keeps on working, and now it separates the alumina into its two parts.
It usually contains a little silica, alumina, and oxide of iron.
To make bottle-glass, oxide of iron and alumina is added to the silica, lime, and soda.
The affinity of alumina for the colouring matter is very remarkable.
The liquors are previously mixed with a little milk of lime, which frees them from ferric oxide, alumina, and silica.
The alumina may be separated from the ferric oxide by potash-lye.
Any of several forms of aluminum oxide used in aluminum production and in abrasives, refractories, ceramics, and electrical insulation. Alumina occurs naturally as the mineral corundum and, with minor traces of chromium and cobalt, as the minerals ruby and sapphire, respectively. In its hydrated form it also occurs as the rock bauxite. Also called aluminum oxide. Chemical formula: Al2O3.