Lime, magnesia, zirconia, and similar oxides were used successfully.
With a diamond, carborundum or zirconia button the photosphere can be as much as one thousand times the volume of the button.
A coating of zirconia or any other oxide, for instance, is far more quickly destroyed.
Cones of zirconia are also used in the same way; or a thorium mantle in conjunction with alcohol vapour may be employed.
With the heat gun he sheared off their tentacles; he could sell the zirconia in the entities.
The sample submitted, like this in your hat, was zirconia; the earth-ore which carries the rare metal zirconium.
zirconia yields with nitrate of cobalt, when ignited, an infusible black mass.