vitrified

At the level of the ground there should be a course of hollow vitrified brick to exclude dampness and to give ventilation.

It was also employed in enamel painting as it vitrified without change.

This substance is capable of being readily vitrified by the addition of alkaline fluxes, and is thus converted into glass.

The oxides thus produced, are dissolved and carried down into the porous cupel in a liquid state, by the vitrified oxide of lead.

If the brick is not properly burned it will be only partly vitrified and therefore not of maximum durability.