The size of the grate varies with the requirements of the ventilation, but from 6 to io ft.
The usual form of ventilating furnace is a plain fire grate placed under an arch, and communicating with the upcast shaft by an inclined drift.
I and 2), where the fire-grate is placed z i ft.
Zinc oxide, ZnO, is maufactured for paint by two processes - directly from the ore mixed with coal by volatilization on a grate, as in the Wetherill oxide process, and by oxidizing the vapour given off by a boiling bath of zinc metal.
Scale be removed by falling through a grate, like ordinary coal-ashes.