in chemistry, a vessel much used in some metallurgical operations. In figure it represents an oblong arch or vault, the hinder part of which is closed by a semicircular plane, and the lower part or floor of which is a rectangular plane. It is a little oven that is placed horizontally in assay and enamelling furnaces, so that its open side corresponds with the door of the fire-place of the furnace. Under this arched oven small cupsels or crucibles are placed; and the substances contained are thus exposed to heat without contact of fuel, smoke, or ashes.