in Chemistry, a vessel employed in some metallurgic operations. In figure it represents an oblong arch or vault, the hinder part of which is closed by a semicircular plane, whilst the lower part or floor is a rectangular plane. It is a little oven, which 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 cupels or crucibles are placed; and the substances contained are thus exposed to intense heat, without contact of fuel, smoke, or ashes.