MUFFLE, in Chemistry, a vessel employed 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 fireplace 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.