Abstract: A liquefying apparatus for melting solid materials has a hopper with a coiled heating element disposed therein which supports and melts the solid materials into a liquid form. The liquid is stored below the heating element in a bottom section of the hopper, and is continually adjusted to a predetermined level, in order to insure that 1) the liquid in the lower section has a substantially constant temperature distribution and 2) a skin or film is not formed on the heating element which would reduce the liquefying rate.