Abstract: According to the present invention an exothermic member is provided freely rotatably and formed in a ring form composed of an exothermic resistor layer of high resistivity formed on an inner peripheral surface and a conductor layer of low resistivity formed on the outer peripheral surface of the exothermic resistor layer. A medium-leading member is provided for forming a conveyance path for media with the outer peripheral surface of the exothermic member in between and a pressing electrode member is provided for supporting the exothermic member in abutting against the exothermic resistor layer in a conductive state in a position opposing to the medium-leading member.

Abstract: A method of producing a precursor pitch suitable for the production of carbon fibers, which method includes dissolving a coal tar pitch in a particular solvent to remove a solvent insoluble matter, distilling off the solvent to obtain a purified pitch containing no free carbon, and heat-treating the purified pitch to obtain an objective precursor pitch.

Abstract: A method of producing a precursor pitch for use in the production of carbon fibers, which comprises hydrogenating a soft or middle tar pitch to obtain a hydrogenated pitch containing no free carbon and high molecular weight components and then subjecting it to a heat treatment. In this method, the hydrogenation is carried out in the presence of tetralin at a temperature of 400.degree.-450.degree. C., and the heat treatment after the removal of solvent insoluble components and solvent is carried out in an inert gas atmosphere at a temperature of 450.degree.-500.degree. C. and under a reduced pressure of 0.1-10 Torr.