Melting apparatus having double wall structure

A melting apparatus comprising:

• a crucible receiving therein a material to be melted, said crucible having a peripheral wall section made of platinum on a platinum alloy;
• an electric power source;
• conductive means having one end thereof connected to said electric power source and the other end connected to said crucible, for causing electric current from said electric power source to pass through said crucible to generate heat thereby melting said material;
• at least a part of said peripheral wall section of said crucible comprising a double-wall structure having an inner peripheral wall and an outer peripheral wall;
• a pair of electricity supply flanges extending radially outwardly respectively from said inner and outer peripheral walls of said double-wall structure, said other end of said conductive means being connected to said part of electricity supply flanges;
• a filling material filled between said inner and outer peripheral walls, said filling material having heat resistance and electric insulation properties;
• and
• wherein said inner and outer peripheral walls of said double-wall structure serve respectively as resistance heating elements, and said electric current is sent to said inner and outer peripheral walls through said conductive means and said pair of electricity supply flanges to generate said heat.