Resistance heating element

Claim 1

A RESISTANCE HEATING ELEMENT FOR OPERATION AT TEMPERATURES IN EXCESS OF 1600*F. COMPRISING AN ELONGATED, FIRST TUBULAR METAL OUTER SHEATH MEANS COMPRISING A TUBULAR INNER COMPONENT FORMED OF STEEL HAVING NO CHROMIUM CONTENT AND A TUBULAR OUTER COMPONENT FORMED OF A CHROMIUM CONTAINING ALLOY COEXTENSIVE WITH AND TIGHTLY EMBRACING SAID INNER COMPONENT, SAID FIRST OUTER SHEATH MEANS INCLUDING FRONT AND REAR END PORTIONS, SAID ALLOY BEING CAPABLE OF REMAINING STRUCTURALLY STABLE AT TEMPERATURES AT WHICH SAID INNER COMPONENT LOSES STRUCTURAL STABILITY, THE FRONT END PORTIONS OF SAID TUBULAR INNER AND OUTER COMPONENTS EACH BEING PROVIDED WITH END CLOSURE MEMBER OF A MATERIAL COMPATIBLE WITH THE INNER AND OUTER COMPONENTS, RESPECTIVELY, A SECOND ELONGATED TUBULAR METAL INNER SHEATH MEANS DISPOSED IN SPACED COAXIAL RELATION WITHIN SAID OUTER SHEATH MEANS INCLUDING FRONT AND REAR ENDS, ELECTRICALLY CONDUCTIVE METALLIC MEANS FORMING A CLOSURE FOR SAID FRONT END OF SAID SECOND INNER SHEATH MEANS, AN ELECTRICAL RESISTANCE ASSEMBLY DISPOSED IN SPACED COAXIAL RELATION WITHIN SAID SECOND INNER SHEATH MEANS, ONE END OF SAID ELECTRICAL RESISTANCE BEING CONNECTED TO SAID CLOSURE MEANS, A FIRST MASS OF COMPACTED MAGNESIUM OXIDE DISPOSED BETWEEN AND HOLDING SAID OUTER AND INNER SHEATH MEANS IN SPACED PARALLEL RELATION, A SECOND MASS OF COMPACTED MAGNESIUM OXIDE DISPOSED IN AND FILLING SAID INNER SHEATH MEANS AND HOLDING SAID RESISTANCE ASSEMBLY IN SAID SPACED COAXIAL RELATION THEREIN, THE REAR END PORTION OF SAID FIRST OUTER SHEATH MEANS AND SAID INNER SHEATH MEANS BEING PROVIDED WITH INSULATING CLOSING MEANS TO PREVENT THE ENTRANCE OF ATMOSPHERE INTO SAID FIRST MASS AND SAID SECOND MASS OF MAGNESIUM OXIDE, AND TERMINAL MEANS FOR COMPLETING AN ELECTRICAL CIRCUIT THROUGH SAID ELECTRICAL RESISTANCE ASSEMBLY AND INNER SHEATH MEANS.