Brazing furnace

Claim 1

A FURNACE COMPRISING SEPARABLE TOP AND BOTTOM SECTIONS, MEANS FOR HEATING THE INTERIOR OF SAID SECTIONS, A PAIR OF PLANAR ENVELOPE SHEETS INTERMEDIATE SAID TOP AND BOTTOM SECTIONS, A CLOSURE MEMBER BETWEEN SAID ENVELOPE SHEETS, THE BOTTOMMOST OF SAID ENVELOPE SHEETS HAVING AN OPENING THERETHROUGH, MEANS FOR MAINTAINING THE UPPERMOST SHEET IN INTIMATE CONTACT WITH A SANDWICH CONSTRUCTION POSITION BETWEEN SUCH SHEETS, SAID MEANS EXTENDING THROUGH SAID BOTTOM SECTION AND IN COMMUNICATION WITH THE SPACE BETWEEN SAID ENVELOPE SHEETS THROUGH THE OPENING IN THE BOTTOMMOST SHEET FOR EVACUATING THE SPACE BETWEEN THE ENVELOPE SHEETS, A REFERENCE SLAB SEATED ON THE BOTTOMMOST ENVELOPE SHEET, A SLAB SEATED ON THE TOPMOST ENVELOPE SHEET, AN INTERMEDIATE ENVELOPE SHEET EXTENDING BETWEEN THE TOPMOST AND BOTTOMMOST ENVELOPE SHEETS AND OVER THE REFERENCE BASE, SAID INTERMEDIATE ENVELOPE SHEET HAVING AN OPENING THERETHROUGH IN ALIGNMENT WITH THE OPENING IN THE BOTTOMMOST ENVELOPE SHEET, THE MEANS EXTENDING THROUGH THE BOTTOM SECTION BEING IN COMMUNICATION WITH THE SPACE BETWEEN THE TOPMOST ENVELOPE SHEET AND THE INTERMEDIATE ENVELOPE SHEET THROUGH THE OPENINGS IN THE BOTTOMMOST ENVELOPE SHEET AND SAID INTERMEDIATE ENVELOPE SHEET, MEANS SEALING THE SPACE BETWEEN THE INTERMEDIATE ENVELOPE SHEET AND THE BOTTOMMOST ENVELOPE SHEET FROM THE PASSAGE THROUGH THE OPENINGS, AND A PAIR OF CLOSURE MEMBERS BETWEEN SAID ENVELOPE SHEETS, ONE OF SAID CLOSURE MEMBERS BEING BETWEEN THE TOPMOST ENVELOPE SHEET AND THE INTERMEDIATE ENVELOPE SHEET AND THE OTHER CLOSURE MEMBER BEING BETWEEN THE BOTTOMMOST ENVELOPE SHEET AND THE INTERMEDIATE ENVELOPE SHEET.