GB835128A - Apparatus for examining a substance utilising the effect of the substance on the q factor of a resonant circuit - Google Patents

Abstract

835,128. Electric furnaces. AJAX ELECTRIC CO. Sept. 5, 1956 [April 13, 1956], No. 27121/56. Class 39(3) An electric salt bath furnace has readily removable electrodes and means for minimizing electrode corrosion by substantially excluding contact of air with the electrodes at the bath surface. As shown, a furnace F comprises a pot P, a rolling cover C, tile means TM, and two pairs of electrodes E. Each electrode has a hot leg HL, positioned below the normal level 20 of the salt bath, connected by an upwardly sloping intermediate portion IL to a laminated cold leg CL which is positioned above the bath surface and connected to busbars B of a power source T. The hot legs of each associated pair of electrodes are offset towards each other to ensure that current will flow through the resulting shorter path between the hot legs and not through the intermediate portions and to provide supporting shoulders 27 for tile means TM. The pot P is chamfered as at 41 to provide a support for the bottom surface of the intermediate portion of each electrode. Removable tile means, comprising tiles 42 and 43 co-operate with the furnace wall and closely surround the portion IL to protect it from the atmosphere. Tile 42 fits between the electrodes and rests on the shoulder 27, and tile 43 which has a sloping surface 44 to conform to the upper surface of portion IL overlies a pair of electrodes and the tile 42, its bottom surface 45 resting on the upper end surface 29 of the hot leg HL, tie rods 39 also being provided to hold the tiles in place. A tile 42a (Fig. 2, not shown) between the two pairs of electrodes may be cemented in position, or may be an integral part of the wall. On initial heating, the outside layers of the portion IL oxidize to form a scale which completely fills the small air spaces between tiles and electrodes and thus prevents the ingress of air and further corrosion. In a modification, Fig. 7, three electrodes are arranged in triangular formation the cold legs being brought out in parallel formation for connection to a three-phase supply, shaped tile means 59, 64, 68, 69, 72, 73 and 77 being provided to enclose the intermediate portions uf the electrodes.