| 摘要 |
In the manufacture of flat glass by the floatation technique such as is described in Specification 893,663 there is confined adjacent the molten metal a compound of an additive element for the molten metal whose release into the molten metal is controlled by the application of a controlled electric current to the compound to cause electrolysis of the compound. The compound, which is preferably a halide salt of lithium, sodium, potassium, magnesium, calcium, strontium, barium, cerium, manganese, iron, zinc, boron, aluminium, silicon, titanium, zirconium, niobium or tantalum is confined in liquid form as a layer above the molten metal in a pocket in the tank structure, the current auxiliary heating and circulation being applied as described in Specification 1,025,581. A modified example is described with reference to Fig. 3. A reservoir 45 is extended from and separated from the pocket 31 by a wall 48. The reservoir 46 and pocket 31 are covered over by a roof 50. A layer 52 of a compound of the additive metal is confined to be in contact with both the molten metal in pocket 31 and molten metal additive element in reservoir 46. Electrodes 42 and 53 extend through the floors into the molten metal and molten metal additive respectively, and are so connected that the molten metal in pocket 31 becomes the negative electrode. When the electrolysing current is applied the compound is continually replenished by the interaction of the element released at the positive electrode with fresh additive metal from the reservoir. |
