Method for the manufacture of glass and similar products

428,198. Fused silica; glass manufacture. SOC. ANON. DES MANUFACTURES DES GLACES ET PRODUITS CHIMIQUES DE ST. GOBAIN, CHAUNY, & CIREY, 1, place des Saussaies, Paris. Nov. 12, 1934, No. 32543. Convention date, Dec. 14, 1933. Addition to 400,472. [Class 56] Apparatus of the kind described in the parent Specification, for producing drawn or rolled vitreous products, is provided with a vertical resistor arranged above and coaxial with the crucible in which the vitreous material is fused. The material 1 is contained in a receptacle 2 surrounding a crucible 15 which is heated by a helical resistor 18, as described in the parent Specification. The crucible 15 is conical in shape and the bottom is constituted by a die 16 through which the fused material is drawn. The vertical resistor consists of a carbon tube 3 and a carbon rod 4 connected together at their lower ends by means of a carbon ring 5. The ring is replaced by a mandrel 31 when tubing is being drawn. The resistor is adjustably supported in the upper part of the receptacle 2 coaxial with the crucible 15, and fusion occurring about the resistor produces an empty space between it and the fused material by which vapours can escape upwards. In a modified construction, the resistor consists of a carbon rod with a diametrical slot.