GB191218371A - Improvements in and relating to Vapour Electric Devices. - Google Patents

Abstract

18,371. British Thomson-Houston Co., [General Electric Co.]. Aug. 9. Low-pressure metallic-vapour apparatus.-A hightemperature mercury or like lamp with a refractory envelope has a solid anode near, but out of contact with, a body of easily-vaporizable material, which is thus heated by radiation and increases the vapour density in the lamp. Fig. 2 shows mercury 7 surrounding the positive leading-in wire of tungsten and serving to fill a side tube the composition of which changes from silica at its inner end to sodium magnesium boro-silicate sealing glass at its outer end, as described in Specification 18,300/12, [Class 39 (ii), Electric lamps, Incandescent]. The upper part of the mercury may be insulated from the wire by a silica tube having a flanged end attached to the side-tube near the middle of the latter tube, which may then be entirely of silica, and be closed by a nickel-steel plug surrounding the wire. In another arrangement, the mercury 7, Fig. 5, is contained in a pocket separate from the sealing tube, which is then filled by a quartz or other body 11, to prevent condensation. Excessive evaporation of the mercury near the anode is in all cases checked by the increase in distance between them. By varying the size of the anode and its leading-in wire, and its distance from the mercury, the current and pressure required may be varied ; the efficiency is high. The cathode may have a narrow active surface, confined by a thick-walled constriction 12, Fig. 6. Specifications 24,470/04, 10,957/06, and 18,372/12, are also referred to.