Gaseous electric discharge lamp device

538,533. Metal-vapour apparatus. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN. April 11, 1940, No. 6569. Convention date, April 14, 1939. Addition to 484,143. [Class 39 (i)] In artificially cooled high-pressure metal vapour discharge tubes as described in the parent Specification, the anode 4 is formed as a hollow body through which a cooling medium is passed to adapt the tube for heavy currents without unduly enlarging the cross-section of the anode, which may be less than 10 times that of the cathode. In the form shown, the cathode 2 is of tungsten with a diameter 1.5 m.m. and may be coated with activating oxides. The anode is a tungsten tube 4 m.m. in diameter with a wall thickness of .8 m.m., and closed at the inner end with a wall 1.5 m.m. thick. The distance between the electrodes is 20 m.m. Cooling medium is led to the interior of the anode by a tube 8 and passes away by apertures 11 in a tubular sleeve 10 connecting the open end of the anode with an enlarged part of the tube 8. The envelope has an internal and external diameter of 6 and 9 m.m. respectively, and is enclosed in the cooling jacket 12 with inlet 17 and outlet 16 for the cooling medium. The electrodes project a distance about 1 m.m. from a surrounding quantity of mercury, which is regulable in manufacture by adjusting the length of the side tube 7.