Patent GB-190314171-A (GB)
Title: Improvements relating to Gas or Vapour Electric Apparatus such as Mercury Vapour Lamps for Lighting or other Purposes
Inventor: TALL FREDERICK WILLIAM LE
Filed: 1903-06-25
Granted: 1904-05-05
Abstract: 14,171. Le Tall, F. W., [Cooper-Hewitt Electric Co.]. June 25. Vacuum tubes; arc lamps.-To maintain the purity and density of the eonducting vapour or gas in mercury vapour lamps and similar apparatus, whether for converting alternating currents o for lighting purposes, and at the same time to keep the apparatus cool, vapour &c. is withdrawn from the containers during the operation of the apparatus either by means of pumps or by circulation of the mercury forming the electrode3. Fig. 2 shows a container 1 suitable for single - phase c i rcuits. The positive and negative electrodes 9, 13 consist of mercury in veriical tubes 2, 6, which form part of or are separate from the container 1 and dip into mercury in vessels 7, 8. The mercury which condenses in the chamber 26 escapes from the. container 1 through a vertical outlet 28, carrying with it some vapour or gas, the action being similar to that of a Sprengel pump. This action tends to maintain the mercury vapour in the proper condition as regards purity and density. Overflow pipes 30 are arranged to supply the condensed mercury to the vessels 7, 8 to maintain the electrodes 9, 13 at their proper level. The vessels 7, 8, 29 may be adjustable vertically, and an auxiliary iron electrode 35 may be provided. As shown, no sealed-in electrodes are necessary, and large currents may be transmitted through the mercury columns in the electrode tubes 2, 6. In the apparatus shown in Fig. 3, the Sprengel-pump action takes place in a central tube 37, the mercury overflowing from the positive electrode 9. The mercury is cooled by radiation from its extended surface in a vessel 38 or by means of a cooling- coil 44, and is pumped back by any suitable device 40 to the positive electrode. If the negative electrode 13 requires to be cooled, similar apparatus is applied to it. The tubes 2, 6 may be replaced by conducting-wires sealed into the container, and in this case the mercury is pumped up to an open reservoir and returned by the atmospheric pressure to the container through pipes terminating in horizontal spraying-nozzles above the electrodes 9, 13. When the vapour is under pressure in the container, pressure is applied to the outer ends of the electrode tubes, e.g., by turning them up to form U-tubes. The tube 37 may then be dispensed with, and the mercury circulated from the top of one electrode tube to the other by a pump, the circulating pipes being cooled, if necessary. In any of the above apparatus, an overflow tube may surround or be surrounded by an electrode tube, and the container may be arranged for use in a polyphase circuit. A pump for drawing off deleterious gases such as oxygen and nitrogen, either continuously or intermittently, may be connected to the top of the container, whether provided with tubular electrodes as described above, or with positive electrodes of iron &c. and a negative electrode consisting of a mass of mercury lying at the bottom of the container ; it is stated that comparatively little mercury vapour is withdrawn by the pump. The Provisional Specification states that the liquid which is circulated to cool and purify the vapour need not be electrically conducting.