GB501038A - Improvements in luminous gas-discharge tubes - Google Patents

Abstract

501,038. Discharge lamps. WATSON, N. G. May 14, 1937, No. 13706. Void. Convention date, June 26, 1936. [Class 39 (i)] The filling of an electric discharge lamp contains phosphorus vapour, neon and mercury vapour. The lamp which is of sodium glass and is provided with tubular, open-ended electrodes of Swedish iron having a low carbon content is " cleaned-up," by passing two discharges therethrough while filled with air and one while filled with helium, the pressure during these operations being 5 mms. Hg. The tube is evacuated and connected to a wash-bottle containing solid yellow phosphorus, the vapour from which passes into the tube until the pressure is from 3 to 5 nun. Hg., when neon'is admitted until the total pressure rises to 8 to 15 mm. A small quantity of metallic mercury is introduced from a side tube, the brightness and whiteness of the light being observed meanwhile spectroscopically. The side tube is sealed off and the lamp aged by burning at normal brilliance for twelve hours. Values of suitable diameter tubes, gas pressures and operating voltages, together with the value of the current flow are given. The lamp is stated to give white light and by adding other gases to the filling light of various tints may be obtained.