Patent Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh

Karl Blum

Rolf Kiesel

To prevent carburation of a tungsten filament, the fill within the bulb is ormed by an inert gas, for example xenon or krypton, and an additive which is formed by a single halogenated hydrocarbon in which iodine is bound, and further includes at least one atom of bromine or chlorine; suitable additives are: CH.sub.2 ClI, CHCl.sub.2 I, CHClI.sub.2, CHClBrI, CH.sub.2 BrI, present in from between about 1.times.10.sup.-8 to 5.times.10.sup.-6 mol per cm.sup.3 of the internal volume of the bulb; particularly preferred are chlor iodine methane (CH.sub.2 ClI), present in about 1-3.times.10.sup.-7 mol per cm.sup.3 of the internal volume of the bulb.

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Sohnstetten, Germany

Karl Blum