SummaryA number of Geiger tubes were constructed using 18: 8 low-carbon stainless steel and 99· 9 + per cent_ aluminium cathode!! with tungsten anodes.Plateaux improved, but threshold voltages rose 2 V /°0 with increase in temperature. Tubes with stainless steel (lathodes operated at 100 °0 for one week showed no deterioration.A few tubes with bromine pressures approximately 0·01 em Hg in a total filling -of ·20 em Hg argon exhibited oscillations over an interval along the length of the plateau. During this interval the tubes were insensitive to external radiations. These tubes, as well as others with higher bromine pressures, also gave, at some defined overvoltage, Geiger pulses with extended tails, upon which 25 kc/s oscillations were superimposed.