THE spectrum of a high-tension D.C. arc between spectrographically pure tungsten electrodes was photographed in the near infra-red, the visible and the ultra-violet regions using the Steinheil 3 ...

It is important to note that a tungsten oxide layer is formed during this process ... This deformity is only large enough to be seen under a scanning electron microscope (SEM), but will render the tip ...

Such conditions are those obtaining when the metal surface is covered with thin oxide layers or dust particles ... out on the electrical properties of tungsten electrodes on which were formed ...