Geissler Tubes

Sealed tubes of gla containing highly rarefied gases, and provided with platinum electrodes extending through the gla tightly sealed as they pa through it, and often extending a short distance beyond its interior surface. On pa ing through them the static discharge luminous effects are produced varying with the degree of exhaustion, the contents (gas), the gla itself, or solutions surrounding it. The two latter conditions involve fluorescence phenomena often of a very beautiful description. The pre ure of the gas is le than one-half of a millimeter of mercury. If a complete vacuum is produced the discharge will not pa . If too high rarefaction is produced radiant matter phenomena (see Radiant State) occur. Gei ler tubes have been used for lighting purposes as in mines, or for illuminating the interior cavities of the body in surgical or medical operations.