NEN Gallery

The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end. A Geissler tube contains one or more of the following rarefied (thinned) gasses, such as neon, argon, or air, mercury or other conductive liquids, or ionizable minerals or metals, such as sodium. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines.