Editing Fluorescent lamp (section)

====Discharge tubes====
By mid-19th century, experimenters had observed a radiant glow emanating from partially evacuated glass vessels through which an [[electric current]] passed. The explanation relied on the nature of electricity and light phenomena as developed by the British scientists [[Michael Faraday]] in the 1840s and [[James Clerk Maxwell]] in the 1860s.<ref>Gribben, John; "The Scientists; A History of Science Told Through the Lives of Its Greatest Inventors"; [[Random House]]; 2004; pp 424–432; {{ISBN|978-0-8129-6788-3}}</ref>

Little more was done with this phenomenon until 1856 when German glassblower [[Heinrich Geissler]] created a [[mercury vacuum pump]] that evacuated a glass tube to an extent not previously possible.  Geissler invented the first gas-discharge lamp, the [[Geissler tube]], consisting of a partially evacuated glass tube with a metal [[electrode]] at either end.  When a high voltage was applied between the electrodes, the inside of the tube illuminated with a [[glow discharge]].  By putting different chemicals inside, the tubes could be made to produce a variety of colors, and elaborate Geissler tubes were sold for entertainment. More important was its contribution to scientific research. One of the first scientists to experiment with a Geissler tube was [[Julius Plücker]], who systematically described in 1858 the luminescent effects that occurred in a Geissler tube. He also made the important observation that the glow in the tube shifted position when in proximity to an [[electromagnetic field]]. [[Alexandre Edmond Becquerel]] observed in 1859 that certain substances gave off light when they were placed in a Geissler tube. He went on to apply thin coatings of luminescent materials to the surfaces of these tubes. Fluorescence occurred, but the tubes were inefficient and had a short operating life.{{sfn|Bright|1949|pp=381–385}}

Inquiries that began with the Geissler tube continued as better vacuums were produced. The most famous was the evacuated tube used for scientific research by [[William Crookes]]. That tube was evacuated by the highly effective mercury [[Sprengel pump|vacuum pump]] created by [[Hermann Sprengel]]. Research conducted by Crookes and others ultimately led to the discovery of the [[electron]] in 1897 by [[J. J. Thomson]] and [[X-rays]] in 1895 by [[Wilhelm Röntgen]]. The [[Crookes tube]], as it came to be known, produced little light because the vacuum in it was too great and thus lacked the trace amounts of gas that are needed for electrically stimulated [[luminescence]].