Materials for Incandescent Lighting: 110 Years for the Light Bulb
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Materials for Incandescent Lighting: 110 Years for the Light Bulb In 1879 Thomas Edison gave a gala exhibition that showed the world not just his electric light bulb but his complète electrical System for making it a practical, commercially viable way to illuminate entire cities. Edison's invention (and others at about the same time) of heating a thin filament to incandescence inside an evacuated glass bulb showed the first fundamental advance in lighting technology since direct fiâmes. In order for incandescent filaments to be put to use in light bulbs, suitable new materials had to be developed. The optimum material needed to be durable, inexpensive, and capable of being heated to incandescence over and over again. In 1802 Sir Humphrey Davy discovered that he could use electridty to heat strips of platinum or other metals to incandescence, which would then give off light for some rime. This proved impractical, though, because no satisfactory source of electridty was available to power the System, and also because the incandescent métal strands in air rapidly burned away. Seven years later, in 1809, Davy used a 2,000-cell battery to pass current through two charcoal sticks separated by four inches. The electridty arced across the gap, creating the first arc lamp. By 1820 De la Rue had made the first attempt at an actual incandescent lamp, endosing a platinum coil inside a section of glass tubing under a vacuum. In 1840 Sir William Robert Grove lit an English auditorium with similar electric lamps—platinum coils heated to incandescence and covered by inverted glass tumblers in dishes partly filled with water. This light was feeble and impractical, but the cost of the current consumed in this one instance came to several hundred pounds per kilowatt-hour! A year later the very first patent for an incandescent lamp went to Frederick de Moleyns in England. His lamp differed from those used by De la Rue and Grove, though, in that powdered charcoal bridged the gap between two platinum filaments inside an evacuated glass globe. A current passing through the platinum filaments heated the charcoal powder to incandescence. Unfortunately, the inside of the globe blackened quickly from the powdered carbon, and the lamp didn't last long. 52
In 1850 Edward G. Shepard invented a lamp that used only incandescent charcoal, and about the same rime English physicist Sir Joseph Wilson Swan created carbon filaments out of paper. In 1856 C. de Chagny, a French inventor, patented an unusual lamp for mining which functioned with an incandescent platinum filament. Using a V-shaped pièce of graphite for his filament, Russian physicist Alexandre de Lodyguine in 1872 created a light source inside a sealed glass globe filled with nitrogen. Two hundred of de Lodyguine's bulbs were installed at the Admiralty dock in St. Petersburg, but maintenance costs and the bulbs' unreliability made the system impractical. In the same year the Russian S.A. Kosloff used multiple rods of graphite, also in a nitrogen-filled chamber, but this, too, yielded poor
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