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Sunday, July 25, 2021

CONTINUITY: Restoring and Demonstrating an Early 1900s Nernst Lamp

The Nernst lamp was invented in 1897 by German physicist and chemist Walther Nernst (who would win the 1920 Nobel prize in chemistry for his work in thermochemistry). The Nernst lamp was an incandescent electric light which used a ceramic rod composed of oxides of yttrium and zirconium instead of the carbon filament employed by the contemporary Edison light bulb. The Nernst lamp produced about twice the light for a given amount of electricity as carbon filament bulbs, and emitted a whiter, more sunlight-like spectrum. Because the light-emitting element was already completely oxidised, it did not require a vacuum or inert gas environment, and operated with no problem in air (although lamps were usually enclosed in a glass bulb to protect objects from touching the hot element).

The main disadvantage was that the ceramic used did not conduct electricity at room temperature, and needed to be initially warmed to its conduction temperature by a separate heater, after which it would self-heat through electrical resistance. Consequently, Nernst lamps required a “starter” circuit not unlike that of fluorescent lights to initially engage the heater and then disconnect it after the light came on.

Due to its efficiency and more natural light, the Nernst lamp became popular, initially in Europe where it was manufactured by AEG in Germany. In the U.S. George Westinghouse licensed the design in 1901 and manufactured it domestically as it evaded Thomas Edison's patents on his light bulb, selling more than 130,000 by the year 1904.

Subsequently, development of tungsten filament bulbs, which emerged in their modern form during the 1910s and were more efficient and less complicated and expensive than the Nernst lamp, rendered it obsolete. Today Nernst lamps are scarce and expensive collectors' items and even more rare to see in working condition.

Posted at July 25, 2021 11:49