The Nernst lamp was an early form of

incandescent lamp An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...

Construction

Nernst lamps did not use a glowing

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...

filament. Instead, they used a

ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain, ...

rod that was heated to

incandescence Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its high temperature. The term derives from the Latin verb ''incandescere,'' to glow white. A common use of incandescence is ...

. Because the rod (unlike tungsten wire) would not further

oxidize Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...

when exposed to air, there was no need to enclose it within a vacuum or

noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low ch ...

environment; the burners in Nernst lamps could operate exposed to the air and were only enclosed in glass to isolate the hot incandescent emitter from its environment. A ceramic of zirconium oxide – yttrium oxide was used as the glowing rod.

Efficiency

Developed by the German physicist and chemist

Walther Nernst Walther Hermann Nernst (; 25 June 1864 – 18 November 1941) was a German chemist known for his work in thermodynamics, physical chemistry, electrochemistry, and solid state physics. His formulation of the Nernst heat theorem helped pave the w ...

in 1897 at the

University of Göttingen The University of Göttingen, officially the Georg August University of Göttingen, (german: Georg-August-Universität Göttingen, known informally as Georgia Augusta) is a public research university in the city of Göttingen, Germany. Founded ...

, these lamps were about twice as efficient as carbon-filament lamps and emitted a more "natural" light (more similar in

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

daylight Daylight is the combination of all direct and indirect sunlight during the daytime. This includes direct sunlight, diffuse sky radiation, and (often) both of these reflected by Earth and terrestrial objects, like landforms and buildings. Sunligh ...

). The lamps were quite successfully marketed for a time, although they eventually lost out to the more efficient tungsten-filament

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxi ...

. One disadvantage of the Nernst design was that the ceramic rod was not electrically conductive at room temperature, so the lamps needed a separate heater filament to heat the ceramic sufficiently to begin conducting electricity.

Manufacturing

In the U.S., Nernst sold the patent to

George Westinghouse George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer based in Pennsylvania who created the railway air brake and was a pioneer of the electrical industry, receiving his first patent at the age ...

, who founded the ''Nernst Lamp Company'' at

Pittsburgh Pittsburgh ( ) is a city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, United States, and the county seat of Allegheny County, Pennsylvania, Allegheny County. It is the most populous city in both Allegheny County and Wester ...

in 1901. Minerals for the production of the glowers were extracted from the company's own mines at the legendary

Barringer Hill Barringer Hill is a geological and mineralogical site in central Texas. It lies on the former west side of the Colorado river, beneath Lake Buchanan, about northeast of the town of Llano. The hill consists of a pegmatite and geologically, lies n ...

, Texas (since 1937 submerged beneath the waters of Lake Buchanan). By 1904 a total of over 130,000 Nernst lamps had been placed in service throughout the country. In Europe, the lamps were produced by the German Allgemeine Elektrizitäts-Gesellschaft (

AEG Allgemeine Elektricitäts-Gesellschaft AG (AEG; ) was a German producer of electrical equipment founded in Berlin as the ''Deutsche Edison-Gesellschaft für angewandte Elektricität'' in 1883 by Emil Rathenau. During the Second World War, ...

, General Electricity Company) at

Berlin Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitu ...

. At the

1900 World's Fair The Exposition Universelle of 1900, better known in English as the 1900 Paris Exposition, was a world's fair held in Paris, France, from 14 April to 12 November 1900, to celebrate the achievements of the past century and to accelerate developme ...

held in Paris, the pavilion of the AEG was illuminated by 800 Nernst lamps, which was said to be quite spectacular at the time.

Later use

In addition to their usage for ordinary electric illumination, Nernst lamps were used in one of the first practical long-distance photoelectric facsimile ( fax) systems, designed by professor Arthur Korn in 1902, in

Allvar Gullstrand Allvar Gullstrand (5 June 1862 – 28 July 1930) was a Swedish ophthalmologist and optician. Life Born at Landskrona, Sweden, Gullstrand was professor (1894–1927) successively of eye therapy and of optics at the University of Uppsala. He ap ...

's slit lamp (1911) for

ophthalmology Ophthalmology ( ) is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders. An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a me ...

, for projection and in microscopy. After Nernst lamps became obsolete, "Nernst glowers" became the infrared-emitting source used in

IR spectroscopy Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or function ...

devices. (Recently, even this has become obsolete as Nernst glowers have been largely replaced for this purpose by

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder and crystal s ...

glow bars or "

globar A Globar is used as thermal light source for infrared spectroscopy. The preffered material for making Globar is silicon carbide that is shaped as rods or arches of various sizes. When inserted into a circuit that provides it with electric current, ...

s", which are conductive even at room temperature and therefore need no preheating.)

Cost

References

External links

* * - video showing the lamp in operation. {{Artificial light sources Walther Nernst Products introduced in 1897 Incandescent light bulbs