A Coleman lantern mantle glowing at full brightness">white gas lantern mantle glowing at full brightness
An incandescent gas mantle, gas mantle or Welsbach mantle is a device for generating bright white light when heated by a flame. The name refers to its original heat source in
gas light
''Gas Light'' is a 1938 thriller play, set in 1880s London, written by the British novelist and playwright Patrick Hamilton. Hamilton's play is a dark tale of a marriage based on deceit and trickery, and a husband committed to driving his w ...
s which illuminated the
streets
Streets is the plural of street, a type of road.
Streets or The Streets may also refer to: Music
* Streets (band), a rock band fronted by Kansas vocalist Steve Walsh
* ''Streets'' (punk album), a 1977 compilation album of various early UK punk ba ...
of
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
and
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
in the late 19th century. ''Mantle'' refers to the way it hangs like a cloak above the flame. Gas mantles are also used in some portable
camping
Camping is a form of outdoor recreation or outdoor education involving overnight stays with a basic temporary shelter such as a tent. Camping can also include a recreational vehicle, sheltered cabins, a permanent tent, a shelter such as a Bivy bag ...
lantern
A lantern is a source of lighting, often portable. It typically features a protective enclosure for the light sourcehistorically usually a candle, a oil lamp, wick in oil, or a thermoluminescence, thermoluminescent Gas mantle, mesh, and often a ...
s,
pressure lanterns and some oil lamps.
Gas mantles are usually sold as a fabric bag which, because of impregnation with metal nitrates, burns away to leave a rigid but fragile mesh of metal oxides when heated during initial use; these metal oxides produce light from the heat of the flame whenever used.
Thorium dioxide
Thorium dioxide (ThO2), also called thorium(IV) oxide, is a crystalline solid, often white or yellow in colour. Also known as thoria, it is mainly a by-product of lanthanide and uranium production. Thorianite is the name of the mineralogical for ...
was commonly a major component; being
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
, it has led to concerns about the safety of those involved in manufacturing mantles. Normal use, however, poses minimal health risk.
Mechanism
left, Hot gas mantles. The lowest visible mantle has partially broken, reducing its light output
upAn 85 mm ''Incandescent Petroleum Vapour Installation''">Chance Brothers ''Incandescent Petroleum Vapour Installation''
The mantle is a roughly
pear
Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosaceae, bearing the Pome, po ...
-shaped fabric bag, made from silk,
ramie
Ramie (pronounced: , ; from Malay ), ''Boehmeria nivea'', is a flowering plant in the nettle family Urticaceae, native to eastern Asia. It is an herbaceous perennial growing to tall; -based artificial silk, or
rayon
Rayon, also called viscose and commercialised in some countries as sabra silk or cactus silk, is a semi-synthetic fiber made from natural sources of regenerated cellulose fiber, cellulose, such as wood and related agricultural products. It has t ...
. The fibers are impregnated with metallic salts; when the mantle is first heated in a flame, the fibers burn away in seconds and the metallic salts convert to solid oxides, forming a brittle ceramic oxide shell in the shape of the original fabric. A mantle glows brightly in the visible
spectrum
A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...
while emitting little
infrared
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
radiation. The
rare-earth
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set of ...
(
cerium
Cerium is a chemical element; it has Chemical symbol, symbol Ce and atomic number 58. It is a hardness, soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it ...
) and actinide (
thorium
Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
) oxides in the mantle have a low
emissivity
The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is n ...
in the infrared (in comparison with an ideal
black body
A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The radiation emitted by a black body in thermal equilibrium with its environment is ...
) but have high emissivity in the
visible spectrum
The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light).
The optica ...
. There is also some evidence that the emission is enhanced by
candoluminescence
Candoluminescence is the light given off by certain materials at elevated temperatures (usually when exposed to a flame) that has an intensity at some wavelengths which can, through chemical action in flames, be higher than the blackbody emission ...
, the emission of light from the combustion products before they reach thermal equilibrium.
The combination of these properties yields a mantle that, when heated by a
kerosene
Kerosene, or paraffin, is a combustibility, combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in Aviation fuel, aviation as well as households. Its name derives from the Greek (''kērós'') meaning " ...
or
liquified petroleum gas
Liquefied petroleum gas, also referred to as liquid petroleum gas (LPG or LP gas), is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, ''n''-butane and isobutane. It can also contain some propyl ...
flame, emits intense radiation that is mostly visible light, with relatively little energy in the unwanted infrared, increasing the luminous efficiency.
The mantle aids the combustion process by keeping the flame small and contained at higher fuel flow rates than in a simple lamp. Concentrating combustion inside the mantle improves the transfer of heat from the flame to the mantle. The mantle shrinks after all the fabric material has burned away during installation leaving a very fragile ceramic oxide shell after its first use.
History
For centuries, artificial light has been generated using open flames.
Limelight
Limelight (also known as Drummond light or calcium light)James R. Smith (2004). ''San Francisco's Lost Landmarks'', Quill Driver Books. is a non-electric type of stage lighting that was once used in theatres and music halls. An intense illum ...
was invented in the 1820s, but the temperature required to produce visible light through
black-body radiation
Black-body radiation is the thermal radiation, thermal electromagnetic radiation within, or surrounding, a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body). It has a specific ...
alone was too high to be practical for small lights. In the late 19th century, several inventors tried to develop an effective alternative based on heating a material to a lower temperature but using the emission of discrete
spectral lines
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...
to simulate white light.
Many early attempts used
platinum
Platinum is a chemical element; it has Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
-
iridium
Iridium is a chemical element; it has the symbol Ir and atomic number 77. This very hard, brittle, silvery-white transition metal of the platinum group, is considered the second-densest naturally occurring metal (after osmium) with a density ...
gauze soaked in metal
nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...
s, but these were not successful because of the high cost of these materials and their poor reliability. The first effective mantle was the
Clamond basket A Clamond basket is a kind of gas mantle, invented in the 1880s by the Parisian Charles Clamond, and which he later patented in the United States. It was the first economically practical gas mantle, since prior mantles had involved expensive materi ...
in 1881, named after its inventor. This device was made from a matrix of
magnesium oxide
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
, which did not need to be supported by a platinum wire cage, and was exhibited in the
Crystal Palace
Crystal Palace may refer to:
Places Canada
* Crystal Palace Complex (Dieppe), a former amusement park now a shopping complex in Dieppe, New Brunswick
* Crystal Palace Barracks, London, Ontario
* Crystal Palace (Montreal), an exhibition buildin ...
exhibition of 1883.
The modern gas mantle was one of the many inventions of
Carl Auer von Welsbach
Carl Auer von Welsbach (1 September 1858 – 4 August 1929), who received the Austrian noble title of Freiherr Auer von Welsbach in 1901, was an Austrian scientist and inventor, who separated didymium into the elements neodymium and praseody ...
, a
chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...
who studied
rare-earth element
The rare-earth elements (REE), also called the rare-earth metals or rare earths, and sometimes the lanthanides or lanthanoids (although scandium and yttrium, which do not belong to this series, are usually included as rare earths), are a set o ...
s in the 1880s and who had been
Robert Bunsen
Robert Wilhelm Eberhard Bunsen (;
30 March 1811
– 16 August 1899) was a German chemist. He investigated emission spectra of heated elements, and discovered caesium (in 1860) and rubidium (in 1861) with the physicist Gustav Kirchhoff. The Bu ...
's student.
Ignaz Kreidl worked with him on his early experiments to create the Welsbach mantle. His first process used a mixture of 60%
magnesium oxide
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...
, 20%
lanthanum oxide
Lanthanum(III) oxide, also known as lanthana, chemical formula , is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock ...
and 20%
yttrium oxide Yttrium oxide may refer to:
* Yttrium(II) oxide
Yttrium(II) oxide or yttrium monoxide is a chemical compound with the formula YO. This chemical compound was first created in its solid form by pulsed laser deposition, using yttrium(III) oxide as ...
, which he called "Actinophor" and patented in 1887 (March 15, 1887, US patent #359,524). These original mantles gave off a green-tinted light and were not very successful. Welsbach's first company established a factory in
Atzgersdorf
Atzgersdorf (; Central Bavarian: ''Atzgasduaf'') is a former municipality in Lower Austria that is now a part of the 23rd Viennese district Liesing. A small part of the former municipality today is part of the 12th Viennese district Meidling.
Tod ...
in 1887, but it failed in 1889. In 1889, Welsbach received his first patent mentioning thorium (March 5, 1889, US patent #399,174). In 1891 he perfected a new mixture of 99%
thorium dioxide
Thorium dioxide (ThO2), also called thorium(IV) oxide, is a crystalline solid, often white or yellow in colour. Also known as thoria, it is mainly a by-product of lanthanide and uranium production. Thorianite is the name of the mineralogical for ...
and 1%
cerium dioxide
Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2. It is an important commercial produc ...
that gave off a much whiter light and produced a stronger mantle. After introducing this new mantle commercially in 1892, it quickly spread throughout Europe. The gas mantle remained an important part of street lighting until the widespread introduction of electric lighting in the early 1900s.
Production
left, Gas mantle in a street lamp (cold)
Mantles in their unused flat-packed form
To produce a mantle,
cotton
Cotton (), first recorded in ancient India, is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure ...
is woven or knit into a net bag, impregnated with soluble nitrates of the chosen metals, and then transported to its destination. The user installs the mantle and then burns it to remove the cotton bag and convert the metal nitrates to nitrites which fuse together to form a solid mesh. As the heating continues, the nitrites finally decompose into a fragile mesh of solid oxides with very high melting points.
Early mantles were sold in the unheated cotton mesh condition, since the post heating oxide structure was too fragile to transport easily. The mantle converts to its working form when the cotton burns away on first use. Originally, unused mantles could not be stored for very long because the cotton quickly rotted due to the corrosive nature of the acidic metal nitrates. The acidic metal corrosion was later addressed by soaking the mantle in an
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
solution to neutralize the excess acid.
Later mantles were made from guncotton (
nitrocellulose
Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
) which can be produced with extremely fine threads when compared with ordinary cotton threads. These had to be converted back to
cellulose
Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...
by immersion in
ammonium sulfide
Ammonium hydrosulfide is the chemical compound with the formula .
Composition
It is the salt derived from the ammonium cation and the hydrosulfide anion. The salt exists as colourless, water-soluble, micaceous crystals. On Earth the compound is e ...
before first use as guncotton is highly flammable and can be explosive. Later, it was discovered that a cotton mantle could be strengthened sufficiently by dipping it in a solution of
collodion
Collodion is a flammable, syrupy solution of nitrocellulose in Diethyl ether, ether and Alcohol (chemistry), alcohol. There are two basic types: flexible and non-flexible. The flexible type is often used as a surgical dressing or to hold dressings ...
to coat it with a thin layer that would be burned off when the mantle was first used.
Mantles have a binding thread to tie them to the lamp fitting. Until
asbestos
Asbestos ( ) is a group of naturally occurring, Toxicity, toxic, carcinogenic and fibrous silicate minerals. There are six types, all of which are composed of long and thin fibrous Crystal habit, crystals, each fibre (particulate with length su ...
was banned due to its
carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
icity, an asbestos thread was used. Modern mantles use a wire or 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, porcela ...
fiber thread.
Safety concerns
Thorium
Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
is radioactive and produces the radioactive gas
radon
Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only Rn has a sufficiently long half-life (3.825 days) for it to b ...
-220 as one of its
decay products
In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps (de ...
. Moreover, when heated to incandescence, the thorium volatilizes its in-growth
radio-daughters, particularly
radium
Radium is a chemical element; it has chemical symbol, symbol Ra and atomic number 88. It is the sixth element in alkaline earth metal, group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, ...
-224. Despite its very short half-life, radium quickly replenishes from its radio-parent (thorium-228), and every new heating of the mantle to incandescence releases a fresh flush of radium-224 into the air. This byproduct can be inhaled if the mantle is used indoors, and is an internal
alpha-emitter radio-toxicity concern. Secondary decay products of thorium include
radium
Radium is a chemical element; it has chemical symbol, symbol Ra and atomic number 88. It is the sixth element in alkaline earth metal, group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, ...
and
actinium
Actinium is a chemical element; it has chemical symbol, symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who gave it the name ''emanium''; the element got its name by being wrongly identified with a substa ...
. Because of this, there are concerns about the safety of thorium mantles. The
Australian Radiation Protection and Nuclear Safety Agency
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) is a regulatory agency under the Commonwealth of Australia that aims to protect Australian citizens from both ionising and non-ionising radiation. ARPANSA works under the g ...
recommends mantles made with yttrium instead.
A study in 1981 estimated that the dose from using a thorium mantle every weekend for a year would be , tiny in comparison to the normal annual
background radiation dose of around , although this assumes the thorium remains intact rather than airborne. A person actually ingesting a mantle would receive a dose of .
[Cecil Adams, Dec. 5, 2003]
The Straight Dope: Are camp lanterns radioactive?
/ref> However, the radioactivity is a major concern for people involved with the manufacture of mantles and an issue with contamination of soil around some former factory sites.
One potential cause for concern is that particles from thorium gas mantles "fall out" over time and get into the air, where they may be ingested in food or drink. These particles may also be inhaled and remain in the lungs or liver, causing long-term exposure exceeding the risk of background radiation. Also of concern is the release of thorium-bearing dust if the mantle shatters due to mechanical impact.
All of these issues have led to the use of alternatives in some countries, usually yttrium
Yttrium is a chemical element; it has Symbol (chemistry), symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost a ...
or sometimes zirconium
Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...
, although these are usually either more expensive or less efficient. Safety concerns were the subject of a federal suit against the Coleman Company
The Coleman Company, Inc. is an American brand of outdoor recreation products, especially camping gear, now owned by Newell Brands. The company's new headquarters are in Chicago, and it has facilities in Wichita, Kansas, and in Texas. There are ...
(''Wagner v. Coleman''), which initially agreed to place warning labels on the mantles for this concern, and subsequently switched to using yttrium.
In June 2001, the U.S. Nuclear Regulatory Commission
The United States Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the ...
published a study about the ''Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials'', stating that radioactive gas mantles are explicitly legal in the US.[NUREG-1717 section 3.14.: "any person is exempt from the requirements for a license to the extent that the person receives, possesses, uses, or transfers any quantity of thorium contained in incandescent gas mantles. This exemption was established on March 20, 1947 (12 FR 1855), and has remained essentially unchanged since that time."]
See also
* Candoluminescence
Candoluminescence is the light given off by certain materials at elevated temperatures (usually when exposed to a flame) that has an intensity at some wavelengths which can, through chemical action in flames, be higher than the blackbody emission ...
* Coleman lantern
The Coleman Lantern is a line of pressure lamps first introduced by the Coleman Company in 1914. This led to a series of lamps that were originally made to burn kerosene or gasoline. Current models use kerosene, gasoline, Coleman fuel (white g ...
* Clamond basket A Clamond basket is a kind of gas mantle, invented in the 1880s by the Parisian Charles Clamond, and which he later patented in the United States. It was the first economically practical gas mantle, since prior mantles had involved expensive materi ...
* Gas lighting
Gas lighting is the production of artificial light from combustion of a fuel gas such as methane, propane, butane, acetylene, ethylene, hydrogen, carbon monoxide, coal gas (town gas) or natural gas. The light is produced either directly by ...
*Kerosene lamp
A kerosene lamp (also known as a paraffin lamp in some countries) is a type of lighting device that uses kerosene as a fuel. Kerosene lamps have a wick or mantle as light source, protected by a glass chimney or globe; lamps may be used on a t ...
References
External links
* {{Cite EB1911, wstitle=Lighting , volume=16 , pages=651–673 , short=1
A Brief History of the Incandescent Mantle Pressure Lamp
Australian Radiation Protection and Nuclear Safety Agency article "Radioactivity in Lantern Mantles"
Document at New Jersey Consumer and Environmental Health Services containing a description of contamination at former factory site at Camden, New Jersey
''Scientific American
''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it, with more than 150 Nobel Pri ...
'', October 2, 1886
Gas technologies
Light fixtures