The Limelight

Gallery opened 9 Apr 2025 Updated 12 June 2025 Oxygen-hydrogen supply updated here Index added

Limelight burners The Bessler Steropticon The Phoenix Steropticon The Limelight Bellows A Theatre Limelight NEW Other Illuminants Oil Lamps Updated The Oxy-Calcium Lamp The Oxy-Ether Lamp The Acetylene Lamp Updated The Electric Arc Lamp Updated

Limelight is a now obsolete method of generating an intense white light. It saw quite wide use in theatres and for slide-projection, until replaced by electric arc lights. The name however lives on, as someone in the public eye is said to be in the limelight. Very few people know what that meant.

Left: Oxygen-gas burners for creating limeight: 18?? Limelight is produced by playing an oxygen-hydrogen flame onto a piece of quicklime. (calcium oxide) This creates a bright white light, brighter and whiter than would be expected of the radiation from a black body at the same temperature. This is thought to be due partly to candoluminescence though there seems to still be some doubt about it. Gas mantels work in a similiar way. The limelight effect was discovered in the 1820s by Goldsworthy Gurney, an archetypal Victorian gentleman scientist. Scottish engineer Thomas Drummond (1797–1840) built a working version in 1826, and so the device is sometimes called the Drummond light. Limelight was first used for indoor stage lighting at the Covent Garden Theatre, London in 1837; it saw widespread use in theatres around the world in the 1860s and 1870s. By the mid 1870s electric arc lighting was beginning to appear. The items to the left are oxygen-hydrogen burners for making limelight. The piece of quicklime was placed on the vertical spindle at the right, on which it could be rotated and raised by means of the bevel gears and a screw thread, so the spot of incandesence traced a spiral path on a cylindrical piece of lime. The twin burner nozzle is at the extreme right. You may well be wondering why the advertisment uses the terms 'hydrogen' and 'coal gas' interchangeably. The answer is that old-style coal gas was made up of roughly equal volume of hydrogen and carbon monoxide; the hydrogen made it explosive and the carbon monoxide made it lethally poisonous. In the limelight, the carbon monoxide no doubt contributed to the heating but it was the hydrogen that produced a suitably hot flame. Limelight wouldn't work with natural gas, which is usually 95% methane. There is a short Wikipedia page for Limelight.

Left: Oxygen-gas burners for creating limeight: 18?? The oxygen consumption of this burner is said to be 10 feet per hour; presumably they meant cubic feet per hour. Now you may also be wondering where the oxygen came from. Oxygen had only been discovered by Joseph Priestley in 1774, so in 1837 it was relatively novel stuff. The standard method of making oxygen in the laboratory is to heat potassium chlorate mixed with a small proportion of manganese dioxide. This method was used but it sometimes led to disastrous explosions. Here's an account from Adelaide in Australia in 1864: ‘Three photographic artists, Messrs. Freeman, Cornock, and Stone, were engaged in making oxygen on Mr Freeman’s premises in Hindley street, when a loud report was heard, a cry of fire was raised, the fire-bell was rung, the engines brought to the spot, and a general alarm was raised in the city. On investigating the cause of the explosion, it was found that the gentlemen named had placed upon the fire a retort filled with gas-making materials. The retort was scarcely heated, when it exploded with a loud report. The room with its furnishings was almost entirely destroyed; Mr Freeman was seriously injured, and lost the sight of an eye; and Mr Cornock subsequently experienced a long illness, brought on by inhaling the suffocating gases which the explosion produced. The manganese in this case had been procured from a respectable chemist in Adelaide.’ However, Mr Cornock was not deterred: ‘A week or two ago [June 1866] Mr Cornock, a little daunted, but not intimidated by his previous experience, procured from the same chemist a second supply of manganese, with the usual proportion of chlorate of potash. Having been duly assured of the purity of the materials he commenced, in conjunction with Mr Dobbie of Gawler Place, a second gas-making experiment. As in the previous case great care was taken in the adjustment of the apparatus, but the fire had scarcely obtained access to the retort when the whole thing again violently exploded, nearly destroying the premises, the operators having a narrow escape with their lives.’ It is much more economical (and safer) to extract oxygen from the air around us. The Brin process was the first practical method. Barium oxide was heated to 500–600 °C with air to form barium peroxide, which on further heating to above 800 °C decomposes and releases oxygen. There were two brothers Brin and they went on to found the British Oxygen Company. The journal Nature for 22 December 1892 gave an analysis of oxygen supplied for limelight use: "The employment of oxygen for limelight and other purposes has increased enormously since the commercial introduction of the Brin method, by which the gas is separated from atmospheric air by a now well-known chemical process.The gas so obtained is practically pure, analysis showing that as now supplied by the Brin companies it contains on an average 95 per cent. of oxygen, the remaining five per cent consisting of inert nitrogen."

Left: A Word on how to supply the gases to the limelight: 1880s Were there really Calcium Light Companies established in most large cities? Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

Left: A Bessler Stereopticon Projector owned by J S Wooley: 1894 This is a double lantern slide projector, allowing rapid changes, or slow fades, from one slide to the next. Across the top is written: 'J S Wooley, Expert Operator of Calcium Light Stereopticon', leaving no doubt that the limelight is used. In 1894 Wooley purchased a Bessler Stereopticon Projector. A Steropticon has two projectors but does not attempt to produce a 3D image. Unfortunately there are no technical details, but there are clearly two gas cylinders (of rather crude riveted design) with two pipes leading up to the limelight controls at the back of the projectors. Presumably one held hydrogen (which can be easily made by dropping sulphuric acid on zinc) and the other Brin's oxygen. Mr Wooley does not have a Wikipedia page.

Left: A Phoenix Stereopticon: 18?? This is the usual format with one projector above the other. The valve at left allowed fading between the two slides. Note the quicklime cylinder visible in the lower projector, with the burner nozzle immediately to its right.

Left: Limelight bellows for storing hydrogen and oxygen This may look a bit crude, but it was actually quite a clever bit of design. The pressure required of the hydrogen and oxygen were equal, so this arrangement ensured they were. There are two 56 pound weights to compress the bellows, showing that the pressure needed was significant. Note that there are four pipes coming from the bellows, indicating a supply of hydrogen and oxygen to two projectors.

Left: Limelight apparatus with sliding colour filters This limelight was used at the Stadsschouwburg (city theatre) in Bruges, Belgium, in the 19th century. With sliding colour filters for green, red, yellow, purple, and blue. At bottom left are two gas hose connections with stop-cocks.

Left: Oxygen and hydrogen generator The oxygen was generated before the show by heating potassium chlorate mixed with a small proportion of manganese dioxide in a retort. As we have seen above, this could be a dangerous business. The hydrogen was made 'from gasoline in the saturator' which appears not to be illustrated. (The small tank appears to be the wash-bottle mentioned, for cleaning one of the gases) Just how this process worked is obscure; making hydrogen from hydrocarbons is today routinely done by steam reforming but this requires great heat and catalysts so it is unlikely to be used here. The word 'saturator' was usually applied to saturating oxygen with ether in the Oxy-Ether system. Why is there only one tank, with one shut-off valve, when we are dealing with two gases? This is all rather puzzling.

Left: Oxygen and hydrogen generator A bit more information here. Two carrying cases plus the tank? Sounds like a rather cumbersome outfit. And there is still no clue as to how the hydrogen is generated.

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OTHER ILLUMINANTS

Before the limelight was introduced, there were other ways of showing magic lantern slides.

OIL LAMPS

Left: A three-wick oil-lamp for magic lantern use Single-wick lamps, even in the improved Argand form, gave an inadequate light. Here there are three wicks, each with its own height adjustment, and three separate oil reservoirs. Mineral oil was used. The multiple-wick lamp gave much brighter results than earlier single-wick lamps, but it was still relatively inefficient as much of the light went sideways and was wasted.

Left: Another three-wick oil-lamp for magic lantern use This appears to be the three-wick version. Note the three separate adjustment wheels for the wicks, and at right a tall chimney to carry the amp fumes up and away. Triunial and Quadriunial are words that seem to have dropped out of use. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

Left: Helpful advice on using kerosene as an illuminant Montgomery Ward issued a large catalogue of magic lantern equipment, so they presumably knew what they were talkng about. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

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THE OXY-CALCIUM LAMP

Left: An oxy-calcium lamp The spirit (alcohol) was held in the tank to the right, and its flow controlled by the tap. The oxy-calcium lamp was the earliest and simplest version of the limelight, and not unnaturally was also the least bright. The flame of a spirit lamp was blown against the lime by a jet of oxygen, raising it to incandescence. It was in use in the 1860s.

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THE OXY-ETHER LIMELIGHT

Left: An Oxy-Ether saturator and burner A different approach used a combination of diethyl ether and oxygen. This required something called a 'saturator' which saturated the oxygen with ether vapour by passing it over some absorbent material soaked in it. The oxygen inlet is at the left From The Magic Lantern, by John Albert Manton: "Personally, I prefer the original form of saturator introduced into this country from America, which consists of two parallel brass barrels, within which are stuffed close-fitting rolls of absorbent flannel rolled round a spiral coil of wire to preserve an open gas passage."

Left: A diagram of an Oxy-Ether system There are two feeds to the burner at right; pure oxygen, and oxygen saturated with hether. In his book Mr Manton describes using methyl ether, but he almost cetainly meant diethyl ether, as dimethyl ether (DME), also known as simply methyl ether, is a gas. The upside-down drawing pin at the right is a poor representation of the burner. From The Magic Lantern, by John Albert Manton: "To Light Up with Ethoxo. See that H jet tap is open and 0 jet tap closed.Turn cylinder key, then give regulator a few turns.When you smell ether, take off chimney of lantern,and after waiting a few seconds apply a light. Don't be alarmed at a big flame. Turn it down by the regulator till there is an inverted cone of burning vapour of about two and a half inches in length. Warm lime as usual, then gradually turn on 0 tap at the jet, and adjust just as you would with a blow-through or a mixed jet." Source: The Magic Lantern, by John Albert Manton, pub 1898 by Iliffe & Sons & Sturmey of London..

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THE ACETYLENE LIGHT

Left: An Acetylene magic lantern and gas generator Acetylene lamps worked by burning acetylene in air, with a brilliant flame; there is some evidence oxygen was sometimes used. No calcium oxide was involved. The acetylene was generated on the spot by dipping calcium carbide into water, presumably by pushing down the plunger on top of the cylinder. Four burners in a row are used to generate more light. Just to the left of the four jets is a round mirror to reflect light forwards. There was a great advantage in not having to carry about bags of oxygen, but the light intensity was much inferior to the limelight.

Left: An Acetylene magic lantern gas generator This is the quadruplex acetylene burner fitted to the Thornward magic lantern shwn just above. The Museum Staff will attempt to find the Naphey patent.

Left: An Acetylene magic lantern gas generator There is unfortunately no explanation of how it works, but it looks like a variation on Kipp's Apparatus. A is a plunger which immerses the carbide in the water. B is a mesh container for the calcium carbide, E is a cylinder open at the bottom. As the gas is generated, the water level in E is pushed down by the pressure, and if no gas is drawn off the water level falls below the carbide and the reaction stops. The process is therefore pretty much self-regulating. Note the coiled tube C which leads the gas from E to the output spigot D. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

Left: Helpful advice on using acetylene as an illuminant Montgomery Ward issued a large catalogue of magic lantern equipment, so they presumably knew what they were talkng about. Note the use of four burners again. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

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THE ELECTRIC ARC LIGHT

Left: Notss on the electric arc light A brilliant light is generated when current passes between two carbon rods. It was invented by Humphry Davy around 1805, and was the first electric light. Arc lamps have a Wikipedia page. It was an admirable light source, but there were snags. The carbon electrodes required frequent adjustment; much ingenuity was applied to doing this automatically with solenoids and the like. Another snag (not realised at the time) was that the arc emitted copious amounts of ultra-violet light. This caused actors in film scenes to suffer conjunctivitis and watery eyes, a condition known as Klieg Eye, after the Klieg Light, a design much used in filming. I am suitably worried by the warning against using arc lights in series, though I have no idea what voltage is implied. The Museum Staff have always thought that series operation led to unstable or 'singing' arcs, but confirmation of this is so far not obtained. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

Left: An electric arc light The carbon rods are held in adjustable clamps, with fine control by the little handwheel at the top. Note that the top carbon is twice the diameter of the lower one. This device claims to be 'thoroughly insulated' but there appears to be no insulation at all. Hopefully the little handwheel was made of an insulating material, but it still looks dangerous to me. Source: Montgomery Ward Catalogue of Magic Lanterns, Stereopticons, and Moving Picture Machines, circa 1880.

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