Carbide lamp
Carbide lamps, or acetylene gas lamps, are simple lamps that produce and burn acetylene (C2H2) which is created by the reaction of calcium carbide (CaC2) with water.
Acetylene gas lamps were used to illuminate buildings, as lighthouse beacons, and as headlights on motor-cars and bicycles. Portable acetylene gas lamps, worn on the hat or carried by hand, were widely used in mining in the early twentieth century. They are still employed by cavers, hunters, and cataphiles.
A mining or caving lamp has calcium carbide placed in a lower chamber, the generator. The upper reservoir is then filled with water. A threaded valve or other mechanism is used to control the rate at which the water is allowed to drip into the chamber containing the calcium carbide. By controlling the rate of water flow, the production of acetylene gas is controlled. This, in turn, controls the flow rate of the gas and the size of the flame at the burner, and thus the amount of light it produces.
This type of lamp generally has a reflector behind the flame to help project the light forward. An acetylene gas powered lamp produces a bright, broad light. Many cavers prefer this type of unfocused light as it improves peripheral vision in the complete dark. The reaction of carbide with water produces a fair amount of heat independent of the flame. In cold caves, carbide lamp users can use this heat to help stave off hypothermia.
When all of the carbide in a lamp has been reacted, the carbide chamber contains a wet paste of slaked lime (calcium hydroxide). This is emptied into a waste bag and the chamber can be refilled.
Small carbide lamps called "carbide candles" or "smokers" are used for blackening rifle sights to reduce glare. They are used because of the sooty flame produced by acetylene.
In 1892, Thomas Willson discovered an economically efficient process for creating calcium carbide in an electric arc furnace from a mixture of lime and coke. The arc furnace provides the high temperature required to drive the reaction. Manufacture of calcium carbide was an important part of the industrial revolution in chemistry, and was made possible in the US as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the twentieth century. In 1895, Willson sold his patent to Union Carbide. Domestic lighting with acetylene gas was introduced circa 1894 and bicycle lamps from 1896. In France, Gustave Trouvé, a Parisian electrical engineer, also made domestic acetylene lamps and gasometers.
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