<P> A central - draught lamp, or Argand lamp, works in the same manner as the flat - wick lamp . The burner is equipped with a tall glass chimney, of around 12 inches (300 mm) tall or taller, to provide the powerful draft this lamp requires to burn properly . The burner uses a wick, usually made of cotton, that is made of a wide, flat wick rolled into a tube, the seam of which is then stitched together to form the complete wick . The tubular wick is then mounted into a "carrier", which is some form of a toothed rack that engages into the gears of the wick - raising mechanism of the burner and allows the wick to be raised and lowered . The wick rides in between the inner and outer wick tubes; the inner wick tube (central draft tube) provides the "central draft" or draft that supplies air to the flame spreader . When the lamp is lit, the central draft tube supplies air to the flame spreader that spreads out the flame into a ring of fire and allows the lamp to burn cleanly . </P> <P> A variation on the "central - draught" lamp is the mantle lamp . The mantle is a roughly pear - shaped mesh made of fabric placed over the burner . The mantle typically contains thorium or other rare - earth salts; on first use the cloth burns away, and the rare - earth salts are converted to oxides, leaving a very fragile structure, which incandesces (glows brightly) upon exposure to the heat of the burner flame . Mantle lamps are considerably brighter than flat - or round - wick lamps, produce a whiter light and generate more heat . Mantle lamps typically use fuel faster than a flat - wick lamp, but slower than a center - draught round - wick, as they depend on a small flame heating a mantle, rather than having all the light coming from the flame itself . </P> <P> Mantle lamps are nearly always bright enough to benefit from a lampshade, and a few mantle lamps may be enough to heat a small building in cold weather . Mantle lamps, because of the higher temperature at which they operate, do not produce much odor, except when first lit or extinguished . Like flat - and round - wick lamps, they can be adjusted for brightness; however, caution must be used, because if set too high, the lamp chimney and the mantle can become covered with black areas of soot . A lamp set too high will burn off its soot harmlessly if quickly turned down, but if not caught soon enough, the soot itself can ignite, and a "runaway lamp" condition can result . </P> <P> One popular model of mantle lamp uses only a wick and is unpressurized . </P>

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