candle

Cylinder of wax (such as tallow or paraffin wax) with a central wick of string. A flame applied to the end of the wick melts the wax, which burns and produces a luminous flame. The wick is treated with a substance such as alum so that it carbonizes but does not rapidly burn out.

Candles and oil lamps were an early form of artificial lighting. Accurately made candles - which burned at a steady rate - were calibrated along their lengths and used as a type of clock. The candle was also the name of a unit of luminous intensity, replaced in 1940 by the candela (cd), equal to 1/60 of the luminance of 1 sq cm of a black body radiator at a temperature of 2,042 K (the temperature of solidification of platinum).