Limelight (also known as Drummond light or calcium light) is a type of stage lighting once used in theatres and music halls. An intense illumination is created when an oxyhydrogen flame is directed at a cylinder of quicklime (calcium oxide), which can be heated to before melting. The light is produced by a combination of incandescence and candoluminescence. Although it has long since been replaced by electric lighting, the term has nonetheless survived, as someone in the public eye is still said to be "in the limelight". The actual lights are called "limes", a term which has been transferred to electrical equivalents. - Source: Wikipedia
