that if you took a lump of lime or magnesia and burned it in a really hot flame, it would glow with an intense white light. Using a flame made from a rich blend of oxygen and alcohol, Gurney could heat a ball of lime no bigger than a child’s marble so efficiently that its light could be seen sixty miles away. The device was successfully put to use in lighthouses, but it was also taken up by theatres. Not only was the light perfect and steady, but it could be focused into a beam and cast on to selected performers – which is where the term ‘in the limelight’ comes from.
