Recent research by Coaton and Phillips has provided a precise explanation of the physical mechanism causing halogen separation in linear tungsten-halogen lamps burning at arbitrary angles from the horizontal. Further investigation has shown that the two components in an argon-nitrogen or krypton-nitrogen gas mixture will separate in angle-burning linear tungsten-halogen lamps, which would have serious consequences if the nitrogen was used as an arc suppressant. The proposed separation mechanism almost certainly applies to any component in the gas filling of a linear lamp which differs in mass or bond energy from the main component. It is also equally applicable to the gases and vapours in linear discharge lamps.