Blau-Gas was the trade name for a combustible gas produced by the destructive distillation of a liquid hydrocarbon, such as mineral oil. Blau-Gas is no longer used, however it was used for brazing and welding aluminum, and was also used with oxygen as a fuel gas for cutting iron and steel with a cutting torch. Blau-gas derived its name from the German chemist, Herman Blau, who invented this gas.