Blau gas (German: Blaugas) is an artificial illuminating gas, similar to propane, named after its inventor, Hermann Blau of Augsburg, Germany. Not or rarely used or produced today, it was manufactured by decomposing mineral oils in retorts by heat, and compressing the resulting naphtha until it liquefied. It was transported in liquid condition, and, like LPG, when released returns to a gaseous state.
Blau gas has a rather water-like color. It was historically stored in steel cylinders for shipment, and, around the turn of the century, had the advantage of possessing the highest specific energy of all artificially produced gases. Chemically, Blau gas is similar to coal gas, but, unlike coal gas, is free from carbon monoxide. Furthermore, Blau gas is difficult to bring to explosion.
Blau gas was burned for lighting and heating; a less-pure form known as Pintsch gas fuelled illuminated buoys and beacons (for navigation), railroad car lights and stoves in the late 19th and early 20th centuries. Blau gas is most famous, however, as the buoyancy compensating fuel for the LZ 127 Graf Zeppelin. Because it weighs approximately the same as air, burning Blau gas and thereby replacing its volume with air does not lighten the gas cells of an airship, thereby eliminating the need to adjust buoyancy or ballast in-flight.
Blau gas contains about 50% olefins (alkenes), 37% methane and other alkanes, 6% hydrogen, while the rest is air. The heat of combustion is 122 MJ/m3.
hermann Blau blaugass.