Editing LZ 129 Hindenburg (section)

===Use of hydrogen instead of helium===
[[Helium]] was initially selected for the lifting gas because it was the safest to use in airships, as it is not flammable.<ref name="Macgregor">MacGregor, Anne. "The Hindenburg Disaster: Probable Cause" (Documentary film). ''Moondance Films/Discovery Channel,'' Broadcast air date: 2001.</ref> One proposed measure to save helium was to make double-gas cells for 14 of the 16 gas cells; an inner hydrogen cell would be protected by an outer cell filled with helium,<ref name="Macgregor"/><ref>{{cite web|last1=Grossman|first1=Dan|title=Hindenburg Design and Technology|url=http://www.airships.net/hindenburg/design-technology|website=Airships.net|access-date=June 9, 2015}}</ref> with vertical ducting to the dorsal area of the envelope to permit separate filling and venting of the inner hydrogen cells. At the time, however, helium was also relatively rare and extremely expensive as the gas was available in industrial quantities only from distillation plants at certain [[oil field]]s in the United States. [[Hydrogen]], by comparison, could be cheaply produced by any industrialized nation and being lighter than helium also provided more lift. Because of its expense and rarity, American rigid airships using helium were forced to conserve the gas at all costs and this hampered their operation.<ref>Vaeth 2005, p. 38.</ref>

Despite a U.S. ban on the export of helium under the [[Helium Act of 1925|Helium Control Act of 1927]],{{sfn|Sears|2015|pages=108–113}} the Germans designed the airship to use the far safer gas in the belief that they could convince the U.S. government to license its export. When the designers learned that the National Munitions Control Board refused to lift the export ban, they were forced to re-engineer ''Hindenburg'' to use flammable hydrogen gas, which was the only alternative [[Lifting gas|lighter-than-air gas]] that could provide sufficient lift.<ref name="Macgregor"/> One of the side benefits of being forced to utilize the flammable yet lighter hydrogen was that more passenger cabins could be added.