hot airships don't really exist. you get hot air balloons, but they're only marginally steerable.
If you were to find a hot air ship, well, then lift would be provided by the hot air. The gas they'd use to create that hot air would be propane.
gas is still used in airships to provide lift.
Hydrogen used to be used in airships.
Airships do use gas, to provide lift.
the gas that helps airships is i hate you wikianswers.com
The gas was Hydrogen.
Helium is used because it is lighter than air
Hydrogen was the gas that was once used to filled airships. It is extremely plentiful and easy to produce. However, it is also extremely flammable and caused a few accidents. Helium is now used.
Zeppelins.
Hydrogen was once used to fill airships. Quite dangerous due to how flammable it is.
Helium is a lighter gas than oxygen, ever seen balloons filled with helium? They rise upwards with heat due to a lesser amount of particles. If we used oxygen, the airships wouldn't get off the ground!
The gas that helium replaced was Hydrogen
The Hindenburg disaster