Acetylene

Acetylene was a gas used in welding, and sometimes for lighting.

Acetylene could be produced by adding water to carbide, which could then be used to light carbide lamps. 

In the 20th century, some torches used acetylene. 

In 2265, the air in 's salvage bay was thick with ozone and acetylene exhaust. 

In 2381, acetylene was used in USS Aventine's engineering to weld critical components back into place.