yeah that would work well. Although the colllumn would be more susceptable to breakage because gydrogen is lighter than methane.

Argon, or Propane.

propane would sink, and argon i dont think is flamable.

Argon is a noble gas! of course it won't burn

But propane is good for bubbles, etc.

it works well for balloons but i love hydrogen balloons. i always bring em too parties then everyones wasted you light em off and everyone shits themselves (not literally)