[Fred Brackin]

This one centers around the Atmospheric Dome spell. the rules text for that one _should_ say "As for Weather Dome except that air pressure is maintained as well" but it doesn't.

Instead, it has a complicated mechanism where the caster sets desired composition and pressure and the dome barrier pushes out or pulls in gasses as desired. If this was a spirit-maintained magic system I'd say it worked that way because Maxwell's Demon had a brother-in-law who needed work.

At any rate there doesn't seem to be anything preventing you from setting composition and pressure to "none" and having the spell produce a sphere of hard vacuum for you. Vacuum gives you about 10% more lift than hydrogen but the real advantage is durability. With no balloon walls or much of anything else it will be hard to damage the vacuum spheres at all. Leaks certainly won't be an issue,

One drawback is the lack of a standard Enchantment version. that would require a Spell Engine from Magic Items III or other general spellcasting device. Use of the Ensorcerel Spell might also be an option. There's also a general issue of cost to cast which is relatively high at 4 per hex.

Ramping up to lifting "gasses" with even more lift it might be possible to contain pure Celestial Ether in your vacuum bubbles. You obviously can't do that with ordinary matter. The Celestial Ether would degrade upon contact with mundane stuff. Everybody knows that. :)

Lifting power of Celestial Ether is uncertain but at least 10x hydrogen is a common estimate. It might also be possible to use "compressed" Celestial Ether and do away with bulky containers. I believe this might be the system in use upon (or actually above) Barsoom.