I've now released a new version with improved physics, I think. The gravity effects are now relative to the medium, so salt should move through water more quickly. I also tweaked lava so that it's possible to destroy thin spreads of lava using copious amounts of water. If there is a lot of lava, you get a nice boiler instead.. A side effect of the physics tweaks is that steam escapes faster from water giving a nice "boiling" effect.