Hide the Bromine and Barium
You devised a block that is only solid for anyone standing on top of it. This block does not have a collision box for anyone who doesn't meet that criterion or is sneaking.
You can also camouflage this block as any other by simply clicking on it. You think you can use this with the Arcane Levitator for some interesting effects.
This is an add-on item not found in vanilla Thaumcraft.