[ryanv777]

Wow, a lot of really helpful feedback. Just something to keep in mind is that if I decide to use substance A and B, then the denser substance(unless were using water for substance B), A, must:
1. Not mix with B
2. Have a density between that of liquid B, and solid B
3. Have a freezing point significantly lower than B
4. Have a low viscosity

I don't believe that silicone oil or simethicone fulfill the second requirement if it were used with water.  Can anyone see any problem using  Acetonitrile and Cyclohexane together? (No water would be used in this case)

[Arkcon]

OK, here's another easier one -- you can suspend carbon powder in water, it is less dense than water, and will often float on top.  It isn't soluble in any organic solvent, either.  So if you shake all three up, will the carbon powder partition itself anywhere?  I just don't see that happening.  Unless a state of affairs is more energetically stable, like dissolves in one or the other, why would it move?  Again, gravity is the answer, but is it enough?  This is a pretty fun question to think about.

[ryanv777]

Indeed, it is interesting.