Question:
I would very much like some help on the following issue.

Consider a vertical column with water (solute) in which a certain materialor a combination of materials (molecules or ions) is completely dissolved.At start this solution is a homogeneous mixture.

I am now looking for a way to turn this homogeneous mixture into one wherethe concentration of the solute (number of items dissolved / osmoticpressure) at the bottom is greater than the concentration at the top. Itwould be the best if this state would be a stabile equilibrium, which wouldcorrect attempts to make it a homogeneous mixture again.

It might not possible but well, maybe one of you has an idea how to do this.

P.S. Maybe gravity can slightly influence concentration levels of a heavysolute or maybe a field of static electricity or magnetism can influence theconcentration if the solute consists of ions.

Answer: Gravity has a very slightly influence on all solutions. There shouldinformation on this effect be available. You could calculate the influenceof a centrifuge.If you have ferromagnetic particles, you could use ferromagnetism.Ions of the "Nebengruppe" of the periodic system of elements are paramagnetic.You could try instationary magnetic fields.

If you have molecules, you should know, that polar molecules are dissolvedby polar solvents (like water) as ions. Nonpolar molecules are dissolvedby nonpolar solvents, but as whole molecules, not as ions. Only that aboveare true solutions. Polar (nonpolar) molecules are dissolved in nonpolar(polar) solvents as emulsion or suspension by emulgators/suspensors.

If you want to get an inhomogenous solution, you have to take a truesolution and to destroy the attractive interactions (forces) at thissolution.

If you give alcohol, sirup, dye stuff or other soluble things slowly intowater, you can get a layered solution. Well, you know how reverse osmosis water filters work. They justuse pressure to force pure water though an osmotic membrane. Theequation is a basic one in thermodynamics, and is in any chem text.You can force out pure water against a chemical gradient of about1/25th of an osmol (.04 Formal) per atmosphere. So a column ofseawater 33 feet high should be able to increase its salt concentrationat the bottom, against a membrane with pure water on the other side, byabout 1/25th eq or 40 meq (normally it's about 3% which is about 1000F, so you go up by about 4%). And that should be pretty stable. Takea look at the osmotic membranes in reverse osmosis water purifiers.There's no sense in developing technology which is already off theshelf.