rainbow

[Brian Weinrick]

Chromatography phenomena actually have more to do with entropy (the 
movement of the solvent molecules to areas of lower concentration and 
therefore energy) than gravity but the metaphor still holds nicely.

On Wed, 1 May 1996 RokyE at aol.com wrote:
> A real literal "Gravitiy's Rainbow" could be found in Paper Chromography.
> This is a technique for seperating chemical components from a solution.  A
> simple example would be a felt tip marker on wet paper, but typicaly, in a
> labrotory, this is acheived using a large vertical tube filled with very fine
> sand.  Gravity pulls the various elements down, leaving them seperated in
> distinct layers.