How Can You Determine Which Layer Is Which Without Using Densities?

[fishfish]

How would you determine which layer is which without using the densities?

 

[PhaseShifter]

I can think of several ways.

Boiling point
freezing point

But the easiest by far is to just add a drop of water and see which layer it mixes with, since you have an organic layer already saturated with water, and an aqueous layer you can always dilute.