In this picture taken by student Hajera Azam. acid sits on top of a denser alkaline layer. A green swirl of neutral salt is also present. Notice the effect of Brownian motion, which will eventually turn the whole solution green. Bromothymol blue's colours are pH sensitive.
Related picture by Joanne S.
The junior scientist holding the test tube is Wener.
The bottom layer was formed by adding cobalt (II) nitrate to 50% water glass. After a few hours, 1.0 M sulfuric acid was added. Finally it was topped off with copper sulfate dissolved in 50% ammonia.
Thanks to Joanne and her cell for the picture.
Same setup but three days later.