Density differences cause objects to “float” in liquids that are already stacked on top of each other.
With this science-magic trick, you’ll put a new spin on our famous Density Column demonstration. First, you’ll discover how to stack nine layers of liquids on top of each other. That alone looks really cool, but then you take it up a notch by making different solid objects “float” in the middle of all those cool looking stacked liquids. You’ll surprise yourself and your friends with what you can do with the 9-Layer Density Tower.
Source: Amazing 9 Layer Density Tower – SICK Science! | Science Experiments | Steve Spangler Science