We just made a density tower to help us identify unknown liquids.
Today we built our density towers from scratch to help us understand the relative densities of different fluids.
We started with a glass with some oil. We then added water and realized that our tower had now 3 substances in it; the water sinks to the bottom, the oil in the middle and air at the top. Adding a heavy liquid, like syrup, allows us to see how an incredibly dense liquid sits at the bottom.
Now add a liquid containing a mixture of substances like balsamic vinegar or mouthwash. The tower “sorts” the unknown liquid into its components parts and allows us to assess the quantity of each included.
This type of testing is still used today.