Volumetric flasks are one of the more precise tools in a chemistry laboratory. They can be used to make solutions or make a series of dilutions in varying shades. These flasks come in a variety of sizes, even as small as 10 mL, like the small flask holding yellow liquid in the background.
One way to characterize chemical concoctions is by measuring their interaction with light via spectroscopy. The different colors in each of the flasks represent the spectrum of visible light. Some things are out of order (like the yellow solution being between the red and orange solution instead of the orange being in the middle), but science is messy and doesn't always work how you'd expect.
Acrylic on canvas