Chromatography is a process that is used to separate various chemicals that have been mixed together. The method is based on the fact that different chemicals, when dissolved, will travel at different speeds in a medium like paper.
In order to do chromatography, you will need the following things: a pie plate, some water, a coffee filter, and a water soluble black marker.
Fold the filter in half, and place some distinct black dots on one half of the filter with the marker. Then suspend it in the pie plate, filled with water, but make sure the dots don't get wet, and that they remain above the surface of the water.
Now wait for a while. Eventually you will notice that the water has crept up the filter; this is called 'capilliary action'. Try the experiment for yourself to see the amazing result.
This is what you will discover:
As the water reaches the black ink and dissolves it, it starts to carry the ink up the filter too. But here's the interesting part ... the black ink is really a mixture of several different inks of different colours. Some of these inks are lighter than others, and dissolve better in water; they're carried farther than the colours that are heavier, or that don't dissolve well.
The end result is that the black dots become a rainbow smear of various colours. You have separated the chemical pigments that make up 'black' ink.
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