Separating colors

This experiment came from friend-of-the-lab Sandy. The goal of the experiment was to show that black is made from a mixture of colors. We put a long strip of paper in a bottle so that the paper went from the bottom of the bottle, up and out the top, and down to the table top. We filled the bottle part way with water and made a thick black line on the paper above the water level using a permanent marker. By the morning, our thick black line had turned into a smearing of colors. Although Jr scientist A would clearly have liked the black to separate before our eyes, the experiment clearly sparked his imagination and he's now asking to see what other colors are made of.