How does paper chromatography work?

Paper chromatography is a technique used to separate coloured chemicals, such as a mixture of inks and dyes. A spot of the mixture to be analysed is spotted onto the bottom of a thin piece of chromatography paper using a capillary tube and the paper is placed in a tank of appropriate solvent, such as water. As the water soaks up the paper, it carries the chemicals in the mixture with it. Different molecules in the mixture will move up the paper at different speeds, depending on how soluble that molecule is in water. If it is very soluble, then that compound will move further up the chromatography paper in the same time than a less soluble compound would. Since the contents of the mixture will all move at different rates, we can separate out the mixture.