Paper chromatography. A scientist studying a selection of paper chromatograms of industrial dyes. Paper chromatography involves placing a small amount of the substance under investigation on a piece of filter paper, then slowly dripping a solvent into the centre of the paper. The solvent then spreads out over the paper by capilliary action, carrying with it the components of the substance at differing rates. The distance travelled along the paper by each component during the time of the experiment is a measure of this characteristic transport rate and may be used to identify each component.