Various compounds are placed, individually in a solvent or as a mixture of compounds in the solvent, side by side on a section of stationary material, termed the baseline, over which a fluid is slowly passed. The various compounds will be adsorbed on the stationary material at different speeds and over the space of different distances. A very polar compound will move further up the stationary material while one that is not as polar will remain closer to the baseline of a chromatograph. The theory of the experiment is that the competing tendency of amino acids to dissolve will cause certain compounds of solvents to move through relatively quickly and some to move through very slowly, because they are comparatively much less soluble in the fluid and more strongly absorbed. By observing the fluids traveling along the stationary material, one can separate compounds that can never be purified of each other by any other technique. It is useful for analytical purposes only, in situations where the compounds to be identified are suitably adsorbed on paper and it is a preferable method to the manipulation of different physical constants. The experimenter controls three variables in paper chromatography- solvent, paper, and distance solvent moves. The distance moved by the solvent is ended with a somewhat unique spot, differing primarily in color. By measuring the distance traveled by a compound marked by the spot at the end and beginning at the baseline, the compounds in unknown solvents can be compared with known amino acids. The ratio used to compare experiments is called the representative fraction, Rf. Rf = Distance from center of spot to starting point (d2)/ Distance from solvent front to starting point (d1). The experimenter should expect to see that the "trails" and spots, and resulting Rf, should each be unique and to conclude that the unknown solvents with matching Rf , and relative movements over the chromatograph, are the compounds comprising the unknown solvents.