A separatory funnel is often used to remove a compound from a mixture (called phase 1) by mixing it with a different solvent (called phase 2) that is immiscible (will not mix) with phase 1. The partition coefficient of the compound is the solubility of the compound in phase 2 divided by the solubility of the compound in phase 1. Thus a phase 2 that has the greatest partition coefficient will be chosen to extract the compound. The best way to extract a compound from a mixture is to use either a phase 2 for which the compound is very soluble (seen by increasing the partition coefficient) or a greater volume of phase 2 compared to phase 1.