Related to solubility and crystallization was Ostwald's finding that dissolution of a solid depends on the size of the crystal. When the crystals are small, typically less than a micron, the solubility of the solid in the solution phase is increased. Ostwald quantified this effect mathematically in a relationship that became known as the Ostwald-Freundlich equation. Ostwald first published his finding in 1900, and his mathematical equation was refined by German chemist Herbert Freundlich in 1909. This mathematical relationship also applies to the partial pressure of substance in the system. The Ostwald-Freundlich equation takes into account the surface tension of the particle in the system, in addition to curvature and temperature. The size dependence of solubility is sometimes utilized is the formulation of pharmaceuticals that have low solubility so as to enhance their uptake by the patient. The size dependence also has a role in Ostwald Ripening.