Precipitation's the formation of a solid in a solution during a chemical reaction. When the reaction occurs, the solid formed's called the precipitate, and the liquid remaining above the solid's called the supernate. Natural methods of precipitation include settling or sedimentation, where a solid forms over a period of time due to ambient forces like gravity or centrifugation. During chemical reactions, precipitation may also occur particularly if an insoluble substance's introduced into a so… (More on Precipitate)