Decantation is a process for the separation of mixtures, carefully pouring a solution from a container, leaving the precipitate (sediments) in the bottom of the container. Usually a small amount of solution must be left in the container and care must be taken to prevent a small amount of precipitate from flowing with the solution out of the container.
It is generally used to separate a liquid from an insoluble solid, e.g. in red wine, where the red wine is segregated from the winestone (tartar, potassium tartrate )
See also : settling.