s the freeing of any fluid from heterogeneous matter or feculence. It is of three kinds: firstly, by decantation, which is performed by letting the liquor to be depurated stand for some time in a pretty deep vessel, till the gross sediment has fallen to the bottom, after which the clear fluid is poured off; secondly, by desumination, which is performed by means of the whites of eggs, or other viscid matter, and is also called clarification; and, thirdly, by filtration, which is effected by passing the fluid through cloth or porous paper.