The word "filitration" is absolutely synonymous with "straining," but in the language of the laboratory it is usually applied to the operation of rendering liquids transparent, or nearly so, by passing them through fine media, as filtering paper, sand, and the like; whilst the term "straining" is employed to designate the mere separation of the grosser portion, by means of coarse media, flannel, horse-hair cloth, etc., through which they flow with considerable rapidity. Filtration is distinguished from "clarification" by its mere mechanical action, whereas the latter operates by depuration, or the subsidence of the suspended substances or faeces, arising from their gravity being naturally greater than the fluid with which they are mixed, or being rendered so by the application of heat, or by the addition of some foreign substance.