We may mention that by the same filtering arrangement oils also are filtered on the large scale; however, this goes only for information. On the small scale the manufacturer of carbonated beverages may be sometimes in need of filtering an oil. Cotton wool, arranged in a funnel, will do the service. (See Fig. 371 )

A convenient method of filtering a single cask of on is, to insert the pipe of a two-way patent filter into the cork-hole, by which means the whole will be filtered as drawn off, without any trouble on the part of the operator. This filter consists of a porous bag stretched over a perforated metallic vessel, nearly the shape and size of the exterior casing, and its edge is tightly screwed between the sides and bottom of the latter, so as to be quite water-tight. The cock communicates with the interior of the perforated plate and filter, and the supply-pipe with the exterior. By this means the interior chamber, which occupies five-sixths of the vessel, rapidly fills with filtered oil, and continues full as long as any liquor remains in the cask. This arrangement is also well adapted to the filtration of wines, beer, cordials, porter, and various other liquors. It is unequaled in simplicity and usefulness. The same filter may be removed from cask to cask, with the facility of a common cock.