Vegetable infusions and decoctions may be cleared by defecation, followed by filtration. The conical bags of flannel before described are usually employed for this purpose. When the liquid is to be evaporated to an extract, they are commonly suspended by a hook over the evaporating pan. A convenient method of straining these fluids, practiced in the laboratory, is to stretch a square of flannel on a frame or "horse," securing it at the corners by pieces of string. (See Fig. 376.) Such a frame, laid across the mouth of a pan, is more easily fed with fresh liquid than a bag, whose mouth is forty or fifty inches higher. The same purpose, for small quantities of liquid., is effected by laying the flannel across the mouth of a coarse hair sieve. The concentrated infusions and decoctions being usually weak tinctures, may be filtered in the same way as the latter.