Infusions are solutions of vegetable principles in water.
The addition of any alcoholic mixture is only made in cases where the medicinal action of the liquor itself is desired, or to act as a preservative. Drugs containing volatile active constituents, or which are deteriorated by a temperature somewhat elevated, or which contain a principle not desired, and which is not readily dissolved by water at a low degree of heat, are better made into infusions by cold instead of hot water. Infusions form a very expeditious and convenient mode of exhibiting many medicines, as the most of them readily yield their active constituents in this way without requiring to be very finely divided. The principal objection to them is the difficulty of keeping them for any length of time, in consequence of which they require to be prepared off-handed, and in limited quantity at a time. Mugs containing a movable diaphragm are now much in use for the preparation of infusions.