INFUSA. L.E.D. Infusion.
These are watery solutions of vegetable matter, obtained by maceration, either in cold or hot[[536]] water without the assistance of ebullition. In selecting and conducting the operation, the following general rules should be observed.
I. Infusion should always be preferred to decoction, where the medicinal virtues of the vegetable substance reside in volatile oil, or in principles which are easily soluble; whereas, if they depend upon resino-mucilaginous particles, decoction is an indispensable operation.
II. The temperature employed must be varied according to the circumstances of each case;[[537]] an infusion made in the cold, is in general more grateful, but less active, than one made with heat.
III. The duration of the process must likewise be regulated by the nature of the substances, or the intention of the prescriber; for the infusion will differ according to the time in which the water has been digested on the materials; thus, the aroma of the plant is first taken up, then, in succession, the colouring, astringent, and gummy parts.
Infusions are liable to undergo decompositions by being kept, and therefore, like decoctions, they must be regarded as extemporaneous preparations. Unless the dose of them be otherwise stated, it is generally from f℥j to f℥ij.
I. Simple Infusions.
Infusum Anthemidis. L.E. It is a good stomachic; and when exhibited warm, is well calculated to assist the operation of emetics: (Form. 66): the cold infusion, i. e. made with cold water, is more grateful. Incompatibles. All soluble preparations of iron; nitrate of silver; oxy-muriate of mercury; acetate, and sub-acetate of lead; solutions of isinglass; infusion of yellow cinchona bark. Dose, f℥j-f℥ij.
Infusum Calumbæ. L.E. See Calumbæ Radix. This infusion is more perishable than that of other bitters; in twenty-four hours a copious precipitation takes place in it, and in two days it becomes ropy, and even musty. Form. 155. Dose, f℥i-f℥ij.
Infusum Caryophyllorum. L. f℥j. of this infusion holds in solution the active matter of grs. vj of cloves. Incompatibles. Precipitates are produced by sulphate of iron; sulphate of zinc; acetate of lead; nitrate of silver; tartarized antimony; lime water, and yellow cinchona. Dose, f℥j-f℥ij.