Preparations. The following methods of preparing decoctions, extracts, tinctures, etc., are from the best practical sources. Other directions for making extracts, essences, attars, etc., for the special purposes of Perfumery, etc., will be found under their respective headings.

34. To Prepare Decoctions

34. To Prepare Decoctions. Decoctions are solutions of the properties of vegetables obtained by boiling, which is presumed to be a more effective method of extracting their properties than mere infusion.

For making decoctions, the substances should be well bruised, or reduced to a very coarse powder, or, if fresh and soft, they should be sliced small. In the former case, any very fine powder or adliering dust should be removed with a sieve, as its presence would tend to make the product thick and disagreeable, and also more troublesome to strain. The vessel in which the boiling is conducted should be furnished with an accurately fitting cover, the better to exclude the air, and the heat should be so regulated that the fluid may be kept "simmering," or only gently boiling, as violent boiling is not only quite unnecessary, but absolutely injurious. In every case the liquor should be strained while hot, but not boiling, and the best method of doing this is to employ a fine hair sieve, or a coarse flannel bag. In general it is found, that as decoctions cool, a sediment is formed, in consequence of the boiling water dissolving a larger portion of vegetable matter than it can retain in solution when cold. This deposit for the most part consists of the active principles of the solution, and should be mingled with the clear liquid by agitation, when the decoction is used. It will thus be seen that the common practice of leaving the filtration until the liquid has become cold, and also of rejecting the sediment, is injudicious, and should be scrupulously avoided; as, however much decoctions so prepared may please the eye, they are not only inferior in strength, but, in many cases, nearly inert. It may be further remarked, that long boiling is in no case necessary, and should be avoided, especially in decoctions prepared from aromatic vegetables, or those abounding in extractive. The colleges, in such cases, direct the ingredients "to be boiled for a short time," or "for 10 minutes," or they limit the time of boiling by stating the quantity that must be volatilized, as - "boil to a pint, and strain," the latter method being generally employed for those substances that do not suffer by lengthened boiling.

Distilled water, or perfectly clean rain water, should alone be used for decoctions. Spring and river water, from their containing lime, have less solvent powers.

Decoctions of all vegetables not exerting a very powerful action on the human system may be made by boiling 1 ounce of the vegetable matter in 1 pint of. water for 10 or 15 minutes. The ordinary dose of such a decoction is the same as that of a similar infusion. (See No. 37 (Infusion).)

"When the medicinal properties of vegetables are volatile, or are injured by a strong heat, infusion should be had recourse to, in preference to boiling; but when a solution of the fixed constituents is alone sought, decoction is preferable. In preparing compound decoctions, those ingredients should be boiled first which least readily impart their active principles, and those which most readily impart them should be added afterwards. In many cases it will be proper simply to infuse the more aromatic substances in the hot decoction of the other ingredients, by which means their volatile principles will be preserved.