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To Prepare Tinctures

Tinctures and sometimes of mineral substances, in spirituous liquids. The spirit most commonly employed is proof-spirit; sometimes rectified spiritis used, and occasionally ether. Ammonia is sometimes conjoined with the spirit, in which case the solution is termed an ammoniated tincture. Rectified spirit is alcohol, with 16 per cent. of water, and its specific gravity is .838. Proof-spirit is composed of 5 parts of rectified spirit mixed with 3 parts of water, the resulting compound containing 47.5 per cent. of water, specific gravity .920. The choice between proof and rectified spirit depends on their respective solvent powers over the active principles of the drugs employed. the solid ingredients to small fragments, Tinctures are usually prepared by reducing coarse powder, or fine powder, macerating them for 7 days or upwards in proof or rectified spirit, straining the solution through linen or muslin, or paper, and finally expressing the residuum strongly, to obtain what fluid is still retained in the mass. They are also prepared by the method of displacement. (See No. 41.) All tinctures should be prcactive principles of the solution, and should pared in close glass or stoneware vessels, and be mingled with the clear liquid by agitation, be shaken frequently during the process of when the decoction is used. It will thus be maceration. Tinctures are better clarified by seen that the common practice of leaving the repose than by filtration, as in the latter case a filtration until the liquid has become cold, and considerable portion is retained by the filalso of rejecting the sediment, is injudicious, tering medium, and lost by evaporation. In and should be scrupulously avoided; as, howordinary cases, it will be sufficient to allow ever much decoctions so prepared may please the tincture to settle for a few days, and then the eye, they are not only inferior in strength, to pour off the clear supernatant portion but, in many cases, nearly inert. It may be through a funnel loosely choked with a piece further remarked, that long boiling is in no of sponge or tow, to keep back any floating fragments of straw or other light substances; | glected in the case of coffee, where its applicaafter which the remaining foul portion of the tion is just as effective. (See French Coffee.) liquid may be filtered through paper. When Infusions of all vegetables that do not it is absolutely necessary to filter a tincture, exert a very powerful action on the human and the quantity is large, conical bags should frame, may be made by pouring 1 pint of be employed. The filtration should be con- boiling water on 1 ounce of the vegetable lucted as rapidly as possible, for the double matter and allowing it to macerate for from purpose of lessening the amount lost by evap-to 1 hour. The ordinary dose of such inoration, and the action of the air on the fluid. fusions is 1 to 2 ounces three or four times a Tinctures long exposed to the air frequently day. lose their transparency within a few days Infusions, like decoctions, are liable to unafter their filtration, owing to the oxidation dergo spontaneous decomposition by keeping, and precipitation of some portion of the mat- especially in warm weather, when a few hours ter previously held in solution. Resinous and are often sufficient for their passage into a oily tinctures, as those of myrrh, tolu, and state of active fermentation; they should lavender, may be usually restored to their therefore be prepared for use daily, as beyond former brightness by the addition of a quansity of spirit, equal to that which they have ost by evaporation; but many tinctures resist this mode of treatment, and require refiltering.

Ethereal tinctures are best prepared by percolation, and should be both made and kept in stoppered bottles.

When both the substances are fluid, as in the case of certain balsams, the spirituous solutior is made by merely mixing the two together in suitable proportions. For instance -'Tincture or essence of Tolu consists of 3 drachms balsam of Tolu and 1 quart of alcohol.

The tinctures of the drug-stores are usually very uncertain and inferior preparations. Not only is their manufacture carelessly conducted, without reference to the respective characters of their ingredients, but the ingredients themselves are often deficient in strength and quantity.

We will now proceed to explain the various methods by which good tinctures are obtained. 36. To obtain Tinctures by Infusion, Maceration, and Digestion. In order to extract the soluble principles of substances which cannot be advantageously distilled, infusion is often resorted to. This consists in submitting them for a greater or less period of time to the action of a liquid, with or without the aid of heat. This is known by the name of infusion, digestion, or maceration, terms all signifying the same process with different modifications in the way of conducting it. 24 hours they cannot be depended on.

Infusions should be made in vessels which cannot be attacked by any of the substances with which they are in contact, and closed sufficiently tight to prevent the loss of the most volatile principles.

The tin cucurbit, with cover, is in these two respects best adapted for infusions in water.