36. To obtain Tinctures by Infusion, Maceration, and Digestion

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.

37. Infusion

37. Infusion. When the principles to be extracted are soluble in water, and at the same time but slightly volatile, boiling water is poured on the substance of which the infusion is required, the vessel is carefully covered, and the whole allowed to remain untouched for some minutes or even some hours, according to the greater or less penetrability of the substance, and the required strength of the infusion; the result is an infusion, properly so called.

If an infusion is required of dried leaves or flowers, they are first moistened with a little boiling water, and a time allowed for them to swell and soften before adding the rest of the water. Infusions made by adding all the water at once, as is still frequently practiced, are deficient both in flavor and perfume. The infusion of tea is an every-day illustration of this; as all who can make a good cup of tea know how necessary it is to first draw the tea with a small portion of water; and yet, strange to say, this principle is utterly neglected in the case of coffee, where its application is just as effective. (See No. 6287 (To Make French Coffee))

Infusions of all vegetables that do not exert a very powerful action on the human frame, may be made by pouring 1 pint of boiling water on 1 ounce of the vegetable matter and allowing it to macerate for from 1/2 to 1 hour. The ordinary dose of such infusions is 1 to 2 ounces three or four times a day.

Infusions, like decoctions, are liable to undergo spontaneous decomposition by keeping, especially in warm weather, when a few hours are often sufficient for their passage into a state of active fermentation; they should therefore be prepared for use daily, as beyond 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.

38. Concentrated Infusions

38.     Concentrated Infusions. These are now very generally met with in trade, and are made of 8 times the pharmacopoeia! strength. They are mostly prepared by employing 8 times the usual quantity of ingredients, and only three-fourths of the proper quantity of water, and adding to the strained liquor, when cold, sufficient spirit of wine to bring the liquid up to the proper strength (about one-third of the weight of the strained infusion). A still better plan is to treat 8 times the usual quantity of the ingredients with a mixture of rectified spirits 1 part and cold water 3 parts; in the usual way for making tinctures, either by maceration for 7 to 14 days, or by percolation. Concentrated infusions made in this way keep well, and deposit scarcely any sediment. Many houses, that are remarkable for the brilliancy and beauty of these preparations, employ one-third spirit of wine and two-thirds water as the menstruum. It may, however, be taken as a general rule, that for vegetable substances that abound in woody fibre, and contain but little extractive matter soluble in water (as quassia for instance), one-sixth to one-fifth part of spirit is sufficient for their preservation ; while for those abounding in mucilage or fecula, or that readily soften and become pulpy and glutinous in weak spirit (as rhubarb), one-fifth to one-third is required. By macerating in the infusion as much bruised mustard seed as can be added without flavoring the liquor, along with a little bruised cloves, most vegetable infusions may be preserved without either fermenting or becoming mouldy with very little spirit (one-ninth or one-tenth).