Tinctures. Two tinctures are directed by our officinal code, one simple, and the other compound.

The simple Tincture (Tinctura Cinchonae, U. S.) is ordered to be made with the officinal yellow or Calisaya bark. This is in order to insure efficiency; for this variety of bark is more uniformly strong with alkaloids than most others; but any variety ascertained to be of equal strength may be employed. The bark is probably completely exhausted when the process is properly conducted, especially if percolation is employed. The tincture would, therefore, be very efficient, were it not that the proportion of alcohol to the active matter dissolved by it is so great as to give undue prominence to its effects, and thus often to render impossible the administration of a sufficient quantity to obtain the desired influence of the bark. Though the tincture is strong, yet a fluidounce of it contains the virtues of only a drachm and a half of the bark. In patients of intemperate habits, or in very prostrate states of fever, this would be an advantage; and, in such cases, the tincture may be used with propriety. But it is more prescribed as an addition to the infusion or decoction, or in connection with sulphate of quinia, in cases requiring alcoholic stimulation, than by itself. It may be thus employed with propriety in cases of pernicious fever, attended with great prostration, as well as in fevers of the typhous character. In consequence of the resin it contains, it becomes turbid on dilution with water. The dose is from one to four fluidrachms.

The Compound Tincture (Tinctura Cinchonae Composita, U. S.) is the preparation commonly known as Huxham's tincture. It differs from the preceding in containing serpentaria and orange-peel with colouring matter, and in being prepared with red instead of yellow bark. It is made with a much smaller proportion of bark than the simple tincture, and is less suitable as an antiperiodic, or in cases requiring a strong impression from the medicine. It is, however, an elegant stomachic cordial, useful in cases of feeble digestion and general debility. The dose is a fluidrachm.

Extracts. An Extract (Extractum Cinchonae Flavae, U. S.) is prepared, according to our officinal code, from the yellow bark; but the preparation would be equally effectual made from the red, if carefully selected. In its preparation, the bark is exhausted first by alcohol and afterwards by water; the tincture and infusion are separately evaporated to the consistence of honey; and the two are then mixed, and the evaporation completed. It thus appears that the bark is deprived of all its active matter; and the extract cannot but be very efficient, if due care is exercised in selecting the bark, and in conducting the evaporation. But, as a large proportion of the matter dissolved by the menstrua is inert, as the gum, resin, and cinchonic red, the preparation is much less efficient than the separated alkaloids, and is now little used. As found in the shops, it is not unfrequently very feeble, from the want of attention to the points above referred to. The dose is from ten to thirty grains.

The Fluid Extract (Extractum Cinchonae Fluidum, U. S.) is a new officinal of our Pharmacopoeia. It is a highly concentrated tincture, from which a considerable proportion of the alcohol has been driven off, and its place as a preservative agent supplied by sugar. It is much preferable to the Extractum Ginchonae. Flavae Liquidum of the British Pharmacopoeia, which is simply an inspissated infusion, to which spirit is added, partly for its preservation, and partly for the solution of matter deposited during the latter part of the process. This latter preparation is no doubt efficacious, but is liable to the same objection as all others in which water alone is the menstruum; namely, that the virtues of the bark are not wholly extracted. The dose of the U. S. fluid extract, representing a drachm of the bark, is two fluidrachms. For antiperiodic effect, at least two fluidounces should be given between the paroxysms.