Extract of Peruvian bark with resin. - Take of Peruvian bark, coarsely powdered, one pound; rectified spirits of wine, four pints; digest for four days, and then pour off the tincture; boil the residuum in ten pints of distilled water to two; then strain the tincture and decoction separately, evaporating the water from the decoction, and distilling the spirit from the tincture, until each begins to"be thickened; lastly, mix the resinous with the aqueous extract, and make the mass fit for forming into pills. Pharm. Lond. 1788. This extract is greatly inferior to the former, and seldom employed.

The extracts are in general carelessly and imperfectly prepared, and among the venial faults we may mention, that, when the evaporated decoctions have attained the consistence of honey, they are brought to that of an extract by adding the powder of bark. The operator thus avoids the most troublesome part of his labour, the cautious regulation of the fire, and the constant stirring when it approaches the form of an extract.

We have lately received, it is said, from South America, a very elegant preparation, supposed to be an in-spissation of the decoctions by exposure to the sun in its native climate. It is by far the most efficacious of the extracts; but we suspect that it is often, at least, the common extract prepared with peculiar care. Some years since a preparation was sold under the title of the essential salt of bark. It was an extract full of flaky-salts, tasting strongly of bark; but as it is no longer known, we may suppose that its efficacy was not considerable.

Tincture of Peruvian bark. Take of the Peruvian bark, four ounces; of proof spirit of wine, a quart; digest with a gentle heat for eight days, and strain. Pharm. Lond. 1788.

This is an agreeable preparation, but it is too heating if a large dose is given. It would be better to add twice the quantity of bark to this proportion of spirit, if the menstruum would dissolve it, which we believe would not be the case.

Compound tincture of bark. Take of Peruvian bark in powder, two ounces; exterior peel of Seville oranges, one ounce and a half; Virginia snake root bruised, three drachms; saffron, one drachm; cochineal powdered, two scruples; proof spirit of wine, twenty ounces; digest for fourteen days, and strain. This was the tinctura corticis Huxhami, and is certainly a good cordial; but it derives little additional virtue from the saffron or cochineal. The snake root and orange peel warm, slightly, a preparation sufficiently heating before.

Tinctura ammoniata cinchonae. - Ammoniated tincture of bark. Take of Peruvian bark in powder, by weight, four ounces; compound spirit of ammonia, two pounds; digest them in a close vessel for ten days, and filter it. Pharm. Lond. 1788. This is a very weak preparation of the bark, and seldom employed. See Lewis's Materia Medica. Neumann's Chem. Works. Percival's Essays. Cullen's Materia Medica.

Cortex Peruvianus ruber. The red Peruvian bark is in much larger and thicker pieces than the common bark. It evidently consists of three different layers. The external is thin, rugged, and frequently covered with a mossy substance, and of a reddish brown colour; the middle is thicker, more compact, and of a darker colour; in this appears chiefly to reside its resinous portion, since it is extremely brittle, and evidently contains a larger quantity of inflammable matter than the similar part of any other kind of bark. The innermost hath a more woody and fibrous appearance, of a brighter red than the former. The entire piece breaks in that brittle manner described by writers on the materia medica, as a proof of the superior excellence of the bark. In reducing it to powder, the middle layer, which seems to contain the greatest proportion of resin, will not give way to the pestle so easily as the other layers: and this should be particularly attended to when it is used in fine powder. In flavour, chiefly discoverable either in powder or solution, it is evidently more aromatic, and has a greater degree of bitterness than the common bark.

It is highly probable that this is the bark of older trees than that which is called quill bark, or from their trunks and larger branches; and more particular care is probably taken in collecting and drying it.

The taste and flavour of the red bark are more difficultly evolved, and are, therefore, at first not so obvious, from the closeness of its texture, and from"the resinous coat being so well defended and inclosed between the other layers. It is evidently heavier than any other kind of bark, and i;. so much warmer that it would seem to answer all the purposes derived from the union of aromatics or serpentaria, recommended in the obstinate quartan intermittents of elderly people.

By the testimony of many practitioners, it appears that intermitting fevers are more speedily and effectually cured, either by infusion, decoction, or powder of the red bark, than by those of the common bark; and this also by smaller doses of the former than of the latter. Dr. Saunders observes, that from the numerous trials he has made with it in intermitting fevers and other diseases, he is disposed to conclude that it need be employed only in half the quantity we generally recommend of the other bark. We must add with regret, that we seldom meet with bark of this superior quality at present. Our red bark is often only the coarser pieces artificially stained.

The infusion, decoction, and tincture, made with red bark, are consiacrably stronger than those from the same quantity of common bark; and it is said to have afforded more than twice the quantity of extract than is obtained from the same portion of common bark.

Dr. Saunders relates the following experiment, in his observations on the superior efficacy of the red Peruvian bark. A decoction of both red and common Peruvian bark was prepared by taking an ounce of each, and boiling them in a pint and a half of water, to one pint; the former had greatly the superiority in strength and power. A pint of fresh water was added to each decoction; the boiling still continued till that quantity was evaporated. The decoction of the common Peruvian bark seemed gradually to lose its sensible qualities, while that of the red bark still retained its own. The same quantity of water was added as before to each, and the decoction repeated until a gallon of water was exhausted; at the expiration of which time the common Peruvian bark was rendered almost tasteless, the red bark still retaining nearly its former sensible qualities.

In an infusion of the red bark, the spirit of vitriol lost its acidity more perfectly than in an infusion of the bark before in use. A decoction of the red bark keeps perfectly good during more than a month in the summer season, whilst that of the common bark is sensibly changed in a few days. In the decoction of the red bark, the powder, which is separated during cooling, remains intimately diffused through the liquor, so that it continues loaded and turbid whilst at rest: in the decoction of the common bark it separates, and easily subsides to the bottom.

Cortex flavus. See Flavus cortex.

Cortex poegerebae is a bark whose country is unknown. It is styptic and bitterish; said to be useful as an astringent in old diarrhoeas, and occasionally in dysentery.

Cortex winteranus spurius. See Canella alba.