Gum aloes. This is the inspissated gum of the whole plant described above. It is reported that Alexander, landing on the island of Succotora, or Zocotria, at the mouth of the Red Sea, in one of his expeditions, took notice of the aloe plant, and from that it was brought into use, and called Suc-cotorina.

Of the gum we have three kinds in the shops.

1. Aloe Succotorina, vel Zocotorina. Succotorine aloe.

It is imported from the island Succotora, in the Indian Ocean, wrapped in skins; it is obtained from the aloe spicata, according to Thunberg. This species is not in the edition of the species published by Linnaeus, but occurs in the Supplement, p. 205, and is the second species of the 659 genus of Wildenow's edition. Its natural order is the Liliaceae. The gum is bright on its surface, and of a reddish colour, with a purple cast; but when powdered it is of a golden hue: it is hard and friable in very cold weather, but in summer it softens very easily betwixt the fingers. It is extremely bitter, and also accompanied with an aromatic flavour, but not so much as to cover its disagreeable taste. Its scent is rather agreeable, being somewhat similar to that of myrrh. It is said to be the juice exuding from an incision of the leaves.

2. Aloe hepatica, vel aloe Barbadensis. The common, Barbadoes, or hepatic aloes, called kada-naku, and catevala, is from the aloe perfoliata Lin. Sp. Pi. 458. The best is brought from Barbadoes in large gourd-shells; an inferior sort in pots, and the worst in casks. It is darker coloured than the Succotorine; drier, and more compact, though sometimes that in casks is soft and clammy; to the taste it is intensely bitterand nauseous, being almost totally without that aroma which is observed in the Succotorine; to the smell it is strong and disagreeable.

3. Aloe cabalina, vel aloe Guineensis, horse aloes. It is not easy to believe, as is generally reported, that this is only the more impure part of the Barbadoes aloe, or rather the residuum after the hepatic aloes have been expressed, because the difference does not consist in the purity, but in the quality. It is very distinguishable from both the others by its strong rank smell; in other respects it so agrees with the Barbadoes species, as to be often sold for it. Sometimes its purity and clearness are such, that it cannot be distinguished from the Succotorine aloe; but either its offensive smell, or its want of the aromatic flavour, betrays it. This aloe is not admitted into the materia medica; but employed by veterinary surgeons.

The general nature of these three kinds is nearly the same; their particular difference only consists in the different proportions of gum to their resin, and in the flavours they possess, which render them more or less pleasant for internal use.

Aloes consist of a small portion of resin, and a large one of gummy matter. Twelve ounces of the Barbadoes aloes yield nearly four ounces of resin, and eight of a gummy extract. The same quantity of the Succotorine yields three ounces of resin, and nearly nine of gummy extract.

The aloes may be purified by solutionin water, and an evaporation so immediately after, that the resin may not have time to settle. When it settles, it may be separated by spirit of wine.

The resin of aloes hath but very little scent; that from the Succotorine hath very little taste, from the Barbadoes a slight bitter, and from the caballine somewhat more of the aloetic flavour.

The gummy extracts are less disagreeable than the crude aloes; that of the Barbadoes smells rather stronger than that of the Succotorine, but in taste is less ungrateful; that of the Succotorine has very little smell, and is scarcely unpleasant to the taste; that of the caballine aloes hath a rank smell, but its taste is not worse than that of the Succotorine.

In the resinous part consists the healing qualities, hence for external uses the Barbadoes is the best; internally, however prepared, the resin hath very little cathartic power. In the gummy extract resides the purgative, and all the other qualities. The gum of the Succotorine aloes is more irritating and active than that of Barbadoes: its effects are uncertain; but it does not seem to leave a costive habit. In small doses, twice a day, it occasions a considerable irritation about the anus, and sometimes a discharge from the haemorrhoidal vessels. These small doses cleanse the first passages, warm the habit, and promote the secretions. In phlegmatic, sedentary, and cachectic habits, and oppressions in the stomach from irregularity,' it is useful; and, in common with bitters and purgatives, has been considered as an anthelmintic, but it is so only in cases' of ascarides. In all diseases of the nervous tribe, aloes is useful, and is supposed to assist digestion. In jaundice it has been thought a succedaneum for the bile, and its title of fel nature has been the cause or effect of this opinion.

Aloes is injurious where inflammation or irritation exists in the bowels or neighbouring parts; in pregnancy, and in habits disposed to piles; from three to five grains are a sufficient dose.

Alkaline salts lessen the purgative quality of aloes; and long boiling quite destroys it.

By means of heat, the crude aloes may be wholly dissolved in water; but the resin is deposited when cold. A mixture of pure water two parts, and proof spirit one part, perfectly dissolves it without heat; though rectified spirit of wine dissolves it most speedily. If water or wine be the menstruum, the aloes becomes tenacious; and dissolves slowly; in this case, white sand should be previously mixed with the powdered aloes.

Cloves cover the offensiveness of aloes the most perfectly, but are too stimulating. The canella alba, or the cassia caryophyllata, is preferable.

The pharmaceutical forms of aloes are various. was for ages fashionable to combine them with myrrh and saffron; a form still in use in the pills styled Ru fus's. These additions were supposed, though little reason, to correct their acrimony; but the formula answers every purpose desired in a mild eccoprotic, and consequently still retains its credit. There is little reason for supposing the myrrh and saffron useful, exceept for the more minute division, and soap answers this purpose, at least as well. In the common aloetic pill, called from Dr. Anderson, aloes is corrected only by the car-damom seeds.

With alkaline salts, aloes loses its bitterness, probably its efficacy; and when the gummy extract is prepared by long boiling, exposed to the air, it becomes inert: as from the absorption of oxygen its extractive matte-is changed to a resin. The resin of aloes, as has been said, is very weakly, if at all, purgative. For the reasons assigned, the volatile aloetic tincture, viz. aloes dissolved in the volatile alkali, is a very inefficient preparation; and the vitriolic elixir proprietatis, which con-sists of aloes dissolved in vitriolic aether, is perhaps little superior. Van Helmont's vinum aloeticum alkalinum, appears to be a preparation of greater efficacy. It con-sists of aloes dissolved in mountain wine, with the ad-dition of kali and crude sal ammoniac. It is not . ever now employed; and seems to have obtained a great part of its credit from the attachment of the Boerhaavian school to alkaline tinctures, which they considered ? saponaceous. In stomach complaints, however, it promises to be of service. In our college we find the pill of Rufus; pil. ex aloe cum myrrha: a similar tincture. styled the compound tincture of aloes; and the aloes dissolved in a weak spirit, the common tinct. aloes. This medicine is also joined with more active purga-tives, as the scammony and colocynth, with guaiacum. asafoetida, and iron, to answer the various purposes of a more powerful cathartic, a more effectual stomachic, antihysteric, and emmenagogue. Any other purgative joined with aloes, neither increases its powers nor lessens any inconvenience it may produce. See Cullen's Materia Medica, Murray's Apparatus, and Woodville's Medical Botany.

Aloe rosata; violata; violata tartarea; insuccata; insuccata tartarea. These are old forms, in which the aloes is repeatedly dissolved in the juice of roses and violets, and as often exsiccated by evaporation. When dissolved in the juices of roses, violets, borage, and bu-gloss, it is styled 'insuccate;' when with the addition of one-third of its weight of cream of tartar, it has the appropriate epithet of tartarea.'

For other preparations, whose principal ingredient is aloes, as

Aloeticus pulvis. See Hiera picra.

Aloeticus pulvis cum myrrha. See Aromaticae: Pilulae; for which it is a substitute.

Aloes vinum. See Sacra tinctura.

Aloes pilulae cum myrrha. See Pilule Rufi

ExTractum Colocynthidis Cum Aloe, Aut Compom