61. Aloë, Linn.—Aloe.

Sex. Syst. Hexandria, Monogynia.
(Succus proprius spissatus foliorum ex variis Aloës speciebus.

History.—Neither aloe plants nor the inspissated juice of their leaves are mentioned by Hippocrates or Theophrastus; but both are described by Dioscorides [Lib. iii. cap. xxv.] and Pliny. [Hist. Nat. lib. xxvii. cap. v.]

Botany. Gen. Char.—Perianth tubular, six-cleft, fleshy, nectariferous at the base, the sepals of the same form as the petals, and closely imbricating them. Stamens hypogynous, as long as the perianth, or even longer. Capsule membranous, scarious, three-corned, three-celled, three-valved, with a loculicidal dehiscence. Seeds numerous, in two rows, roundish or angular. (Lindley).—Succulent plants.

Species.—The following species furnish the greater part of the substance called in the shops aloes:—

1. Aloë vulgaris, Lam. L. D.; Aloë perfoliata π, vera Linn.; A. bardadensis, Miller, Haworth; Αλόη, Dioscor. Sibth.—Stem woody, simple, cylindrical, short. Leaves fleshy, amplexicaul, first spreading, then ascending, lanceolate, glaucous, green, flat above, convex below, armed with hard, distant, reddish spines, perpendicular to the margin; a little mottled with darker colour; the parenchyma slightly coloured brown, and very distinct from the tough leathery cuticle. Scape axillary, glaucous reddish, branched. Spike cylindrical-ovate. Flowers at first erect, then spreading, afterwards pendulous, yellow, not larger than the stamens. (Lindley).—East Indies, Barbary, Spain, Italy, Sicily, Malta, Greece, West Indies.

Specimens of this species are frequently brought to London from the West Indies by sailors, a tarred cloth being closely lied around the truncated stem to prevent the escape of the juices of the plant. If suspended by a cord from the ceiling of a room, they continue to live for a considerable time, and throw out fresh leaves. I have had one in my possession for nearly two years, and it is still living and growing.

This species yields Barbados aloes (Aloe Barbadensis, Ph. Lond.).—The brownish-yellow, bitter, resinous juice which, by inspissation, forms aloes, is contained in parallel greenish vessels beneath the epidermis of the leaves.

2. A. Abyssinica, Lam. is by some writers considered to be a variety of A. vulgaris. By Kunth it is regarded as a distinct species. Its flowers are greenish yellow. It is a larger and more resinous species than the preceding, and was brought from Africa by Druce. It may, perhaps, yield a portion of the aloes of commerce. It contains a very bitter juice, which becomes brown in the air.

3. Aloë socotrina, Lam. De Cand.—Stem woody, straight, one and a half feet high or more, naked below, where it is strongly marked with the scars of leaves. Leaves amplexicaul, ascending, ensiform, green, curved inwards at the point, convex below, rather concave above, marked with numerous small white marginal serratures, the parenchyma abounding in a bright brownish-yellow juice. Raceme cylindrical, unbranched. Flowers scarlet at the base, pale in the middle, green at the point. Stamens unequal, three of them longer than the flowers. (Lindley.)— Socotra; also, according to Nees von Esenbeck, Cape of Good Hope.

Lieut. Wellstead [Journal of the Royal Geographical Society, vol. v.] says that the hills on the west side of Socotra are covered for an extent of miles with aloe plants; and he observes that it is not likely, at any future period, that the whole quantity will be collected which might be required.

It is said to yield socotrine (and real hepatic ?) aloes.— Under the epidermis of the leaves are parallel greenish vessels containing the bitter resinous juice, as in the last-mentioned species. By drying, the leaves of A. socotrina (like those of A. purpurascens, but unlike those of A. vulgaris) acquire a purplish-red colour, which commences first in the parallel vessels, and is probably produced by the oxidation of the resinous juice contained in these vessels.

4. A. purpurascens, Haworth.—This species has dark red flowers and glaucous leaves, which become purplish-red when drying. It has the same localities as the last-mentioned species. Its juice is very bitter and resinous, and becomes blood-red in the air.

5. Aloe spicata, Thunb. D.—Stem three to four feet high, as thick as a man's arm. Leaves thick, fleshy, broad at the base, gradually narrowing to the point, channelled, full two feet long, distantly toothed, with a few white spots; their parenchyma almost colourless. Spike a foot long, very compact, with the flowers campanulate and horizontal. The three petals broader, ovate, obtuse, white, with a triple green line, the sepals narrower, less concave. Stamens much longer than the perianth. The flowers are filled with a purplish honey. (Lindley.)—This species is a native of the interior of the Cape of Good Hope, and contributes to yield Cape Aloes. Thunberg [Dissertatio Botanica-Medica de Aloë, 1785.] states that it yields the best hepatic aloes, ("succus Aloës hepaticus purus et optimus.")

6. Aloe ferox, Lam.—Stem very lofty. Leaves perfoliate, thick, juicy, sword-shaped, deflexed, glaucous, prickly throughout, but bearing larger and sharper spines along the margins. Flowers racemose, crowded. Stamens double as long as the corolla. L. Pappe, Fl. Capensis Med. Prodr.—A native of Swellendam, Cape of Good Hope. Yields the best Cape aloes.

7. Aloe Africana, Miller.—Yields Cape aloes almost equally good with A. ferox, but not so bitter, nor so powerful a drastic.

8. Aloe plicatilis, Miller.—Inhabits the mountainous range near the Paarl, Drakenstein, and Fransche Hock, at the Cape of Good Hope. It yields the aloes commonly used by the colonists, which is milder than the preceding, and much resembles Barbados aloes.

Other Species.—It is probable that several other species contribute to the supply of the aloes of commerce. I have received four species from Mr. Dunsterville, of Algoa Bay, who writes that from all of them, as well as from other species, the so called Cape aloes is obtained. Thunberg [Diss. Med. Bot. p. 10.] states that A. perfoliata yields a large quantity of aloes at the Cape, and he also says [Ibid, p. 7.] that

A. linguaeformis, Linn, yields the best and purest sort. Dr. Christison [Dispensatory, 2d edit.] suggests that A. Commelini of Willdenow may yield some. He was informed, by Mr. John Lyell, that at Swellenden and George (South Africa), aloes is obtained from A. spicata, A. Africana of Haworth, and varieties of these crossed with A. ferox. The last-mentioned species is now cultivated in Barbados, according to Schomburgk. [Hist. of Barbados, p. 590.

In Arabia, Forskål [Flora Aegyptiaco-Arabica, p. 73, 1775.] found A. officinalis (A. rubescens of De Candolle?), whose juice had the odour of the officinal socotrine aloes. Its flowers were red.

In India, there is also a species with reddish flowers, which Dr. Royle [Illust. of the Botany of the Himalayan Mountains.] has called A. Indica. This, if known to Roxburgh, was probably included by him in A.perfoliata.

Nees von Esenbeck mentions the following species as being rich in a bitter resinous juice: A. humilis, Lam.; A. Ferra, De Cand.; A. ferox, Lam.; and A. subferox, Spreng. He also found that the following were feebly bitter, but in different degrees: A. glauca, Mill.; A. paniculata, Jacq.; A. saponaria, Haw.; A. cassia, S. D.; A. plicatilis, Mill.; A. arborescens, Mill.; and A. frutescens, S. D. He says that A. glauca, Mill, was also slightly bitter, but that the juice became dark brown in the air, which shows that this colouring matter is a peculiar principle originally different from the bitter matter.

Preparation.—The finest kind of aloes is obtained by evaporating the juice which flows spontaneously from the transversely-cut leaves. This juice is lodged in vessels running longitudinally beneath the epidermis. The exudation of it is promoted by gravity, by dipping the leaves in hot water, and by making fresh sections of the leaves. But if pressure be employed, the proper aloetic juice becomes mixed with the mucilaginous liquid of the leaves, and thus an inferior kind of aloes is obtained. A still commoner variety is procured by boiling the leaves, from which the juice has been previously allowed to escape, in water.

α. Of Socotrine Aloes.—In the Island of Socotra the leaves are plucked at any period, and by any one who chooses to take the trouble; and after being placed in a skin, the juice is allowed to exude from them. [Welstead, op. citato.] The following mode of preparing socotrine aloes, as related by Hermann, was communicated to Kay by Dr. Palmer: [Dale, Pharmacologia.] "When the leaves which have been pulled from the roots are gently compressed by the hand or an instrument, the juice drops from them into a receiving vessel; and being allowed to stand during a night deposits the grosser parts. The next day it is transferred to another vessel, in which it is exposed to the sun that it may harden and become dry, when it acquires a brownish-yellow colour."

β. Of Barbados Aloes.—In Barbados, the aloes is best procured in the month of March. It is obtained as follows: "Every slave hath by him three or four portable tubs. The leaves being cut near the roots, are thrown into these with their broken ends downwards; and as the leaves are full of large longitudinal veins or vessels, they yield an easy passage to the juice (which is of a greenish-yellow colour) to drip out. This being boiled for about five hours in a copper or kettle, the watery particles evaporate, and the remainder comes to a consistency and thickening as sugar doth when sufficiently boiled. The way to know when it is enough boiled is, to dip a stick in the liquor, and observe whether the aloe sticking to it, when cold, breaks short: if it doth, then it is boiled to perfection, and fit to be poured into gourds or calabashes, or other vessels, for use." [Hughes, Natural History of Barbados, p. 154, 1760. This account is further confirmed by that of Mr. Millington, Lond. Med. Journ. vol. viii. p. 422. But Dr. Christison states, the Barbados aloes of the present day is the extract of a decoction.]

Dr. Wright [Lond. Med. Journ. vol. viii. p. 219.] says, that in Jamaica, the leaves contained in hand-baskets or nets are boiled in water, and the strained liquor evaporated to a proper consistence, and then poured into gourds or calabashes. Dr. Patrick Browne, [History of Jamaica, p. 198, 1789.] on the other hand, states that the sun-dried juice is called socotrine aloes; but the common aloes, he adds, is obtained by squeezing out the juice by the hand, adding water to it, and boiling down to a proper consistence.

γ. Of Cape Aloes.—The method of preparing aloes followed at the Cape of Good Hope has been described by Thunberg, [Travels in Europe, Asia, and Africa, between the Years 1770 and 1799, vol ii. p.49.] Lieut. Moody, [Ten Years in South Africa, vol. ii. p. 2, 1835.] and others. [Four Months in Cape Colony, in Chambers's Miscellany of Useful and Entertaining Tracts, vol. xx. No. 173, Edinb. 1847; also, Mr. John Lyell in Christison's Dispensatory, 2d ed.]

Mr. George Dunsterville, surgeon of Algoa Bay, and formerly one of my pupils, has furnished me with the following information respecting the manufacture of Cape aloes: "A shallow pit is dug, in which is spread a bullock's hide or sheep's skin. The leaves of the aloe plants in the immediate vicinity of this pit are stripped off, and piled up on the skin, to variable heights. These are left for a few days. The juice exudes from the leaves, and is received by the skin beneath. The Hottentot then collects in a bucket or other convenient article the produce of many heaps, which is then put in an iron pot capable of holding 18 or 20 gallons. Fire is applied to effect evaporation, during which the contents of the pot are constantly stirred to prevent burning. The cooled liquor is then poured into wooden cases of about three feet square by one foot deep, or into goat or sheep skins, and is thus fitted for the market. In the colony, aloes realizes about 2 ¼ d. to 3 ½ d. per lb." Mr. Dunsterville also informs me that the Hottentots and Dutch boors employ indiscriminately different species of Aloë in the preparation of Cape aloes. He adds, that "the Cape aloes, which is usually prized the highest in the English market, is that made at the Missionary Institution of Bethelsdorp (a small village about nine miles from Algoa Bay, and chiefly inhabited by Hottentots and their missionary teachers). Hence it is called Bethelsdorp Aloes. Its superiority arises, not from the employment of any particular species of Aloe, for all species are indiscriminately used; but from the greater care and attention paid to what is technically called 'the cooking of the aloes,' that is, to the evaporation, and to the absence of all adulterating substances (fragments of lime-stone, sand, earth, &c.) often introduced by manufacturers."

Description and Varieties.—I am acquainted with seven commercial varieties of aloes; namely, Socotrine, Hepatic, Barbados, Cape, Mocha, Caballine, and Indian. To these must be added Curacoa Aloes.

The terms socotrine, hepatic, and caballine, have been used to indicate rather the quality and purity, than the origin, of aloes. Thus Thunberg [Dissertatio Botanico-Medica de Aloë. 1785.] says, "Pro diversa puritate potius, quam quidem sua origine, triplicem imprimis Aloes speciem in Pharmacopolis nostris introductam invenimus, scilicet socotrinam, hepaticam, et caballinam." And Jussieu [Elements of Chemistry, by M. J. A. Chaptal, vol. iii. p. 86, 1791.] states that he saw all three varieties prepared at Morviedro, in Spain, from the Aloë vulgaris.

The term Aloë lucida, or clear aloes, has been applied by Schröder, [The Compleat Chymical Dispensatory, p. 500, 1669.] Geoffroy, [Tractatus de Materia Medica, t. ii. p. 649, 1741.] Fée, [Cours d'Hist. Nat. Pharm, t. i. p. 327, 1828.] and others, to a clear or transparent aloes supposed to be formed by the concretion of the juice on the leaves after they have been incised. It is probable that by this term are meant the clearest and most transparent pieces of socotrine aloes. I have never met with, in English commerce, any aloes by this name: and a similar remark has been made by Alston. [Lectures on the Materia Medica, vol. ii. p. 422, 1770.]

1. Socotrine Aloes (Aloë socotrina, L.; Aloë socotorina and Aloë Indica, E.). [I have received from Dr. D. Maclagan, Lecturer on Materia Medica in Edinburgh, two specimens of aloes; one marked "True Socotrine Aloes, garnet red in their fragments;" the other "Aloes given to me as True Socotrine, rough fracture nearly garnet red in thin fragments. Included under Aloe indica, Ed. Pharm." Both kinds are Socotrine aloes.] A few years ago this kind of aloes was brought by way of Smyrna, and hence was frequently termed Turkey aloes. But since the expiration of the charter of the East India Company, it is usually brought by way of Bombay. It is the kind sold at Apothecaries' Hall, London, and at other places under the name of extract of spiked aloes (extractum aloës spicatum), although there is no evidence of its being obtained from Aloë spicata. The London College (1851) states it to be the juice of the cut-off leaves, dried in the air, of an uncertain species of aloe. It comes over in skins [I am informed that they are the skins of the Gazelle.] contained in casks (holding from 11 to 15 cwt. each), kegs, and chests. Its consistence and colour are subject to considerable variation. The exterior portion of each skinful is usually hard, but the internal portion is frequently soft or even semi-liquid.

The hardened portions vary in colour in different parts of the same mass; sometimes they are garnet red, at other times much paler, and when quite dry are golden red, and yield a golden yellow powder. By exposure to the air the colour is deepened. The fracture of fine selected pieces is smooth, glassy, and conchoidal; but socotrine aloes of excellent quality often breaks with a roughish fracture. The finest kind of socotrine which I have met with had the semi-transparent red colour observed when we break a fine tear of myrrh. Thin films of pure and hardened socotrine aloes are usually translucent or nearly transparent. The fragments, which have a ruby colour, are called aloe socotrina vera. The odour of fresh broken pieces (especially when breathed on) is very fragrant, and is much stronger in recent and soft specimens. The same agreeable odour is obtained by heating the aloes on a point of a knife in a candle. By distillation with water, we obtain a liquid having the same odour, but free from any bitter taste. When fresh, socotrine aloes posesses considerable acidity, and the late Mr. Hennell informed me that, in the preparation of the compound extract of colocynth, he had frequently observed the fatty acid of the soap set free by the acid of the socotrine aloes. I have been shown a sample of what was declared to be socotrine aloes, which was soft or semi-liquid, and had a bright or palm-oil yellow colour, and a very fragrant odour.

When a package of socotrine aloes arrives at a druggist warehouse, it is usually garbled or sorted. The finest, clear, and hard pieces are separated for sale. The soft portions are placed upon slabs or in shallow tin trays, or other vessels, and exposed to a very gentle heat to harden them (hardened socotrine aloes), and at the same time to preserve the favourite colour of this kind of aloes. Mr. Whipple, who has had great experience in these matters, informs me that "the loss would be frightful, if, after selecting or separating the clean aloes, the skins were not washed and the aloes obtained by subsequent evaporation."

It is brittle, bitter, reddish brown, with an aromatic odour; fresh thin films of it are translucent. Ph. Lond.

"In thin pieces, translucent, and garnet red; almost entirely soluble in spirit of the strength of sherry. Very rare." P. Ed.

But socotrine aloes as imported is not "in thin pieces;" this character being given to it in the garbling process, or by drying the soft portions in thin layers as above mentioned. Translucency and a garnet red colour are qualities not possessed by many fine specimens of socotrine aloes. The alcoholic strength of sherry is subject to variation, and, therefore, the statement of the College as to the solubility of socotrine aloes is not very definite. Lastly, as to socotrine aloes being very rare, I may observe that the late Mr. Hennell, of Apothecaries' Hall, informed me (Dec. 21, 1841), that he would be happy to take an order for 500 lbs. of it.

The impure and dirty pieces of socotrine aloes are sometimes melted and strained (strained socotrine aloes), by which the colour and odour are impaired, and the other qualities somewhat altered.

Socotrine aloes has long been regarded as the best kind of aloes, though its commercial value is now below that of Barbados aloes. It is, I suspect, inferior in activity.

Socotrine aloes is mentioned by Avicenna and Mesue, both of whom regarded it as the best kind. By Fée, [Court d'Hist. Nat. Pharm. t.i, p. 325.] and some other continental writers, it is confounded with Cape aloes.

The aloes prepared in the Island of Socotra is probably procured from Aloë socotrina; and perhaps also A. purpurascens. In 1833, the quantity exported from this island was 83 skins, or 2 tons. But a much larger quantity might be procured if required. [Wellstead, Journ. Geograph Soc. vol. v.] Two samples (one of which I have in my museum) brought direct from the Island of Socotra, by a friend of Professor Royle, are largely intermixed with foreign substances, as sand, skins, &c.

Sir Whitelaw Ainslie [Materia Indica, vol. i p. 9.] says, that the greater part of the extract now sold under the name of socotrine aloes is prepared in the kingdom of Melinda; and I am informed by an eminent drug merchant that both socotrine and hepatic aloes have been imported into London directly from Zanzibar.

2. Genuine Hepatic Aloes; Liver-coloured Socotrine Aloes (Aloë hepatica, L. D.; Aloë Indica, E.). [I suspect hepatic aloes is included by the Edinburgh College ander "Aloë indica." For, in preparing Decoction of Aloes, the College orders Socotrine or Hepatic Aloes, though the term hepatic does not occur in the list of Materia Medica.]—This sort of aloes usually comes to London from Bombay (hence it is sometimes called Bombay or East India Aloes) in skins, contained in casks holding from 200 to 300 pounds, [Mr. Whipple informs me that it is "received in packages varying from 56 lbs. to 12 cwt. casks, most commonly in firkins. Lately, it has come over in boxes lined with tin, and holding about 56 lbs. All of these, except the last, contain the skin packages."] or in kegs. The London College (1851) declares it to be the "inspissated juice of the leaf?" of "an uncertain species of aloe." Its odour is very much the same as that of the socotrine kind, or perhaps it is a little less fragrant. It is distinguished from the latter by its opacity and its liver colour. It might, therefore, be called opake liver-coloured socotrine aloes. It appears to me to bear very much the same relation to the transparent or real socotrine aloes that the opake yellow rosin bears to the dark transparent or fiddler's rosin. It is sometimes imported in a soft or liquid state, and in this condition I know not how to distinguish it from liquid socotrine aloes. The similarity of the odour of socotrine and hepatic aloes leads to the suspicion that they are obtained from the same plants; and which is further confirmed by the two being sometimes brought over intermixed, the socotrine occasionally forming a vein in a cask of hepatic aloes. Some samples of hepatic aloes, when digested in rectified spirit of wine, yield a tincture, at the bottom of which there remains undissolved a yellowish granular powder (in appearance something like lycopodium), which is insoluble in water, alcohol, ether, and dilute sulphuric acid, but is readily soluble in a solution of caustic potash, forming a red-coloured liquid.

The place of produce of this species is probably the same as that of the so-called socotrine aloes.

Opake, liver-coloured, bitter, with an unpleasant odour. Ph. Lond.

3. Barbados Aloes; Aloes in gourds (Aloë barbadensis, Ph. L. and Ed.)—This is the kind denominated by most continental writers (as Geiger, Theod. Martius, Pfaff, Fée, and others), hepatic aloes (aloe hepatica), but its colour is not constantly that of the liver. It is imported from Barbados or Jamaica usually in gourds (Lagenaria vulgaris), weighing about 60 to 70 pounds, or even more than this; and sometimes in cases or boxes holding 50 lbs. each. The hole in the gourd-shell is partially closed by a piece of gourd let in and covered by a portion of coarse cloth, which is nailed down over the aperture.

The finest Barbados aloes is the inspissated juice, which I have heard called by an inhabitant of the island cold drawn Barbados aloes, to distinguish it from the extract of the decoction, which is of inferior quality.

Barbados aloes varies in colour from a dark brown or black (brown or black Barbados aloes) to a reddish-brown or liver colour (liver-coloured or hepatic Barbados aloes): even in the same gourd a difference of colour is occasionally observed. The fracture also varies, sometimes being dull, at other times glossy, or even resinous. Its unpleasant odour (which is much increased by breathing on it) will always distinguish it from the foregoing kinds. Its powder is of a dull olive-yellow colour. This kind of aloes is obtained chiefly, if not exclusively, from the Aloë vulgaris. [Dr. Maycock (Flora Barbadensis, 1830) notices no other species of Aloë indigenous, naturalized, or cultivated in Barbados. But Dr. Christison observes that, though at one time Barbados aloes was made only from A. vulgaris, he is assured by various pupils from that island that, while this species is commonly used, others are likewise employed. Sir R. H. Schomburgk (History of Barbados, p. 590, 1847) mentions A. ferox, Lam. or Great Hedge-hog Aloe, as having been introduced from the Cape of Good Hope. Kunth (Enum. Plant.) says, but I know not on what authority, that A. socotrina is cultivated at Barbados.]

The London College (1851) declares it to be the "inspissated juice of the cut-off leaves of Aloe vulgaris".

Opake, not glistening, liver-coloured, becoming blackish, with a bitter nauseous taste, and very unpleasant odour.—Ph. Lond.

The quantity of aloes annually exported from Barbados is stated by Sir R. H. Schomburgk (op.cit. pp. 149, 150, and 160) to be as follows:—

4. Cape Aloes (Aloë capensis; A. lucida of Geiger).—This kind is imported, as its name indicates, from the Cape of Good Hope. It is brought over in chests and skins, the latter being preferred, as the aloes contained therein are usually purer and more glossy. It has a shining resinous appearance, is of a deep brown colour, with a greenish tint, and has a glossy or resinous fracture; its edges, or thin laminae, viewed by transmitted light, have a yellowish red or ruby colour; its odour is stronger and more disagreeable than the Barbados aloes; its powder is greenish yellow. Some of the commoner kinds of Cape aloes have a rough fracture. The finest kind of Cape aloes is called Bethelsdorp aloes (see ante, p. 196).

Occasionally it has been imported of a reddish-brown colour, like that of the liver, and opake (liver-coloured or hepatic Cape aloes). Some years since an experienced dealer bartered 3 lbs. of Cape aloes for 1 lb. of what he thought to be the genuine hepatic aloes, but which turned out to be a fine sort of Cape aloes. I presume this is the kind which Professor Guibourt, [Hist. des Drog. simpl. 3me édit. t. ii. p. 418.] to whom I sent a specimen of it, formerly termed false hepatic aloes; and which more recently [Ibid. 4me édit. p. 168.] he calls opake Cape aloes. Its odour, when breathed on, instantly detects it.

I have received four species of Aloë plants from Mr. Dunsterville, of Algoa Bay, and the four extracts which he was informed were obtained respectively from the species sent. Two of the plants were dead and rotten; and the others were unknown to the late Mr. Anderson, of the Chelsea Gardens. The four extracts are as follows:—

α. Ordinary Cape Aloes.—Dark, glossy, very resinous, with a strong disagreeable odour, and greenish tint.

β. Socotrine Cape Aloes.—This, in colour, resembled socotrine aloes; but it was more glossy, brittle, and transparent. Its odour, though disagreeable, was less so than the first kind.

γ. Hepatic Cape Aloes.—This is an intermixture of an opake liver-coloured extract (hepatic Cape aloes) with a dark, glossy, transparent extract.

δ. This very much resembled the preceding, and might equally claim for its opake portion the name of hepatic Cape aloes.

Cape aloes is procured from Aloë spicata and other species (see ante, p. 194).

5. Fetid, Horse, or Caballine Aloes (Aloë caballina).—I have never met with any particular kind of aloes under this name in English commerce; Barbados aloes being used in England for horses. From Prof. Guibourt I have received two substances, which he denominates Aloès Cahallin.

α. One is impure or foot Cape aloes.

β. The other is in black opake masses, intermixed with straws, pieces of bark, sand, charcoal, and other impurities. Its fracture is uniform. It is difficult to pulverize, adheres to the pestle, gives a greenish powder, has a very little odour, and yields a dark browrt decoction. It is probably an extract prepared by boiling the leaves in water.

Guibourt says Caballine aloes is procured either in the countries which furnish ordinary aloes, or in Spain [Formerly the inhabitants of Morviedro, in Valencia, cultivated the aloe plant (A. vulgaris), and obtained from it three kinds of aloes, called respectively socotrine, hepatic, and caballine (Jussieu in Chaptal's Elements of Chemistry, vol. iii. p. 86); but Laborde (View of Spain, vol. i. p. 302, 1809) says the cultivation is now neglected.] or Senegal.

6. Mocha Aloes (Aloë de Mochâ).—Under this name, I found in a drug warehouse, where it had lain for many years, an impure kind of aloes, in large irregular masses, opake, and black externally, intermixed with sand, strings, &c. In its brittleness, odour, and the pale colour of its decoction, it resembles Cape aloes. The interior of the mass is not uniform: in some places it is dark and opake, somewhat like Barbados aloes; in other places it resembles socotrine aloes, and here and there we find portions having the transparency and resinous appearance of Cape aloes. Recently, this kind of aloes has been imported under the name of Mocha aloes from Muscat, in chests containing nearly 2 cwt. each. [Mr. Whipple tells me that, in dissolving and straining Mocha aloes, he has never found less than 25 per cent. of impurities (sand, stones, &c.).] Dr. Christison thinks it is East Indian aloes of low quality. It is described by Guibourt under the name blackish or fetid aloes (aloès noirâtre et fétide).

7. Indian Aloes (Aloë indica; not the Aloe indica of the Edinburgh Pharmacopoeia).—Dr. O'Shaugnessy [Bengal Dispensatory.] mentions two kinds of Indian aloes: Kurachee aloes, nearly black, opake, and soluble in water to the extent of 52 per cent.; and Deckan aloes, deep brown, and soluble to the extent of 98 per cent.

Through the kindness of Professor Royle, I have examined four kinds of aloes brought from the interior of India:—

α. Aloes from Northern India.—Is dull, black, and brittle, and has little odour. It came from the northern parts of India, where it is common in the bazaars (Bazaar aloes). It is probably the kind which Ainslie [Mat. Ind. vol. ii. p. 10.] says resembles Barbados aloes, and is brought to India from Yemen, in Arabia. Is this the produce of Aloe officinalis, Forskål?

β. Guzerat Aloes.—Is dark, more gummy in its appearance and feel, more difficult to fracture.

γ. Salem Aloes.—In blackish masses. It was brought from Salem. It is distinguished from all the preceding by the numerous large air cavities observed in its interior. Its odour is analogous to that of socotrine aloes. Its price is marked one anna and nine pice [about two-pence halfpenny] a pound.

δ. Trichinopoli Aloes.—Resembles Cape aloes in its brittleness, odour, and colour, but is more opake. Its price is marked at two annas [about three pence] a pound.

These aloes are the produce, in part at least, of Aloë indica; [Royle, Bot. of the Himalayan Mountains.] a species with reddish flowers, common in dry situations in the northwestern provinces of India, and which, if known to Roxburgh, was included by him in the A. perfoliata, Linn., and perhaps also of A. vulgaris, or the plant mentioned by Rheede. [Hort. Malab. ii. t. 3.]

8. Curacoa Aloes.—This species of aloes is not known in the London market, but a notice of it has been published by Mr. A. Faber. [Pharmaceutical Journal, vol. vii. p. 547, 1848.] It is the produce of the Dutch West India Island, Curacoa; but as even in Holland it cannot be regularly obtained, it is probable that its production is scanty.

It is most like Cape aloes, but does not possess the greenish colour which is sometimes perceived in the latter; its appearance is more dull; and its colour is often that of the liver. From hepatic aloes it differs by its saffron-like odour. It is probably the produce of A. vulgaris.

Powdered Aloes.—In January, 1846, the lecture assistant of the Pharmaceutical Society carefully powdered selected samples of five kinds of aloes in the Society's museum. The colour of the various powders were as follows:—

Strained Aloes; Aloë colata.—In order to deprive aloes of the various foreign matters with which they are frequently mixed, the wholesale druggist purifies the extract by melting and straining it. The fusion is effected in a metallic vessel heated by steam or hot water, a hair or wire sieve being used for straining the liquor. By this process the aloes suffers a physical, and probably also a chemical change. It becomes darker coloured, harder, and somewhat less odorous. It is probable that the deepened colour is produced by the action of atmospheric oxygen.

Composition.—Aloes has been analyzed by Trommsdorff, [Ann. de Chim. t. lxviii. p. 11, 1808.] by Bouillon-Lagrange and Vogel, [Ibid. p. 155.] by Braconnot, [Journ. de Physiq. t. lxxxiv. p. 334, 1817.] and by Winkler. [Geiger, Hand. d. Pharm. Bd. ii. 782, 1829.]

1. Aloesin, Pfaff (Saponaceous Matter; Extractive; Bitter Principle of Aloes or Aloe bitter; Aloin).—This is the principal constituent of aloes. It is contained in the cold infusion of aloes, and also in a decoction which has cooled: it may be obtained from either by evaporation. Thus procured, it is a brown and bitter mass, readily soluble in water, but difficultly so in spirit of wine. In pure alcohol or ether it is said to be insoluble, or nearly so. Besides carbon, hydrogen, and oxygen, it contains nitrogen, for it yields ammonia by destructive distillation, and furnishes carbazotic acid when treated by nitric acid. Aloesin is probably a mixture or compound of various proximate principles. Obtained as above, Braconnot says it contains some of the puce-coloured principle, which may be removed by oxide of lead.

2. Aloe Resin.—The substance which deposits from a decoction of aloes as it cools is usually denominated resin. Braconnot says it is a mixture of aloesin and puce-coloured principle; while Berzelius regards it as apothëme combined with unaltered extract. It is transparent, brown, fusible, soluble in alcohol, ether, and alkaline solutions. The puce coloured principle of Braconnot is an odourless and tasteless powder, combustible, but not fusible; and is prepared by digesting aloes with water and oxide of lead: a compound of the puce principle and the oxide is procured, which is to be washed and decomposed by weak nitric acid: the oxide is dissolved, and the puce principle left. From Braconnot's observations, this principle seems to be rather oxidized extractive (apothême, Berz.) than resin.

3. Vegetable Albumen.—This term is applied to a substance insoluble in both water and alcohol.

4. Aloesic Acid.—This is the acid which Trommsdorff supposed to be gallic acid. A solution of aloes reddens litmus, darkens ferruginous solutions, but does not precipitate gelatin: hence Trommsdorff assumed the presence of gallic acid. But while gallic acid causes a blue colour with the persalts of iron, infusion of aloes produces an olive brown one. Furthermore, if excess of diacetate of lead be added to this infusion, and sulphuretted hydrogen be passed through the filtered liquor, to throw down the excess of lead, the boiled and strained liquor possesses the property of becoming olive brown on the addition of sesquichloride of iron. Hence it appears to me that the acid is a peculiar one, and I have accordingly termed it aloesic acid. It must not be confounded with an acid obtained by the action of nitric acid on aloes, and which has been termed aloetic acid.

Meissner [Pfaff's Mat. Med. vol. vii. p. 171.] has given the name of Aloine to a supposed alkali in aloes. Its solution was brown, and acted as an alkali on reddened litmus paper. With sulphuric acid, aloine formed a crystalline salt.

Winkler [Schwartz, Pharm. Tabell. p. 294, 2te Ausg.] regards aloes as a neutral vegetable salt, composed of two peculiar basic substances (viz., a non-bitter resin, and a bitter substance) and an acid, viz., a colouring, non-bitter matter.

Fabroni [Ann. de Chim. xxv. 301.] obtained a fine violet colour from the recent juice of the Aloe, which bas been proposed as a dye for silk. It is formed by the action of the oxygen of the air on the juice.

Messrs. T. and H. Smith [Chemical Gazette, March 15, 1851.] have obtained a yellow crystalline substance from aloes, to which they have given the name of aloine. Its composition is stated by Dr. Stenhouse to be C₃₄H₁₈O₄. In doses of one or two grains it operates as a purgative.

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The Elements of Materia Medica and Therapeutics, Vol. II, 3th American ed., was written by Jonathan Pereira in 1854.