ALOË.

Aloes; F. Aloès ou Suc d’Aloès; G. Aloë.

Botanical Origin—Several species of Aloë[2539] furnish a bitter juice which when inspissated forms this drug. These plants are natives of arid, sunny places in Southern and Eastern Africa, whence a few species have been introduced into Northern Africa, Spain,[2540] and the East and West Indies.

The aloes are succulent plants of liliaceous habit with persistent fleshy leaves, usually prickly at the margin, and erect spikes of yellow or red flowers. Many are stemless; others produce stems some feet in height, which are woody and branching. In the remote districts of Namaqua Land and Damara Land in Western South Africa, and in the Transkei Territory and Northern Natal to the eastern, aloes have been discovered which attain 30 to 60 feet in height, with stems as much as 12 feet in circumference.[2541] The following species may be named with more or less of certainty as yielding the drug.[2542]

Aloë socotrina Lam. (A. vera Miller), native of the southern shores of the Red Sea and Indian Ocean, Socotra, and Zanzibar (?). It is the source of the Socotrine and Moka Aloes. A. officinalis Forsk. and A. rubescens DC. are considered to be varieties of this plant. A. abyssinica Lam. may probably contribute to the aloes shipped from the Red Sea.

A. vulgaris Lam. A. perfoliata, var. π. vera Linn., A. barbadensis Mill., a plant of India and of Eastern and Northern Africa, now found also on the shores of Southern Spain, Sicily, Greece, and the Canaries; introduced in the beginning of the 16th century (or earlier) into the West Indies. It affords Barbados and Curaçao Aloes. A. indica Royle, a plant of the North-west Provinces of India, common in Indian gardens, appears to be a slight variety of A. vulgaris Lam. A. litoralis König, said to grow in abundance at Cape Comorin, is unknown to us. Dr. Bidie suggests that it is a form of the preceding, stunted by a poor saline soil and exposure to the sea breeze. Both A. indica and A. litoralis are named in the Pharmacopœia of India.

Aloë ferox L., and hybrids obtained by crossing it with A. africana Mill. and A. spicata Thunberg, A. perfoliata Linn. (quoad Roxb.) and A. linguæformis are reputed to yield the best Cape Aloes.

A. africana Mill. and its varieties, and A. plicatilis Mill. afford an extract which Pappe[2543] says is thought to be less powerful.

A. arborescens Mill., A. Commelini Willd. and A. purpurascens Haworth are stated to produce a portion of the Cape Aloes of commerce.[2544]

Various species of Agave, especially A. americana L., are largely grown, since the first half of the 16th century, in the south of Europe, and popularly called Aloë. All of them are plants of Mexico, while the true aloes are natives of the old world. Botanically the genus Agave differs from Aloë, in that the former has the ovary inferior, while in the latter it is superior. From a chemical point of view there is also no analogy at all between Aloë and Agave.

History—Aloes was known to the Greeks as a production of the island of Socotra as early as the 4th century b.c., if we might credit a remarkable legend thus given in the writings of the Arabian geographer Edrisi.[2545] When Alexander had conquered the king of the Persians and his fleets had vanquished the islands of India, and he had killed Pour, king of the Indies, his master Aristotle recommended him to seek the island that produces Aloes. So when he had finished his conquests in India, he returned by way of the Indian Sea into that of Oman, conquered the isles therein, and arrived at last at Socotra, of which he admired the fertility and the climate. And from the advice which Aristotle gave him he determined to remove the original inhabitants and to put Greeks in their place, enjoining the latter to preserve carefully the plant yielding aloes, on account of its utility, and because that without it certain sovereign remedies could not be compounded. He thought also that the trade in and use of this noble drug would be a great advantage for all people. So he took away the original people of the island of Socotra, and established in their stead a colony of Ionians, who remained under his protection and that of his successors, and acquired great riches, until the period when the religion of the Messiah appeared, which religion they embraced. They then became Christians, and so their descendants have remained up to the present time (circa a.d. 1154).

This curious account, which Yule[2546] says is doubtless a fable, but invented to account for facts, is alluded to by the Mahomedan travellers of the 9th century[2547] and in the 10th by Masudi,[2548] who says that in his time aloes was produced only in the island of Socotra, where its manufacture had been improved by Greeks sent thither by Alexander the Great.

Aloes is not mentioned by Theophrastus, but appears to have been well known to Celsus, Dioscorides, Pliny and the author of the Periplus of the Erythrean Sea, as well as to the later Greek[2549] and the Arabian physicians. From the notices of it in the Anglo-Saxon leech-books and a reference to it as one of the drugs recommended to Alfred the Great by the Patriarch of Jerusalem, we may infer that its use was not unknown in Britain as early as the 10th century.[2550]

At this period and for long afterwards the drug was imported into Europe by way of the Red Sea and Alexandria. After the discovery of a route to India by the Cape of Good Hope the old line of commerce probably began to change.

Pires, an apothecary at Cochin, in a letter on Eastern drugs[2551] addressed to Manuel, king of Portugal, in 1516, reports that aloes grows in the island of Çacotora, Aden, Cambaya, Valencia of Arragon, and in other parts,—the most esteemed being that of Çacotora, and next is that of Spain; while the drug of Aden and Cambaya is so bad as to be worthless.

In the early part of the 17th century there was a direct trade in aloes between England and Socotra; and in the records of the East India Company there are many notices of the drug being bought of the “King of Socotra.” Frequently the king’s whole stock of aloes is mentioned as having been purchased.[2552]

Wellstead, who travelled in Socotra in 1833,[2553] says that in old times the aloë was far more largely grown there than at present, and that the walls which enclosed the plantations may still be seen. He adds that the produce was a monopoly of the Sultan of the island. At the present day the few productions of Socotra that are exported are carried by the Arab coasting vessels, coming annually from the Persian Gulf to Zanzibar, at which place they are transshipped for Indian and other ports. Dr. Kirk, who has resided at Zanzibar from 1866 to 1873, informs us that aloes from Socotra arrives in a very soft state packed in goatskins. From these it is transferred to wooden boxes, in which it concretes, and is shipped to Europe and America. To avoid loss the skins have to be washed; and the aloetic liquor evaporated.

Ligon,[2554] who visited the island of Barbados in 1647-50, that is about twenty years after the arrival of the first settlers, speaks of the aloë as if it were indigenous, mentioning also the useful plants which had been introduced. At that period the settlers knew how to prepare the juice for medicinal use, but had not begun to export it. Barbados aloes was in the drug warehouses of London in 1693.[2555]

The manufacture of aloes in the Cape Colony of South Africa was observed by Thunberg in 1773 on the farm of a boer named Peter de Wett, who was the first to prepare the drug in that country.[2556] Cape Aloes is enumerated in the stock of a London druggist in 1780, its cost being set down as £10 per cwt. (1s. 9½d. per lb.).

A new and distinct sort of aloes, manufactured in the colony of Natal, appeared in English commerce in 1870. It will be described further on.

Lignum Aloes—It is important to bear in mind that the word Aloes or Lign Aloës, in Latin Lignum Aloës, is used in the Bible and in many ancient writings to designate a substance totally distinct from the modern Aloes, namely the resinous wood of Aquilaria Agallocha Roxburgh, a large tree[2557] of the order Thymeleaceæ, growing in the Malayan Peninsula. Its wood constituted a drug[2558] which was, down to the beginning of the present century, generally valued for use as incense, but now esteemed only in the East.

Structure of the Leaf—The stout fleshy leaves of an aloë have a strong cuticle and thick-walled epidermis. Their interior substance is formed of very loose, large-celled, colourless pulp, traversed by vascular bundles, which, on transverse section, are seen to be accompanied by a group of large thin-walled cells[2559] containing the bitter juice which constitutes the drug under notice. These cells, on a longitudinal section, are seen to be considerably elongated, adjoining a single row of smaller, prismatic, truncated cells,[2560] by which the former are separated from the cortical layer. The prismatic cells contain a yellow juice, apparently different from that which yields aloes. The cortical tissue is filled with granules of chlorophyll, and exhibits between the cells groups of needles of calcium oxalate. Similar crystals are also found sparingly in the pulp.

The transparent pulp-tissue[2561] is rich in mucilage, which after dilution with water is precipitated by neutral acetate of lead, but is not coagulated by boiling.

The amount of bitter principles in the leaf probably varies with the age of the latter and with the season of the year. Haaxman mentions that, in Curaçao, the maximum is found when the leaves are changing from green to brown.

Cultivation and Manufacture—In Barbados,[2562] where Aloë vulgaris is systematically cultivated for the production of the drug, the plants are set 6 inches apart, in rows which are 1 to 1½ foot asunder, the ground having been carefully prepared and manured. They are kept free from grass and weeds, but yams or pulse are frequently grown between them. The plants are always dwarf, never in the least degree arborescent; almost all of those above a year old bear flowers, which being bright yellow, have a beautiful effect. The leaves are 1-2 feet long; they are cut annually, but this does not destroy the plant, which, under good cultivation, lasts for several years.

The cutting takes place in March and April, and is performed in the heat of the day. The leaves are cut off close to the plant, and placed very quickly, the cut end downwards, in a V-shaped wooden trough, about 4 feet long and 12 to 18 inches deep. This is set on a sharp incline, so that the juice which trickles from the leaves very rapidly flows down its sides, and finally escapes by a hole at its lower end into a vessel placed beneath. No pressure of any sort is applied to the leaves. It takes about a quarter of an hour to cut leaves enough to fill a trough. The troughs are so distributed as to be easily accessible to the cutters. Their number is generally five; and by the time the fifth is filled, the cutters return to the first and throw out the leaves, which they regard as exhausted. The leaves are neither infused nor boiled, nor is any use afterwards made of them except for manure.

When the vessels receiving the juice become filled, the latter is removed to a cask and reserved for evaporation. This may be done at once, or it may be delayed for weeks or even months, the juice, it is said, not fermenting or spoiling. The evaporation is generally conducted in a copper vessel; at the bottom of this is a large ladle, into which the impurities sink, and are from time to time removed as the boiling goes on. As soon as the inspissation has reached the proper point, which is determined solely by the experienced eye of the workman, the thickened juice is poured into large gourds or into boxes, and allowed to harden.

The drug is not always readily saleable in the island, but is usually bought up by speculators who keep it till there is a demand for it in England. The cultivators are small proprietors, but little capable as to mind or means of making experiments to improve the manufacture of the drug. It is said, however, that occasionally a little aloes of very superior kind is made for some special purpose by exposing the juice in a shallow vessel to solar heat till completely dry. But such a drug is stated to cost too much time and trouble to be profitable.[2563] The manufacture of aloes in the Dutch West Indian island of Curaçao is conducted in the same manner.[2564]

The manufacture of aloes in the Cape Colony has been thus described to us in a letter[2565] from Mr. Peter MacOwan of Gill College, Somerset East:—The operator scratches a shallow dish-shaped hollow in the dry ground, spreads therein a goatskin, and then proceeds to arrange around the margin a radial series of aloë leaves, the cut ends projecting inwards. Upon this, a second series is piled, and then a third—care being taken that the ends of each series overhang sufficiently, to drop clear into the central hollow. When these preparations have been made, the operator either “loafs about” after wild honey, or, more likely, lies down to sleep. The skin being nearly filled, four skewers run in and out at the edge square-fashion, give the means of lifting this primitive saucer from the ground, and emptying its contents into a cast-iron pot. The liquid is then boiled, an operation conducted with the utmost carelessness. Fresh juice is added to that which has nearly acquired the finished consistence; the fire is slackened or urged just as it happens, and the boiling is often interrupted for many hours, if neglect be more convenient than attention. In fact, the process is thoroughly barbarous, conducted without industry or reflection; it is mostly carried on by Bastaards and Hottentots, but not by Kaffirs. “The only aloë I have seen used,” says Mr. MacOwan, “is the very large one with di-or tri-chotomous inflorescence,—A. ferox, I believe.” Backhouse[2566] also names “Aloë ferox?” as the species he saw used near Port Elizabeth in 1838.

From another correspondent, we learn that the making of aloes in the Cape Colony is not carried on by preference, but is resorted to when more profitable work is scarce. The drug is sold by the farmers to the merchants of the towns on the coast, some of whom have exerted themselves to obtain a better commodity, and have even imported living aloe-plants from Barbados.

Nothing is known of the manufacture of the so-called Socotrine or Zanzibar Aloes, or even with certainty in what precise localities it is carried on.

General Description—The differences in the several kinds of commercial aloes are due to various causes, such as the species of Aloë employed and the method of extracting the juice. The drug varies exceedingly: some is perfectly transparent and amorphous, with a glassy conchoidal fracture; some is opaque and dark with a dull waxy fracture, or opaque and pallid; or it may be of a light orange-brown and highly crystalline. It varies in consistence in every degree, from dry and brittle to pasty, and even entirely fluid and syrup-like.

These diverse conditions are partially explained by an examination of the very fluid aloes that has been imported of recent years from Bombay. If some of this aloes is allowed to repose, it gradually separates into two portions,—the upper a transparent, black liquid,—the lower, an orange-brown crystalline sediment. If the whole be allowed to evaporate spontaneously, we get aloes of two sorts in the same mass; the one from the upper portion being dark, transparent and amorphous, the other rather opaque and highly crystalline. Should the two layers become mixed, an intermediate form of the drug results.

The Hepatic Aloes of the old writers[2567] was doubtless this rather opaque form of Socotrine Aloes; but the term has come to be used somewhat vaguely for any sort of liver-coloured aloes, and appears to us unworthy to be retained. Much of the opaque, so-called Hepatic Aloes does not however owe its opacity to crystals, but to a feculent matter the nature of which is doubtful.

The odour of aloes is a character which is much depended on by dealers for distinguishing the different varieties, but it can only be appreciated by experience, and certainly cannot be described.[2568]

Varieties—The principal varieties of aloes found in English commerce are the following:—

1. Socotrine Aloes—also called Bombay, East Indian, or Zanzibar Aloes, and when opaque and liver-coloured, Hepatic Aloes. It is imported in kegs and tin-lined boxes from Bombay, whither it has been carried by the Arab traders from the African coast, the Red Sea ports, or by way of Zanzibar, from Socotra. When of fine quality, it is of a dark reddish-brown, of a peculiar, rather agreeable odour, comparable to myrrh or saffron. In thin fragments, it is seen to be of an orange-brown; its powder is of a tawny reddish-brown. When moistened with spirit of wine, and examined in a thin stratum under the microscope, good Socotrine Aloes is seen to contain an abundance of crystals. As imported, it is usually soft, at least in the interior of the mass, but it speedily dries and hardens by keeping.[2569] It is occasionally imported in a completely fluid state (Liquid Socotrine Aloes, Aloë Juice), and is not unfrequently somewhat sour and deteriorated.

Some fine aloes from Zanzibar, of which a very small quantity was offered for sale in 1867, was contained in a skin, and composed of two layers, the one amorphous, the other a granular translucent substance of light colour, which when softened and examined with a lens, was seen to be a mass of crystals. A very bad, dark, fœtid sort of aloes is brought to Aden from the interior. It seems to be the Moka Aloes of some writers.

The quantity of aloes imported into Bombay in the year 1871-72 was 892 cwt., of which 736 cwt. are reported as shipped from the Red Sea ports and Aden.[2570]

2. Barbados Aloes—Characteristic samples show it as a hard dry substance of a deep chocolate-brown, with a clean, dull, waxy fracture. In small fragments it is seen to be translucent and of an orange-brown hue. When breathed upon, it exhales an odour analogous to, but easily distinguishable from, that of Socotrine aloes. It is imported in boxes and gourds. The gourds, into which the aloes has been poured in a melted state through a square hole, over which a bit of calico is afterwards nailed, contain from 10 to 40 lb. or more. Of late years, Barbados aloes having a smooth and glassy fracture has been imported; it is known to the London drug-brokers as “Capey Barbados.” By keeping, it passes into the usual variety having a dull fracture.

The export of aloes from Barbados in 1871, as shown by the Blue Book for that colony, was 1046 cwt., of which 954 cwt. were shipped to the United Kingdom.

3. Curaçao Aloes—manufactured in the Dutch West Indian islands of Curaçao, Bonaire, and Aruba, is imported into this country by way of Holland, packed in boxes of 15 to 28 lb. each. In appearance it resembles Barbados aloes, but has a distinctive odour.

4. Cape Aloes—The special features of this sort of aloes are its brilliant conchoidal fracture and peculiar odour. Small splinters seen by transmitted light are highly transparent and of an amber colour; the powder is of a pale tawny yellow. When the drug is moistened and examined under the microscope, no crystals can be detected, even after the lapse of some days. Cape aloes has the odour of other kinds of aloes, with a certain sourish smell which easily distinguishes it. Several qualities are recognized, chiefly by the greater or lesser brilliancy of fracture, and by the tint of the powder.

From the Blue Book for the Colony of the Cape of Good Hope, published at Cape Town in 1873, it appears that the export of aloes in 1872 was 484,532 lb. (4326 cwt.); and that the average market value during the year was 3¾d., the lowest price, 1½d., being at Riversdale and Mossel Bay, and the highest, 11d., at Swellendam. The drug is shipped from Cape Town, Mossel Bay and Algoa Bay.

5. Natal Aloes—Aloes is also imported from Natal, and since 1870 in considerable quantity. Most of it is of an hepatic kind and completely unlike the ordinary Cape aloes, inasmuch as it is of a greyish-brown and very opaque. Moreover it contains a crystalline principle which has been found in no other sort of aloes.

The drug is manufactured in the upper districts of Natal, between Pietermaritzburg and the Quathlamba mountains, especially in the Umvoti and Mooi River Counties, at an elevation of 2000 to 4000 feet above the sea. The plant used is a large aloë which has not yet been botanically identified. The people who make the drug are British and Dutch settlers, employing Kaffir labourers. The process is not very different from that followed in making Cape aloes, but is conducted with more intelligence. The leaves are cut obliquely into slices, and allowed to exude their juice in the hot sunshine. The juice is then boiled down in iron pots, some care being taken to prevent burning, by stirring the liquid as it becomes thick. The drug while still hot, is poured into wooden cases, in which it is shipped to Europe.[2571] The exports from the colony have been as follows:—[2572]

Chemical Composition—All kinds of aloes have an odour of the same character and a bitter disagreeable taste. The odour which is often not unpleasant, especially in Socotrine aloes, is due to a volatile oil, which the drug contains only in minute proportion. T. and H. Smith of Edinburgh, who contributed a specimen of it to the Vienna Exhibition of 1873, inform us that they obtained it by subjecting to distillation with water 400 lb. of aloes, which quantity they estimate to have yielded about an ounce. The oil is stated in a letter we have received from them, to be a mobile pale yellow liquid, of sp. gr. 0·863, with a boiling point of 266-271° C.

Pure aloes dissolves easily in spirit of wine with the exception of a few flocculi; it is insoluble in chloroform and bisulphide of carbon, as well as in the so-called petroleum ether, the most volatile portion of American petroleum. The sp. gr. of fine transparent fragments of aloes, dried at 100° C., and weighed in the last named fluid at 16° C., was found by one of us (F.) to be 1·364; showing that aloes is much more ponderous than most of the resins, which seldom have a higher sp. gr. than 1·00 to 1·10. In water aloes dissolves completely only when heated. On cooling, the aqueous solution, whether concentrated or dilute, becomes turbid by the separation of resinous drops, which unite into a brown mass,—the so-called Resin of Aloes.[2573] The clear solution, after separation of this substance, has a slightly acid reaction; it is coloured dark brown by alkalis, black by ferric chloride, and is precipitated yellowish-grey by neutral lead acetate. Cold water dissolves about half its weight of aloes, forming an acid liquid which exhibits similar reactions. The solution of aloes in potash or ammonia is precipitated by acids, but not by water.

The most interesting constituents of aloes are the substances known as Aloïn. This name was originally applied to an aloïn which, as it appears to be found exclusively in Barbados aloes, is now termed Barbaloïn, in order to distinguish it from allied substances occurring in Natal and Socotrine aloes.

Barbaloïn was discovered by T. and H. Smith of Edinburgh in 1851,[2574] and was described (1851) by Stenhouse. From good qualities of the drug it can be obtained, according to Tilden,[2575] as a crystalline mass, to the extent of 20 to 25 per cent., but in others it appears to occur partly amorphous or in a chemically altered state. Barbaloïn is a neutral substance, crystallizing in tufts of small yellow prisms. These crystals represent hydrated aloïn, and part with one molecule of water (=2·69 per cent.) by desiccation in vacuo, or by the prolonged heat of a water-bath. Barbaloïn, C₃₄H₃₆O₁₄ + H₂O, dissolves sparingly in water or alcohol but very freely if either liquid be even slightly warmed; it is insoluble in ether.

The solutions alter quickly if made a little alkaline, but if neutral or slightly acid, are by no means very prone to decomposition. By oxidation with nitric acid, barbaloïn yields, as Tilden (1872) has shown, about a third of its weight of chrysammic acid, besides aloëtic, oxalic, and picric acids. It easily combines with bromine to form yellow needles of Bromaloïn, C₃₄H₃₀Br₆O₁₄; Chloraloïn, C₃₄H₃₀Cl₆O₁₄ + 6H₂O, crystallizing in prisms, has likewise been obtained.

In examining Natal aloes in 1871, we observed it to contain a distinct crystalline body, much less soluble than the ordinary aloïn of Barbados aloes. We have accordingly named it Nataloïn.

Nataloïn exists naturally in Natal aloes, from which it can be easily prepared in the crude state, if the drug is triturated with an equal weight of alcohol at a temperature not exceeding 48° C. This will dissolve the amorphous portion, from which the crystals should be separated by a filter, and washed with a small quantity of cold spirit. From 16 to 25 per cent. of crude nataloïn in pale yellow crystals may be thus extracted. When purified by crystallization from methylic alcohol or spirit of wine, it forms thin, brittle, rectangular scales, often with one or more of their angles truncated. The formula assigned to nataloïn by Tilden, which is supported by the composition of the acetyl derivative he has succeeded in obtaining, is C₂₅H₂₈O₁₁.

At 15·5° C., 60 parts of alcohol, 35 of methylic alcohol,[2576] 50 of acetic ether, 1236 of ether, and 230 of absolute alcohol, dissolve respectively one part of nataloïn. It is scarcely more soluble in warm than in cold spirit of wine, so that to obtain crystals it is best to allow the solution to evaporate spontaneously. Water hot or cold dissolves it very sparingly. Nataloïn gives off no water when exposed over oil of vitriol, or to a temperature of 100° C. By the action of nitric acid, it affords both oxalic and picric acids, but no chrysammic acid. It appears not to combine with chlorine or bromine, and we have failed in obtaining from it any such body as bromaloïn.

Liquid Socotrine aloes, imported into London about 1852, was noticed by Pereira to abound in minute crystals, which he termed the Aloïn of Socotrine Aloes, and regarded as probably identical with that of Barbados aloes. Some fine dry aloes from Zanzibar of very pale hue, in our possession, is in reality a perfectly crystalline mass.

Histed was the first to assert that the crystalline matter of Socotrine or Zanzibar aloes is a peculiar substance, according neither with barbaloïn nor with nataloïn. This observation was fully corroborated by our own experiments,[2577] made chiefly on the Zanzibar aloes just described, and we shall call the substance thus discovered Socaloïn. In this drug, the crystals are prisms of comparatively large size, such as we have never observed in Natal aloes. They cannot be so easily isolated as nataloïn, since they are nearly as soluble as the amorphous matter surrounding them. Histed recommends treating the powdered crude drug with a little alcohol, sp. gr. 0·960, and strongly pressing the pasty mass between several thicknesses of calico; then dissolving the yellow crystalline cake in warm weak alcohol, and collecting the crystals which are formed by cooling and repose.

Socaloïn forms tufted acicular prisms, which by solution in methylic alcohol may be got 2 to 3 millimetres long. It is much more soluble than nataloïn. At ordinary temperatures, 30 parts of alcohol, 9 of acetic ether, 380 of ether, 90 of water are capable of dissolving respectively one part of socaloïn; while in methylic alcohol, it is most abundantly soluble. Socaloïn is a hydrate, losing when dried over oil of vitriol 11 to 12 per cent. of water, but slowly regaining it if afterwards exposed to the air. Its elementary composition according to the analysis made by one of us (F.) is C₃₄H₃₈O₁₅ + 5 H₂O. We have not succeeded in obtaining any well-defined bromine compound of socaloïn.

The three aloïns, Barbaloïn, Nataloïn, and Socaloïn, are easily distinguished by the following beautiful reaction first noticed by Histed:—a drop of nitric acid on a porcelain slab gives with a few particles of barbaloïn or nataloïn, a vivid crimson,[2578] but produces little effect with socaloïn. To distinguish barbaloïn from nataloïn, test each by adding a minute quantity to a drop or two of oil of vitriol, then allowing the vapour from a rod touched with nitric acid to pass over the surface. Barbaloïn (and socaloïn) will undergo no change, but nataloïn will assume a fine blue.[2579]

The researches of E. von Sommaruga and Egger in Vienna (1874) have been directed in particular to the aloïn of Socotrine aloes. The melting point of this aloïn was found to be between 118° and 120° C., that of barbaloïn being much higher. The authors conclude that the three form an homologous series, that their composition may probably be represented thus:—

They derive in all probability from anthracene, C₁₄H₁₀.

The portion of aloes insoluble in cold water was formerly distinguished as Resin of Aloes, from the soluble portion which was called Bitter of aloes or Aloëtin. From the labours of Kossmann (1863), these portions appear to have nearly the same composition. The soluble portions treated with dilute sulphuric acid, is said to yield Aloëresic and Aloëretic Acids, both crystallizable, besides the indifferent substance Aloëretin. These observations have not to our knowledge been confirmed.

It has been shown by Tilden and Rammell[2580] that the Resin of Aloes may by prolonged treatment with boiling water be separated into two bodies, which they distinguish as Soluble Resin A. and Insoluble Resin B. With the first it is possible to form a brominated compound, which though non-crystalline is apparently of definite composition. In the view of these chemists the Resin A. is a kind of anhydride of barbaloïn—Barbaloïn, 2(C₃₄H₃₆O₁₄) less H₂O = Aloe Resin A., C₆₈H₇₀O₂₇. The resin boiled with nitric acid yields a large amount of chrysammic acid, together with picric and oxalic acids, and carbonic anhydride. Insoluble Resin B. was found to have nearly the same composition as Resin A.

Aloes treated with various reagents affords a number of remarkable products. Thus, according to Rochleder and Czumpelick (1861) it yields, when boiled with soda-lye, colourless crystals an inch long, which appear to consist of a salt of Paracumaric Acid, together with small quantities of fragrant essential oils and volatile fatty acids.

When boiled with dilute sulphuric acid, aloes yields paracumaric acid, from which by fusion with caustic potash, as also directly from aloes, Hlasiwetz (1865) obtained Para-oxybenzoic Acid (p. 408). Weselsky (1872-73) has shown that accompanying the last two products, there is a peculiar, crystallizable acid, C₉H₁₀O₃, which he has named Alorcinic Acid.

By distillation with quicklime, E. Robiquet (1846) obtained Aloïsol, a yellowish oil, which Rembold (1866) proved to be a mixture of dimethylated phenol (Xylenol)

Nitric acid forms with Barbadoes aloes, but still better, as Tilden has shown, with barbaloïn, Aloëtic Acid, C₁₄H₄(NO₂)₄O₂, Chrysammic Acid, C₁₄H₄(NO₂)₄O₄, and finally Picric Acid, together with Oxalic Acid. The first two of these acids are distinguished by the splendid tints of their salts, which might be utilized in dyeing.

Chlorine, passed into an aqueous solution of aloes, forms a variety of substitution-products, and finally Chloranil, C₆Cl₄O₂.

When somewhat strongly heated, aloes swells up considerably, and after ignition leaves a light, slow-burning charcoal, almost free from inorganic constituents. Ordinary Cape aloes, for example, dried at 100° C., leaves only 1 per cent. of ash.

Commerce—There were imported into the United Kingdom in the year 1870, 6264 cwt. of aloes. Of this quantity, South Africa shipped 4811 cwt.; and Barbados 970 cwt. The remainder was probably furnished by Eastern Africa.

The commercial value of the varieties of aloes is very different. In 1874, Barbados Aloes was quoted in price-currents at £3 5s. to £9 10s. per cwt.; Socotrine at £5 to £13; while Cape Aloes was offered at £1 10s. to £2. In England, the first two alone are allowed for pharmaceutical preparations. Even the Veterinary Pharmacopœia[2581] names only Aloë Barbadensis. Cape Aloes is esteemed on the Continent, and chiefly consumed there.

Use—Aloes is a valuable purgative in very common use, it is generally given combined with other drugs.

Adulteration—The physical characters of aloes, such as colour of the powder, odour, consistence and freedom from obvious impurity, coupled with its solubility in weak alcohol, usually suffice for determining its goodness.

BULBUS SCILLÆ.

Radix Scillæ; Squill; F. Bulbe ou squames de Scille, Ognon marin; G. Meerzwiebel.

Botanical Origin—Urginea maritima Baker[2582] (Scilla maritima L., Urginea Scilla Steinheil). It is found generally in the regions bordering the Mediterranean, as in Southern France, Italy, Dalmatia, Greece, Asia Minor, Syria, North Africa and the Mediterranean islands. In Sicily, where it grows most abundantly, Urginea ascends to elevations of 3000 feet. It is also very common throughout the South of Spain, where it is by no means confined to the coast; it occurs also in Portugal. In the Riviera of Genoa the peasants like to see it growing under the fig trees.

Two varieties of squill, termed respectively white and red, are distinguished by druggists. In the first, the bulb-scales are colourless; in the second they are of a roseate hue. No other difference in the plants can be pointed out, nor have the two varieties distinct areas of growth.

History—Squill is one of the most ancient of medicines. Epimenides, a Greek who lived in the 30th Olympiad, is said to have made much use of it, from which circumstance it came to be called Epimenidea[2583]. It is also mentioned by Theophrastus, and was probably well known to all the ancient Greek physicians. Pliny was not only acquainted with it, but had noticed its two varieties. Dioscorides describes the method of making vinegar of squills; and a similar preparation, as well as compounds of squill with honey, were administered by the Arabian physicians, and still remain in use. The medical school of Salerno preferred the red variety of the drug, which on the whole is not frequently met with in mediæval literature.

Description—The bulb of squill is pear-shaped, and of the size of a man’s fist or larger, often weighing more than four pounds. It has the usual structure of a tunicated bulb; its outer scales are reddish-brown, dry, scarious, and marked with parallel veins. The inner are fleshy and juicy, colourless or of a pale rose tint, thick towards the middle, very thin and delicate at the edges, smooth and shining on the surface. The fresh bulb has a mucilaginous, bitter, acrid taste, but not much odour.

For medicinal use, squill is mostly imported ready dried. The bulbs are collected in the month of August, at which period they are leafless, freed from their dry outer scales, cut transversely into thin slices, and dried in the sun. Thus prepared, the drug appears in the form of narrow, flattish or four-sided curved strips, 1 to 2 inches long, and ⅜ to ⅝ of an inch wide, flexible, translucent, of a pale dull yellowish colour, or when derived from the red variety, of a decided roseate hue. When thoroughly dried, they become brittle and pulverizable, but readily absorb water to the extent of about 11 per cent. Powdered squill by the absorption of water from the air, readily cakes together into a hard mass.

Microscopic Structure—The officinal portion of the plant being simply modified leaves, has the histological characters proper to many of those organs. The tissue is made up of polyhedral cells, covered on both sides of the scales by an epidermis provided with stomata. It is traversed by numerous vascular bundles, and also exhibits smaller bundles of laticiferous vessels. If thin slices of squill be moistened with dilute alcohol, most of the parenchymatous cells are seen to be loaded with mucilage, which contracts into a jelly on the addition of alcohol. In the interior of this jelly, crystalline particles are met with consisting of oxalate of calcium. This salt is largely deposited in cells, forming either bundles of needle-shaped crystals, or large solitary square prisms, frequently a millimetre long. In either case they are enveloped by the mucilaginous matter already mentioned. Oxalate of calcium as occurring in other plants has been shown in many instances to originate in the midst of mucilaginous matter. The fact is remarkably evident in Scilla, especially when examined in polarized light.

On shaking thin slices of the bulb with water, the crystals are deposited in sufficient quantity to become visible to the naked eye, though their weight is actually very small. Direct estimation of the oxalic acid (by titration with chamæleon solution) gave us only 3·07 per cent. of C₂CaO₄,3H₂O from white squill dried at 100° C., which moreover yielded only 2 to 5 per cent. of ash. It is these extremely sharp brittle crystals which occasion the itching and redness, and sometimes even vesication, which result from rubbing a slice of fresh squill on the skin. These effects, which have long been known, were attributed to a volatile acrid principle, until their true cause was recognized by Schroff.[2584]

The mucilage also contains albuminous matters, hence the orange colour it assumes on addition of iodine. The vascular bundles are accompanied by some rows of longitudinally extended cells, containing a small number of starch granules. In the red squill the colouring matter is contained in many of the parenchymatous cells, others being entirely devoid of it. It turns blackish-green if a persalt of iron be added.

Chemical Composition—The most abundant among the constituents of squill are mucilaginous and saccharine matters. Mucilage may be precipitated by means of neutral and basic acetate of lead, yet there remains in solution another substance of the same class, called Sinistrin. It was discovered in 1879 by Schmiedeberg, who obtained it by mixing the powder of squill, either red or white, with a solution of basic acetate of lead in slight excess. The gummy matters thus forming insoluble lead compounds being removed, the liquid is deprived of the lead and mixed with slaked lime. An insoluble compound of sinistrin and calcium separates and yields the former on decomposing the well washed precipitate with carbonic acid. The small amount of calcium remaining in the filtrate is to be removed by adding cautiously to the warm solution the small quantity just required of oxalic acid. Lastly, sinistrin is thrown down by alcohol. It is a white amorphous powder, on exposure to air soon forming transparent brittle lumps. The composition of sinistrin is that of dextrin = C₆H₁₀O₅, both these substances being very closely allied, yet the aqueous solution of sinistrin deviates the plane of polarization to the left. The rotatory power appears not to be much influenced by the concentration or the temperature of the solution of sinistrin.

An alkaline solution of tartrate of copper is not acted upon by sinistrin. It is transformed into sugar by boiling it for half an hour with water containing 1 per cent. of sulphuric acid. The sugar thus produced is stated by Schmiedeberg to consist of lævulose[2585] and another sugar, which in all probability, when perfectly pure, must prove devoid of rotatory power.

The name sinistrin[2586] has also been applied to a mucilaginous matter extracted from barley (see Hordeum decorticatum); it remains to be proved that the latter is identical with the sinistrin of squill.

We have obtained a considerable amount of an uncrystallizable levogyre sugar by exhausting squill with dilute alcohol.[2587] Alcohol added to an aqueous infusion of squill causes the separation of the mucilage, together with albuminoid matter. If the alcohol is evaporated and a solution of tannic acid is added, the latter will combine with the bitter principle of squill, which has not yet been isolated, although several chemists have devoted to it their investigations, and applied to it the names of Scillitin or Skuleïn. Schroff, to whom we are indebted for a valuable monograph on Squill,[2588] infers from his physiological experiments the presence of a non-volatile acrid principle (Skulein?), together with scillitin, which latter he supposes to be a glucoside.

Merck of Darmstadt has isolated Scillipicrin, soluble in water; Scillitoxin, likewise a bitter principle, insoluble in water, but readily dissolving in alcohol; and Scillin, a crystalline substance, abundantly soluble in boiling ether. The physiological action of these substances and of Scillaïn has been examined (1878) by Moeller, and by Jarmersted (1879); that of scillitoxin and scillaïn was found to be analogous to that of Digitalis.

Commerce—Dried squill, usually packed in casks, is imported into England from Malta.

Use—Commonly employed as a diuretic and expectorant.

Substitutes—There are several plants of which the bulbs are used in the place of the officinal squill, but which, owing to the abundance and low price of the latter, never appear in the European market.

1. Urginea altissima Baker (Ornithogalum altissimum L.), a South African species, very closely related to the common squill, and having, as it would appear, exactly the same properties.[2589]

2. U. indica Kth. (Scilla indica Roxb.), a widely diffused plant, occurring in Northern India, the Coromandel Coast, Abyssinia, Nubia, and Senegambia. It is known by the same Arabic and Persian names as U. maritima, and its bulb is used for similar purposes. But according to Moodeen Sheriff[2590] it is a poor substitute for the latter, having little or no action when it is old and large.

3. Scilla indica Baker[2591] (non Roxb.), (Ledebouria hyacinthina Roth), native of India and Abyssinia, has a bulb which is often confused in the Indian bazaars with the preceding, but is easily distinguishable when entire by being scaly (not tunicated); it is said to be a better representative of the European squill.[2592]

4. Drimia ciliaris Jacq., a plant of the Cape of Good Hope, of the order Liliaceæ. Its bulb much resembles the officinal squill, but has a juice so irritating if it comes in contact with the skin, that the plant is called by the colonists Jeukbol, i.e. Itch-bulb. It is used medicinally as an emetic, expectorant, and diuretic.[2593]

5. Crinum asiaticum var. toxicarium Herbert (C. toxicarium Roxb.), a large plant, with handsome white flowers and noble foliage, cultivated in Indian gardens, and also found wild in low humid spots in various parts of India and the Moluccas, and on the sea-coast of Ceylon. The bulb has been admitted to the Pharmacopœia of India (1868), chiefly on the recommendation of O’Shaughnessy, who considers it a valuable emetic. We have not been able to examine a specimen, and cannot learn that the drug has been the subject of any chemical investigation.