FRUCTUS LIMONIS.

Botanical Origin—Citrus Limonum Risso (C. Medica var. β Linn.), a small tree 10 to 15 feet in height, planted here and there in gardens in many subtropical countries, but cultivated as an object of industry on the Mediterranean coast between Nice and Genoa, in Calabria, Sicily, Spain, and Portugal.

The tree which is supposed to represent the wild state of the lemon and lime, and as it seems to us after the examination of numerous specimens in the herbarium of Kew, of the citron (Citrus Medica Risso) also, is a native of the forests of Northern India, where it occurs in the valleys of Kumaon and Sikkim.

The cultivated lemon-tree is of rather irregular growth, with foliage somewhat pallid, sparse, and uneven, not forming the fine, close head of deep green that is so striking in the orange tree. The young shoots are of a dull purple; the flowers, which are produced all the year except during the winter, and are in part hermaphrodite and in part unisexual, have the corolla externally purplish; internally white, and a delicate aroma distinct from that of orange blossom. The fruit is pale yellow, ovoid, usually crowned by a nipple.

History—The name of the lemon in Sanskrit is Nimbuka; in Hindustani, Limbu, Limu, or Ninbu. It is probably originally a Cashmere word, which was transferred to the Sanskrit in comparatively modern times, not in the antiquity.[453] From these sounds the Arabians formed the word Limun, which has passed into the languages of Europe.

The lemon was unknown to the inhabitants of ancient Greece and Rome; but it is mentioned in the Book of Nabathæan Agriculture,[454] which is supposed to date from the 3rd or 4th century of our era. The introduction of the tree to Europe is due to the Arabians, yet at what precise period is somewhat doubtful. Arance and Limone are mentioned by an Arabic poet living in the 11th century, in Sicily, quoted by Falcando.[455] The geographer Edrisi,[456] who resided at the court of Roger II., king of Sicily, in the middle of the 12th century, mentions the lemon (limouna) as a very sour fruit of the size of an apple which was one of the productions of Mansouria on the Mahrân or Indus; and he speaks of it in a manner that leads one to infer it was not then known in Europe. This is the more probable from the fact that there is no mention either of lemon or orange in a letter written a.d. 1239 concerning the cultivation of the lands of the Emperor Frederick II. at Palermo,[457] a locality in which these fruits are now produced in large quantity.

On the other hand the lemon is noticed at great length by Ibn Baytar of Malaga, who flourished in the first half of the 13th century, but of its cultivation in Spain at that period there is no actual mention.[458] In 1369 at least citron trees, “arbores citronorum,” were planted in Genoa,[459] and there is evidence that also the lemon-tree was grown on the Riviera di Ponente about the middle of the 15th century, since Limones and also Citri are mentioned in the manuscript Livre d’Administration of the city of Savona, under date 1486.[460] The lemon was cultivated as early as 1494 in the Azores, whence the fruit used to be largely shipped to England; but since the year 1838 the exportation has totally ceased.[461]

Description—The fruit of Citrus Limonum as found in the shops[462] is from about 2 to 4 inches in length, egg-shaped with a nipple more or less prominent at the apex; its surface, of a pale yellow, is even or rugged, covered with a polished epidermis. The parenchyme within the latter abounds in large cells filled with fragrant essential oil. The roughness of the surface of the rind is due to the oil-cells. The peel, which varies considerably in thickness but is never so thick as that of the citron, is internally white and fibrous, and is adherent to the pale yellow pulp. The latter is divided into 10 or 12 segments each containing 2 or 3 seeds. It abounds in a pale yellow acid juice having a pleasant sour taste and a slight peculiar odour quite distinct from that of the peel. When removed from the pulp by pressure, the juice appears as a rather turbid yellowish fluid having a sp. gr. which varies from 1·040 to 1·045, and containing in each fluid ounce from 40 to 46 grains of citric acid, or about 9½ per cent.[463] In Italy all the fine and perfect fruit is exported; the windfalls and the damaged fruit are used for the production of the essential oil and the juice. About 13,000 lemons of this kind yield one pipe (108 gallons) of raw juice. Sicilian juice in November will contain about 9 ounces of citric acid per gallon, but 6 ounces when afforded by the fruit collected in April. The juice is boiled down in copper vessels, over an open fire, till its specific gravity is about 1·239.[464] Lemon juice (Succus limonis) for administration as a medicine should be pressed as wanted from the recent fruit whenever the latter is obtainable.

The peel (Cortex limonis) cut in somewhat thin ribbons from the fresh fruit is used in pharmacy, and is far preferable to that sold in a dried state.

Microscopic Structure of the Peel.—The epidermis exhibits numerous stomata; the parenchyme of the pericarp encloses large oil-cells, surrounded by small tabular cells. The inner spongy tissue is built up of very remarkable branched cells, separated by large intercellular spaces. A solution of iodine in iodide of potassium imparts to the cell-walls a transient blue coloration. The outer layers of the parenchymatous tissue contain numerous yellowish lumps of a substance which assumes a brownish hue by iodine, and yields a yellow solution if potash be added. Alkaline tartrate of copper is reduced by this substance, which probably consists of hesperidin. There also occur large crystals of oxalate of calcium, belonging to the monoclinic system. The interior tissue is irregularly traversed by small vascular bundles.

Chemical Composition—The peel of the lemon abounds in essential oil, which is a distinct article of commerce, and will be described hereafter.

Lemons, as well as other fruits of the genus Citrus, contain a bitter principle, Hesperidin, of which E. Hoffmann[465] obtained 5 to 8 per cent. from unripe bitter oranges. He extracted them with dilute alcohol, after they had previously been exhausted by cold water. The alcohol should contain about 1 per cent. of caustic potash; the liquid on cooling is acidulated with hydrochloric acid, when it yields a yellowish crystalline deposit of hesperidin, which may be obtained colourless and tasteless by recrystallization from boiling alcohol. By dilute sulphuric acid (1 per cent.) hesperidin is broken up as follows:—

Hesperidin is very little soluble even in boiling water or in ether, but dissolves readily in hot acetic acid, also in alkaline solutions, the latter then turning soon yellow and reddish. Pure hesperidin, as presented to one of us by Hoffmann, darkens when it is shaken with alcoholic perchloride of iron, and turns dingy blackish brown when gently warmed with the latter.

Hesperetin forms crystals melting at 223° C., soluble both in alcohol or ether, not in water; they taste sweet. They are split up by potash in Phloroglucin and Hesperetic acid, C₁₀H₁₀O₄.

On addition of ferric chloride, thin slices of the peel are darkened, owing probably to some derivative of hesperidin, or to hesperidin itself.

The name hesperidin had also been applied to yellow crystals extracted from the shaddock, Citrus decumana L., the dried flowers of which afford about 2 per cent. of that substance. It is, as shown in 1879 by E. Hoffmann, quite different from hesperidin as described above; he calls it Naringin and assigns to it the formula C₂₃H₂₆O₁₂+4OH₂. Naringin is readily soluble in hot water or in alcohol, not in ether or chloroform. Its solutions turn brown-red on addition of ferric chloride.

Lemon juice, some of the characters of which have been already noticed, is an important article in a dietetic point of view, being largely consumed on shipboard for the prevention of scurvy. In addition to citric acid it contains 3 to 4 per cent. of gum and sugar, and 2·28 per cent. of inorganic salts, of which according to Stoddart only a minute proportion is potash. Cossa[466] on the other hand, who has recently studied the products of the lemon tree with much care, has found that the ash of dried lemon juice contains 54 per cent. of potash, besides 15 per cent. of phosphoric acid.

Stoddart has pointed out the remarkable tendency of citric acid to undergo decomposition,[467] and has proved that in lemons kept from February to July this acid generally decreases in quantity, at first slowly, but afterwards rapidly, until at the end of the period it entirely ceases to exist, having been all split up into glucose and carbonic acid. At the same time the sp. gr. of the juice was found to have undergone but slight diminution:—thus it was 1·044 in February, 1·041 in May, and 1·027 in July, and the fruit had hardly altered in appearance. Lemon juice may with some precautions be kept unimpaired for months or even years. Yet it is capable of undergoing fermentation by reason of the sugar, gum, and albuminoid matters which it contains.

Commerce—Lemons are chiefly imported from Sicily, to a smaller extent from the Riviera of Genoa and from Spain. From the published statistics of trade, in which lemons are classed together with oranges under one head, it appears that these fruits are being imported in increasing quantities. The value of the shipments to the United Kingdom in 1872 (largely exceeding those of any previous year) was £1,154,270. Of this sum, £986,796 represents the value of the oranges and lemons imported from Spain, Portugal, the Canary Islands and Azores; £155,330 the shipments of the same fruit from Italy; and £3,825 those from Malta.

Of concentrated lemon juice there were exported in 1877 from Messina 1,631,332 kilogrammes, valued at 2,446,996 lire. The value of concentrated lime juice exported in 1874 from Montserrat was £3,390. From Dominica, 11,285 gallons, value £1,825, were shipped in 1875.

Uses—Lemon peel is used in medicine solely as a flavouring ingredient. Freshly prepared lemon juice is often administered with an alkaline bicarbonate in the form of an effervescing draught, or in a free state.

Concentrated lemon juice is imported for the purpose of making citric acid; it is derived not only from the lemon, but also, to a smaller extent, from the lime and bergamot. Lime juice of the West Indies is chiefly used as a beverage; small quantities of it are also exported for the manufacture of citric acid. The culture of Citrus Limetta Risso, the lime, was introduced in Montserrat in 1852.

OLEUM LIMONIS.

Botanical Origin—Citrus Limonum Risso (see p. 114).

History—The chemists of the 16th century were well acquainted with the method of extracting essential oils by distillation. Besson in his work L’art et moyen parfaict de tirer huyles et eaux de tous medicaments simples et oleogineux, published at Paris in 1571, mentions lemon-(citron) and orange-peel among the substances subjected to this process. Giovanni Battista Porta,[468] a learned Neapolitan writer, describes the method of preparing Oleum ex corticibus Citri to consist in removing the peel of the fruit with a rasp and distilling it so comminuted with water; and adds that the oils of lemon and orange may be obtained in the same manner. Essence of lemon of two kinds, namely expressed and distilled, was sold in Paris in the time of Pomet, 1692.

Production—Essential oil of lemon is manufactured in Sicily, at Reggio in Calabria, and at Mentone and Nice in France.

The lemons are used while still rather green and unripe, as being richer in oil than when quite mature. Only the small and irregular fruit, such as is not worth exporting, is employed for affording the essence.

The process followed in Sicily and Calabria may be thus described;[469] it is performed in the months of November and December.

The workman first cuts off the peel in three thick longitudinal slices, leaving the central pulp of a three-cornered shape with a little peel at either end. This central pulp he cuts transversely in the middle, throwing it on one side and the pieces of peel on the other. The latter are allowed to remain till the next day and are then treated thus: the workman seated holds in the palm of his left hand a flattish piece of sponge, wrapping it round his forefinger. With the other he places on the sponge one of the slices of peel, the outer surface downwards, and then presses the zest-side (which is uppermost) so as to give it for the moment a convex instead of a concave form. The vesicles are thus ruptured, and the oil which issues from them is received in the sponge with which they are in contact. Four or five squeezes are all the workman gives to each slice of peel, which done he throws it aside. Though each bit of peel has attached to it a small portion of pulp, the workman contrives to avoid pressing the latter. As the sponge gets saturated the workman wrings it forcibly, receiving its contents in a coarse earthen bowl provided with a spout; in this rude vessel, which is capable of holding at least three pints, the oil separates from the watery liquid which accompanies it and is then decanted.

The yield is stated to be very variable, 400 fruits affording 9 to 14 ounces of essence. The prisms of pulp and the exhausted pieces of peel are submitted to pressure in order to extract from them lemon juice, and are said to be also subjected to distillation. The foregoing is termed the sponge-process; it is also applied to the orange. It appears rude and wasteful, but when honestly performed it yields an excellent product.

Essence of lemon is prepared at Mentone and Nice by a different method. The object being to set free and to collect the oil contained in the vesicles of the peel, an apparatus is employed, which may be thus described:—a stout saucer or shallow basin of pewter, about 8½ inches in diameter with a lip on one side for convenience of pouring. Fixed in the bottom of this saucer are a number of stout, sharp, brass pins, standing up about half an inch; the centre of the bottom is deepened into a tube about an inch in diameter and five inches in length, closed at its lower end. This vessel, which is called an écuelle à piquer, has therefore some resemblance to a shallow, dish-shaped funnel, the tube of which is closed below.

The workman takes a lemon in the hand, and rubs it over the sharp pins, turning it round so that the oil-vessels of the entire surface may be punctured. The essential oil which is thus liberated is received in the saucer whence it flows down into the tube; and as this latter becomes filled, it is poured into another vessel that it may separate from the turbid aqueous liquid that accompanies it. It is finally filtered and is then known as Essence de Citron au zeste. A small additional produce is sometimes obtained by immersing the scarified lemons in warm water and separating the oil which floats off.

A second kind of essence termed Essence de Citron distillée is obtained by rubbing the surface of fresh lemons, or of those which have been submitted to the process just described, on a coarse grater of tinned iron, by which the portion of peel richest in essential oil is removed. This grated peel is subjected to distillation with water, and yields a colourless essence of very inferior fragrance, which is sold at a low price.

Description[470]—The oil obtained by the sponge-process and that of the écuelle à piquer are mobile liquids of a faint yellow colour, of exquisite fragrance and bitterish aromatic taste.

The different specimens which we have examined are readily miscible with bisulphide of carbon, but dissolve sparingly in spirit of wine (0·830). An equal weight of the oil and of spirit of wine forms a turbid mixture. No peculiar coloration is produced by mixture with perchloride of iron.

The oils are dextrogyre, but differ in their rotatory power, as may be illustrated by the following results, which we obtained by examining them in a column 50 millimetres long in the polaristrobometer of Wild. The oil of Signori Panuccio, due to the sponge-process (p. 118, note 2), deviated 20·9°, that of Monsieur Médecin (Essence de Citron au zeste) obtained by the éculle à piquer deviated 33·4° and his distilled oil 28·3°.

Chemical Composition—The prevailing portion of most essential oils of the Aurantiaceæ agrees with the formula C₁₀H₁₆; the differences which they exhibit chiefly concern their optical properties, odour, and colour. The boiling point mostly varies from about 170° to 180° C., the sp. gr. between 0·83 and 0·88. These oils are a mixture of isomeric hydrocarbons, and also contain a small amount of cymene, C₁₀H₁₄, and of oxygenated oils, not yet well known; of these we may infer the presence either from analytical results or simply from the fact that the crude oils are altered by metallic sodium. If they are purified by repeated rectification over that metal, they are finally no longer altered by it. Oils thus purified cease to possess their original fragrance, and often resemble oil of turpentine, with which they agree in composition and general chemical behaviour.

As to essential oil of lemons, its chief constituent is the terpene, C₁₀H₁₆, which, like oil of turpentine, easily yields crystals of terpin, C₁₀H₁₆ 3OH₂. There is further present, according to Tilden (1879) another hydrocarbon, C₁₀H₁₆, which already boils at 160° C., whereas the foregoing boils at 176° C. Lastly a small amount of cymene and of a compound acetic ether, C₂H₃O(C₁₀H₁₇O), would appear to occur also in oil of lemons. The crude oil of lemons already yields the crystalline compound C₁₀H₁₆ + 2HCl, when saturated with anhydrous hydrochloric gas, whereas by the same treatment oil of turpentine affords the solid compound C₁₀H₁₆ + HCl.

Essential oil of lemons (not the distilled) when long kept deposits a greasy mass, from which we have obtained small crystals apparently of Bergaptene (p. 123).

Commerce—Essence of lemons is shipped chiefly from Messina and Palermo, packed in copper bottles called in Italian ramiere and by English druggists “jars” holding 25 to 50 kilo. or more; sometimes in tin bottles of smaller size. The quantity of essences of lemon, orange and bergamot exported from Sicily in 1871 was 368,800 lb., valued at £144,520, of which about two-thirds were shipped to England.[471] In 1877 the export of these essential oils from Messina amounted to 306,948 kilogrammes, valued at 6,130,960 lire.

Uses—Essence of lemon is used in perfumery, and as a flavouring ingredient; and though much sold by druggists is scarcely employed in medicine.

Adulteration—Few drugs are more rarely to be found in a state of purity than essence of lemon. In fact it is stated that almost all that comes into the market is more or less diluted with oil of turpentine or with the cheaper distilled oil of lemons. Manufacturers of the essence complain that the demand for a cheap article forces them to this falsification of their product.

OLEUM BERGAMOTTÆ.

Botanical Origin—Citrus Bergamia var. vulgaris Risso et Poiteau,[472] a small tree closely resembling in flowers and foliage the Bitter Orange. Its fruit is 2½ to 3 inches in diameter, nearly spherical, or slightly pear-shaped, frequently crowned by the persistent style; it is of a pale golden yellow like a lemon,[473] with the peel smooth and thin, abounding in essential oil of a peculiar fragrance; the pulp is pale yellowish green, of a bitterish taste, and far less acid than that of the lemon.

The tree is cultivated at Reggio in Calabria, and is unknown in a wild state.

History—The bergamot is one of the cultivated forms which abound in the genus Citrus, and which constitute the innumerable varieties of the orange, lemon and citron. Whether it is most nearly related to the lemon or to the orange is a point discussed as early as the beginning of the last century. Gallesio[474] remarks that it so evidently combines the characters of the two that it should be regarded as a hybrid between them. The bergamot first appeared in the latter part of the 17th century. It is not mentioned in the grand work on orange trees of Ferrari,[475] published at Rome in 1646, nor in the treatise of Commelyn[476] (1676), nor in the writings of Lanzoni (1690),[477] or La Quintinie (1692).[478] So far as we know, it is first noticed in a little book called Le Parfumeur François, printed at Lyons in 1693. The author who calls himself Le Sieur Barbe, parfumeur, says that the Essence de Cedra ou Bergamotte is obtained from the fruits of a lemon-tree which has been grafted on the stem of a bergamot pear; he adds that it is got by squeezing small bits of the peel with the fingers in a bottle or globe large enough to allow the hand to enter.

Volkamer of Nuremberg, who produced a fine work on the Citron tribe in 1708, has a chapter on the Limon Bergamotta, which he describes as gloria limonum et fructus inter omnes nobilissimus. He states that the Italians prepare from it the finest essences, which are sold at a high price.[479]

But, as shown by one of us,[480] the essential oil of bergamot had already, in 1688, a place among the stores of an apothecary of the German town of Giessen.

The name Bergamotta was originally applied to a large kind of pear, called in Turkish “beg-ârmûdî,” i.e. prince’s pear.[481]

Production—The bergamot is cultivated at Reggio, on low ground near the sea, and in the adjacent villages. The trees are often intermixed with lemon and orange trees, and the soil is well irrigated and cropped with vegetables.

The essential oil (Oleum Bergamottæ) is obtained from the full-grown but still unripe and more or less green fruits, gathered in the months of November and December. They are richer in oil than any one of the allied fruits. It was formerly made like that of lemon by the sponge-process, but during the last 20 years this method has been generally superseded by the introduction of a special machine for the extraction of the essential oil. In this machine the fruits are placed in a strong, saucer-like, metallic dish, about 10 inches in diameter, having in the centre a raised opening which with the outer edge forms a broad groove or channel; the dish is fitted with a cover of similar form. The inner surface both of the dish and cover is rendered rough by a series of narrow, radiating metal ridges of blades which are about ¼ of an inch high and resemble the backs of knifes. The dish is also furnished with some small openings to allow of the outflow of essential oil; and both dish and cover are arranged in a metallic cylinder, placed over a vessel to receive the oil. By a simple arrangement of cog-wheels moved by a handle, the cover, which is very heavy, is made to revolve rapidly over the dish, and the fruit lying in the groove between the two is carried round, and at the same time is subjected to the action of the sharp ridges, which, rupturing the oil-vessels, cause the essence to escape, and set it free to flow out by the small openings in the bottom of the dish. The fruits are placed in the machine, 6, 8, or more at a time, according to their size, and subjected to the rotatory action above described for about half a minute, when the machine is stopped, they are removed, and fresh ones substituted. About 7,000 fruits can thus be worked in one of these machines in a day. The yield of oil is said to be similar to that of lemon, namely 2½ to 3 ounces from 100 fruits.

Essence of bergamot made by the machine is of a greener tint than that obtained by the old sponge-process. During some weeks after extraction it gradually deposits a quantity of white greasy matter (bergaptene), which, after having been exhausted as much as possible by pressure, is finally subjected to distillation with water in order to separate the essential oil it still contains.

The fruits from which the essence has been extracted are submitted to pressure, and the juice, which is much inferior in acidity to lemon juice, is concentrated and sold for the manufacture of citric acid. Finally, the residue from which both essence and juice have been removed, is consumed as food by oxen.

Description[482]—Essential oil of bergamot is a thin and mobile fluid of peculiar and very fragrant odour, bitterish taste, and slightly acid reaction. It has a pale greenish yellow tint, due to traces of chlorophyll, as may be shown by the spectroscope. Its sp. gr. is 0·86 to 0·88; its boiling point varies from 183° to 195° C.

The oil is miscible with spirit of wine (0·83 sp. gr.), absolute alcohol, as well as with crystallizable acetic acid. Four parts dissolve clearly one part of bisulphide of carbon, but the solution becomes turbid if a larger proportion of the latter is added. Bisulphide of carbon itself is incapable of dissolving clearly any appreciable quantity of the oil. A mixture of 10 drops of the oil, 50 drops of bisulphide of carbon and one of strong sulphuric acid has an intense yellow hue. Perchloride of iron imparts to bergamot oil dissolved in alcohol a dingy brown colour.

Panuccio’s oil of bergamot examined in the same way as that of lemon (p. 120) deviates 7° to the right, and has therefore a dextrogyre power very inferior to that of other oils of the same class.[483] But it probably varies in this respect, for commercial specimens which we judged to be of good quality deviated from 6·8° to 10·4° to the right.

Chemical Composition—If essential oil of bergamot is submitted to rectification, the portions that successively distill over do not accord in rotatory power or in boiling point, a fact which proves it to be a mixture of several oils, as is further confirmed by analysis. It appears to consist of hydrocarbons, C₁₀H₁₆, and their hydrates, neither of which have as yet been satisfactorily isolated. Oil of bergamot, like that of turpentine, yields crystals of the composition C₁₀H₁₆ + 3H₂O, if 8 parts are allowed to stand some weeks with 1 part of spirit of wine, 2 of nitric acid (sp. gr. 1·2) and 10 of water, the mixture being frequently shaken. No solid compound is produced by saturating the oil with anhydrous hydrochloric gas.

The greasy matter that is deposited from oil of bergamot soon after its extraction, and in small quantity is often noticeable in that of commerce, is called Bergaptene or Bergamot Camphor. We have obtained it in fine, white, acicular crystals, neutral and inodorous, by repeated solution in spirit of wine. Its composition according to the analysis of Mulder (1837) and of Ohme (1839) answers to the formula C₉H₆O₃, which in our opinion requires further investigation. Crystallized bergaptene is abundantly soluble in chloroform, ether, or bisulphide of carbon; the alcoholic solution is not altered by ferric salts.

Commerce—Essence of bergamot, as it is always termed in trade, is chiefly shipped from Messina and Palermo in the same kind of bottles as are used for essence of lemon.

Uses—Much employed in perfumery, but in medicine only occasionally for the sake of imparting an agreeable odour to ointments.

Adulteration—Essence of bergamot, like that of lemon, is extensively and systematically adulterated, and very little is sent into the market entirely pure. It is often mixed with oil of turpentine, but a finer adulteration is to dilute it with essential oil of the leaves or with that obtained by distillation of the peel or of the residual fruits. Some has of late been adulterated with petroleum.

The optical properties, as already mentioned, may afford some assistance in detecting fraudulent admixtures, though as regards oil of turpentine it must be borne in mind that there are levogyre as well as dextrogyre varieties. This latter oil and likewise that of lemon is less soluble in spirit of wine than that of bergamot.

CORTEX AURANTII.

Botanical Origin—Citrus vulgaris Risso (C. Aurantium var. a amara Linn., C. Bigaradia Duhamel).

The Bitter or Seville or Bigarade Orange, Bigaradier[484] of the French, is a small tree extensively cultivated in the warmer parts of the Mediterranean region, especially in Spain, and existing under many varieties.

Northern India is the native country of the orange tree. In Gurhwal, Sikkim, and Khasia there occurs a wild orange which is the supposed parent of the cultivated orange, whether Sweet or Bitter.

The Bitter Orange reproduces itself from seed, and is regarded, at least by cultivators, as quite distinct from the Sweet Orange, from which however it cannot be distinguished by any important botanical characters. Generally speaking, it differs from the latter in having the fruit rugged on the surface, of a more deep or reddish-orange hue, with the pulp very sour and bitter. The peel, as well as the flowers and leaves, are more aromatic than the corresponding parts of the Sweet Orange, and the petiole is more broadly winged.

History—The orange was unknown to the ancient Greeks and Romans; and its introduction to Europe is due to the Arabs, who, according to Gallesio,[485] appear to have established the tree first in Eastern Africa, Arabia, and Syria, whence it was gradually conveyed to Italy, Sicily, and Spain. In the opinion of the writer just quoted, the bitter orange was certainly known at the commencement of the 10th century to the Arabian physicians, one of whom, Avicenna,[486] employed its juice in medicine.

There is strong evidence to show that the orange first cultivated in Europe was the Bitter Orange or Bigarade. The orange tree at Rome, said to have been planted by St. Dominic about a.d. 1200, and which still exists at the monastery of St. Sabina, bears a bitter fruit; and the ancient trees standing in the garden of the Alcazar at Seville are also of this variety. Finally, the oranges of Syria (ab indigenis Orenges nuncupati) described by Jacques de Vitri, Bishop of Acon (ob. a.d. 1214) were acidi seu pontici saporis.[487]

The Sweet Orange began to be cultivated about the middle of the 15th century, having been introduced from the East by the Portuguese. It has probably long existed in Southern China, and may have been taken thence to India. In the latter country there are but few districts in which its cultivation is successful, and the Bitter Orange is hardly known at all. The name it has long borne of China[488] or Portugal Orange indicates what has been the usual opinion as to its origin. It probably alludes more exactly to a superior variety brought about 1630 from China to Portugal.[489]

One of the first importations of oranges into England occurred in a.d. 1290, in which year a Spanish ship came to Portsmouth, of the cargo of which the queen of Edward I. bought one frail of Seville figs, one of raisins or grapes, one bale of dates, 230 pomegranates, 15 citrons, and 7 oranges (“poma de orenge”).[490]

Description—The Bitter Orange known in London as the Seville Orange is a globular fruit, resembling in size, form, and structure the common Sweet Orange, but having the peel much rougher, and when mature of a somewhat deeper hue. The pulp of the fruit is filled with an acid bitter juice. The ripe fruit is imported into London; the peel is removed from it with a sharp knife in one long spiral strip, and quickly dried, or it is sold in the fresh state. It is the more esteemed when cut thin, so as to include as little as possible of the white inner layer.

Well-dried orange peel should be externally of a bright tint and white on its inner surface; it should have a grateful aromatic smell and bitter taste. The peel is also largely imported into London ready dried, especially from Malta. We have observed it from this latter place of three qualities, namely in elliptic pieces or quarters, in broad curled strips, and lastly a very superior kind, almost wholly free from white zest, in strips less than ⅛ of an inch in width, cut apparently by a machine. Such needless subdivision as this last has undergone must greatly favour an alteration and waste of the essential oil. Foreign-dried orange peel fetches a lower price than that dried in England.

Microscopic Structure—There is no difference between the tissues of this drug and those of lemon peel.

Chemical Composition—The essential oil to which the peel of the orange owes its fragrant odour, is a distinct article of commerce, and will be noticed hereafter under a separate head. The other constituents of the peel probably agree with those of lemon peel. The substance mentioned under the name of Hesperidin (p. 116) particularly abounds in unripe bitter oranges.

Uses—Bitter orange peel is much used in medicine as an aromatic tonic.

OLEUM NEROLI.

Botanical Origin—Citrus vulgaris Risso. (See page 124.)

History—Porta, the Italian philosopher of the 16th century referred to (p. 118), was acquainted with the volatile oil of the flowers of the citron tribe (“Oleum ex citriorum floribus”), which he obtained by the usual process of distillation, and describes as possessing the most exquisite fragrance. That distilled from orange flowers acquired a century later (1675-1685) the name of Essence of Neroli from Anne-Marie de la Trémoille-Noirmoutier, second wife of Flavio Orsini, duke of Bracciano and prince of Nerola or Neroli. This lady employed it for the perfuming of gloves, hence called in Italy Guanti di Neroli.[491] It was known in Paris to Pomet, who says[492] the perfumers have given it the name of Neroli, and that it is made in Rome and in Provence.

Production—Oil of Neroli is prepared from the fresh flowers of the Bigarade or Bitter Orange by the ordinary process of distillation with water, conducted in small copper stills. The flowers of all the allied plants are far less aromatic. The water which distills over with the oil constitutes, after the removal of the latter from its surface, the Orange Flower Water (Aqua aurantii florum vel Aqua Naphæ)[493] of commerce. The manufacture is carried on chiefly in the south of France at Grasse, Cannes, and Nice. The yield is about 0·6 to 0·7 per cent. of oil from fresh flowers, as stated by Poiteau et Risso.[494] The flowers of the sweet orange afford but half that amount of oil.

Description and Chemical Composition—Oil of Neroli as found in commerce is seldom pure, for it generally contains an admixture of the essential oil of orange-leaf called Essence of Petit Grain.

By the kind assistance of Mr. F. G. Warrick of Nice, we have obtained a sample of Bigarade Neroli of guaranteed purity, to which the following observations relate. It is of a brownish hue, most fragrant odour, bitterish aromatic taste, and is neutral to test-paper. Its sp. gr. at 11° C. is 0·889. When mixed with alcohol, it displays a bright violet fluorescence, quite distinct from the blue fluorescence of a solution of quinine. In oil of Neroli the phenomenon may be shown most distinctly by pouring a little spirit of wine on to the surface of the essential oil, and causing the liquid to gently undulate. The oil is but turbidly miscible with bisulphide of carbon. It assumes a very pure, intense, and permanent crimson hue if shaken with a saturated solution of bisulphide of sodium. Examined in a column of 100 mm. we observed the oil to deviate the ray of polarized light 6° to the right.

Subjected to distillation, the larger part of the oil passes over at 185°-195° C.; we found this portion to be colourless, yet to display in a marked manner the violet fluorescence and also to retain the odour of the original oil. The portion remaining in the retort was mixed with about the same volume of alcohol (90 per cent.) and some drops of water added, yet not sufficient to occasion turbidity. A very small amount of the crystalline Neroli Camphor then made its appearance, floating on the surface of the liquid; by re-solution in boiling alcohol it was obtained in crystals of rather indistinct form. The redistilled oil gave no camphor whatever.

Neroli Camphor was first noticed by Boullay in 1828. According to our observations it is a neutral, inodorous, tasteless substance, fusible at 55° C., and forming on cooling a crystalline mass. The crystallization should be effected by cooling the hot alcoholic solution, no good crystals being obtainable by slow evaporation or by sublimation. The produce was extremely small, about 60 grammes of oil having yielded not more than 0·1 gramme. Perhaps this scantiness of produce was due to the oil being a year and a half old, for according to Plisson[495] the camphor diminishes the longer the oil is kept.[496] We were unable to obtain any similar substance from the oils of bergamot, petit grain, or orange peel.

Orange Flower Water is a considerable article of manufacture among the distillers of essential oils in the south of Europe, and is imported thence for use in pharmacy. According to Boullay[497] it is frequently acid to litmus when first made,—is better if distilled in small than in large quantities, and if made from the petals per se, rather than from the entire flowers. He also states that only 2 lb. of water should be drawn from 1 lb. of flowers, or 3 lb. if petals alone are placed in the still. As met with in commerce, orange flower water is colourless or of a faintly greenish yellow tinge, almost perfectly transparent, with a delicious odour and a bitter taste. Acidulated with nitric acid, it acquires a pinkish hue more or less intense, which disappears on saturation by an alkali.

Uses—Oil of Neroli is consumed almost exclusively in perfumery. Orange flower water is frequently used in medicine to give a pleasant odour to mixtures and lotions.

Adulteration—The large variation in value of oil of Neroli as shown by price-currents[498] indicates a great diversity of quality. Besides being very commonly mixed, as already stated, with the distilled oil of the leaves (Essence de Petit Grain)[499], it is sometimes reduced by addition of the less fragrant oil obtained from the flowers of the Portugal or Sweet Orange. In some of these adulterations we must conclude that orange flower water participate: metallic contamination of the latter is not unknown.

Other Products of the genus Citrus.

Essence or Essential Oil of Petit Grain—was originally obtained by subjecting little immature oranges to distillation (Pomet—1692); but it is now produced, and to a large extent, by distillation of the leaves and shoots either of the Bigarade or Bitter Orange, or of the Portugal or Sweet Orange. The essence of the former is by far the more fragrant, and commands double the price. Poiteau and Risso[500] state that the leaves of the Brigaradier with bitter fruit are by far the richest in essential oil among all the allied leaves; they are obtained in the lemon-growing districts of the Mediterranean where the essence is manufactured. Lemon-trees being mostly grafted on orange-stocks, the latter during the summer put forth shoots, which are allowed to grow till they are often some feet in length. The cultivator then cuts them off, binds them in bundles, and conveys them to the distiller of Petit Grain. The strongest shoots are frequently reserved for walking-sticks. The leaves of the two sorts of orange are easily distinguished by their smell when crushed. Essence of Petit Grain, which in odour has a certain resemblance to Neroli, is used in perfumery and especially in the manufacture of Eau de Cologne.

According to Gladstone (1864) it consists mainly of a hydrocarbon probably identical with that from oil of Neroli.

Essential Oil of Orange Peel—is largely made at Messina and also in the south of France. It is extracted by the sponge-, or by the écuelle-process, and partly from the Bigarade and partly from the Sweet or Portugal Orange, the scarcely ripe fruit being in either case employed. The oil made from the former is much more valuable than that obtained from the latter, and the two are distinguished in price-currents as Essence de Bigarade and Essence de Portugal.

These essences are but little consumed in England, in liqueur-making and in perfumery. For what is known of their chemical nature, the reader can consult the works named at foot[501].

Essence of Cedrat—The true Citron or Cedrat tree is Citrus medica Risso, and is of interest as being the only member of the Orange tribe the fruit of which was known in ancient Rome. The tree itself, which appears to have been cultivated in Palestine in the time of Josephus, was introduced into Italy in about the 3rd century. In a.d. 1003 it was much grown at Salerno near Naples, whence its fruits were sent as presents to the Norman princes[502].

At the present day, the citron appears to be nowhere cultivated extensively, the more prolific lemon tree having generally taken its place. It is however scattered along the Western Riviera, and is also grown on a small scale about Pizzo and Paola on the western coast of Calabria, in Sicily, Corsica, and Azores. Its fruits, which often weigh several pounds, are chiefly sold for being candied. For this purpose the peel, which is excessively thick, is salted and in that state shipped to England and Holland. The fruit has a very scanty pulp[503].

Essence of Cedrat which is quoted in some price-lists may be prepared from the scarcely ripe fruit by the sponge-process; but as it is more profitable to export the fruit salted, it is very rarely manufactured, and that which bears its name is for the most part fictitious.

FRUCTUS BELÆ.