part 2

. 1844) 516-537.

[1542] _Géographique Botanique_ (1855) 912.

[1543] _Bot. Zeitung_, 1868. 860.

[1544] Arnoux, _Revue des Deux Mondes_, Janvier 1879. 381.

The olive would appear to have been introduced at a very remote period into north-western Africa and Spain. Willkomm (1876) is of the opinion that it was originally a native of the whole Mediterranean region.

At the present day it is largely cultivated in Algeria, Spain, Portugal, Southern France, Italy, the Greek Peninsula and Asia Minor. In the Crimea the tree grows well, but does not afford good fruit. It was carried to Lima in Peru about 1560 and still flourishes there, and in great plenty in the coast valleys further south as far as Santiago in Chili.[1545]

Olive oil is mentioned in the Bible so frequently that it must have been an important object with the ancient Hebrews. It held an equally prominent place among the Greeks and Romans,[1546] whose writers on agriculture and natural history treat of it in the most circumstantial manner. Olive fruits preserved in brine were used by the Romans as an article of food,[1547] and were an object of commerce with Northern Europe as early as the 8th century.[1548]

=Production=—In common with many important cultivated plants, the olive occurs under several varieties differing more or less from the wild form, the finer of which are propagated by grafting. It is also increased by the suckers which old trees throw up from their naked roots, and which are easily made to develope into separate plants.[1549] The fruit, an oval drupe, half an inch to an inch or more in length, and of a deep purple, is remarkable for the large amount of fat oil contained in its pulpy portion (sarcocarp). The latter is most rich in oil when ripe, containing then nearly 70 per cent., besides 25 per cent. of water. The unripe fruit, as well as other parts of the plant, abounds in mannite, which disappears in proportion as the oil increases. The ripe olive contains no mannite, it having probably been transformed into fatty oil.[1550]

[1545] Perez-Rosales, _Essai sur le Chili_, Hambourg, 1857. 133.

[1546] Hehn, _Kulturpflanzen und Hausthiere in ihrem Uebergange aus Asien nach Griechenland und Italien_, Berlin, 1877. 88-142,—an interesting account of the importance of the olive in ancient times.

[1547] Specimens may be seen among the antiquities found at Pompei.

[1548] Diploma of Chilperic, A.D. 716.—Pardessus, _Diplomata_, _Chartæ_, etc., Paris, ii. (1849) 309.

[1549] Winter, in _Pharm. Journ._ Sept. 7, 1872.

[1550] De Luca in _Journ. de Pharm._ xlv. (1864) 65.—Some further researches by Harz on the formation of olive oil may be found in the _Jahresbericht_ of Wiggers and Husemann (1870) 392.

The process for extracting olive oil varies slightly in different countries, but consists essentially in subjecting the crushed pulp of the ripe fruit to moderate pressure. The olives, which are gathered from the trees, or collected from the ground, in November, or during the whole winter and early spring, are crushed under a millstone to a pulpy mass. This is then put into coarse bags, which, piled upon one another, are subjected to moderate pressure in a screw press. The oil thus obtained is conducted into tubs or cisterns containing water, from the surface of which it is skimmed with ladles. This is called _Virgin Oil_. After it has ceased to flow, the contents of the bags are shovelled out, mixed with boiling water, and submitted to stronger pressure than before, by which a second quality of oil is got. If the fruit is left for a considerable time in heaps it undergoes decomposition, yielding by pressure a very inferior quality of oil called in French _Huile fermentée_. The worst oil of all, obtained from the residues, has the name of _Huile tournante_ or _Huile d’enfer_.

It is said that in some districts the millstones are so mounted as to crush the pulp without breaking the olive-stones, and that thus the oil of the pulp is obtained unmixed with that of the kernels.[1551] We have made many inquiries in Italy and France as to this method of oil-making, but cannot find that it is anywhere followed.

The fixed oil of the kernels of ripe olives has been extracted and examined by one of us (F.). Though the kernels have a bitterish taste, the oil they yield is quite bland; by exposure to the vapour of hyponitric acid, it concretes like that of the pulp. If the whole of it were extracted in making olive oil, it would only be about as 1 part of oil of the _kernel_, to 40 parts of oil of the _pulp_.

=Description=—Olive Oil is a pale yellow or greenish yellow, somewhat viscid liquid, of a faint agreeable smell and of a bland oleaginous taste, leaving in the throat a slight sense of acridity.[1552] Its specific gravity on an average is 0·916 at 17° C. In cold weather, olive oil loses its transparency by the separation of a crystalline fatty body. The deposition takes place at a few degrees above the freezing point of water, and in some oils even at 10° C. (50° F.) If the oil is allowed to congeal perfectly, and is then submitted to strong pressure, about one-third of its weight of solid fat may be separated. After repeated crystallizations, this fat melts at 20 to 28° C. The fluid part or _Olein_, continues fluid at -4° to -10° C. Olive oil belongs to the class of the less alterable, non-drying oils.

The foregoing description does not apply to the inferior sorts of oil, which congeal more easily, are more or less deep-coloured, have a disagreeable odour and taste, and quickly turn rancid. These inferior oils have their special applications in the arts.

=Chemical Composition-=-The chief constituent of olive oil is _Olein_ or more correctly _Triolein_, C₃H₅(O·C₁₈H₃₃O)₃, identical so far as at present ascertained with the fluid part of all oils of the non-drying class. The proportion of olein in olive oil, as well as in other oils, is liable to variation, the result partly of natural circumstances and

## partly of the processes of manufacture. The best oils are rich in olein.

[1551] _The Grocer_, April 25, 1868, supplement; Pereira, _Elem. of Mat. Med._ ii. (1850) 1505.

[1552] This according to our experience is the case even with oil as it runs from the pulp and therefore in the freshest condition; but the acrid after-taste is more perceptible in oil which has been long kept.

As to the solid part of olive oil, Chevreul believed it to be constituted of _Margarin_, which he first examined in 1820. But Heintz (1852 and later) showed margarin to be a mixture of palmitin with other compounds of glycerin and fatty acids. Collett in 1854 isolated _Palmitic Acid_, C₁₆H₃₂O₂, from olive oil; and Heintz and Krug (1857) further proved that _Tripalmitin_ is the chief of the solid constituents of olive oil. They also met with an acid melting at 71°·4 C., which they regarded as _Arachic Acid_ (p. 187). As to stearic acid, Heintz and Krug did not fully succeed in evidencing its presence in olive oil.

Lastly, Benecke discovered in olive oil a small quantity of _Cholesterin_, C₂₆H₄₄O. It may be removed by means of glacial acetic acid or alcohol, which dissolve but very little of the oil.

=Commerce=—Various sorts of olive oil are distinguished in the English market, as Florence, Gallipoli, Gioja, Spanish (Malaga and Seville), Sicily, Myteline, Corfu and Mogador.

Olive oil was imported into the United Kingdom in the year 1872 to the value of £1,193,064. Nearly half the quantity was shipped from Italy, one-fifth from Spain, and the remainder from other Mediterranean countries.

The average annual production in Italy is estimated at about 3 millions of hectolitres (66 million gallons), but the quantity exported does not reach half that amount.

The statistics of the French Government indicate the annual production of olive oil in France to be not more than 250,000 hectolitres, equivalent in value to 30 millions of francs (£1,200,000).[1553]

=Uses=—The uses of olive oil in medicine and its immense consumption in the warmer parts of Europe as an article of food, are too well known to require more than a passing allusion.

=Adulteration=—Olive Oil is the subject of various fraudulent admixtures with less costly oils, the means of detecting which has engaged much attention. Of the various methods by which chemists have endeavoured to ascertain the purity of olive oil, the following are the more noteworthy:—

=a.= Drying oils (such as the oils of poppy and walnut) may be distinguished by their not being converted into solid crystallizable elaidin by hyponitric acid or concentrated solution of nitrate of protoxide of mercury. Olive oil which contains any considerable proportion of one of these oils, no longer solidifies if exposed for a moment to one of the above-mentioned reagents. This test however is not of sufficient delicacy for small amounts of drying oils.

=b.= Olive oil being one of the lighter oils, the specific gravity may to some degree indicate admixture with a heavier oil. To make use of this fact, Gobley and other chemists have invented an instrument called an _elaiometer_, for taking the specific gravity of oils.

=c.= Observation of the Cohesion-figure.—This test, proposed by Tomlinson in 1864,[1554] depends on the forces of cohesion, adhesion, and diffusion. Thus, if a drop of any oil hanging from the end of a glass rod is gently deposited upon the surface of chemically clean water, contained in a clean glass, a contest takes place between the forces in question the moment the drop flattens down by its gravity upon the surface of the water. The adhesion of the liquid surface tends to spread out the drop into a film, the cohesive force of the particles of the drop strives to prevent that extension, and the resultant of these forces is a figure which Mr. Tomlinson believes to be definite for every independent liquid. The figure thus produced is named the _cohesion-figure_.

[1553] Exposition de 1867 à Paris, _Rapports du Jury International_, xi. 108.—In the work of Coutance, quoted p. 417, note 7, nearly 400,000 hectolitres are calculated for the year 1866.

[1554] _Pharm. Journ._ v. (1864) 387. 495, with figures.

So far as our experience goes, the processes hitherto recommended for testing olive oil (and there are several that we have not mentioned) are only available in cases where the adulteration is considerable, and are quite insufficient for discovering a small admixture of other oils. How little they are appreciated, may be inferred from the fact that the Chamber of Commerce of Nice[1555] offered a reward of 15,000 francs (£600) for a simple and easy process for making evident an admixture with olive oil of 5 per cent. at least of any seed-oil.

APOCYNEÆ.

=CORTEX ALSTONIÆ.=

_Cortex Alstoniæ scholaris_; _Dita Bark_;[1556] _Alstonia Bark_.

=Botanical Origin=—_Alstonia[1557] scholaris_ R. Brown (_Echites scholaris_ L.), a handsome forest tree, 50 to 90 feet in height, common throughout the Indian Peninsula from the sub-Himalayan region to Ceylon and Burma; found also in the Philippines, Java, Timor and Eastern Australia, likewise in Tropical Africa. It has oblong obovate leaves, in whorls of 5 to 7, and slender pendulous pods a foot or more in length.

=History=—Saptachhada and saptaparna (literally seven-leaf), occurring in early Sanskrit epic poetry and also in Susruta, are ancient names of Alstonia (Dr. Rice). Rheede[1558] in 1678 and Rumphius[1559] in 1741 described and figured the tree, and mentioned the use made of its bark by the native practitioners. Rumphius also explained the trivial name _scholaris_ as referring to slabs of the close-grained wood which are used as school-slates, the letters being traced upon them in sand. The tonic properties of the bark were favourably spoken of by Graham in his _Catalogue of Bombay Plants_ (1839), and further recommended by Dr. Alexander Gibson in 1853[1560]. The drug has a place in the _Pharmacopœia of India_, 1868.

=Description=—The drug, as presented to one of us by the late Dr. Gibson and by Mr. Broughton of Ootacamund, consists of irregular fragments of bark, ⅛ to ½ an inch thick, of a spongy texture, easily breaking with a short, coarse fracture. The external surface is very uneven and rough, dark grey or brownish, sometimes with blackish spots; the interior substance and inner surface (liber) is of a bright buff. A transverse section shows the liber to be finely marked by numerous small medullary rays. The bark is almost inodorous; its taste is purely bitter and neither aromatic nor acrid.

[1555] _Annales de Chimie et de Physique_, March, 1869. 309.

[1556] From _Dita_, the name of the tree in the island of Luzon.

[1557] So named in honour of Charles Alston, Professor of Botany and Materia Medica (1740-1760) in the University of Edinburgh.—The plant is figured in Bentley and Trimen, _Med. Pl._