part 5

. p. 22.

=Description=—Cutch is imported in mats, bags, or boxes. It is a dark brown, extractiform substance, hard and brittle on the surface of the mass, but soft and tenacious within, at least when newly imported. The large leaf of _Dipterocarpus tuberculatus_ Roxb., the _Ein_ or _Engben_ of the Burmese, is often placed outside the blocks of extract.

Cutch when dry breaks easily, showing a shining but bubbly and slightly granular fracture. When it is soft and is pulled out into a thin film, it is seen to be translucent, granular and of a bright orange-brown. When further moistened and examined under the microscope, it exhibits an abundance of minute acicular crystals, precisely as seen in gambier. We have observed the same in numerous samples of the dry drug when rendered pulpy by the addition of water, or moistened with glycerin and viewed by polarized light.

The pale cutch referred to as manufactured in the north of India, is in the form of irregular fragments of a cake an inch or more thick, which has a laminated structure and appears to have been deposited in a round-bottomed vessel. It is a porous, opaque, earthly-looking substance of a pale pinkish-brown, light, and easily broken. Under the microscope it is seen to be a mass of needle-shaped crystals exactly like gambier, with which in all essential points it corresponds. We have received from India the same kind of cutch made into little round cakes like lozenges, with apparently no addition. The taste of cutch is astringent, followed by a sensation of sweetness by no means disagreeable.

=Chemical Composition=—Extractiform cutch, such as that of Pegu, which is the only sort common in Europe, when immersed in cold water turns whitish, softens and disintegrates, a small proportion of it dissolving and forming a deep brown solution. The insoluble part is _Catechin_ in minute acicular crystals. If a little of the thick chocolate-like liquid made by macerating cutch in water, is heated to the boiling point, it is rendered quite transparent (mechanical impurities being absent), but becomes turbid on cooling. Ferric chloride forms with this solution a dark green precipitate, immediately changing to purple if common water or a trace of free alkali be used.

Ether extracts from cutch, catechin. This substance has been investigated by many chemists, but as yet with discrepant results. It agrees, according to Etti (1877), with the formula C₁₉H₁₈O₈, when dried at 80° C. By gently heating catechin, _Catechu-tannic acid_, C₃₈H₃₄O₁₅, is produced:

2(C₁₉H₁₈O₈)-OH₂ = C₃₆H₃₄O₁₅.

This is an undoubted acid, readily soluble in water, of decidedly tanning properties, precipitating also the alkaloids and albumin. Catechu-tannic acid being the first anhydride of catechin, there are several more substances of that class; one of them is called _Catechuretin_. This blackish brown almost insoluble substance is obtained by heating catechin with concentrated hydrochloric acid at 180°:

2(C₁₉H₁₈O₈)-4 OH₂ = C₃₈H₂₈O₁₂. Catechin, by melting it with caustic potash, affords Protocatechuic acid, C₆H₃(OH)₂COOH, and Phloroglucin, C₆H₃(OH)₃:

C₁₉H₁₈O₈ + 2 OH₂ = 4 H · C₇H₆O₄ · 2 C₆H₆O₃.

Gautier (1877) also obtained the two latter products, but he is of the opinion that they are due to a somewhat different reaction, the formula of catechin, as derived from his analyses, being C₂₁H₁₈O₈. He also asserts that the so-called catechin from Uncaria (see Gambier) is not identical with the substance under notice, nor with that found in the Mahogan wood, to which Gautier assigns the formula C₄₂H₃₄O₁₆.

Crystallized deposits of catechin are sometimes met with in fissures of the trunk of Acacia Catechu, and used medicinally in India under the name _Keersal_.[936]

Löwe (1873), by exhausting cutch with cold water and then agitating the solution with ether, obtained upon the evaporation of the latter a yellow crystalline substance which he ascertained to be _Quercetin_, C₂₇H₁₈O₁₂. Its solubility in water is probably favoured by the presence of catechin, water having but very little action upon pure quercetin. The amount of quercetin in cutch is exceedingly small.

When either cutch or gambier is subjected to dry distillation it yields, in common with many other substances, _Pyrocatechin_, C₆H₄(OH)₂.

=Commerce=—The importations of cutch into the United Kingdom from British India (excluding the Straits Settlements and Ceylon) were as under, almost the whole being from Bengal and Burma:—

1869 1870 1871 1872 2257 tons. 5252 tons. 4335 tons. 5240 tons.

The total value of the cutch imported in 1872 was estimated at £124,458.

=Uses=—Cutch under the name of _Catechu_, which name it shares with gambier, is employed in medicine as an astringent.

=Analogous Products=—See our articles Semen Arecæ and Gambier.

ROSACEÆ.

AMYGDALÆ DULCES.

_Sweet Almonds_; F. _Amandes douces_; G. _Süsse Mandeln_.

=Botanical Origin=—_Prunus Amygdalus_ Baillon[937] var. β. _dulcis_ (_Amygdalus communis_ L. var. β. _dulcis_ DC.)—The native country of the almond cannot be ascertained with precision. A. de Candolle,[938] after reviewing the statements of various authors concerning the occurrence of the tree in an apparently wild state, arrives at the conclusion that its original area possibly extended from Persia, westward to Asia Minor and Syria, and even to Algeria. The tree is found ascending to 4000 feet in the Antilebanon, to 3000 in Mesopotamia, and even to 9000 feet in the Avroman range, not far from Sulemānia, Southern Kurdistan.[939]

[936] Dymock, _Ph. Journ._ vii. (1876) 109.

[937] _Hist. des Plantes_ (_Monogr. des Rosacées_, 1869) i. 415.

[938] _Géographie Botanique_, ii. (1855) 888.

[939] Boissier, _Flora Orientalis_, ii. (1872) 641.

At an early period the tree was spread throughout the entire Mediterranean region, and in favourable situations, far into the continent of Europe. It was apparently introduced into Italy from Greece, where according to Heldreich,[940] the bitter variety is truly wild. The almond-tree matures its fruit in the south of England, but is liable to destruction by frost in many parts of central Europe.

=History=—The earliest notice of the almond extant is that in the Book of Genesis,[941] where we read that the patriarch Israel commanded his sons to carry with them into Egypt a present consisting of the productions of Palestine, one of which is named as _almonds_.

From the copious references to the almond in the writings of Theophrastus, one cannot but conclude that in his day it was familiarly known.

In Italy, M. Porcius Cato[942] mentions towards the middle of the 2nd century B.C. _Avellanæ Græcæ_ which we know from later authors signified _almonds_. Columella, who wrote about A.D.. 60, calls them _Nuces Græcæ_. Bitter almonds (“_Amygdali amari_”) are named about this latter period by Scribonius Largus.

As to more northern Europe, almonds are mentioned together with other groceries and spices as early as A.D. 716, in a charter granted by Chilperic II., King of France, to the monastery of Corbie in Normandy.[943] In 812 Charlemagne ordered the trees (_Amandalarii_) to be introduced on the imperial farms. In the later middle ages, the cultivation of the almond was carried on about Speier and in the Rhenish Palatinate. We learn from Marino Sanudo[944] that in the beginning of the 14th century, almonds had become an important item of the Venetian trade to Alexandria. They were doubtless in large part produced by the islands of the Greek Archipelago, then under Christian rule. In Cyprus for instance, the Knights Templar levied tithes in 1411 of _almonds_, honey, and sesamé seed.[945]

The consumption of almonds in mediæval cookery was enormous. An inventory made in 1372 of the effects of Jeanne d’Evreux, queen of France, enumerates only 20 lb. of sugar, but 500 lb. of almonds.[946]

In the _Form of Cury_, a manuscript written by the master cooks of King Richard II., A.D. 1390, are receipts for “_Creme of Almand_, _Grewel of Almand_, _Cawdel of Almand Mylke_, _Jowt of Almand Mylke_,” &c.[947]

Almonds were sold in England by the “_hundred_” _i.e._ 108 lb. Rogers[948] gives the average price between 1259 and 1350 as 2d., and between 1351 and 1400 as 3⅛d. per lb.

[940] _Nutzpflanzen Griechenlands_, Athen, 1862. 67.

[941] Ch. xliii. v. 11; Num. xvii. 8.

[942] _De Re Rustica_, cap. viii.

[943] Pardessus, _Diplomata Chartæ_, etc., Paris, 1849. ii. 309.

[944] _Liber Secretorum Fidelium_, ed. Bongars, 1611. 24.

[945] De Mas Latrie, _Hist. de l’île de Chypre_, ii. (1852) 500.

[946] Leber, _Appréciation de la fortune privée au moyen-âge_, éd. 2, Paris, 1847. 95.

[947] Published by Pegge, Lond. 1780.—Boorde in his _Dyetary of Helth_, 1542, mentions _Almon Mylke_ and _Almon Butter_, the latter “_a commendable dysshe, specyallye in Lent_.”

[948] _Agriculture and Prices in England_, i. (1866) 641.

=Description=—The fruit of the almond tree is a drupe, with a velvety sarcocarp which at maturity dries, splits, and drops out leaving bare and still attached to the branch, an oblong, ovate pointed stone, pitted with irregular holes. The seed, about an inch in length, is ovate or oblong, more or less compressed, pointed at the upper, blunt at the lower end, coated with a scurfy, cinnamon-brown skin or testa. It is connected with the stone or putamen by a broad funicle, which runs along its edge for more than a third of its length from the apex; hence the raphe passes downwards to the rounded end of the seed, where a scar marks the chalaza. From this, a dozen or more ramifying veins run up the brown skin towards the pointed end. After an almond has been macerated in warm water, the skin is easily removed, bringing with it the closely attached translucent inner membrane or endopleura. As the seed is without albumen, the whole mass within the testa consists of embryo. This is formed of a pair of plano-convex cotyledons, within which lie the flat leafy plumule and thick radicle, the latter slightly projecting from the pointed or basal end of the seed.

Almonds have a bland, sweet, nutty flavour. When triturated with water, they afford a pure white, milk-like emulsion of agreeable taste.

=Varieties=—The different sorts of almond vary in form and size, and more particularly in the firmness of the shell. This in some varieties is tender and easily broken in the hand, in others so hard as to require a hammer to fracture it. The form and size of the kernel likewise exhibit some variation. The most esteemed are those of Malaga, known in trade as _Jordan Almonds_. They are usually imported without the shell, and differ from all other sorts in their oblong form and large size. The other kinds of sweet almonds known in the London market are distinguished in the order of value as _Valencia_, _Sicily_, and _Barbary_.[949]

=Microscopic Structure=—Three different parts are to be distinguished in the brown coat of an almond. First, a layer of very large (as much as ⅓ mm. in diameter) irregular cells, to which the scurfy surface is due. If these brittle cells are boiled with caustic soda, they make a brilliant object for microscopic examination in polarized light. The two inner layers of the skin are made up of much smaller cells, traversed by small fibro-vascular bundles. The brown coat assumes a bluish hue on addition of perchloride of iron, owing to the presence of tannic matter.

The cotyledons consist of thin-walled parenchyme, fibro-vascular bundles being not decidedly developed. This tissue is loaded with granular albuminous matter, some of which exhibits a crystalloid aspect, as may be ascertained in polarized light. Starch is altogether wanting in almonds.

=Chemical Composition=—The sweet almond contains fixed oil extractable by boiling ether to the extent of 50 to 55 per cent. A produce of 50 per cent. by the hydraulic press is by no means uncommon.

The oil (_Oleum Amygdalæ_) is a thin, light yellow fluid, of sp. gr. 0·92, which does not solidify till cooled to between -10 and-20° C. When fresh, it has a mild nutty taste, but soon becomes rancid by exposure to the air; it is not, however, one of the drying oils. It consists almost wholly of the glycerin compound of _Oleic Acid_, C₁₈H₃₄O₂.

[949] To be consulted for further information: Bianca, _G. Manuale della Cultivazione del Mandorlo in Sicilia_, Palermo, 1874 (444 pages).

Almonds easily yield to cold water a sugar tasting like honey, which reduces alkaline cupric tartrate even in the cold, and is therefore in part grape sugar. Pelouze however (1855) obtained from almonds 10 per cent. of cane-sugar. The amount of gum appears to be very small; Fleury (1865) found that the _total amount_ of sugar, dextrin and mucilage was altogether only 6·29 per cent.

If almonds are kept for several days in alcohol, crystals of asparagine (see article Rad. Althææ, p. 93) make their appearance, as shown by Henschen (1872), and by Portes (1876).

The almond yields 3·7 per cent. of nitrogen, corresponding to about 24 per cent. of albuminoid matters. These have been elaborately examined by Robiquet (1837-38), Ortloff (1846), Bull (1849), and Ritthausen (1872).[950] The experiments tend to show that there exist in the almond two different protein substances; Robiquet termed one of these bodies _Synaptase_, while others applied to it the name _Emulsin_.[951] Commaille (1866) named the second albuminous substance _Amandin_; it is the _Almond-legumin_ of Gmelin’s _Chemistry_, the _Conglutin_ of Ritthausen. Emulsin has not yet been freed from earthly phosphates which, when it is precipitated by alcohol from any aqueous solution, often amount to a third of its weight. Amandin may be precipitated from its aqueous solution by acetic acid. According to Ritthausen, these bodies are to be regarded as modifications of one and the same substance, namely vegetable casein.

Blanched almonds comminuted yield, when slightly warmed with dilute potash, a small quantity of hydrocyanic acid and of ammonia; the former may be made manifest by means of Schönbein’s test pointed out at p. 250.

The ash of almonds, amounting to from 3 to nearly 5 per cent., consists chiefly of phosphates of potassium, magnesium and calcium.

=Production and Commerce=—The quantity of almonds imported into the United Kingdom in 1872 was 70,270 cwt., valued at £204,592. Of this quantity, Morocco supplied 33,500 cwt., and Spam with the Canary Islands 22,000 cwt., the remainder being made up by Italy, Portugal, France, and other countries. The imports into the United Kingdom in 1876 were 77,169 cwt., valued at £244,078. Almonds are largely shipped from the Persian Gulf: in the year 1872-73, there were imported thence into Bombay, 15,878 cwt., besides 3,049 cwt. from other countries.[952]

=Uses=—Sweet almonds may be used for the extraction of almond oil, yet they are but rarely so employed (at least in England) on account of the inferior value of the residual cake. The only other use of the sweet almond in medicine is for making the emulsion called _Mistura Amygdalæ_.

AMYGDALÆ AMARÆ.

_Bitter Almonds_; F. _Amandes amères_; G. _Bittere Mandeln_.

=Botanical Origin=—_Prunus Amygdalus_ Baillon var. _a. amara_ (_Amygdalus communis_ L. var. _a. amara_ DC.). The Bitter Almond tree is not distinguished from the sweet by any permanent botanical character, and its area of growth appears to be the same (see p. 244).

[950] _Die Eiweisskörper der Getreidearten, Hülsenfrüchte und Oelsamen_, Bonn, 1872. 199.

[951] Gmelin, _Chemistry_, xviii. (1871) 452.

[952] _Statement of the Trade and Navigation of Bombay for_ 1872-73, pt. ii. 31.

=History=—(See also preceding article.) Bitter almonds and their poisonous properties were well known in the antiquity, and used medicinally during the middle ages. Valerius Cordus prescribed them as an ingredient of trochisci.[953]

As early as the beginning of the present century, it was shown by the experiments of Bohm, a pharmaceutical assistant of Berlin, that the aqueous distillate of bitter almonds contains hydrocyanic acid and a peculiar oil which cannot be obtained from sweet almonds. It was then inferred that hydrocyanic acid itself might be poisonous, a fact which, strange to say, had not been noticed by Scheele, when he discovered that acid in 1782, as obtained by distilling potassium ferrocyanate with sulphuric acid. The dangerous action of hydrocyanic was then ascertained in 1802 and 1803 by Schaub and Schrader.[954]

=Description=—Bitter almonds agree in outward appearance, form, and structure with sweet almonds; they exist under several varieties, but there is none so far as we know that in size and form resembles the long sweet almond of Malaga.[955] In general, bitter almonds are of smaller size than sweet. Triturated with water, they afford the same white emulsion as sweet almonds, but it has a strong odour of hydrocyanic acid and a very bitter taste.

=Varieties=—These are distinguished in their order of goodness, as French, Sicilian, and Barbary.

=Microscopic Structure=—In this respect, no difference between sweet and bitter almonds can be pointed out. If thin slices of the latter are deprived of fat oil by means of benzol, and then kept for some years in glycerin, an abundance of crystals is slowly formed, of what we suppose to be amygdalin.

=Chemical Composition=—Bitter almonds, when comminuted and mixed with water, immediately evolve the odour of bitter almond oil. The more generally diffused substances are the same in both kinds of almond, and the fixed oil in particular of the bitter almond is identical with that of the sweet. Bitter almonds however contain on an average a somewhat lower proportion of oil than the sweet. In one instance that has come to our knowledge in which 28 cwt. of bitter almonds were submitted to pressure, the yield of oil was at the rate of 43·6 per cent. Mr. Umney, director of the laboratory of Messrs. Herrings and Co., where large quantities of bitter almonds are submitted to powerful hydraulic pressure, gives 44·2 as the average percentage of oil obtained during the years 1871-2.

[953] _Dispensator_., Paris, 1548. 336. 337. 343.

[954] J. B. Richter, _Neuere Gegenstände der Chymie_, Breslau, xi. (1802) 65. J. B. Trommsdorffs _Journ. d. Pharm._ xi. (Leipzig, 1803) 262. Preyer, _Die Blausäure_, Bonn, 1870. 152.

[955] Hence to avoid bitter almonds being used instead of sweet, the _British Pharmacopœia_ directs that _Jordan Almonds_ alone shall be employed for Confection of Almonds.

Robiquet and Boutron-Charland in 1830 prepared from bitter almonds a crystalline substance, _Amygdalin_, and found that bitter almond oil and hydrocyanic acid can no longer be obtained from bitter almonds, the amygdalin of which has been removed by alcohol. Liebig and Wöhler in 1837 showed that it is solely the decomposition of this body (under conditions to be explained presently), that occasions the formation of the two compounds above named. Disregarding secondary products (ammonia and formic acid), the reaction takes place as represented in the following equation:

C₂₀H₂₇NO₁₁ + 3 OH₂ = OH₂ · 2 (C₆H₁₂O₆) · NCH · C₇H₆O. Crystallized Anhydrous Hydro- Bitter Amygdalin. Dextro- cyanic Almond glucose. Acid. Oil.

This memorable investigation first brought under notice a body of the glucoside class, now so numerous.

Amygdalin may be obtained crystallized when almonds deprived of their oil are boiled with alcohol of 84 to 94 per cent. The product amounts at most to 2½ or 3 per cent. Amygdalin _per se_ dissolves in 15 parts of water at 8-12° C., forming a neutral, bitter, inodorous liquid, quite destitute of poisonous properties.

It would appear from the investigations of Portes (1877) that in young almonds, amygdalin is formed before the emulsin.

When bitter almonds have been freed from amygdalin and fixed oil, cold water extracts from the residue chiefly emulsin and another albuminoid matter separable by acetic acid. The emulsin upon addition of alcohol falls down in thick flocks, which, after draining, form with cold water a slightly opalescent solution. This liquid added to an aqueous solution of amygdalin, renders it turbid, and developes in it bitter almond oil. The reaction takes place in the same manner, if the emulsin has not been previously purified by acetic acid and alcohol, or if an emulsion of sweet almonds used. But after boiling, an emulsion of almonds is no longer capable of decomposing amygdalin.

What alteration the emulsin itself undergoes in this reaction, or whether it suffers any alteration at all, has not been clearly made out. The reaction does not appear to take place necessarily in atomic proportions; it does not cease until the emulsin has decomposed about three times its own weight of amygdalin, provided always that sufficient water is present to hold all the products in solution.

The leaves of _Prunus Lauro-cerasus_ L., the bark of _P. Padus_ L., and the organs of many allied plants, also contain emulsin or a substance analogous to it, not yet isolated. In the seeds of various plants belonging to natural orders not botanically allied to the almond, as for example in those of mustard, hemp, and poppy, and even in yolk of egg, albuminous substances occur which are capable of acting upon amygdalin in the same manner. Boiling dilute hydrochloric acid induces the same decomposition, with the simultaneous production of formic acid.

The distillation of bitter almonds is known to offer some difficulties on account of the large quantity present of albuminous substances, which give rise to bumping and frothing. Michael Pettenkofer (1861) has found that these inconveniences may be avoided by immersing 12 parts of powdered almonds in boiling water, whereby the albuminous matters are coagulated, whereas the amygdalin is dissolved. On then adding an emulsion of only 1 part of almonds (sweet or bitter), the emulsin contained in it will suffice to effect the required decomposition at a temperature not exceeding 40° C. In this manner, Pettenkofer obtained in some experiments performed with small quantities of almonds, as much as 0·9 per cent. of essential oil. In the case alluded to on the opposite page, in which 28 cwt. of almonds were treated, the yield of essential oil amounted to 0·87 per cent. From data obligingly furnished to us by Messrs. Herrings and Co. of London, who distill large quantities of almond cake, it appears that the yield of essential oil is very variable. The yearly averages as taken from the books of this firm, show that it may be as low as 0·74, or as high as 1·67 per cent., which, assuming 57 pounds of cake as equivalent to 100 pounds of almonds, would represent a percentage from the latter of 0·42 and 0·95 per cent. respectively. Mr. Umney explains this enormous variation as due in part to natural variableness in the different kinds of bitter almond, and in part to their admixture with sweet almonds. He also states that the action of the emulsin on the amygdalin when in contact with water, is extremely rapid, and that 200 pounds of almond marc are thoroughly exhausted by a distillation of only three hours.

In the distillation, the hydrocyanic acid and bitter almond oil unite into an unstable compound. From this, the acid is gradually set free, and partly converted into cyanide of ammonium and formic acid. Supposing bitter almonds to contain 3·3 per cent. of Amygdalin, they must yield 0·2 per cent. of hydrocyanic acid. Pettenkofer obtained by experiment as much as 0·25 per cent., Feldhaus (1863) 0·17 per cent.

Some manufacturers apply bitter almond oil deprived of hydrocyanic acid, but such purified oil is very prone to oxidation, unless carefully deprived of water by being shaken with fused chloride of calcium. The sp. gr. of the original oil is 1·061-1·065; that of the purified oil (according to Umney) 1·049. The purification by the action of ferrous sulphate and lime, and re-distillation, as recommended by Maclagan (1853), occasions, we are informed, a loss of about 10 per cent.

Bitter almond oil, C₆H₅(COH), being the aldehyde of benzoic acid, C₆H₅(COOH), is easily converted in that acid by spontaneous or artificial oxidation. The oil boils at 180°C. and is a little soluble in water; 300 parts of water dissolve one part of the oil.

There are a great number of plants which if crushed, moistened with water, and submitted to distillation, yield both bitter almond oil and hydrocyanic acid. In many instances the amount of hydrocyanic acid is so extremely small, that its presence can only be revealed by the most delicate test,—that of Schönbein.[956]

Among plants capable of emitting hydrocyanic acid, probably always accompanied with bitter almond oil, the tribes _Pruneæ_ and _Pomeæ_ of the rosaceous order may be particularly mentioned.

The farinaceous rootstocks of the Bitter Cassava, _Manihot utilissima_, Pohl, of the order _Euphorbiaceæ_, the source of tapioca in Brazil, have long been known to yield hydrocyanic acid.

A composite, _Chardinia xeranthemoides_ Desf., growing in the Caspian regions, has been shown by W. Eichler also to emit hydrocyanic acid.[957] The same has been observed by the French in Gaboon[958] with regard to the fruits of _Ximenia americana_ L. of the order _Olacineæ_, and the fact has been confirmed by Ernst of Caracas,[959] near which place the plant abounds. Mr. Prestoe of the Botanical Garden, Trinidad, informs us (1874) that in that island a convolvulaceous plant, _Ipomœa dissecta_ Willd., contains a juice with a strong prussic acid odour. According to Lösecke, a common mushroom, _Agaricus oreades_ Bolt., emits hydrocyanic acid.[960]

[956] Applied in the following manner:—Let bibulous paper be imbued with a fresh tincture of the wood or resin of guaiacum, and after drying, let it be moistened with a solution composed of one part of sulphate of copper in 2000 of water. Such paper moistened with water will assume an intense blue coloration in the presence of hydrocyanic acid.

[957] _Bull. de la Soc. imp. des nat. de Moscou_, xxxv. (1862) ii. 444.

[958] Exposition Univers. de 1867.—_Produits des Colonies Françaises_, 92.

[959] _Archiv der Pharmacie_, 181 (1867) 222.

[960] _Jahresbericht_ of Wiggers and Husemann for 1871. 11.

This acid is consequently widely diffused throughout the vegetable kingdom. Yet amygdalin has thus far only been isolated from a few plants belonging to the genus _Prunus_ or its near allies.[961] In all other plants in which hydrocyanic acid has been met with, we know nothing as to its origin. Ritthausen and Kreusler (1871) have proved the _absence_ of amygdalin in the seeds of a _Vicia_, which yield bitter almond oil and hydrocyanic acid. These chemists followed the process which in the case of bitter almonds easily affords amygdalin.

=Commerce=—See preceding article.

=Uses=—Bitter almonds are used almost exclusively for the manufacture of _Almond Oil_, while from the residual cake is distilled _Bitter Almond Oil_. An emulsion of bitter almonds is sometimes prescribed as a lotion.

=Adulteration=—The adulteration of bitter almonds with sweet is a frequent source of loss and annoyance to the pressers of almond oil, whose profit largely depends on the amount of volatile oil they are able to extract from the residual cake.

FRUCTUS PRUNI.

_Prunes_; F. _Pruneaux à médecine_.

=Botanical Origin=—_Prunus domestica_ L., var. ζ. _Juliana_ DC.—It is from this tree, which is known as _Prunier de St. Julien_,[962] that the true _Medicinal Prunes_ of English pharmacy are derived. The tree is largely cultivated in the valley of the Loire in France, especially about Bourgueil, a small town lying between Tours and Angers.

=History=—The plum-tree (_P. domestica_ L.) from which it is supposed the numerous cultivated varieties have descended, is believed to occur in a truly wild state in Greece, the south-eastern shores of the Black Sea (Lazistan), the Caucasus, and the Elburz range in Northern Persia, from some of which countries it was introduced into Europe long before the Christian era. In the days of Pliny, numerous species of plum were already in cultivation, one of which afforded a fruit having laxative properties.

Dried prunes, especially those taking their name from Damascus (_Pruna Damascena_), are frequently mentioned in the writings of the Greek physicians, by whom as well as at a later period by the practitioners of the Schola Salernitana, they were much employed.

[961] Gmelin, _Chemistry_, vii. 389; xv. 422.

[962] Loiseleur-Deslongchamps et Michel, _Nouveau Duhamel, ou Traité des arbres et arbustes que l’on cultive en France_, v. (1812) 189, pl. 54. fig. 2, pl. 56. fig. 9.

In the older London pharmacopœias, many sorts of plum are enumerated, but in the reformed editions of 1746, 1788, and 1809, the French Prune (_Prunum Gallicum_) is specially ordered, its chief use being as an ingredient of the well-known _Lenitive Electuary_; and this fruit is still held by the grocers to be the legitimate _prune_. The same variety is regarded in France as the prune of medicine.

=Description=—The prune in its fresh state is an ovoid drupe of a deep purple hue, not depressed at the insertion of the stalk, and with a scarcely visible suture, and no furrow. The pulp is greenish and rather austere, unless the fruit is very ripe; it does not adhere to the stone. The stone is short (⁷/₁₀ to ⁸/₁₀ of an inch long, ⁵/₁₀ to ⁶/₁₀ broad), broadly rounded at the upper end and slightly mucronulate, narrowed somewhat stalk-like at the lower, and truncate; the ventral suture is broader and thicker than the dorsal.

The fruit is dried partly by solar and partly by fire-heat, that is to say, it is exposed alternately to the heat of an oven and to the open air. Thus prepared, it is about 1¼ inches long, black and shrivelled, but recovers its original size and form by digestion in warm water. The dried pulp or sarcocarp is brown and tough, with an acidulous, saccharine, fruity taste.

=Microscopic Structure=—The skin of the prune is formed of small, densely packed cells, loaded with a dark solid substance; the pulp consists of larger shrunken cells, containing a brownish amorphous mass which is probably rich in sugar. This latter tissue is traversed by a few thin fibro-vascular bundles, and exhibits here and there crystals of oxalate of calcium. By perchloride of iron, the cell-walls, as well as the contents of the cells, acquire a dingy greenish hue.

=Chemical Composition=—We are not aware of any analysis having been made of the particular sort of plum under notice, nor that any attempt has been made to discover the source of the medicinal property it is reputed to possess. Some nearly allied varieties have been submitted to analysis in the laboratory of Fresenius, and shown to contain saccharine matters to the extent of 17 to 35 per cent., besides malic acid, and albuminoid and pectic substances.[963]

=Uses=—The only pharmaceutical preparation of which the pulp of prunes is an ingredient, is _Confectio Sennæ_, the _Electuarium lenitivum_ of the old pharmacopœias. The fruit stewed and sweetened is often used as a domestic laxative.

=Substitute=—When French prunes are scarce, a very similar fruit, known in Germany as _Zwetschen_ or _Quetschen_, is imported as a substitute.[964] It is the produce of a tree which most botanists regard as a form of _Prunus domestica_ L., termed by De Candolle var. _Pruneauliana_. K. Koch,[965] however, is decidedly of opinion that it is a distinct species, and as such he has revived for it Borkhausen’s name of _Prunus œconomica_. The tree is widely cultivated in Germany for the sake of its fruit, which is used in the dried state as an article of food, but is not grown in England.

[963] Liebig’s _Ann. der Chemie_, ci. (1857) 228.

[964] This was especially the case in the winter of 1873-74.

[965] _Dendrologie_,