part 1

(1871) 287.

[2261] Elliot, _Experiences of a Planter in the Jungles of Mysore_, ii. (1871) 237; also verbal information communicated by Capt. Campbell Walker, Deputy Conservator of Forests, Madras.

In 1863 a sort of sandal-wood afforded by _Fusanus spicatus_ (p. 599) was one of the chief exports of Western Australia, whence it was shipped to China. A trifling payment for permission to cut growing timber of any kind was the only barrier placed on the felling of the trees. The farmers employed their teams during the dull season in bringing to Perth or Guildford the logs of sandal which had been felled and trimmed in the bush; and there was a flourishing trade so long as trees of a fair size could be obtained within 100 or even 150 miles of the towns, where the commodity was worth £6 to £6 10_s._ per ton. But the ill-regulated and improvident destruction of the trees in the more easily accessible districts has so reduced their numbers that the trade in that part of Australia soon came to an end.[2262] Australian sandal-wood appears however to be still an article of commerce, if one may draw such an inference from the fact that 47,904 cwt. of sandal wood were imported into Singapore from Australia in the year 1872. It was mostly re-shipped to China.[2263]

=Description=—sandal-wood is not much known in English commerce, and is by no means always to be found even in London. That which we have examined, and which we believe was Indian, was in cylindrical logs, mostly about 6 inches in diameter (the largest 8 inches—smallest 3: inches) and 3 to 4 feet long, extremely ponderous; the bark had been removed. A transverse section of sandal-wood exhibits it of a pale brown, marked with rather darker concentric zones and (when seen under a lens) numerous open pores. The tissue is traversed by medullary rays, also perceptible by the aid of a lens. The wood splits easily, emitting when comminuted an agreeable odour which is remarkably persistent; it has a strongish aromatic taste.

The varieties of sandal-wood are not classified by the few persons who deal in the article in London, and we are unable to point out characters by which they may be distinguished. In the price-currents of commercial houses in China three sorts of sandal-wood are enumerated, namely, _South Sea Island_, _Timor_, and _Malabar_; the last fetches three or four times as high a price as either of the others. Even the Indian sandal-wood may vary in an important manner. Beddome,[2264] conservator of forests in Madras, and an excellent observer, remarks that the finest sandal-wood is that which has grown slowly on rocky, dry and poor land; and that the trees found in a rich alluvial soil, though of very fine growth, produce no heartwood and are consequently valueless. A variety of the tree with more lanceolate leaves (var. β _myrtifolium_ DC.), native of the eastern mountains of the Madras Presidency, affords a sandal-wood which is nearly inodorous.

=Microscopic Structure=—The woody rays or wedges show a breadth varying from 35 to 420 mkm., the primary being frequently divided by secondary medullary rays. These latter rays consist of one, often of two, rows of cells of the usual form. The woody tissue which they enclose is chiefly made up of small ligneous fibres with pointed ends, some larger parenchymatous cells, and thick-walled vessels. The resin and essential oil reside chiefly in the medullary rays, as shown by the darker colour of these latter.

=Chemical Composition=—The most important constituent is the essential oil, which the wood yields to the extent of from 2 to 5 per cent.[2265] In India, with imperfect stills, 2·5 per cent. of the oil are obtained; the roots yield the largest amount and the finest quality of it.[2266] It is a light yellow, thick liquid, possessing the characteristic odour of sandal; that which we examined had a sp. gr. of 0·963. We did not succeed in finding a fixed boiling point of the oil; it began to boil at 214° C., but the temperature quickly rose to 255°, the oil acquiring a darker hue. Oil of sandal-wood varies much in the strength and character of its aroma, according to the sort of wood from which it is produced.

[2262] Millett, _An Australian Parsonage_, Lond., 1872, 43. 95. 382.

[2263] _Straits Settlements Blue Book for 1872_, Singapore, 1873. 298. 347.—It is possible that the sandal-wood in question may have been the produce of the South Sea Islands, shipped from an Australian port.

[2264] _Op. cit._

[2265] Information obligingly communicated by Messrs. Schimmel and Co., Leipzig (1878).

[2266] Dr. Bidie, in _Pharmacopœia of India_, 1868, p. 461.

The oil as largely prepared by Messrs. Schimmel & Co., in a column 100 millimetres long, deviates the plane of polarization 18·6° to the _left_. Oil of Venezuela sandal-wood, from the same distillers, examined in the same manner, deviates 6°·75 to the _right_.

From the wood, treated with boiling alcohol, we obtained about 7 per cent. of a blackish extract, from which a tannate was precipitated by alcoholic solution of acetate of lead. Decomposed by sulphuretted hydrogen, the tannate yielded a tannic acid having but little colour, and striking a greenish hue with a ferric salt. The extract also contained a dark resin.

=Commerce=—The greatest trade in sandal-wood is in China, which country in the year 1866 imported at the fourteen treaty ports then open 87,321 peculs, equivalent to 5,197 tons; of this vast quantity the city of Hankow on the river Yangtsze, received no less than 61,414 peculs, or more than seven times as much as any other port.[2267] The imports into Hankow have recently been much smaller, namely, 14,989 peculs in 1871 and 12,798 peculs in 1872.[2268] On the other hand, Shanghai lying near the mouth of the same great river, imported in 1872, 59,485 peculs of sandal-wood, the estimated value of which was about £100,000. In 1877 the imports of all China were 72,934 peculs.

A considerable trade in sandal-wood is done in Bombay, the quantity imported thither annually being about 650 tons, and the animal export about 400 tons.[2269]

Oil of sandal-wood is largely manufactured on the ghats between Mangalore and Mysore, where fuel for the stills is abundant. Official returns[2270] represent the quantity of the oil imported into Bombay in the year 1872-73 as 10,348 lbs., value £8,374; 4,500 lbs. were re-exported by sea.

=Uses=—The essential oil has of late been prescribed as a substitute for copaiba, otherwise sandal-wood has hardly any uses in modern European medicine. It is employed as a perfume and for the fabrication of small articles of ornament. Among the natives of India it is largely consumed in the celebration of sepulchral rites, wealthy Hindus showing their respect for a departed relative by adding sticks of sandal-wood to the funereal pile. The powder of the wood made into a paste with water is used for making the caste mark, and also for medicinal purposes. The consumption of sandal-wood in China appears to be principally for the incense used in the temples.

[2267] _Reports on Trade at the ports in China open to foreign trade for 1866_, published by order of the Inspector-General of Customs, Shanghai, 1867. 120. 121.—One pecul = 133⅓ lb.

[2268] _Commercial Reports of H. M. Consuls in China for 1871_ (p. 50) and 1872 (pp. 62. 159).

[2269] From the official document quoted at p. 601, note 1.

[2270] See p. 333, note 3.

_Gymnosperms._

CONIFERÆ.

TEREBINTHINA VULGARIS.

_Crude or Common Turpentine_; F. _Térebenthine commune_; G. _Gemeiner Terpenthin_.

=Botanical Origin=—The trees which yield Common Turpentine may be considered in two groups, namely, European and American.

1. _European_—In Finland and Russia Proper, the Scotch Pine, _Pinus sivestris_ L.; in Austria and Corsica, _P. Laricio_ Poiret; and in South-western France, _P. Pinaster_ Solander (_P. maritima_ Poiret), extensively cultivated as the _Pin maritime_, yield turpentine in their respective countries.

2. _American_—In the United States, the conifers most important for terebinthinous products are the Swamp Pine, _Pinus australis_ Michaux (_P. palustris_ Mill.), and the Loblolly Pine, _P. Tæda_ L.

=History=—The resin of pines and firs was well known to the ancients, who obtained it in much the same manner as that practised at the present day. The turpentine used in this country has for many years past been derived from North America. Up to the last century, both it and the substance called _Common Frankincense_ were imported from France. The late civil war in the United States and the blockade of the Southern ports, occasioned a great scarcity of American turpentine; and terebinthinous substances from all other countries were poured into the London market. The actual supplies, however, were mainly furnished by France.

Kopp[2271] quotes a passage showing that the essential oil of turpentine was known to Marcus Græcus, who termed it _Aqua ardens_. This almost unknown personage is the reputed inventor of _Greek Fire_, a dreaded engine of destruction in mediæval warfare.

=Secretion=—The primary formation of resin-ducts in the bark of coniferous trees has been explained by Dippel,[2272] Müller,[2273] and Frank.[2274] The subsequent diffusion of the resinous juice through the heartwood, sapwood, and bark, has been elaborately investigated by Hugo von Mohl.[2275] From the various forms under which this diffusion exists in the different species have arisen the diverse methods of obtaining the terebinthinous resins.

[2271] _Geschichte der Chemie_, iv. (1847) 392.

[2272] _Botanische Zeitung_, 1863.

[2273] Pringsheim, _Jahrb. für wissenschaftl. Botanik._ 1866.

[2274] _Beiträge zur Pflanzenphysiologie_, Leipzig, 1868. 119.

[2275] _Botanische Zeitung_, 1859. 329.

Thus in the wood of the Silver Fir (_Pinua Picea_ L.) resin-ducts are altogether wanting;—and led by experience, the Alpine peasant collects the turpentine of this tree by simply puncturing the little cavities which form under its bark. In the Scotch Pine (_P. silvestris_ L.), they are more abundant in the wood than in the bark, a fact which might be anticipated by observing how rarely this tree exudes resin spontaneously.

Oil of turpentine, like volatile oils in general, undergoes on exposure to the air certain alterations giving rise to what is called _resinification_. The formic acid which is produced in small quantity during this change characterizes it as one of oxidation; the chief products however are not exactly known, and not one of them has been proved identical with any natural resin. The common assumption that resins are produced from volatile oils by simple oxidation, is consequently not yet entirely justified.

=Extraction=—In the United States[2276] turpentine is obtained to the largest extent from _Pinus australis_, of which tree there are vast forests, the piny woods or pine-barrens, extending from Virginia to the Mexican Gulf, especially through North and South Carolina, Georgia and Alabama. But it is in North Carolina that the extraction of turpentine is principally carried on.

In the winter, _i.e._ from November to March, the negroes in a _Turpentine Orchard_, as the district of forest to be worked is called, are occupied in making in the trunks of the trees, cavities which are technically known as _boxes_. For this purpose a long narrow axe is used, and some skill is required to wield it properly. The boxes are made from 6 to 12 inches above the ground, and are shaped like a distended waistcoat-pocket, the bottom being about 4 inches below the lower lip, and 8 or 10 below the upper. On a tree of medium size, a box should be made to hold a quart. The less the axe approaches the centre of the tree the better, as vitality is the less endangered. An expert workman will make a box in less than 10 minutes. From one to four boxes are made in each tree, a few inches of bark being left between them. The greater number of trees from which turpentine is now obtained, are from 12 to 18 inches in diameter, and have three boxes each.

The boxes having been made, the bark and a little of the wood immediately beneath it, which are above the box, are _hacked_; and from this excoriation, the sap begins to flow about the middle of March, gradually filling the box. Each tree requires to be freshly hacked every 8 or 10 days, a very slight wound above the last being all that is needed. The hacking is carried on year after year, until it reaches 12 to 15 feet or more, ladders being used. The turpentine, which is called _dip_, is removed from the boxes by a spoon or ladle of peculiar form, and collected into barrels, which are made on the spot and are of very rude construction. The first year’s flow of a new tree, having but a small surface to traverse before it reaches the box, is of special goodness and is termed _Virgin dip_.

[2276] The account here given is taken from F. L. Olmsted’s _Journey in the Seaboard Slave States_, New York, 1856, p. 338, etc.

The turpentine which concretes upon the trunk is occasionally scraped off and barrelled by itself, and is known in the market as _scrape_, or by English druggists as _Common Frankincense_ or _Gum thus_.

Although a large amount of turpentine is shipped to the northern ports for distillation, a still larger is distilled in the neighbourhood of the turpentine orchards. Copper stills are used, capable of containing 5 to 20 barrels of turpentine. The turpentine is distilled without water, the volatile oil as it flows from the worm being received in the barrel in which it is afterwards sent to market. When all the oil that can be profitably drawn off has been obtained, a spigot is removed from an opening in the bottom of the still, and the residual _Rosin_, appearing as a viscid fluid-like molasses, is allowed to flow out. Only the first qualities of rosin, as that obtained from _Virgin dip_, are generally considered worth saving, the less pure sorts being simply allowed to run to waste. When it is intended to save the rosin, the latter is drawn off into a vat of water, which separates the chips and other rubbish, and the rosin is then placed in barrels for the market. A North Carolina turpentine orchard will remain productive under ordinary treatment for fifty years.

The collection of turpentine in the departments of the Landes and Gironde in the south-west of France, is performed in a more rational manner than in America, inasmuch as the plan of making deep cavities in the tree for the purpose of receiving the resin, is avoided by the simple expedient of placing a suitable vessel beneath the lowest incision.[2277] The turpentine which concretes upon the stem is termed in France _Galipot_ or _Barras_.

[2277] For further particulars, see Guibourt, _Hist. des drog._ ii. (1869) 259, also Curie, _Produits résineux du Pin maritime_. Paris 1874. 24 pages, 1 plate; Matthieu, _Flore forestière_ 1860, p. 353.

=Description=—Common turpentine is chiefly of two varieties, namely, _American_ and _Bordeaux_; the first alone is commonly found in the English market.

_=American Turpentine=_—A viscid honey-like fluid, of yellowish colour, somewhat opaque, but becoming transparent by exposure to the air; it has an agreeable odour and warm bitterish taste. When long kept in a bottle, it is seen to separate into two layers, the upper clear and faintly fluorescent, the lower somewhat turbid or granular. When the latter portion is examined under the microscope, it is found to consist mainly of minute crystals of peculiar curved or bluntly elliptic form. These crystals are abietic acid; when the turpentine is warmed, the crystals are speedily dissolved.

_Bordeaux Turpentine_—in all essential particulars agrees with American Turpentine; it appears to separate rather more readily than the latter into two layers,—a transparent and an opaque or crystalline.

=Chemical Composition=—The turpentines are mixtures of resin and essential oil. The latter, which amounts to from 15 to 30 per cent., consists for the greater part of various hydrocarbons, corresponding to the formula C₁₀H₁₆. Many of the crude turpentine oils, and some of them even after rectification, are energetically acted on by metallic sodium. This reaction proves the presence of a certain quantity of oxygenated oils, not one of which has thus far been isolated.

The turpentine oils, although agreeing in composition, exhibit a series of physical differences according to their origin. One and the same tree, indeed, yields from its several organs oils of different properties. The boiling point varies between 152° and 172° C. The sp. gr. at mean temperatures ranges from 0·856 to 0·870. Greater differences are exhibited in the optical properties, some varieties of the oil turning the plane of polarization to the right, others to the left. This rotatory power differs in many cases from that of the turpentine from which the oil was derived.[2278] The odour of oil of turpentine varies with the species from which it has been obtained.

When crude turpentine is distilled with water, nearly the whole of the oil passes over, while the resin remains. This resin is called _Colophony_ or _Rosin_. When it still contains a little water, it is distinguished in English trade as _Yellow Rosin_; when fully deprived of water, it becomes what is called _Transparent Rosin_. That of deeper colour acquired by a still longer application of heat, bears the name of _Black Rosin_.

Colophony softens at 80° C., and melts completely at 100° into a clear liquid. At about 150° it forms a somewhat darker liquid, but without undergoing a loss in weight; at higher temperatures, it gradually decomposes. Pure colophony has a sp. gr. of 1·07, and is homogeneous, transparent, amorphous, and very brittle. At temperatures between 15° and 20° C., it requires for solution 8 parts of dilute alcohol (0·883). On addition of a caustic alkali, it dissolves in spirit much more freely. It is plentifully soluble in acetone or benzol.

The composition of colophony agrees with the formula C₄₄H₆₂O₄. By shaking coarsely powdered colophony with warm dilute alcohol, it is converted into a crystalline body, _Abietic Acid_, C₄₄H₆₄O₅,—a result due simply to hydration. Under such treatment, colophony yields 80 to 90 per cent. of abietic acid,[2279] and therefore consists chiefly of the anhydride of that acid. This is probably the case with the resins of other conifers. The living tree contains only the anhydride, for the fresh resinous juice is clear and amorphous after the expulsion of the oil; and when exposed to the air it loses oil, takes up water and solidifies as the crystalline acid,—a change which may easily be traced by the aid of the microscope, in drops taken direct from the trunk. Amorphous colophony retains its transparency even in a moist atmosphere, and appears to be capable of passing into the state of abietic acid, only when the assumption of the needful molecule of water is aided, in nature by the presence of the essential oil, or artificially by that of alcohol.

[2278] For some particulars, see my notice in the _Jahresbericht_ of Wiggers and Husemann for 1869, p. 36.—F. A. F.

[2279] Flückiger in _loc. cit._ 1867. 36.—Most chemists assign to this acid the formula C₂₀H₃₀O₂, and call it _silvic acid_.

Colophony when boiled with alkaline solutions forms greasy salts of abietic acid, the so-ccalled _resin-soaps_, which are used as additions to other soaps.

Siewert’s _Silvic Acid_ is regarded by Maly (1864) as a product of the decomposition of abietic acid; and the _Pimaric_, _Pinic_ and _Silvic Acids_ of former investigators, as impure abietic acid. Pimaric acid however, which is the chief constituent of _Galipot_, appears to be decidedly different, so far as we can judge from the experiments of Duvernoy (1865) and of one of ourselves (F.).

Abietic acid, as well as the unaltered coniferous resins, deviate the ray of polarized light, whereas American colophony, dissolved in acetone, is devoid of optical power.

=Commerce=—The supplies of turpentine are chiefly derived from the United States, but the trade has undergone a great change, as shown by the following figures, which represent the quantities imported in the several years:—

1869 1870 1871 1872 60,468 cwt. 51,257 cwt. 2,231 cwt. 1,000 cwt.

This greatly diminished importation of the crude article is partially explained by a larger importation of Oil of Turpentine and Rosin; but the increase is by no means sufficient to account for the vast diminution indicated by the above figures. The quantities of these latter articles imported into the United Kingdom during the year 1872 were as follows:—_Oil of Turpentine_, 220,292 cwt., value £470,085, six-sevenths being furnished by the United States of America and the remainder chiefly by France. _Rosin_, 919,494 cwt., value £492,246; of this quantity, the United States supplied nine-tenths, and France the larger part of the remainder.[2280]

=Uses=—Turpentine, Common Frankincense and Colophony are ingredients of certain plasters and ointments. Oil of turpentine is occasionally administered internally as a vermifuge or diuretic, and applied externally as a stimulant. But these substances are immeasurably less important in medicine than in the arts.

Thus Americanum vel vulgare.

This substance, known among druggists as _Common Frankincense_ or _Gum Thus_, is the resin which, as explained at p. 605, concretes upon the stems of the pines in the American turpentine orchards, and is there called _Scrape_. It corresponds to the _Galipot_ or _Barras_ of the French, which in old times supplied its place.

It is a semi-opaque, softish resin, of a pale yellow colour, smelling of turpentine; it is generally mixed with pine leaves, bits of wood and other impurities, so that it requires straining before it is used. By keeping, it becomes dry and brittle, of deeper colour and milder odour. Under the microscope, it exhibits a crystalline structure due to _Abietic Acid_, of which it chiefly consists. It is imported from America in barrels, but in insignificant quantities and only for the druggist’s use. Sometimes, however, it is distilled as common turpentine.

Dry pine resin, of which Common Frankincense is the type, evolves when heated an agreeable smell; hence in ancient times it was commonly used in English churches in place of the more costly olibanum. At present it is scarcely employed except in a few plasters.

[2280] _Annual Statement of the Trade of the U.K. for 1872._ pp. 53. 56. 60. 210.

TEREBINTHINA VENETA.

_Terebinthina Laricina_; _Venice Turpentine_, _Larch Turpentine_; F. _Térébenthine de Venise ou de Briançon_, _Térébenthine du mélèze_; G. _Venetianischer Terpenthin_, _Lärchen-Terpenthin_.

=Botanical Origin=—_Pinus Larix_ L. (_Larix europæa_ DC.), a tall forest tree of the mountains of Southern Central Europe, from Dauphiny through the Alps to Styria and the Carpathians, ascending to an elevation of 3000 to 5500 feet above the sea-level. It is largely grown in plantations in England and also, since 1738, in Scotland.

=History=—The turpentine of the larch was known to Dioscorides as imported from the Alpine regions of Gaul.[2281] Pliny also was acquainted with it, for he correctly remarks that it does not harden. Galen in the 2nd century also mentions it, admitting that it may well be substituted for Chian turpentine (see p. 165), the true, legitimate _Terebinthina_. Yet even in the beginning of the 17th century many pharmacologists complained of such a substitution. Mattioli[2282] gave an account of the method of collecting it about Trent in the Tirol, by boring the trees to the centre, which is true to the present day. It used formerly to be exported from Venice, then the great emporium for drugs of all kinds; the turpentine may even at times have been collected in the territories of the Venetian republic. We find it expressly called _Terebinthina Veneta_ by Guintherus of Andernach.[2283]

The name _larch_ seems to belong to the turpentine rather than to the tree. Dioscorides says the resin is called by the natives λάρικα, and a similar name is mentioned by Galen. In Pasi’s _Tariffa de pesi e misure_, 1521 (see Appendix), we find “_Termentina sive Larga_,”—and _larga_ is still an Italian name for larch turpentine. The peasants of the Southern Tirol call it _Lerget_, and in Switzerland the common name in German is _Lörtsch_.

=Extraction=—Larch turpentine is collected in the Tirol, chiefly about Mals, Meran, Botzen and Trent. A very small amount is obtained occasionally in the Valais in Switzerland, and in localities in Piedmont and France where the larch is found. The resin is obtained from the heartwood, by making in the spring a narrow cavity reaching to the centre of the stem at about a foot from the ground. This is then stopped up until the autumn of the same or of the following year, when it is opened and the resin taken out with an iron spoon. If only one hole is thus made, the tree yields about half a pound yearly without appreciable detriment. But if on the other hand a number of wide holes are made, and especially if they are left open, as was formerly the practice in the Piedmontese and French Alps, a larger product amounting to as much as 8 lb. is obtained annually, but the tree ceases to yield after some years, and its wood is much impaired in value.

[2281] Lib. i. cap. 92.

[2282] _Comment. in libr. i. Dioscoridis_, Venetiis, 1565. 106.

[2283] _De medicina veteri et nova etc._, Basileæ, 1571. 183.

Mohl, who witnessed the collection of this turpentine in the Southern Tirol,[2284] observed that when a growing larch stem was sawn through, the resin flowed most abundantly from the heartwood, and in smaller quantity, though somewhat more quickly, from the sapwood, and that the bark contained but few resin-ducts. The practice of closing the cavities is adopted, not only for the sake of preserving the wood and for the greater convenience of removing the turpentine, but also because it tends to maintain the transparency and purity of the latter.

=Description=—Venice turpentine is a thick, honey-like fluid, slightly turbid, yet not granular and crystalline; it has a pale yellowish colour and exhibits a slight fluorescence. Its odour resembles that of common turpentine, but is less powerful; its taste is bitter and aromatic. When exposed to the air, it thickens but slowly to a clear varnish, and hardens but very slowly when mixed with magnesia. Larch turpentine, though common on the Continent, is seldom imported into England,[2285] and the article sold for it is almost always spurious.

=Chemical Composition=—Larch turpentine dissolves in spirit of wine, forming a clear liquid which reddens litmus; hot water agitated with it also acquires a faint acid reaction, due to formic and probably also to succinic acid. Glacial acetic acid, amylic alcohol, and acetone mix with it perfectly. By distillation it yields on an average 15 per cent. of essential oil of the composition, C₁₀H₁₆, which boils at 157° C., and when saturated with dry hydrochloric acid gas, easily produces crystals of the compound C₁₀H₁₆ + HCl. The residual resin is soluble in two parts of warm alcohol of 75 per cent., and more copiously in concentrated alcohol.

Two parts of the turpentine diluted with one of benzol or acetone deviate the ray of polarized light 9·5° to the _right_. The essential oil deviates 6·4° to the _left_; the resin perfectly freed from volatile oil and dissolved in half its weight of acetone, deviates 12·6° to the _right_ in a column 50 mm. long.

We have not succeeded in preparing a crystallized acid from the resin of Venice turpentine, although its composition according to _Maly_ (1864) is the same as that of American colophony, which is easily transformed into crystallized abietic acid.

=Uses=—Venice turpentine appears to possess no medicinal properties that are not equally found in other substances of the same class, and as a medicine it has fallen into disuse. But in name at least it is in frequent requisition for horse and cattle medicines.

=Adulteration=—Alston (1740-60) said of Venice turpentine[2286] that it is seldom found in the shops,—a remark equally true at the present day, for but few druggists trouble themselves to procure it genuine. The Venice turpentine usually sold is an artificial mixture of common resin and oil of turpentine, which may be easily distinguished from the product of the larch by the facility with which it dries when spread on a piece of paper,[2287] and by its stronger turpentine smell.

[2284] _Botanische Zeitung_, xvii. (1859) 329, abstracted in the _Jahresbericht_ of Wiggers, 1859. 18.

[2285] On one occasion I observed Venice Turpentine in a public drug sale in London, 21 barrels imported from Trieste being offered, 14 July, 1864.—D. H.

[2286] _Lectures on the Materia Medica_, Lond. ii. (1770) 398.

[2287] Thus if a thin layer of true Venice turpentine and another of common turpentine be spread on two sheets of paper it will be found after the lapse of some weeks that the former cannot be touched without adhering to the fingers, while the latter will have become a dry, hard varnish.

CORTEX LARICIS.

_Larch Bark._

=Botanical Origin=—_Pinus Larix_ L.—see p. 609.

=History=—The bark of the larch has long been known to possess astringent properties; hence it has been used in tanning. Gerarde,[2288] who wrote near the close of the 16th century, likened it to that of the pine, which he described to be of a binding nature; but there is no evidence that it was an officinal drug.

About the year 1858 larch bark was recommended by Dr. Frizell of Dublin, and afterwards by other physicians, as a stimulating astringent and expectorant. In consequence of the favourable effects which have resulted from its use it has been included in the _Additions to the Pharmacopœia of 1867_.

=Description=—The bark that we have seen is in flattish pieces or large quills, externally reddish-brown. In those taken from older wood there is a large amount of an exfoliating corky coat, displaying as it is removed bright rosy tints, while the liber is of a different texture, slightly fibrous and whitish. The inner surface is smooth and of a pinkish-brown, or pale yellow. The bark breaks with a short fracture, exhaling an agreeable balsamic terebinthinous odour; it has a well-marked astringent taste. For medicinal use the inner bark is to be preferred.

=Microscopic Structure=—A transverse section exhibits resin-ducts, but far less numerous than in the bark of many allied trees. The medullary rays are not very distinct. Throughout the middle layer of the bark large isolated thick-walled cells of very irregular shape are scattered.

=Chemical Composition=—Larch bark has been examined by Stenhouse,[2289] who finds it to contain a considerable amount of a peculiar tannin, yielding olive-green precipitates with salts of iron. The same chemist also discovered[2290] in larch bark an interesting crystallizable substance called _Larixin_ or _Larixinic Acid_, which has the composition C₁₀H₁₀O₅. It may be obtained by digesting the bark in water in 80° C. and evaporating the infusion to a syrupy consistence. From this, by still further cautious heating in a retort, the larixin may be distilled, during which operation some of it crystallizes on the inner surface of the receiver, the remainder being dissolved in the distilled liquor. From the latter it may be obtained in crystals by evaporation. The substance forms colourless crystals, sometimes as much as an inch long; it volatilizes even at 93° C., and melts at 153°. It requires about 88 parts of water for solution at 15° C., but more freely dissolves in boiling water or in alcohol. From ether, in which it is but sparingly soluble, it separates in brilliant crystals. The solutions have a bitterish astringent taste and a slightly acid reaction, and assume a purple hue on addition of ferric chloride. When a solution of baryta is added to a concentrated solution of larixin, the latter being in excess, a bulky gelatinous precipitate falls; it is readily soluble in boiling water and is deposited again on cooling. Stenhouse failed to obtain it either from the bark of _Pinus Abies_ L., or from that of _P. silvestris_ L.

[2288] _Herball, enlarged by Johnson_, Lond. 1636. 1366.

[2289] _Proceedings of the Royal Society_, xi. (1862) 404.

[2290] _Phil. Trans._, vol. 152 (1862) 53.—We write the name _Larixin_ instead of _Larixine_, with the concurrence of Dr. Stenhouse.

=Uses=—Larch bark, chiefly in the form of tincture, has been prescribed to check profuse expectoration in cases of chronic bronchitis; it has also been found useful in arresting internal hæmorrhage.

TEREBINTHINA CANADENSIS.

_Balsamum Canadense_; _Canada Balsam_, _Canadian Turpentine_; F. _Térébenthine ou Baume de Canada_; G. _Canada Balsam_.

=Botanical Origin=—_Pinus balsamea_ L. (_Abies balsamea_ Marshall), the Balsam Fir or Balm of Gilead Fir, a handsome tree, 20 to 40 feet high, with a trunk 6 to 12 inches in diameter, sometimes attaining still larger dimensions, growing in profusion in the Northern and Western United States of America, Nova Scotia and Canada, but not observed beyond 62° N. lat. It resembles the Silver Fir of Europe (_Pinus Picea_ L.), but has the bracts short-pointed and the cones more acute at each end.

Canada balsam is also furnished by _Pinus Fraseri_ Pursh, the Small-fruited or Double Balsam Fir, a tree found on the mountains of Pennsylvania, Virginia, and southward on the highest of the Alleghanies.[2291]

_Pinus canadensis_ L. (_Abies canadensis_ Michx.), the Hemlock Spruce or Pérusse, a large tree abundant in the same countries as _P. balsamea_, and extending throughout British America to Alaska, is said to yield a similar turpentine, which however has not yet been sufficiently examined. The Hemlock Spruce is of considerable importance on account of the resin collected from its trunk, and the essential oil distilled from its foliage, the latter operation being performed on a large scale in Madison County, New York. The inner bark of the tree is a valuable material for tanning.

=History=—The French, in whose possession Canada remained until the year 1763, were probably acquainted with Canada balsam long before this period. Yet no mention of it is found in Pomet’s work, but in 1759 it was at Strassburg a current article of the pharmacy.[2292] As to England, Lewis, in his _History of the Materia Medica_ published in 1761, says that “_an elegant balsam_,” obtained from the Canada Fir, is sometimes brought into Europe under the name of _Balsamum Canadense_. Canada balsam was first introduced into the London Pharmacopœia in 1788. From the books of a London druggist, J. Gurney Bevan, we find that its wholesale price in 1776 was 4_s._, in 1788, 5_s._ per lb.

=Description=—Canada balsam is a transparent resin of honey-like consistence, and of a light straw-colour with a greenish tint. By keeping, it slowly becomes thicker and of a somewhat darker hue, but always retains its transparency. When carefully examined in direct sunlight, it exhibits a slight greenish fluorescence in the same degree as other turpentines or as copaiba; this optical power appears to increase if the balsam is exposed to a heat of about 200° C.

[2291] Asa Gray, _Botany of the Northern United States_, New York, 1866. 422.

[2292] Flückiger, _Pharm. Journ._ vi. (1876), 1021.

Canada balsam has a pleasant aromatic odour and bitterish, feebly acrid, not disagreeable taste. On account of its flavour it is sometimes called _Balm of Gilead_, but erroneously, as this latter is derived from a tree of the genus _Balsamodendron_ growing in Arabia. We found a good commercial balsam to have a sp. gr. of 0·998 at 14·5° C., water at the same temperature being 1·000. Four parts, mixed with one of benzol and examined in a column of 50 mm. in length, deviated a ray of polarized light 2° to the right. The balsam is perfectly soluble in any proportion in chloroform, benzol, ether, or warm amylic alcohol; and the solution in each case reddens litmus. With sulphate of carbon it mixes readily, but the mixture is somewhat turbid. Glacial acetic acid, acetone or absolute alcohol dissolve the balsam

## partially, leaving, after ebullition and cooling, a considerable amount

of amorphous residue. Colophony and Venice turpentine are completely dissolved by the liquids in question, as well as by spirit of wine containing 70 to 75 per cent. of alcohol.

=Chemical Composition=—Like all analogous exudations of the _Coniferæ_, Canada turpentine is a mixture of resins with an essential oil. If the latter is allowed to evaporate, the former are left as a transparent, somewhat tough and elastic mass. The proportion of the components is within certain limits, variable in different samples. The specimen before mentioned lost after an exposure in a steam-bath during several days, no less than 20 per cent. of volatile oil, or even 24 per cent. if the experiment was made on a very small scale, as with 20 grammes or less in a thin layer.

By distillation with water, it is not easy to obtain more than 17 to 18 per cent. of essential oil. The resin in this case is a tough, elastic, non-transparent mass, retaining obstinately a large proportion of water, which can only be removed by keeping it for some time at a temperature of 100°-176° C.

The oil as obtained by distillation with water is colourless, and has the odour of common oil of turpentine rather than the agreeable smell of the balsam; it consists of an oil, C₁₀H₁₆, mixed with an insignificant proportion of an oxygenated oil, the presence of which may be proved by the slight evolution of hydrogen on addition of metallic sodium, after the oil has been freed from water by contact with fused chloride of calcium. After this treatment, a small proportion begins to distil at about 160°, but by far the larger part boils at 167° C., a small portion only distilling at last at 170° and above. The oil obtained at 167°, examined under the conditions already mentioned, has a sp. gr. of 0·863, and the power of rotating a ray of polarized light 5·6° to the left. The portion distilling at 160° does not differ in this respect; but that passing over at 170°, deviates the ray 7·2° to the left. The oil readily dissolves a large proportion of glacial acetic acid; an equal weight of each mixes perfectly at about 54° C., but some acetic acid separates on cooling.

The essential oil of Canada balsam, saturated with dry hydrochloric acid, does not yield a solid crystallizable compound; but this is easily obtained on addition of fuming nitric acid and gently heating, when the inside of the retort becomes covered by sublimed crystals of C₁₀H₁₆ + HCl.

Thus this oil in its general characters bears a close resemblance to the essential oils of the cones of _Pinus Picea_ L., and of the leaves of _P. Pumilio_ Hänke, and to most of the French varieties of oil of turpentine, rather than to the American turpentine oils, which rotate to the right, and combine immediately with HCl to form a solid crystalline compound.

On the other hand, the resin of Canada balsam is dextrogyre: two parts of it, entirely deprived of essential oil and dissolved in one of benzol, deviating the ray 8·5° to the right. The optical powers of the two components (oil and resin) are therefore antagonistic.

The resin of Canada balsam consists however of two different bodies, 78·7 per cent. of it being soluble in boiling absolute alcohol, and 21·3 (in our specimen) remaining as an amorphous mass, readily soluble in ether. Neither the alcoholic nor the ethereal solution yields a crystalline residue if allowed to evaporate. They redden litmus, but we did not succeed in obtaining any crystallized resinous acid, crystals of which are formed if common turpentine or colophony is digested with dilute alcohol. Glacial acetic acid acts upon the resins like absolute alcohol. Caustic alkalis do not dissolve either the balsam or the resin; the former however is considerably thickened by incorporation with ⅕ of its weight of recently calcined magnesia. If the mixture, moistened with dilute alcohol, is kept at 93° C. for some days and frequently stirred, a mass of hard consistence, finally translucent, results. Caustic ammonia heated with the balsam in a closed bottle, forms a thick milky jelly, which does not afterwards separate.

Hence, according to our investigations, 100 parts of Canada turpentine consist of

Essential oil, C₁₀H₁₆}, with a very small proportion of an oxygenated oil 24 Resin soluble in boiling alcohol 60 Resin soluble only in ether 16

The result of Wirzen’s examination of Canada balsam[2293] are not in complete accordance with those here stated. He found 16 per cent. of oil and three different amorphous resins, one of which had the composition of abietic acid.

[2293] _De balsamis et præsertim de Balsamo Canadense_, Helsingforsiæ, 1849,—abstracted in the _Jahresbericht_ of Wiggers for 1849. 38.

=Production and Commerce=—Canada balsam is obtained either by puncturing the vesicles which form under the suberous envelope of the trunk and branches, and collecting their fluid contents in a bottle, or by making incisions. It is obtained principally in Lower Canada, and is shipped from Montreal and Quebec, in kegs or large barrels. In the neighbourhood of Quebec, about 2000 gallons (20,000 lb.) used to be collected annually; but in 1868, owing to distress among the farmers, the quantity obtained was unusually large, and it was estimated that nearly 7000 gallons would be exported to England and the United States.[2294] During a recent scarcity (1872-73) a sort of balsam from Oregon has been substituted in the American market for true Canada balsam.[2295]

=Uses=—The medicinal properties of Canada balsam resemble those of copaiba and other terebinthinous oleo-resins, yet it is now rarely employed as a remedy. The balsam is much valued for mounting objects for the microscope, as it remains constantly transparent and uncrystalline. It is also used for making varnish.

TEREBINTHINA ARGENTORATENSIS.

_Strassburg Turpentine_; F. _Térébenthine d’Alsace ou de Strasbourg_, _Térébenthine du sapin_; G. _Strassburger Terpenthin_.

=Botanical Origin=—_Pinus Picea_ L. (_Abies pectinata_ DC.), the Silver Fir,[2296] a large handsome tree, growing in the mountainous parts of Middle and Southern Europe from the Pyrenees to the Caucasus, and extending under a slightly different form (var. β. _cephalonica_) into continental Greece and the islands of Eubœa and Cephalonia.

=History=—Belon in his treatise _De Arboribus coniferis_ (1553) described this turpentine, which is also briefly yet accurately noticed by Samuel Dale,[2297] a learned apothecary of London and the friend of Sloane and Ray. It had a place in the London Pharmacopœia until 1788, when it was omitted from the materia medica.

=Extraction=—The oleo-resin of _P. Picea_, like that of _P. balsamea_, is contained in little swellings of the bark[2298] of young stems, and is extracted by the tedious process of puncturing them and receiving in a suitable vessel the one or two drops which exude from each. It is still collected near Mutzig and Barr, in the Vosges (1878), though only to a very small extent.

=Description=—An authentic sample collected for one of us by the Surveyor of Forests in the Bernese Jura, Switzerland, resembles very closely Canada balsam, but is devoid of any distinct fluorescence. It has a light yellow colour, a very fragrant odour,[2299] more agreeable than that of Canada balsam, and is devoid of the acrid bitterish taste of the latter.

We found our specimen to have sp. gr. of distilled water. It deviates a ray of polarized light 3° to the left, if examined either pure or diluted with a fourth of its weight of benzol, in the manner described at p. 610. Our drug is soluble in the same liquids as the Canadian, yet is miscible with glacial acetic acid, absolute alcohol and acetone, without leaving any considerable flocculent residue. It is even soluble in spirit of wine, the solution being but very little turbid. The solutions have an acid reaction.

[2294] From information obligingly communicated by Mr. N. Mercer of Montreal and Mr. H. Sugden Evans of London.—See also _Proc. Am. Pharm. Assoc._, 1877, page 337, abstracted in _Ph. Jour._ viii. (1878) 813.

[2295] _Proceedings of the American Pharmaceutical Association_, Philadelphia, 1873. 119—also 1874. 433.

[2296] _Sapin_ in French; _Weisstanne_ or _Edeltanne_ in German.

[2297] _Pharmacologia_, Lond. 1693. 395.

[2298] See Morel, _Ph. Jour._ viii. (1877) 21.

[2299] Hence it is sometimes called in French _Térébenthine au citron_.

=Chemical Composition=—After the complete desiccation of a small quantity, there remained 72·4 per cent. of a brittle, transparent resin, soluble in glacial acetic acid, but not entirely in absolute alcohol or in acetone. By submitting half a pound of the turpentine to distillation with water, we obtained 24 per cent. of essential oil, the remaining resin being when cold perfectly friable. The fresh oil, purified by sodium, deviates the ray of polarized light to the left, whereas the remaining resin, dissolved in half its weight of benzol, shows a weak dextrogyre rotation. The oil boils at 163° C. After having kept it for two years and a half in a well-stopped bottle, we find that it has become considerably thicker and now deviates to the right. If saturated with dry hydrochloric acid, the oil does not yield a solid compound.

This oil has nearly the same agreeable odour as the crude oleo-resin, yet the essential oil of the _cones_ of the same tree is still more fragrant. The latter is one of the most powerfully deviating oils, the rotation being 51° to the left, and it is consequently extremely different from the oil obtained from the turpentine of the stem, though its composition is represented by the same formula, C₁₀H₁₆.

A peculiar sugar called _Abietite_, nearly related to mannite but having the composition C₁₂H₁₆O₆, has been detected by Rochleder[2300] in the leaves of the Silver Fir.

=Uses=—Strassburg turpentine possesses the properties of common turpentine, with the advantage of a very agreeable odour. It was formerly held in great esteem, but has now become nearly forgotten.

PIX BURGUNDICA.

_Pix abietina_; _Burgundy Pitch_; F. _Poix de Bourgogne ou des Vosges_, _Poix jaune_; G. _Fichtenharz_, _Tannenharz_.

=Botanical Origin=—_Pinus Abies_ L. (_Abies excelsa_ DC.), the Norway Spruce Fir,[2301] a noble tree attaining an elevation of 100-160 feet, widely distributed throughout Northern and the mountainous parts of Central Europe, but not indigenous to Great Britain, though extensively planted. In Russian Lapland it reaches at 68° N. lat. almost the extreme limit of tree-vegetation, while southward it extends to the Spanish Pyrenees. In the Alps it ascends to 6,000 feet above the level of the sea.

=History=—In accordance with the definition of the London Pharmacopœias and the custom of English druggists the name _Burgundy Pitch_ is restricted to the product of the above-named species. The pharmacologists of France use an equivalent term with the same limitations; but in other parts of the Continent _Pix Burgundica_ has a wider meaning, and is allowed to include the turpentines of other _Coniferæ_. We here employ it in the English sense.

Parkinson, an apothecary of London and herbarist to King Charles I., speaks of “_Burgony Pitch_” as a thing well known in his time.[2302] Dale in his _Pharmacologia_ (1693) mentions _Pix Burgundica_ as being imported into England from Germany, and it is also noticed by Salmon (1693), who says “it is brought to us out of Burgundy, Germany and other places near Strasburgh.”[2303]

[2300] Wiggers and Husemann, _Jahresbericht_, 1868. 53.

[2301] _Pesse_ or _Epicéa_ of the French; _Fichte_ or _Rothtanne_ of the Germans.

[2302] _Theater of Plants_, 1640. 1542.

[2303] _Compleat English Physician_, 1693. 1031.

Pomet, writing in Paris about the same period, discards the prefix _Burgundy_ as a fiction, remarking that the best _Poix grasse_ comes from Holland and Strassburg.[2304]

Whether this resin ever was collected in Burgundy we are unable to determine. It may probably have acquired the name through having been brought into commerce from Switzerland and Alsace by way of Franche Comté, otherwise called Comté de Bourgogne or Haute Bourgogne.[2305]

Burgundy pitch is enumerated among the materia medica of the London Pharmacopœia of 1677, and in every subsequent edition. In that of 1809 it was defined under the name of _Pix arida_, as the _prepared resin of Pinus Abies_.

=Production=—Burgundy pitch is produced in Finland, in the Black Forest in the Grand Duchy of Baden, Austria and Switzerland. On the estate of Baron Linder at Svarta near Helsingfors, it is obtained by melting the crude resin in contact with the vapour of water, and straining. The quantity annually produced there was stated in 1867 to be 35,000 kilogr. (689 cwt.);[2306] that afforded by an establishment at Ilm in the same country amounted to 80,000 kilogr. (1,575 cwt.).[2307]

In the neighbourhood of Oppenau and on the Kniebis mountain in the Grand Duchy of Baden the stems of the firs are wounded at equal distances by making perpendicular channels, 1½ inches wide and the same in depth. The resin which exudes from these channels is scraped off with an iron instrument made for the purpose, and purified by being melted in hot water and strained. This is performed in three or four small establishments at Oppenau and the neighbouring village of Löcherberg. In this state the resin, which is opaque and contains much moisture, is called _Wasserharz_. By further straining and evaporating a portion of the water its quality is improved.

The manufacture in that part of Germany is on the decline, partly in consequence of the timber being injured by the wounding of the trees, so that the collecting of resin is not permitted in the large forests belonging to the governments of Baden and Württemberg. We have had the opportunity of observing[2308] that in the establishments in question French turpentine or _galipot_, imported from Bordeaux, as well as American rosin or colophony, are used in quantities certainly exceeding that of the resin grown on the spot.

In the middle of the last century some Burgundy pitch was produced, according to Duhamel,[2309] in the present canton of Neuchâtel, but no such branch of industry is now pursued there, at least on a large scale. On the other hand, in the districts of Moutier and Delémont in the Bernese Jura this resin is still collected, though it is not known as _Burgundy Pitch_, but is termed simply _Poix blanche_ (White Pitch). The surveyor of the forests of this district, which is one of the richest in _Pinus Abies_, has informed one of us that from 790 to 850 quintals are collected and exported to Basle, Zürich, Aarau and Vaud. The pitch is worth _in loco_ (1868) 100 to 110 francs (£4 to £4 8_s._) the _bosse_ of 6 quintals. The quantities collected in other parts of Switzerland are even less considerable.

[2304] _Hist. des Drogues_, Paris, 1694.