[C]Dingler's Polyt. Journal, vol. 220, p. 167.
[C]Dingler's Polyt. Journal, vol. 220, p. 167.
Hide Albumen.—The fresh hide, besides this coriin (which, very possibly, is only evolved by the action of the lime), contains a portion of actual albumen, viz. that of the blood serum and of the lymph, which is not only contained in the abundant blood-vessels, but saturates the fibrous connective tissue, of which it forms the nourishment. This albumen is mostly removed by the liming and working on the beam, which is preparatory to tanning. Probably for sole-leather, the albumen itself would be rather advantageous if left in the hide, as it combines with tannin, and would assist in giving firmness and weight to the leather. It is, however, for reasons which will be seen hereafter, absolutely necessary to get rid of any lime which may be in combination with it. The blood also must be thoroughly cleansed from the hide before tanning, as its colouring matter contains iron, and, in combination with the tannin, would give a bad colour.
The reactions of blood and lymph albumen are very similar to those of ordinary white of egg. It is precipitated bystrong mineral acids, especially nitric, and also by boiling. The precipitate produced by strong hydrochloric acid redissolves by the aid of heat to a blue or purple solution. Tribasic phosphoric, tartaric, acetic, and most other organic acids, do not precipitate moderately dilute solutions of albumen, but convert it into a sort of jelly, which, like gelatin, does not coagulate, but liquefies on heating. It is precipitated by neutral salts of the alkali metals. Blood-albumen slightly acidified (with acetic acid) is precipitated by potassium ferrocyanide. It is not precipitated by dilute infusions of oak bark, but is rendered uncoagulable by heat, hence it cannot be employed to remove tannins from their solutions.
Elastic Fibres.—The elastic or yellow fibres of the hide are of a very stable character. They are not completely dissolved even by prolonged boiling, and acetic acid and hot solutions of caustic alkalies scarcely attack them. Probably they do not combine with tannin, and are very little changed in the tanning process.
Hair, Epidermis, and Glands.—These are, as has been seen, all derived from the epithelial layer, and hence, as might be inferred, have much in common in their chemical constitution. They are all classed by chemists under one name, "keratin," or horny tissue, and their ultimate analysis shows that in elementary composition they nearly agree. It is evident, however, that the horny tissues are rather a class than a single compound.
The keratins are gradually loosened by prolonged soaking in water, and, by continued boiling in a Papin's digester, are dissolved to an extract which does not gelatinise on cooling. Keratin is dissolved by caustic alkalies; the epidermis and the softer horny tissues are easily attacked, while hair and horn require strong solutions and the aid of heat to effect complete solution. The caustic alkaline earths act in the same manner as dilute alkaline solutions; hence lime easily attacks the epidermis, and loosens the hair, but does not readily destroy the latter. Alkaline sulphides, on the other hand, seem to attack the harder tissues with at least the samefacility as the soft ones, the hair being often completely disintegrated, while the epidermis is still almost intact; hence their applicability to unhairing by destruction of the hair. Keratins are dissolved by fuming hydrochloric acid, with the production of a blue or violet coloration, like the albuminoids. They also resemble albumen, in the fact that their solution in sulphuric acid is precipitated by potassium ferrocyanide. By fusion with potash, or prolonged boiling with dilute sulphuric acid, keratin is decomposed, yielding leucin, tyrosin, ammonia, &c. The alkaline solution of keratin (hair, horns, &c.) is precipitated by acids, and, mixed with oil and baryta sulphate, is employed under Dr. Putz's patent as a filling material for leather, for which purpose it acts in the same way as the egg-yolks and meal used in kid-leather manufacture. Eitner attempted to use it for the same purpose with bark-tanned leather, but without much success. Putz has also proposed to precipitate the material after working its solution into the pores of the leather.
COMMERCIAL TANNING MATERIALS.
Algarobilla.—The seed-pods ofProsopis pallidaandP. Algarroboare known asalgarobilla, the two kinds being distinguished asnegroandblanco. The trees are abundant in mountainous parts of South America, notably Chili and the Argentine Republic. The pods contain up to 50 per cent. of a bright-yellow tannin, somewhat resembling that of myrobalans. The friable tannin is readily soluble in cold water, and is so loosely held in the fibrous network of the pod, that great loss is sustained by careless handling. The commerce in algarobilla does not figure in the official trade returns; but J. Gordon & Co., Liverpool, obligingly state that they imported 50 tons, at an average value of 18l.10s.a ton, in 1880. Widow Duranty & Son, also of Liverpool, are good enough to add that they received 160 tons in 1881, the first that had reached them for a long time. Havre imported 50 tons in 1881. The namealgarrobois also applied toBalsamocarpon brevifoliumin Chili, and toHymenæa Courbarilin Panama.
Chestnut-extract.—The wood of the chestnut (Castanea vesca) contains 14-20 per cent. of a dull-brown tannin. It is quite different from the bark and bark-extract of the American chestnut-oak (Quercus sessiliflora). Its extract is used largely to modify the colour produced by hemlock-extract, and for tanning and dyeing. The pulverised wood is also extensively employed in France. The imports are included in barks and extracts,p. 39.
Cork-bark.SeeOak-barks.
Cutch, Catechu, or Terra Japonica(Fr.,Cachou;Ger.,Catechu).—The termkát,kut, or "cutch," is applied tothe dried extract, containing 45-55 per cent. of dark-coloured mimo-tannic acid, prepared chiefly from 2 trees:—(1)Acacia Catechu[Mimosa Catechu,M. sundra], a tree of 30-40 ft., common in most parts of India and Burma, growing also in the hotter and drier districts of Ceylon, and abundant in tropical East Africa—the Soudan, Sennar, Abyssinia, the Noer country and Mozambique, though the utilisation of its tannin is restricted to India; (2)A.[M.]Suma, a large tree inhabiting South India (Mysore), Bengal, and Gujerat.
The process for preparing cutch varies slightly in different districts. The trees are reckoned to be of proper age when their trunks are about 1 ft. diam. They are then cut down, and the whole of the woody part, with the exception of the smaller branches and the bark, is reduced to chips: some accounts state that only the darker heart-wood is thus used. The chips are placed with water in earthen jars, arranged in a series over a mud fire-place, usually in the open air. Here the water is made to boil, the liquor as it becomes thick and strong being decanted into another vessel, in which the evaporation is continued until the extract is sufficiently inspissated, when it is poured into moulds made of clay, or of leaves pinned together in the shape of cups, or in some districts on to a mat covered with the ashes of burnt cow-dung, the drying in each case being completed by exposure to the sun and air. The product is a dark-brown extract, which is the usual form in which cutch is known in Europe.
In Kumaon, North India, a slight modification of the process affords a drug of very different appearance. Instead of evaporating the decoction to the condition of an extract, the inspissation is stopped at a certain point, and the liquor is allowed to cool, coagulate, and crystallise over twigs and leaves thrown into the pots for the purpose. By this method is obtained from each pot about 2 lb. ofkathor catechu, of an ashy-whitish appearance. In Burma, the manufacture and export of cutch form one of the most important items of forest revenue. The quantity of cutch exported from the province in 1869-70 was 10,782 tons, valued at 193,602l., ofwhich nearly half was the produce of manufactories situated in British territory. The article is imported in mats, bags, and boxes, often enveloped in the large leaf ofDipterocarpus tuberculatus. It is brought down from Berar and Nepal to Calcutta. That of Pegu has a high reputation.
Our imports of cutch in 1880 were 5155 tons, value 173,040l., from the British East Indies; 539 tons, 15,572l., from other countries; total, 5694 tons, 188,612l.Our exports in the same year were:—892 tons, 28,527l., to Germany; 676 tons, 24,562l., to the United States; 478 tons, 15,505l., to France; 303 tons, 10,537l., to Holland; 177 tons, 5859l., to Russia; 141 tons, 4835l., to Belgium; 245 tons, 8719l., to other countries; total, 2912 tons, 98,544l.The approximate London market value of Pegu cutch is 21-42s.a cwt.
An astringent extract prepared from the areca nut (Areca Catechu) is said to contribute to commercial cutch; if so, it is a totally distinct product from those just described.
Divi-divi, or Libi-dibi.—These names are applied to the seed-pods ofCæsalpinia coriaria, a tree of 20-30 ft., indigenous to several of the West Indies, Mexico, Venezuela, and North Brazil, and naturalised in Madras and Bombay Presidencies, and in the North-West Provinces. The pod may be known by its drying to the shape of a letterS; it contains 30-50 per cent. of a peculiar tannin, somewhat similar to that of valonia. It is cheap, and may be used in admixture with barks; but it is dangerously liable to undergo fermentation, suddenly staining the leather a dark-red colour, and is therefore not in extensive use. The imports of it are mainly from Maracaibo, Paraiba, and St. Domingo. Maracaibo, in 1880, exported 197,674 lb. of divi-divi, value 32221/4dol. (4s.2d.), to New York. Our imports of divi-divi into Liverpool, according to figures kindly furnished by Haw & Co., were 2200 tons in 1877, 1740 in 1878, 2132 in 1879, and 780 in 1880. The approximate market value is 12-17l.a ton.
Galls.—The generic term "gall" is applied to those excrescences on plants which are produced by the puncturesof insects, for the purpose of depositing their eggs. The excrescences are usually considered to be a diseased condition of vegetable tissue, resulting from the injection of some secretion of the insects. But this has been combated by A. S. Wilson, of Aberdeen, who considers that all insect galls are in reality leaf-buds, or fruit-buds, and not mere amorphous excrescences. The vascular lines which would form leaves can easily be followed up in the structure of the oak-leaf galls. And in cases where the egg has been deposited in the tissue of a young branch, the cap of the gall is sometimes surmounted by a leaf 2-3 in. long. But in the large blue Turkish galls, many lacunæ occur where the fleshified leaves have not filled up the spaces between them. If a dissection be made of one of the weevil-galls on the bulb of the turnip, the second or third slice will show the outer foliations, exactly similar to those of the root-buds. When the centre has been reached, where the maggot will be found, there will also be a vascular pencil running up from a medullary ray in the bulb, and bearing on its top a bud of the same description as that produced by a ray running out from a root. The insertion of the ovipositor brings a medullary ray into action, producing a tuberculated bud, and it is only the bud which the larva feeds upon. The growth of a bud is an intelligible cause of the growth of a gall, but nothing can be inferred from the injection of a fluid. The analogy to leaves is further shown by the fact that various microscopic fungi are matured in the interior of imperforate galls.
The principal commercial kinds of gall are oak-galls and Chinese galls.
Oak-galls,Nut-galls,AleppoorTurkey-galls(Fr.,Noix de Galle,Galle d'Alep;Ger.,LevantischeorAleppische Gallen,Galläpfel).—These are formed by the punctures ofCynips[Diplolepis]Gallæ tinctoriæonQuercus lusitanicavar.infectoria[Q. infectoria], a shrubby tree of Greece, Cyprus, Asia Minor, and Syria, and probably other varieties and even species of oak. The female insect is furnished with a delicate ovipositor, by means of which she pierces the tender shoots ofthe tree, and lays her eggs therein. In the centre of the full-grown gall, the larva is hatched and undergoes its transformations, finally (in 5-6 months) becoming a winged insect, and boring for itself a cylindrical exit-hole. The best commercial galls are those which have been gathered while the insect is still in the larval state. Such have a dark olive-green colour, and are comparatively heavy; but after the fly has escaped, they become yellowish-brown in hue, and lighter. Hence they are distinguished in the London market as "blue" or "green," and "white." In Smyrna, they are classified as "white," "green," and "black," the first two sorts generally fetching nearly the same price, while the black obtain considerably more, the approximate quotations being: white and green, per Turkishoke(of 2·83 lb.), 81/2-9piastres(of 2d.); black, 131/2-14piastres. The "nuts" come mostly from Melemen, Cassaba, and Magnesia, also from the Syrian coasts, being plentiful on the east of the river Jordan, and are chiefly forwarded to France, England, and Salonica. The triennial yield is said to be invariably the best. They begin to reach Smyrna from the interior towards the end of July. The crop of 1880 was estimated at over 50,000okes. The province of Aleppo, which used to afford 10,000-12,000quintals(of 2 cwt.) annually, only exported 3000 in 1871. The galls collected in the Kurdistan mountains are marketed at Diarbekir, and sent thence to Trebizonde for shipment. Bussora, Bagdad, and Bushire also export considerable quantities.
Knoppern, a species of gall formed from the immature acorns ofQuercus pedunculataandQ. sessiliflora, are largely used for tanning throughout Austria.
The exports from Aleppo (including yellow berries) in 1880 were:—60 tons, 3600l., to Great Britain; 322 tons, 19,320l., France; 15 tons, 900l., Italy; 44 tons, 2640l., Austria; 55 tons, 3300l., Turkey; 30 tons, 1800l., Egypt; total, 526 tons, 31,560l.In 1878, the figures were 673 tons, 38,400l.Alexandretta exported in 1879 (including yellow berries):—41 tons, 2460l., to England; 299 tons, 17,940l., France; 20 tons, 1200l., Italy; 25 tons, 1500l., Austria;87 tons, 5220l., Turkey; 6 tons, 360l., Egypt; total 478 tons, 28,680l.The shipments from Trebizonde by steamer in 1880 were (from Turkey):—47 sacks (of 2 cwt.), 188l., to Turkey; 240 sacks, 960l., Great Britain; 264 sacks, 1056l., France; 103 sacks, 412l., Austria and Germany; 26 sacks, 104l., Greece; total, 680 sacks, 2720l.; (from Persia): 25 sacks, 100l., Great Britain; 31 sacks, 124l., France; 30 sacks, 120l., Austria and Germany; total, 86 sacks, 344l.Bushire despatched 5000r.worth to India in 1879. Syra sent 248l.worth to Great Britain in 1879. Venice exported 1745 tons of gall and bark, value 34,906l., in 1879.
The best oak-galls contain 60-70 per cent. of tannic or gallotannic acid, and 3 per cent. of gallic acid. "Rove" is a small crushed gall, containing 24-34 per cent. of gallotannic acid. There are many other varieties of non-commercial oak-gall.
Chinese or Japanese Galls.—These are vesicular protuberances formed on the leaf-stalks and branches of theRhus semialata[Bucki-amela], a tree of 30-40 ft., common in North India, China, and Japan, ascending the outer Himálaya and the Khasia Hills to 2500-6000 ft., by punctures of the female ofAphis chinensis. The galls are collected when their green colour is changing to yellow, and are then scalded. They are light and hollow, 1-21/2in. long, and of very varied and irregular form. The Japanese are the smaller and paler, and usually more esteemed. The galls contain about 70 per cent. of tannic or gallotannic acid, and 4 per cent. of another tannin. They are consumed mainly in Germany, for the manufacture of tannic acid.
Hankow exported 30,949piculs(of 1331/3lb.) in 1872; and 21,611piculs, value 136,214taels(of about 6s.), in 1874. In 1877, the total Chinese export did not exceed 17,515piculs. Hankow exported 24,7421/2piculsin 1878, and 28,392piculs, 59,614l., in 1879; Pakhoi, 62l.worth in 1879; Canton, 31551/3piculsin 1877, 1939 in 1878, 31631/2in 1879; Ichang, 1001/2piculs, 132l., in 1878, 4021/2piculs, 586l., in 1879; Shanghai, 27,6591/2piculsin 1879.
In China trade returns, they are always miscalled "nut-galls" or "gall-nuts": correctly, they arewu-pei-tze. Oak-galls are exported from China resembling those of Western Asia. Japanese galls,kifushi, are sent in increasing quantities from Hiogo.
Our imports of galls in 1880 were:—24,590 cwt., 68,697l., from China; 17,311 cwt., 60,648l., from Turkey; 9182 cwt., 9013l., from other countries: total, 51,083 cwt., 138,358l.Our re-exports in the same year were:—6260 cwt., 18,479l., to Holland; 6022 cwt., 18,147l., to Germany; 3214 cwt., 11,002l., to France; 3045 cwt., 8598l., to Belgium; 2651 cwt., 11,004l., to the United States; 1625 cwt., 5205l., to other countries; total, 22,817 cwt., 72,435l.The approximate London market values of galls are:—Bussora, blue, 82-102s.a cwt.; do., white and in sorts, 50-90s.; China, 50-70s.; Japan, 55-56s.
Gambier, Pale Catechu, or Terra Japonica(Fr.,Gambir,Cachou jaune;Ger.,Gambir).—These names are conferred upon an extract from the leaves ofUncaria Gambier[Nauclea Gambir] andU. acida, containing 36-40 per cent. of a brown tannin, which rapidly penetrates leather, and tends to swell it, but alone gives a soft porous tannage; it is largely used in conjunction with other materials for tanning both dressing- and sole-leather. The plants are stout climbing shrubs, the first-named being a native of the countries bordering the Straits of Malacca, and especially the islands at the eastern end, though apparently not indigenous to any of the islands of the volcanic band, growing also in Ceylon, where no use is made of it; while the second, probably a mere variety, flourishes in the Malay islands.
The shrubs are cultivated in plantations, often formed in jungle clearings; the soil is very rapidly exhausted, and further injured by excessive growth of the ineradicablelalang-grass (Andropogon caricosus). It is found advantageous to combine pepper-culture with that of gambier, the boiled leaves of the latter forming excellent manure for the former. The gambier-plants are allowed to grow 8-10 ft. high, andas their foliage is always in season, each plant is stripped 3 or 4 times in the year. The tools and apparatus for the manufacture of the extract are of the most primitive description. A shallow cast-iron pan about 3 ft. across is built into an earthen fire-place. Water is poured into the pan, a fire is kindled, and the leaves and young shoots, freshly plucked, are scattered in, and boiled for about an hour. At the end of this time, they are thrown on to a capacious sloping trough, the lower end of which projects into the pan, and are squeezed with the hand so that the absorbed liquor may run back into the boiler. The decoction is then evaporated to the consistence of a thin syrup, and baled out into buckets. When sufficiently cool, it is subjected to curious treatment: instead of simply stirring it round, the workman pushes a stick of soft wood in a sloping direction into each bucket; and, placing two such buckets before him, he works a stick up and down in each. The liquid thickens round the stick, and, the thickened portion being constantly rubbed off, while at the same time the whole is in motion, it gradually sets into a mass, a result which, it is said, would never be produced by simple stirring: it is reasonable to suppose that this manner of treating the liquor favours the crystallisation of the catechin in a more concrete form than it might otherwise assume. The thickened mass, resembling soft yellowish clay, is now placed in shallow square boxes; when somewhat hardened, it is cut into cubes, and dried in the shade. The leaves are boiled a second time, and finally washed in water, which is saved for another operation.
A second plan is as follows:—The leaves are boiled, and bruised in a wooden mortar (lesong), from which they are put into a kind of basket of rattan open-work, which is pressed by a long piece of wood acting as a lever; the liquid is received into a trough, and there allowed to settle. When the sediment has acquired sufficient substance, it is put into akulit-kayo, formed like a tub without a bottom, which lets the superfluous water drain off; when that is done, it is taken out, made into small cakes, and dried for use. Aplantation employing 5 labourers contains 70,000-80,000 shrubs, and yields 40-50catties(of 11/3lb.) of gambier daily.
Plantations were commenced in Singapore in 1829, and once numbered 800; but owing to scarcity of fuel, abundance of which is essential to the manufacture, and dearness of labour, the culture was fast declining in 1866. In 1872, it had much recovered. It is largely pursued on the mainland (Johore), and in the Rhio-Lingga Archipelago, S.-E. of Singapore; on Bintang, the most northerly of the group, there were 1250 plantations of it in 1854. None is cultivated in Sarawak, though found wild in many parts; the foreign export from Sarawak in 1879 had a total value of 88,148 dol. The best kind is brought largely from Sumatra, but is often adulterated with sago. The Rhio product is also thus sophisticated, and rendered heavier by the Chinese purposely packing it in baskets lined with wetcajangs, occasioning a loss to the purchaser of about 30 per cent.
Singapore is the great emporium for gambier, and exported 34,248 tons in 1871, 19,550 tons having been imported, chiefly from Rhio and the Malay Peninsula. In 1876, the export increased to over 50,000 tons of pressed block, and 2700 tons of cubes. In 1877, it fell to 39,117 tons, owing to differences with the Chinese dealers concerning adulteration; of this quantity, 21,607 tons were for London, 7572 for Liverpool, and 2345 for Marseilles. The United Kingdom imports in 1872 were 21,155 tons, 451,737l., almost all from the Straits Settlements; in 1880, they were 26,061 tons, 461,781l., from the Straits, and 352 tons, 6468l., from other countries; total, 26,413 tons, 468,249l.Our re-exports in 1880 were:—2487 tons, 48,507l., to Holland; 1591 tons, 31,542l.to Germany; 1137 tons, 23,694l., to Russia; 594 tons, 12,026l., to other countries; total, 5809 tons, 115,769l.The approximate London market values are 15s.6d.-21s.6d.a cwt. for block, 18-24s.for pressed cubes, and 23-27s.for free cubes.
Hemlock.—The bark of the hemlock or hemlock spruce (Abies canadensis), of Canada and the United States, contains nearly 14 per cent. of tannin. The stripping of the barkcommences in the southern parts of the United States in spring, and lasts during April-May; in New York, Michigan, and Wisconsin, the season is June-July; and farther north, it is still later. It is said that the best product is obtained farthest south. The destruction of the hemlock forests is fast approaching. Within the last 25 years, the preparation of an extract from the bark, containing 18-25 per cent. of a deep-red tannin, giving considerable weight and firmness to leather, has superseded the export of crude bark. One mode of preparing the extract is as follows:—The bark in pieces1/2-1 in. thick, and several inches long, is soaked for about 15 minutes in water at 200° F. (93° C.); it is then fed into a hopper, which conducts it to a 3-roller machine, something like a sugar-cane mill, through which it passes, coming out lacerated and compressed; it next falls into a vat of hot water, where it is agitated by a wheel, that the tannin from the crushed cells may be dissolved in the water; hence it is raised by a series of buckets on an endless chain, somewhat in the manner of a grain-elevator, to another hopper, whence it is fed to another 3-roller mill; here it receives its final compression, and comes out in flakes or sheets, like coarse paper, and almost free from tannin. The buckets are made of coarse wire, that the water may drip through during the elevation. In order to avoid the blackening action of iron, wherever this metal will come into contact with the solutions it is thickly coated with zinc. The solution is evaporated to a solid consistency, generally by vacuum-pans. About 2 tons of bark are represented by 1 bar. (of less than 500 lb.) of extract. The chief makers are A. S. Thomas, Elmira, N.Y.; S. Brown & Co., New York; Canada Tanning Extract Co., St. Leonard and Bulstrode; J. Miller & Co., Millerton, New Brunswick. The total production is probably over 10,000 tons annually, ranging in value between 14l.and 20l.a ton. Our imports are included in barks and extracts.
Kino(Fr.,Kino;Ger.,Kino).—The term "gum kino" is applied to a class of astringent extracts of varied origin, none of which can accurately be called either resins or gums.
Pl. II.E. & F. N. Spon, London & New York."INK-PHOTO." SPRAGUE & CO. LONDON.REMOVING THE HAIR; SCRAPING AND CLEANING THE SKINS.
Pl. II.
E. & F. N. Spon, London & New York.
"INK-PHOTO." SPRAGUE & CO. LONDON.
REMOVING THE HAIR; SCRAPING AND CLEANING THE SKINS.
(1)East Indian or Amboyna Kino.—This is obtained fromPterocarpus Marsupium, a common tree in the central and southern parts of the Indian peninsula, and in Ceylon; and a liquid kind fromP. indicus, of South India, Burma, Malacca, Penang, the Andamans, and Malaysia. The collection of the juice is effected in the following manner. A perpendicular incision, with lateral offshoots, is made in the stem of the tree when blossoming has set in, and a receptacle is placed at the foot of the incision. The exuding juice appears like red-currant jelly, but it soon thickens by exposure to the air, and when sufficiently dried, is packed into wooden boxes for exportation. It is one of the reserved timber-trees of the Government forests in Madras, and its juice is collected by natives, who pay a small fee for the permission. The hardened juice consists of blackish-red, angular, pea-like grains, partially soluble in water, almost entirely in spirit of wine of sp. gr. 0·838, readily in caustic alkaline solutions, and largely in a saturated solution of sugar. The liquid kino produces a very inferior article on drying. The annual collection of kino in Madras probably does not exceed 1-2 tons. Its approximate London market value is 60-150s.a cwt. It is employed medicinally, and in the manufacture of wines, and might be employed as a source of tannin in dyeing and tanning, if sufficiently cheap.
(2)Butea, Bengal, Palas or Dhak Kino.—This variety is afforded by thepalasordhaktree (Butea frondosa), common throughout India and Burma, and affording a dyestuff, and a fibre, as well as byB. superbaandB. parviflora. During the hot season, there issues from natural fissures and from wounds made in the bark of the stem, a red juice, which quickly hardens to a ruby-coloured, brittle, astringent mass. It occurs in small drops or tears, and in flat pieces which have been dried on leaves, and is almost always mixed with bark-fragments. It is transparent, freely soluble in cold water, and does not soften in the mouth. It is unknown in European commerce, but is employed in India as a substitute for the kind first described.
(3)African or Gambia Kino.—This is derived fromPterocarpus erinaceus, a native of Tropical West Africa, from Senegambia to Angola. The juice exudes naturally from fissures in the bark, but more abundantly from incisions, and soon coagulates to a blood-red and very brittle mass, known to the Portuguese of Angola assangue del drago("dragon's-blood"). It is practically undistinguishable from the officinal kind first described, but is not a regular article of commerce.
(4)Australian, Botany Bay, or Eucalyptus Kino.—Several species ofEucalyptusafford astringent extracts, those from the "red," "white," or "flooded" gum (E. rostrata), the "blood-wood" (E. corymbosa), andE. citriodora, being quite suitable for replacing the officinal kind. It is chiefly obtained by woodcutters, being found in a viscid state in flattened cavities in the wood, and soon becoming inspissated, hard, and brittle. Minor quantities are procured in a liquid state by incising the bark of living trees, forming a treacly fluid yielding 35 per cent. of solid kino on evaporation. It is imported from Australia, but there are no statistics to show in what quantity.
Mimosa- or Wattle-bark.—The bark of numerous species ofAcacia, natives of Australia, contains considerable percentages of deep-red mimo-tannic acid, which forms a hard and heavy tannage if used strong, though soft upper-leathers may be tanned with it in weak liquors. The chief kinds are as follows:—The common wattle (Acacia decurrens), including its varietyA. mollissima, is known also under the names of green, black, and feathery, but must not be confounded with the silver wattle (A. dealbata), though but doubtfully a distinct species. The bark is obtainable in vast abundance, and is much used by tanners. The trees are stripped in September and the 2 or 3 months following, and the bark, being allowed to dry, is then in a marketable condition. This tree, which grows in the uplands, affords a larger percentage of tannin than the silver wattle.
Blackwood or lightwood (A. melanoxylon) yields tanners'bark, which, is inferior, however, to that fromA. decurrens. The bark ofA. penninervisyields of tannic acid 17·9 per cent., and of gallic acid 3·8 per cent. The bark of the native hickory (A. suppurosa) yields of tannic acid 6·6 per cent., and of gallic acid 1·2 per cent.
The bark ofA. saligna, of South-Western Australia, is much used by tanners, as it contains nearly 30 per cent. of mimo-tannin.A. harpophylla, of South Queensland, furnishes a considerable share of the mercantile wattle-bark for tanning purposes. The bark ofA. lophanthacontains only about 8 per cent. of tannin.
The broad-leaved or golden wattle (A. pycnantha), of Victoria and South Australia, deserves extensive cultivation. It is of rapid growth, will succeed even in sandy tracts, and yields seed copiously, which germinates with the greatest ease. The perfectly-dried bark contains about 25 per cent. of tannin. The aqueous infusion of the bark can be reduced by boiling to a dry extract, which in medicinal and other respects is equal to the best Indian cutch. It yields approximately 30 per cent. of tannin, about half of which, or more, is mimo-tannic acid. Probably no other tanning plants give so quick a return in cultivation as theA. pycnanthaandA. decurrensof Australia. The latter varies in its proportions of tannin from 8 to 33 per cent. In the mercantile bark, the percentage is somewhat less, according to the state of its dryness, it retaining about 10 per cent. of moisture. The bark of the silver wattle (A. dealbata) is of less value, often even fetching only half the price of that of the black wattle. The bark improves by age and desiccation, and yields 40 per cent. of tannin, rather more than half of which is tannic acid.
Amongst all the kinds, the bark of the broad-leaved wattle is considered the most valuable, containing the greatest quantity of tannin; that of the silver wattle is not so valuable, being deficient in tannin; the black wattle is considered the most productive species; it can be barked at 8 years of age, and will produce 40-60 lb. dried bark, and full-grown trees will yield 100-150 lb. per tree.
The cultivation of wattles for commercial purposes has till now remained undeveloped; but no doubt, as soon as it is understood, the utilisation of many acres of land lying waste, or which have already been exhausted and rendered unfit for the growth of cereals, will be effected by the cultivation of the wattle. It requires so little attention as to make it very profitable, and wattle-growing and grazing can be combined satisfactorily. After the first year, when the young trees in the plantation have reached the height of 3-4 ft., sheep can be turned in.
Wattles grow in almost any soil, even the poorest, but their growth is most rapid on loose sandy patches, or where the surface has been broken for agricultural purposes. When the soil is hard and firm, plough furrows should be made at a regular distance of 6-8 ft. apart, into which the seeds are dropped. The seed should be sown in May, having been previously soaked in hot water, a little below boiling temperature, in which they may be allowed to remain for a few hours. The seed should be dropped at an average distance of 1 ft. apart along the furrow, in which case, about 7200 seeds would suffice for one acre of land. The seed should not be covered with more than about1/4in. of soil.
On loose sandy soil, it might even be unnecessary to break up the soil in any way; the furrows may be dispensed with, and the seed sown broadcast after the land is harrowed. After the plants have come up, they should be thinned so that they stand 6-8 ft. apart. When the young trees have attained the height of 3-4 ft., the lower branches should be pruned off, and every effort afterwards made to keep the stem straight and clear, in order to facilitate the stripping, and induce an increased yield of bark. It is advisable that the black and broad-leaved should be grown separately, as the black wattle, being of much larger and quicker growth, would oppress the slower-growing broad-leaved one. Care should be taken to replace every tree stripped by re-sowing, in order that there should be as little variation in the yield as possible. The months of September-December, in Victoria,are those in which the sap rises without intermission, and the bark is charged with tannin. Analysis proves that the bark from trees growing on limestone is greatly inferior in tannin to that obtained from other formations, differing 10-25 per cent.
The estimated expenditure on a wattle-bark plantation of 100 acres during 8 years is:—
The receipts derivable from a wattle plantation of 100 acres, planted in the manner proposed, would be:—
The exports of mimosa-bark in 1876 were 11,899 tons from Victoria, 4758 from South Australia, and 1735 from Tasmania. Later returns are included in barks,p. 39. Shanghai imported 7038piculs(of 1331/3lb.) in 1879. The approximate London market values of mimosa-bark are:—Ground, 6-13l.a ton; chopped, 5-12l.; long, 5l.-9l.10s.A very superior extract has been made from this bark.
Myrobalans or Myrabolams.—The fruits of several species ofTerminaliaconstitute the myrobalans of commerce; they are chieflyT. ChebulaandT. Bellerica, natives of India, the former being a tree 40-50 ft. high, and esteemed for its timber also. The fruits contain 30-35 per cent. of gallotannic and ellagitannic acids, producing a soft and porous tannage, and good samples giving a bright-yellow colour. The tannin exists in the pulp, and is absent from the very hard "stone." The dried fruits are known locally ashar,harra, orbahera, and are used commonly for dyeing, but not for tanning.
Our imports of myrobalans in 1880 were:—238,151 cwt., 121,465l., from Bombay and Sind; 115,670 cwt., 51,339l., from Madras; 11,020 cwt., 4717l., from Bengal and Burma; 3520 cwt., 1402l., from other countries; total, 368,361 cwt., 178,923l.Our re-exports in 1880 were 8015 cwt., 4328l., to Germany; 16,127 cwt., 8515l., to other countries; total, 24,142 cwt., 12,843l.The approximate London market values of myrobalans are 7-14s.a cwt. for good, and 5-10s.for common. Shanghai imported 4403piculs(of 1331/3lb.) in 1879.
Oak-barks(Fr.,Écorces de Chêne;Ger.,Eichenrinden).—The barks of several species of oak have valuable tanning properties. They are chiefly:—The common oak (Quercus Robur, varieties:sessiliflora, Ger.Traubeneiche;pedunculata, Ger.Stieleiche), which is of even greater importance as a timber-tree; the cork-oak (Q. Suber); the evergreen oak (Q. Ilex); and the American chestnut-oak (Q. Castanea). These barks are among the most esteemed tannins as regards quality of leather, but are incapable of giving much weight, and from their bulk are costly to handle, containing only 10-12 percent. of tannin (quercitannic acid). They give a reddish fawn-coloured leather, and deposit a good deal of bloom, but yield little or no gallic acid. The barks of the cork-oak and evergreen oak from Southern Europe, are stronger and darker-coloured than English bark. The American chestnut-oak contains a peculiar fluorescent principle like æsculin.
Our imports of unspecified barks for tanners' and dyers' use in 1880 were:—189,399 cwt., 101,108l., from Australia; 123,302 cwt., 32,974l., Belgium; 57,232 cwt., 20,988l., United States; 22,100 cwt., 6030l., Holland; 18,648 cwt., 3676l., Italy; 16,151 cwt., 6972l., Algeria; 22,669 cwt., 8838l., other countries; total, 449,501 cwt., 180,586l.Our imports of unenumerated bark-extracts in the same year were valued at:—516,578l.from Holland, 92,654l.France, 30,187l.United States, 16,315l.British North America, 12,796l.Belgium, 13,769l.other countries; total, 682,299l.Our re-exports of barks in 1880 were:—19,548 cwt., 10,348l., to Germany; 14,627 cwt., 7425l., France; 4555 cwt., 3041l., Holland; 10,304 cwt., 6080l., other countries; total, 49,034 cwt., 26,894l.
With regard to cork-tree bark, James Gordon & Co., Liverpool, obligingly write that very little comes to England, the great bulk going direct to Ireland, where the consumption is large. The imports at Liverpool in 1880 were 186 tons, average value 8l.per ton. Of oak-bark, Hungary, in 1877, produced 25,000 tons, of which, 20,000 were exported to Germany for tanning purposes. The approximate London market values of oak-bark are:—English, 12-16l.per load of 45 cwt.; Foreign, tree, 5-8l.a ton; ditto, coppice, 6-8l.In 1879, Algiers exported 12,660,047kilo.(of 2·2 lb.) of tanning bark.
Quebracho.—The local namequebracho, contracted fromquebra-hacho("axe-breaker"), is applied to several South American trees possessing hard wood, belonging to distinct genera. They are chiefly as follows:—(1)Aspidosperma Quebracho, thequebracho blanco, a tree growing in the province of Catamarca, Argentine Republic; (2)Loxopterygium[Quebrachia]Lorentzii, thequebracho colorado, most prevalent in the province of Corrientes, the wood and bark of which come largely into commerce as tanning materials; (3)Iodina rhombifolia, thequebracho flojo, whose wood and bark are mixed with those of No. 2; (4)Machærium fertile[Tipuana speciosa], thetipa, which affords both wood and bark of less tanning value than No. 2. It would seem that the wood and bark of No. 2 are by far the most largely employed, containing 15-23 per cent. of a bright-red tannin. The wood and an extract from it are imported into Europe.
From information kindly furnished by James Gordon & Co., and Haw & Co., of Liverpool, it appears that the imports of quebracho-wood into Liverpool in 1880 were 200 tons, value about 4l.10s.a ton; and of quebracho-bark, about 20 tons, none of which had been sold.
Sumach or Shumac(Fr.,Sumac;Ger.,Gerbersumach,Schmack).—The commercial term "sumach" is applied to the dried leaves of a number of South European and American tannin-yielding plants. These are chiefly as follows:—In Sicily, the European or tanning-sumach (Rhus Coriaria); in Tuscany,R. Coriaria, often adulterated with leaves ofPistacia lentiscus; in Spain, severalRhus spp., the products being divided into 3 kinds—Malaga or Priego, Malina, and Valladolid; in the Tyrol, the smoke-tree or fragrant or Venetian sumach (R. Cotinus); in France,Coriaria myrtifolia, divided into 4 sorts—fauvis,douzère,redoulorredon, andpudis; in Algeria, Tezera sumach (R. pentaphylla), used by the Arabs for making morocco-leather; in North America, the smooth or white sumach (R. glabra), the Canadian sumach (R. canadensis), the staghorn sumach (R. typhina), and the dwarf or black sumach (R. copallina). These are found growing wild in the countries indicated, and are further subjected to cultivation in some districts, notably in Sicily.R. glabraandR. copallinaare recommended chiefly for extended cultivation in the United States.
The soil usually chosen for cultivation of the plants is poor and light; but a much larger crop of leaves can besecured from strong, rich, deep soils, and it is generally admitted that the product in the latter case is also better. In Italy, limestone soils are considered to be especially suited to this culture, but the American varieties appear to be well adapted to sandy and clay soils as well. The primary requisite in a soil is that it shall be well drained, the presence of stagnant water about the roots being exceedingly prejudicial. To prepare the soil for planting, it is ploughed as deeply as possible, and laid out in rows about 2 ft. apart. In Italy, small holes are made about 2 ft. long, 7 in. wide, and 5 in. deep, and a plant is inserted at each end. A more convenient method would consist in marking the field in shallow furrows in one direction 2 ft. apart, and then, with a heavy plough, tolerably deep furrows the same distance apart as, and at right angles to, the first. A plant may then be placed in the deep furrows at each intersection, the furrow again filled with the plough, and the earth pressed about the plant with the foot. If this were done in early spring-time, as soon as the earth is sufficiently dry to be conveniently worked, there can be no doubt that it would be successful, while it would certainly involve little cost. Plants are generally propagated from the young shoots which form each year about the base of an older plant, but may also be produced from cuttings made from young well-ripened wood, rooted by setting in a nursery or in frames, as in the propagation of grape-vines from cuttings. This latter method is scarcely ever required, however, when the cultivation has been started. Plants are also raised from seed, and seedlings are always found to be strong, vigorous, and thoroughly hardy; but on account of the greater time and labour involved in their production, this method of propagation has not received extended application. The first-mentioned generally gives the quickest, and probably most satisfactory results.
In selecting plants from any source, there are certain points to be observed:—(1) The shoots should come from young vigorous plants; (2) they should be over 1 ft. long;(3) those with large roots and few rootlets should be rejected; (4) those having white roots, covered with a fibrous, white, silky down, are also to be rejected, this being an indication of the presence of a very injurious subterranean parasitic fungus, capable of destroying the entire crop; (5) a good shoot is straight, at least1/2in. diam., 18 in. long, furnished with numerous buds close to each other, root short, but covered with rootlets. Shoots for planting may be collected in autumn, after the leaves have fallen, and be preserved in a nursery until spring; or this may be done in early spring, when the ground is very moist and soft. In either case, care should be observed that the rootlets are not injured by drying, or from any other cause.
The culture to be given the plant is somewhat similar to that required by Indian corn: the earth about it should be kept tolerably mellow and free from weeds, and such conditions can probably be maintained to a degree sufficient for sumach, by working several times during the growing season with a cultivator, and passing through the rows occasionally with a plough. All this work is not absolutely necessary to the life of the plant, but its vigour, and consequently its yield in leaves, may be considerably increased and strengthened thereby. After the first year, the number of operations may be diminished, but they should always be sufficient to keep the ground free from weeds and grass.
Shortly after planting, and when the plant is well set, the stock is pruned to a length of 6-8 in., when the plant is left to assume any form, and is no further pruned except by the process of collecting the leaves, unless hand-picking is resorted to; in such case, after the 2nd year, pruning takes place each year in the fall or winter, the plant being reduced to a height of 6-10 in. After the 3rd year, the plant begins to produce the shoots from about its base, already mentioned; these, if not needed for new plantations, should be removed each year, for if left to develop, they weaken the plant. If not removed during the summer, the operation should without fail be effected during the fall or winter.
The 1st crop of leaves may be secured during the year following that of planting. This develops and matures somewhat later than that from older plants, and in Italy it is not collected until the end of August or the 1st of September; but there are reasons for believing that in the United States, especially in the Northern States, the collection of leaves from native varieties should be made much earlier, because the summer is much shorter, and the habits of the varieties grown differ from the Sicilian. Macagno has shown (Chem. Soc. Journ., xxxviii., p. 733) that the leaves from the upper side of the branches contain much more tannin than those below, and that especially in the lower leaves the percentage of tannin is much higher in June than in August. All the leaves, except the young and tender ones of the extremities of the branches, are stripped off and placed in baskets, in which they are carried to a threshing-floor, where they are spread out in thin layers to dry. Here they must be frequently stirred and turned over, for which purpose a fork with wooden prongs is employed. In the fall, when growth is finished, and before the leaves have had time to become red, those remaining on the extremities are collected. To this end, the branches are broken just below the tuft of leaves, and the latter are allowed to remain suspended from the branch by a piece of bark not detached, and left in this condition until nearly or quite dry. They are then collected and treated in the same manner as other leaves, but the product obtained in this way is always of inferior quality.
After the 2nd year, crops of larger quantity and superior quality are obtained, and the collection is made in a different way, and much more frequently. The two methods followed in Sicily are (1) pruning, and (2) defoliation. The first, which is the more ancient, but much less costly, requires less care, and is simple and rapid; but it is injurious to the future condition of the plant, and the quantity of subsequent crops. The second, though slower, serves to better maintain the vigour of the plant, and the uniform quantity of the cropfrom year to year; in consequence, it reduces the necessity for frequent renewal of stocks.
Harvest by pruning is carried on in Italy as follows. During May, the lower leaves, which, from greater age, appear to have attained full maturity, and may be in danger of loss from falling, are removed in the same manner as described for collecting the leaves from yearling plants. Toward the end of June, and during the course of July, all branches bearing leaves are cut away, reducing the plant to the principal stock: by this means, the crop is harvested and the plant is pruned at the same time. But even in Sicily, the time for this operation is limited to no absolute period, and varies with the development of the leaf, as indicated by cessation of growth and increase in size. In this condition, also, the leaves will have acquired their deepest green colour, and attained their maximum weight and best quality. It is further stated that while this time varies according to locality, about Palermo it is never earlier than June nor later than July. The harvest by pruning must always be made by men accustomed to the work, and equal to the exertion required. Provided with a pruning-bill, they cut off all leaf-bearing branches, collecting them an the left arm, until each has cut as much as he can conveniently carry, when he places the armful on the ground with the butts in the direction of the prevailing wind, which, if tolerably strong, might carry away some of the leaves if turned in the opposite direction; finally, he presses down the branches with his foot, to make the heap more compact, and leave less surface exposed to the wind and sun. Another labourer deposits a second armful in the same place, presses it with his foot in like manner, and the two deposits constitute a bundle. At the close of the operation, there remain the young shoots which are formed about the base of the plant, the leaves of which are not fully developed, and consequently not fit for collection until at least 20 days later. After this time, they are removed by hand, care being observed not to injure the buds, especially if the shoots areto be used for stocks in the formation of plantations in the following year.
Defoliation, or collection by hand, is carried on whenever the leaf may be fully developed and ripe, beginning at first with the lower leaves, and continuing eventually to the ends of the branches. It takes place at 3 different times during the season: the 1st in May, the 2nd late in July or early August, and the 3rd in September. At the last collection, the extremities of the branches are broken down, and the leaves are allowed to dry before removal from the plant, as described under collections of the 2nd year. In the application of this method, the regular pruning is effected during the fall or winter, when the plant is dormant, and under such conditions the operation becomes a regenerative one, giving in this particular an advantage over the other method, in which the pruning is effected in the summer when the plant is in full vegetative activity, and so has a strongly deteriorating influence. In both methods of pruning, care should be observed to leave a long slanting section, upon which water will be less likely to settle and promote decay.
The leaves collected by either method are dried in the open field where they have grown, and when dried, are carried to a threshing-floor to be beaten, or at once to the threshing-floor and dried there. In the former, the operation is rather more rapid, but there is greater danger of injury by rain, the effect of which is very deleterious, especially if it fall upon the leaves when they are partially dried. The damage resulting from this cause is less if the leaves are not lying upon the ground, and are so arranged that the air may circulate freely about and under them. In the pruning method, the leaves are dried upon the branches and in the heaps where they are first deposited. Sometimes they are turned, but generally it is considered better not to disturb them until completely dried, and ready for transportation to the threshing-floor. In this way, they are protected to a greater extent from the action of direct sunlight, which is said to be injurious to the quality of the product. Whenthe leaves are collected by hand, they are dried upon the threshing-floor, where they are spread in thin layers, and stirred 3-4 times a day. They are then beaten with a flail to separate the leaves from the branches and stems. If this be done during the middle of the day, when the leaves are most thoroughly dry and consequently brittle, they are reduced to small particles, producing what is called "sumach for grinding." But if it be done in the morning, or on damp days, when the air is charged with moisture and the leaves are tough, they are separated from the stems more nearly entire and less broken, and the product obtained is called "sumach for baling." The stems remaining after the separation of sumach for baling still retain small particles of leaves attached to them, and they are therefore again beaten when perfectly dry for the production of a low-grade sumach, called by the Italiansgammuzza. The products are classed as follows:—
To prepare these different grades for ultimate consumption, they are ground in mills similar to those employed for crushing olives, that is, in which two large stone wheels follow each other, revolving upon a circular bed, the whole construction being about the same as the Spanish or Mexicanarrastre. The sumach thus pulverised is passed through bolting-screens, to separate the finer from the coarser particles.
In Virginia, the leaves are collected and cured by the country people, and sold and delivered to owners of mills for grinding. Their particular object being to secure the largest possible quantity of product at the lowest cost, little attention is given to the quality obtained, or the manner of collecting. The most intelligent dealers in the raw material urge upon collectors to observe the following particulars:—The leafshould be taken when full of sap, before it has turned red, has begun to wither, or has been affected by frost, to ensure a maximum value for tanning purposes. Either the leaf-bearing stems may be stripped off, or the entire stalk may be cut away, and the leaves upon it allowed to wither before being carried to the drying-shed; but care must be observed that they are neither scorched nor bleached by the sun. When wilted, they are carried to a covered place, and spread upon open shelving or racks to dry, avoiding the deposit in any one place of a quantity so great as to endanger the quality of the product by overheating and fermentation. Sumach should be allowed to remain within the drying-house at least one month before sending to the market; in case of bad weather, a longer period may be required. When ready for packing for shipment, it should be perfectly dry and very brittle, otherwise it is likely to suffer injury in warehouses from heating and fermentation.
Buyers of sumach leaves for grinding depend largely upon colour for the determination of the value; the leaves should, therefore, when ready for market, present a bright-green colour, which is evidence that they have suffered neither from rain after being gathered, nor from heating during the process of drying. Leaves having a mouldy odour or appearance are rejected. The Virginian crop reaches 7000-8000 tons, and is collected at any time between July 1 and the appearance of frost.
There is an important difference in the value of the European and American products. The proportion of tannic acid in the latter exceeds that found in the former by 6-8 per cent., yet the former is much preferred by tanners and dyers. By using Sicilian sumach it is possible to make the finer white leathers, in great demand for gloves and fancy shoes; while by the employment of the American product, the leather has a disagreeable yellow or dark colour, apparently due to a colouring matter, which, according to Loewe, consists of quercitrin and quercetin, and exists in larger quantity in the American than in the Sicilian.
The experimental results obtained by collecting sumach at different seasons were:—
It is evident, therefore, that in order to secure the maximum amount of tannic acid, the sumach should be collected in July, but the colouring matter of the leaves has an important influence upon the value of the product. The leaves of the upper extremities of the stalks are always richer in tannic acid than those of the base; and the increase of age of the plant is accompanied by a general diminution of this acid. Yet the collection of the crop should be delayed as long as possible, because the diminution of tannin in the leaves will be abundantly compensated for by the quality of the product.
Experiments upon the presence of colouring matters were made by treating gelatine solutions, and gave the following results:—
It is therefore advised that for the purpose of tanning white and delicately-coloured leathers, the collection should be made in June; while for tanning dark-coloured leathers, and for dyeing and calico-printing in dark colours, where the slightly yellow colour will have no injurious effect, the collection be made in July. It appears that for all purposes, the sumach collected after the 1st of August is inferior in quality.