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 12,660,047 kilo. (of 2·2 lb.) of tanning bark.
Quebracho.—The local name quebracho, contracted from quebra-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, the quebracho blanco, a tree growing in the province of Catamarca, Argentine Republic; (2) Loxopterygium [Quebrachia] Lorentzii, the quebracho colorado, most prevalent in the province of Corrientes, the wood and bark of which come largely into commerce as tanning materials; (3) Iodina rhombifolia, the quebracho flojo, whose wood and bark are mixed with those of No. 2; (4) Machærium fertile [Tipuana speciosa], the tipa, 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 of Pistacia lentiscus; in Spain, several Rhus 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, redoul or redon, and pudis; 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. glabra and R. copallina are 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 be secured 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 least 1/2 in. 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.