Nature.

Waikato Times, Volume XIX, Issue 1574, 5 August 1882, Page 6

Nature.

■ * 'THE COB.X OAK. The tree from which is obtained the cork of comracice is a species of evergreen oak {Querem subcr), growing in several of the departments of Prance, in Spaiu, Portugal, Sicily, Italy, and Algeria: It is principally cultivated, however, in Spain and Portugal. This species of oak loses its foliage only in the month of May, and when the growth of leaves is sufficiently strong to replace the old ones of the preceeding year. It flowers in May, and its fruit is fit for gathering only in the month of November of the next season ; that is, eighteen months after flowering. Its acorns are less astringent than those of other species of oaks and are used for fattening swine, sheep, and poultry. They are also employed to a considerable extent in the manufacture of certain kind of fecula. The cork oak flourishes best in arid, sandy soils, and under favorable conditions reaches a height of forty to fifty feet, with a circumference of ten to thirteen feet. The trunk, from its base to where the first branchs begin, is nine to thirteen feet long ; and it is this portion of the tree from which tht bark is peeled the bark that constitutes the cork of commerce. This substance, " cork," consists of the outer layer of bark, which, by annual additions fiom within, gradually becomes a thick spongy mass, the rapidity of growth determing'the quality of the bark. A quick growth is represented by a fine grain and light weight ; a slow growth producing a coutraiy effect. The bark, if allowed to remain on the tree, becomes so fissured and cracked as to be unfit for use. There are two varities of the cotk bark known in commerce, the whito and the black ; the former of these is the product Of trees growing in France and the latter of those cultivated in Spain. The white is superior to the other on account of its greater beauty, its smoothness, and its greater freedom from ciacks and inequalities. It is of a yellow ish-gicy color on both surfaces, and cuts (on account of its much finer grain) nioie smoothly than the black. The operation of stripping the bark takes place when the trees have attained the age of fifteen to twenty years. In the men'h of August, when the sap is in movement the workmen begin by making a transverse incision in the bark, just beneath the branches, and another at the base of the trees : then two longitudinal incisions are made, and the bark beaten on evcryside with the back of an axe, in order to loosen it from the adjacent fiber then, by means of their axe handles, or of leavers prepared for the purpose, they pry off the loosened bark, which falls to the ground in cylindrical pieces. During this process the gieatest care is used not to injure the newly formed layer of suber or cork lying beneath. After collection, the rough exterior of the bark is either rasped off or slightly charred, then piled in stacks and allowed to dry during which process, it loses |one-fifth of its weight. In the charring process, the pores become closed up. and. the cork is rendered denser or receives whatis technically known as " nerve." In this state, after being flattened it is cut into lenghts of about four feet and put up in bales for export. The stripping takes place about every ten years, the pioduct improving with each successive removal. The operation seems to bo beneficial to the tree, for if the bark be allowed to remain on it naturally, the cork oak rarely lives longer than fifty or -sixty years ; if, on the contrary, it be removed periodically, the tree continues to flourish from one hundred to one hundred and fifty years. The first product is always ot a very rough and woody nature, and useful only in rustic work or as a tanning material. The second stripping is also of a course natuie, and useful only for floats for nets, water conduits, andsuch purposes. The economic uses to which cork isapplied are much too numerous to pass in review ; it will be sufficient to speak of one only, that of the manufacture of stoppers. For the purpose of stopping bottles cork was not generally used till near the end of the fcventcpnth century. Many substitutes for it have been proposed, but except in the case of terated liquids none of these have been generally employed. In the manufactuie of bottle corks, the bark is cut up into slips, which, by means of gauges, aic made narrow or wide, according to the size of the corks or bungs wanted. The slips aic then cut into squares or "quarters," which are trimmed into the required shape by means of a very long, thin knife, kept very sharp. In this operation the knife is kept immovable -while the cork is drawn over its edge by the workman. The coiks are then thrown into baskets and soi ted out according to size, by women and children. Coik cutting iv Catalonia and the south of France furnishes a livelihood for a considerable portion of the population of those districts. Seveial attempt have boon made to cut corks by machinery, but they have not succeeded in superseding hand labor which is comparatively cheap abroad. The machine which is principally used for this purpose was exhibited in operation at the Paris exhibition ; it was woiked by a woman, and near her was seated a man patiently carving out his corks (with the usual knife), quite as neatly and nearly as rapidly as the machine. The eorkeutting machine is an instrument similar to a carpenter's plane Avorking in a groove, the knife being horizontal. The slip of cork is placed between two chucks, and by pushing the plane along the groove the cork is caused to rotate in front of the knife as it passes along. No economic use is made of the wood of the cork oak except that of fuel, although it it might be useful as a timber, since it is very heavy and as hard as boxwood. — Scientific American.