Online Encyclopedia

CORK (perhaps through Sp. corcha from...

Online Encyclopedia
Originally appearing in Volume V07, Page 160 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!

CORK (perhaps through Sp. corcha from
See also:
Lat. cortex, bark, but possibly connected with quercus, oak)
  , the
See also:
outer layer of the bark of an
See also:
evergreen
See also:
species of oak (Quercus Suber) . The tree reaches the height of about 30 ft., growing in the south of
See also:
Europe and on the North
See also:
African coasts generally; but it is principally cultivated in Spain and .
See also:
Portugal . The outer layer of bark in the cork oak by
See also:
annual additions from within gradually becomes a thick soft homogeneous mass, possessing those cornpre9sible and elastic properties upon which the economic value of the material chiefly depends . The first stripping of cork from young trees takes place when they are from fifteen to twenty years of age . The yield, which is rough, unequal and woody in texture, is called virgin cork, and is useful only as a tanning substance, or for forming rustic
See also:
work in ferneries, conservatories, &c . Subsequently the bark is removed every eight or ten years, the quality of the cork improving with each successive stripping; and the trees continue to live and thrive under the operation for 15o years and upwards . The produce of the second
See also:
barking is still so coarse in texture that it is only
See also:
fit for making floats for nets and for similar applications . The operation of stripping the trees takes place during the months of
See also:
July and August . Two cuts are made round the stem—one a little above the ground, and the other immediately under the spring of the main branches . Between these three or four
See also:
longitudinal incisions are then made, the utmost care being taken not to injure the inner bark . The cork is thereafter removed in the sections into which it has been cut, by inserting under it the wedge-shaped handle of the implement used in making the incisions .

After the outer

See also:
surface has been scraped and cleaned, the pieces are flattened by
See also:
heating them over a fire and submitting them to pressure on a flat surface . In the heating operation the surface is charred, and thereby the pores are closed up, and what is termed " nerve " is given to the material . In this state the cork is ready for manufacture or exportation . Though specially
See also:
developed in the cork-oak, the substance cork is an almost universal product in the stems (and roots) of woody
See also:
plants which increase in diameter
See also:
year by year . Generally towards the end of the first year the
See also:
original thin protective layer of a stem or branch is replaced by a thin layer of " cork," that is a layer of cells the living contents of which have disappeared while the walls have become thickened and toughened as the result of the formation in them of a substance known as suberin . Fresh cork is formed each season by an active formative layer below the layer developed last season, which generally peels off . Where the formation is extensive and persistent as in the cork-oak, a thick covering of cork is formed . In some cases, as on young shoots of the cork-
See also:
elm, the development is irregular and wing-like outgrowths of cork are formed . In
See also:
northern Russia a similar method to that used for obtaining cork from the cork-oak is employed with the birch . Cork possesses a combination of properties which peculiarly fits it for many and diverse uses, for some of which it alone is found applicable . The leading purpose for which it is used is for forming bungs and stoppers for bottles and other vessels containing liquids . Its compressibility,
See also:
elasticity and
See also:
practical imperviousness to both air and
See also:
water so fit it for this purpose that the
See also:
term cork is even more applied to the
See also:
function than to the substance .

Its specific lightness, combined with strength and durability, recommend it above all other substances for forming

See also:
life-buoys, belts and jackets, and in the constructionof life-boats and other apparatus for saving from drowning . On account of its lightness, softness and non-conducting properties it is used for
See also:
hat-linings and the soles of shoes, the latter being a very ancient application of cork . It is also used in making artificial limbs, for lining entomological cases, for pommels in leather-dressing, and as a
See also:
medium for making architectural
See also:
models . Chips and cuttings are ground up and mixed with india-rubber to form kamptulicon floor-
See also:
cloth, or "cork-
See also:
carpet." The inner bark of the cork-tree is a valuable tanning material . Certain of the properties and uses of cork were known to the ancient Greeks and Romans, and the latter, we find by Horace (Odes iii . 8), used it as a stopper for wine-vessels:-- " corticem adstrictum pice dimovebit amphorae " It appears, however, that cork was not generally used for stopping bottles till so
See also:
recent a period as near the end of the 17th century, and bottles themselves were not employed for storing liquids till the 15th century . Many substitutes have been proposed for cork as a stoppering agent; but except in the case of aerated liquids none of these has recommended itself in practice . For aerated water bottles several successful devices have been introduced . The most
See also:
simple of these is an indiarubber ball pressed upwards into the narrow of the bottle neck by the force of the
See also:
gas contained in the water; and in another
See also:
system a glass ball is similarly pressed against an india-rubber
See also:
collar inserted in the neck of the bottle . By analogy the term " to cork " is used of any such devices for sealing up a bottle or aperture .

End of Article: CORK (perhaps through Sp. corcha from Lat. cortex, bark, but possibly connected with quercus, oak)
[back]
CORK
[next]
COUNTESS MARY CORK AND ORRERY

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.