238. _CORK is the external bark of a species of oak_ (Quercus suber) _which grows in Spain, Portugal, and other southern parts of Europe, and is distinguished by the fungous texture of its bark; and by its leaves being evergreen, oblong, somewhat oval, downy underneath, and waved._
The principal supply of the cork that is consumed in Europe, is obtained from Catalonia in Spain; and the culture and the preparation of it yield to the inhabitants of that province near 250,000_l._ per annum.
In the collecting of cork, it is customary to slit it with a knife, at certain distances, in a perpendicular direction from the top of the trees to the bottom; and to make two incisions across, one near the top and the other near the bottom of the trunk. For the purpose of stripping off the bark, a curved knife with a handle at each end is used. Sometimes it is stripped in pieces the whole length, and sometimes in shorter pieces, cross cuts being made at certain intervals. In some instances the perpendicular and transverse incisions are made, and the cork is left upon the trees until, by the growth of the new bark beneath, it becomes sufficiently loose to be removed by the hand.
After the pieces are detached they are soaked in water; and, when nearly dry, are placed over a fire of coals, which blackens their external surface. By the latter operation they are rendered smooth, and all the smaller blemishes are thereby concealed: the larger holes and cracks are filled up by the artful introduction of soot and dirt. The pieces are next loaded with weights to make them even; and lastly they are dried, stacked, or packed in bales for exportation.
Many of the uses of cork were well known to the ancients. Its elasticity renders it peculiarly serviceable for the stopping of vessels of different kinds; and thus preventing either the liquids therein contained from running out, or the external air from passing in. The use of cork for stopping glass bottles is generally considered to have been introduced about the fifteenth century. The practice of employing this substance for jackets to assist in swimming is very ancient; and it has lately been applied in various ways towards the preservation of life, when endangered by shipwreck. The floats of nets used for fishing are frequently made of cork: pieces fastened together make buoys, which, by floating on the surface of the water, afford direction for vessels in harbours, rivers, and other places. In some parts of Spain it is customary to line the walls of houses with cork, which not only renders them warm, but prevents the admission of moisture. The ancient Egyptians sometimes made coffins of it. On account of its lightness, cork is used for false legs; and, from its being impervious by water, it is sometimes placed betwixt the soles of shoes to keep out moisture. When burned, it constitutes that light black substance known by the name of _Spanish black_.