CORK. 163 



further succeeded in obtaining another crystalline m%tter from the 

 leaves of the aspen (populus tremula) populine. 



Cork. The oak which yields cork is known in Spain under the 

 name of the alcornoque It forms extensive forests upon the abrupt 

 slopes of the Pyrenees, where it is often seen growing upon arid and 

 stony soils, that seem doomed to eternal sterility. The cork-tree 

 has flexible and strong roots, which creep over the naked surface of 

 the granitic masses, turning round blocks, and searching everywhere 

 for fissuj-es and collections of sand and alluvium, into which they 

 penetrate deeply, in search of the nourishment necessary to the tree. 

 At maturity, the alcornoque rises to a height of sixty-five feet, and 

 its trunk may be three feet and a quarter in diameter. 



In the Spanish Pyrenees, the superior limit of the cork-tree region, 

 is that of the vine, about 1640 feet above the level of the Mediter- 

 ranean. In France this tree grows luxuriantly in the communes of 

 Passa, Lauro, &c., the mean elevation of which is 1148 feet. In 

 Spain, as in France, the soils on which the cork forests grow are of 

 primitive origin ; and it is said, on good authority, that the cork- 

 tree only grows on soils derived from granite, gneiss, mica-slate, or 

 porphyry, and never on soils of calcareous origin. 



The cork-tree is reproduced spontaneously on these silicious soils, 

 among cistuses and heaths ; but the reproduction in this way is so 

 slow, that art often interferes advantageously to aid it. There are 

 many varieties of cork oak; and as that which is covered with a 

 smooth and grayish cuticle, yields the article which is most prized 

 in commerce, the seeds of this variety ought to be selected for sow- 

 ing. The acorns of the cork-oak are tumid, of considerable size, 

 and a sweet taste ; the acorns ripen from October to December, and 

 are much employed as food for hogs. The Catalonians sow the 

 acorns in a cultivated soil at the same time that they plant the vine, 

 and for twenty or twenty-five years the produce of the vine compen- 

 sates the outlay upon the young cork-trees ; but the produce of the 

 vine diminishes as the cork-tree overshadows it, and finally there 

 comes a time when the vines die out completely. The cork-tree is 

 of slow growth, and at four years of age it may be from thirty-six to 

 forty inches in height, and requires incessant care until the trunk is 

 from seven to ten feet high, at which time it may be about twenty 

 years of age ; and its total height, including its branches, may be 

 about twenty-two feet. 



The barking of the cork-tree begins about the middle of July, and 

 may be continued so long as the sap is in motion. When stripped 

 oflf, good cork is formed of from ten to twelve layers, each of which 

 indicates an annual deposition. The two outer layers constitute the 

 cuticle ; the others adhere closely together, and although of variable 

 thickness they present a homogeneous mass. The time for remov- 

 ing the cork is indicated by the interior acquiring a slightly rosy 

 tint, which happens about the tenth year. The barking is performed 

 by me»ns of an axe, with which a cut is made the whole length of 

 the t»--mk, care being taken not to wound the woody layers : two 

 otJ**' ':ross cuts are then made at the top and bottom of the trunk. 



