relates that the Indians extracted an oil from the acorns of this species, with which they prepared their food. The quercitron (Quercus tinctoria) is, after the white oak, commonly preferred for the construction of houses in the United States. The bark of this species affords a yellow dye, which is a considerable article of commerce; it is used for dyeing silk and wool. The quercitron is employed by the Americans in tanning leather, chiefly on account of its abundance; but the yellow colour which it imparts to skins is considered a defect, and is generally removed by a subsequent chemical process. In the United States, the bark of almost every sort of tree is used for tanning; the abundance with which it is procured rendering selection less necessary. In England, oak bark is almost exclusively applied to this purpose, as it contains the largest quantity of tannin of any known substance. The leaves of some trees may be so applied. The Chinese use the coarser leaves of the tea-tree in the preparation of leather.

A fine oak is one of the most picturesque of trees. It conveys to the mind associations of strength and duration, which are very impressive. The oak stands up against the blast, and does not take, like other trees, a twisted form from the action of the winds. Except the cedar of Lebanon, no tree is so remarkable for the stoutness of its limbs: they do not exactly spring from the trunk, but divide from it; and thus it is sometimes difficult to know which is stem and which is branch. The twisted branches of the oak, too, add greatly to its beauty; and the horizontal direction of its boughs, spreading over a large surface, completes the idea of its sovereignty over all the trees of the forest. Even a decayed oak,—

dry and dead,

Still clad with reliques of its trophies old,
Lifting to heaven its aged, hoary head,
Whose foot on earth hath got but feeble hold-"

-even such a tree as Spenser has thus described is strikingly beautiful: decay in this case looks pleasing. To such an oak Lucan compared Pompey in his declining state.

The CORK OAK (Quercus suber) is not so large a tree as the common oak. There are several varieties: a broad leaved and a narrow leaved, which are evergreens; besides other varieties which shed their leaves. The broad-leaved evergreen is, however, the most common, and it is the one from which the cork of commerce is chiefly obtained. It is mentioned by Theophrastus, Pliny, and some other ancient naturalists as being well known in the days of the Greeks and Romans,-the latter of whom used it for a variety of purposes, and among the rest for the stopping of bottles. They used it for floats to their nets and fishing tackle; for buoys to their anchors; and when Camillus was sent to the Capitol, through the Tiber, during the siege by the Gauls, he had a lifepreserver of cork under his dress.

The Cork Oak is indigenous, or at least abundant, in Portugal, Spain, part of the south of France, and Italy; on the opposite coast of the Mediterranean, and the Levant. Spain and Portugal supply the greater portion of the cork which is consumed in Europe. The cork is the bark which the tree pushes outwards, as is common to all trees; but here the outer bark is of larger quantity, and is more speedily renewed. When removed, there is a liber, or inner bark, below it, and from this the cork is reproduced in the course of a few years,-while the tree is said to live longer, and grow more vigorously, than if the cork were not removed. The first time that the cork is taken off, is when the tree is about fifteen years old. That crop is thin, hard, full of fissures, and consequently of little value; and the

C

second, which is removed about ten years after, is also of an inferior quality. After this, the operation is repeated once in eight or ten years, the produce being greater in quantity, and superior in quality, each successive time. According to Duhamel, a corktree thus barked will live a hundred and fifty years. The months of July and August are those which are chosen for removing the cork. The bark is cleft longitudinally, at certain intervals, down to the crown of the root, with an axe, of which the handle terminates in a wedge; and a circular incision is then made from each extremity of the longitudinal cuts. The bark is then beaten, to detach it from the liber; and it is lifted up by introducing the wedged handle, taking care to leave sufficient of the inner

laminæ upon the wood, without which precaution the tree would certainly die. The bark being thus removed, it is divided into convenient lengths; and it is then flattened, and slightly charred, to contract the pores. This substance is the rough cork of commerce; and it is thus fit to be cut into floats, stoppers, shoesoles, and other articles of domestic use, by the manufacturer. The cork of the best quality is firm, elastic, and of a slightly red colour. Two thousand five hundred tons of cork were imported into the United Kingdom in 1827. Cork burned in vessels

of a particular construction gives the substance called Spanish black.

The Oak from which the nut-galls of commerce are procured (Quercus infectoria) is minutely described by M. Olivier, in his travels. The species is very common in Asia-Minor; but, till the time of this traveller, Europeans had very little information on the subject, although the galls were a considerable article of commerce. It is a shrub, seldom exceeding six feet in height; and it has not only been accurately described by M. Olivier, but was introduced by him into France, where it is cultivated as a garden shrub, and grows well in the open air.

The gall is a morbid excrescence produced by the puncture of a winged insect, to which Olivier has given the name of Diplolepis Galle Tinctoriæ. This excrescence is of a globular form, with an unequal and tuberculous surface. It is developed on the young shoots of the tree, and contains within it the eggs which the insect has deposited. The best galls are gathered before the transformation of the insect, because in that state they are heavier, and contain more of the tannin principle. When the insect has left them, they are pierced from the interior to the surface. The best galls come from Aleppo. The substance of which they are composed is peculiarly astringent; of which, according to Sir Humphry Davy, five hundred parts contain a hundred and eighty parts of soluble matter, principally formed of tannin and gallic acid. One hundred and seventy-four tons of galls were imported into the United Kingdom in 1827.

The instinct by which certain insects choose for the nests of their future offspring the substance of various vegetable bodies, is one of the most curious provisions in the economy of nature. After having pierced those bodies, they deposit their eggs, which, being hatched, produce larvæ, that are more or