In the cutting of corks for use, the only tool employed is a broad, thin, and sharp knife; and, as the cork tends very much to blunt this, it is sharpened upon a board by one whet, or stroke on each side, after every cut; and, now and then, upon a common whet-stone. The corks for bottles are cut in the length way of the bark, and consequently the pores lie across. Bungs, and corks of large size, are cut in a contrary direction: the pores in these are therefore downward, a circumstance which renders them much more defective in stopping out the air than the others. The parings of cork are sold to the makers of Spanish black.
239. The WALNUT is a well-known shell fruit, produced by a tree (Juglans regia, Fig. 69), which grows wild in the northern parts of China and Persia, and has winged leaves; the leaflets, about nine in number, large, oblong, smooth, thick; and the end one with a stalk.
Although greatly admired, both for the beauty of its foliage, and for the excellence of its fruit, the cultivation of the walnut-tree in England is by no means attended to so much as it was formerly, when its wood was considered the most ornamental timber produced in our island. It is pleasingly veined, and admits of a fine polish, but its colour is much less rich than that of mahogany; and consequently, except for the making of gunstocks, it has, of late, been wholly superseded by that more favourite wood. On the Continent, however, the walnut-tree is still in request for furniture of various kinds.
The fruit of the walnut-tree is covered externally with a thick and smooth green husk, the juice of which stains the fingers black. In an unripe state, before the shells are formed, the whole fruit may be made into a pickle, and also into ketchup. In medicine the unripe fruit is considered of use for the destruction of worms, and is usually administered in the form of an extract.
Walnuts become ripe about the beginning of October; and, as they grow in clusters, generally at the ends of the branches, it is customary to beat them down with long poles. The kernel, which is covered with a tough, yellow, and bitter skin, is more esteemed than that either of the hazel-nut or filbert. It yields, on pressure, a sweet kind of oil, which, in quantity, amounts to about half the weight of the kernel.
There are several varieties of walnut, which are well known to the cultivators of that tree.
240. The HICKORY-NUT (Juglans alba) is a North American species of walnut, the shell of which is very hard, does not split asunder like that of the walnut, and is of smoother and lighter colour than that.
Its kernel is sweet and well tasted, and affords a considerable portion of oil.
241. The HAZEL-NUT and FILBERT are well-known fruits, the former of a shrub (Corylus avellana, Fig. 67) which grows in hedges and thickets; and the latter of a somewhat similar shrub, which is cultivated in orchards and kitchen gardens.
Each of these kinds of nuts is much esteemed, but particularly the latter; the flavour of its kernels being very delicious. They are, however, difficult of digestion, and, when eaten in considerable quantity, sometimes produce very unpleasant effects. The oil which is obtained from hazel-nuts by pressure is little inferior in flavour to that of almonds, and, under the name of nut-oil, is often used by painters. Chemists employ it as the basis of fragrant oils artificially prepared, because it easily combines with and retains odours. This oil is found serviceable in obstinate coughs.