If wood be submitted to destructive distillation, it is decomposed, and the consequence is the production of acetio acid and an oil, which pass off, leaving a certain quantity of charcoal. Taking them one with another, the chief kinds of English timber yield, by the distilla tion of I lb. weight, about 71 ozs. of wood acid, 31 07.8. of charcoal, and 11 ozs. of oiL The woods that are used by the cabinet-maker for furniture of a more delicate kind are called fancy-woods. The use of these has become much more general since the introduction of the art of veneering ; and now that this is done by machinery, instead of by hand, many woods are used for furniture and other purposes which, on account of their scarcity, could have been formerly used only to a very limited extent. The most common of the fancy woods, and that which is used most by the cabinetmaker, is mahogany. Next in point of importance and use to mahogany is rose-wood. King-wood is a beautiful wood, used only for delicate articles. Bcef-wood is a very heavy wood, of a pale red colour, and is brought from Australia in logs 9 feet long and 13 or 14 inches wide. Tulip-wood is brought into the market in very small pieces, not more than 4 feet long and 5 inches in diameter. It is clouded with red and yellow colours, and is used for bordering and making small articles, such as caddies and work boxes. Zebra-wood is the production of a large tree, and is cheap enough to be made into tables, piano-fortes, &e. It is coloured brown on a white ground, and clouded with black. Satin-wood is of a brilliant yellow colour, with delicate glowing shades. It is found in the market in logs 2 feet wide and 7 or 8 feet long. Sandal-wood is of a light brown colour, with golden-coloured waves. Ebony and iron-wood are the names given to some very hard woods, mostly brought from India, although some of the species are found in Europe and America. Canary-wood has a deep yellow colour. Purple-wood has a purple colour, without veins. Snake-wood is of a deep red colour, with black shades. Calamander-wood is a handsome cheap wood, taking a high polish, and is brought from Ceylon. Other woods are called from the places they come from, as Coromandel wood, Amboyna wood, &c.
The practice of staining wood is sometimes had recourse to for the purpose of making the more common woods resemble in colour the fancy-woods. A method has been proposed of doing this by introducing into the tree during its growth various colouring agents, so that during the course of the ascent of the sap the colouring matter may be taken up and deposited in the woody tissue. Some of the woods thus treated have been made to assume very remarkable colours • but as the trees on which it can be practised are too soft and coarselior fine work, it is not likely that this method will at all supersede the use of the naturally beautiful fancy-woods.
Growing trees are exposed to the attacks of animals and of insects, in addition to their own natural causes of decay ; and when they are used as timber they are still liable to the attacks of insects and of worms of a peculiar description. The mischief done by animals is of a comparatively simple and limited description ; and may briefly be described as consisting iu blows and wounds of the trunk, and in tile violent disruption of the smaller boughs, thus rendering the formation of knots more frequent than might otherwise be the case. Birds are
actually of service in woods, for the carnivorous birds do good by keep ing down insect life. The woodpecker and nuthatch only attack the bark of trees when in search of the larvae boring in them ; rooks and crows destroy immense numbers of the larger beetles ; and, in fact, nearly all the forest-feeding birds render the same service. Squirrels, bats, and other insect-devouring mammalia, play the same part in the economy of nature ; so that our attention may almost exclusively be devoted to the consideration of the attacks of insects and of the boring worms.
There are three descriptions of insects which prey upon trees, which may be classified aecordiug to the parts they especially attack, namely, those which attack the leaves, those which attack the bark and the alburnum, and those which attack the heart-wood. The leaf-eaters are of countless varieties, some of them eating the upper, some the under surfaces, and others the substance of the leaves without touching the epidermis. Again, there are insects which only attack the flowers, some living upon the farina of the flowers, others on the fluids in the vessels of the flowers, and others on their leaves ; whilst there are also other insects which injuriously affect growing timber by giving rise to galls or other analogous excrescences. The principal mischief caused by this description of insects consists in the interferences they produce in the flow of the sap, and in their interferences with the respiratory functions of the leaves ; but fortunately their ravages are apparent, and their enemies are extremely numerous, both in the ani mal and the insect tribes. There are several varieties of the bark feeders ; some of them attacking exclusively the outer bark, some the inner bark, some the alburnum. Their ravages, however, in all cases are exercised only superficially, so to speak, and they do not affect the quality of the timber in any serious manner. These insects may kill a tree, but the heart-wood will remain sound, whatever be their numbers. Such insects as the Scolytus destructor will, nevertheless, do more injury to a forest in a month than all the animals it may shade could do in a decade. The Ilylesimus fraxini, the Tomicus typographi mu, the Bostrichus pinastri, the Sphinx apiformis, the Curculio abrestis, and the Curculio notatus are almost equally mischievous; • whilst the Lymexylon attacks both the album= and the Of the heart-wood devourers the most dangerous in our latitudes are the Coma ligniperda, the Cryptorhynchus lapathi, the Lueanidw, the Ceram (welder, the Sirex gigas, the Sirex duplex, and the Zengera mittens ; and of these, the Cossus and Sirex of our own latitudes, and the Primus gigantcua and the Callidium giganteum of tropical climates, together with the L!pnexylon, attack the converted timber after it has been long removed from the forest.