woo tention to the most advantageous expedients that have been devised for preserving this useful substance j and conclude with an account of t!>e best modes of imparting to it different colours. To render timber more durable, it has been recommended to saw the trees into scantlings ; or, where the wood is designed to be used entire, to hew it into the requisite shape ; when it is to be laid in a bed of sand (contained in a case or shell of brick- work) and heated by- means of a furnace, built beneath. As soon as the wood becomes hot, the sap exudes, and is imbibed by the sand 5 in consequence of which, the quality of the timber is greatly improved. This method has been Succ-ssfully tried; but, as it is too expensive, Dr. Lewis advises all wood, that is exposed to the incle- mency of the weather, to be coated with a preparation of pulverized pit-coal and melted tar, reduced to the consistence of paint, which he has found very efficacious. In those cases, however, where piles, or other masses of timber, are subjeft to the action of water, the most simple mode of preserving it, is that employed in the Bermuda Islands, and other parts of Ame- rica. It consists in covering such wood repeatedly with , train or whale-oil, allovi-ing each coat to become perfeiStly dry, before an- other is applied. — For preventing the combustion of wood, the read- er will consult the article Fire- PHOOF. IVLahogany, ebony, and the finer woods, being very expensive, ai- tisans have contrived various pre- parations for tinging timber, so as to be with difficulty distinguish- ed from them. Thus, ebony may be imitated, by boiling clean. woo [343 smooth box in oil, till it become perfeSly black; or, by washing pear-tree wood, that* has been pre- viously planed, with aqua-fortis, and drying it in a shady place, in the open air; after which, writing- ink must repeatedly be passed over it, and the wood dried in a similar manner, till it acquire a deep black colour. It may then be polished with wax and a woollen cloth, which will give it a fine lustre. In the new " TransaBions of the Royal Society of GiJttingen," Prof. Beckmann has published the re- sult of numerous experiments, re- lative to the staining or dyeing of wood. He dire6ls, for instance, a piece of plane-tree to be put into a glass vessel, containing pulverized dragon's-blood mixed with oil ot turpentine, and placed over the fire : in a short time, the wood will acquire a beautiful colour, resem- bling that of mahogany 3 and the dragon's-blood, adhering to the sur- face, may be sepamted by applying reftified spirit of wine. If gam- boge be dissolved in spirit of tur- pentine, it will imi)art a bright-yel- low colour; and one part of dra- gon's-blood, with two of gamboge, communicate various shades to the wood of the beech and plane-trees. A fine walrmt-trec tint may be obtained, by rubbing common wood with a mixture, prepared of the bark of the trees, or the shells of walnuts, previously dried, pulve* rixed, and reduced to a proper coh- sistence with nut-oil. Another preparation for commu- nicating a perfefit mahogany-colour to inferior woods, especially those of the elm, maple, and sycamore- trees, consists of the following in- gredients : Dissolve two drams of dragon's-blood, one dram of wild alkanet (Anchusa tiyi f ioria, L.), -Mid Z4 half
