Though steaming or boiling impairs the strength and elasticity of timber, it gives another property, which for some purposes is still more desirable than strength; for boiled or steamed timber shrinks less and stands better than that which is naturally

* ' Transport des Bois,' pp. 172 and 176.

† 'Silva,' vol. ii., p. 217.

‡According to M. De Lapparent, Director of the French Dockyards, timber cannot be seasoned in salt water. ' Essay on the Prevention of Decay in Timber.' seasoned. Therefore it may often be useful to season timber in this manner where joiners' work is to be executed in oak of British growth, as without this precaution it requires a long time to season it so as to be fit for such purposes.

The timber should not remain long in boiling water or steam; four hours will, in general, be quite sufficient: and after boiling or steaming, the drying goes on very rapidly, but it is well not to hasten the drying too much. Steamed wood dries sooner than that which is boiled, according to Mr. Hookey's experiments.*

How far steaming or boiling affects the durability of timber has not been satisfactorily ascertained; but it is said that the planks of a ship, near the bows, which are bent by steaming, have never been observed to be affected with the dry rot.† The changes produced by boiling, as observed by Duhamel, are not very favourable to the opinion that it adds to the durability of timber. For when a piece of dry wood was immersed in boiling water, and afterwards dried in a stove, it not only lost the water it had imbibed, but also a part of its substance; and when the experiment was repeated with the same piece of wood, it lost more of its substance the second time than it did the first. The same thing takes place in green wood; and tender woods, or those of a middling quality, are more altered by these operations than hard woods, or those of a good quality. ‡ Dr. Watson found steeping long in cold water produced similar effects; and that box, oak, and ash lost more weight by this process than mahogany, walnut, or deal. § Both cold and hot water has, therefore, to a certain extent, the power of dissolving the woody fibre.

* Barlow's ' Essay on the Strength of Timber.'

† ' Ency. Brit.,' art. Dry Rot.

‡ ' Transport des Bois,' pp. 138 and 144.

§ ' Chemical Essays,' vol. iii, p. 24.