The wood should be carefully brushed before being operated upon. (12) To destroy ants and insects in wood. - (a) Corrosive sublimate is an effectual poison to them. (6) Oils, especially essential oils, are good preventives, (c) Cajeput-oil has been proved effectual for destroying the red ant. (d) Payne's, Bethell's, and Burnett's processes are said to be proof against the white ant of India, (e) Dust the parts with pounded quicklime, and then water them with the ammoniacal liquor of gas-works, when the ammonia will be instantly disengaged by the quick-lime, and this is destructive to insect life. (/) For the black ant, use powdered borax; or smear the parts frequented by them with petroleum oil; or syringe their nests with fluoric acid or spirits of tar, to be done with a leaden syringe; or pour down the holes boiling water to destroy their nests, and then stop up the holes, with cement. Ants dislike arsenic, camphor, and creosote. (Britton.)
(13) Nicholson, noting that railway sleepers lying on ground which had formerly been the bed of a salt lake, in Nebraska, retained their power to resist decay for an unusually long period, and showed an excess of alkaline salts in their ash, suggests that here is a cheap and effective preservative.
(14) Lostal, a French railway contractor, recommends the use of quicklime for preserving timber. He puts the plunks in tanks and covers them with quicklime, which is gradually slaked with water. Timber, such as is used in mines, takes about a week to become thoroughly impregnated. The wood acquires a remarkable hardness and toughness, and, it is said, will never rot. Beech wood has been prepared in this way for hammers and other tools in several ironworks, and is reported to have been as hard as oak, without losing its peculiar elasticity.
(15) Wood will be effectually preserved from the action of the air if it is covered by a paint-brush with a solution of persulphate of iron, marking 2° to 2 1/2° B. The blue tint which is developed by drying changes to brown when a coat of linseed-oil is laid on. (Revue Indust.)
(16) Lay timber up, when perfectly dry, in an airy place, that it may not be exposed to the sun or wind, and taking care that it does not stand upright, but let it be laid along, one piece upon another, interposing here and there some short blocks, to prevent that mouldiness which is usually contracted when planks sweat. Lay planks in a stream of running water for a fortnight, and then set them up in the sun and wind, so that the air may freely pass between them, and turn them frequently. Boards thus seasoned will floor much better than those which have been kept in a dry place for many years. Elm, felled ever so green, if kept for 4 or 5 days, obtains a good seasoning and is rendered fit for immediate use. This water seasoning is not only a remedy against the worm, but also prevents distortions and warping. Where huge massy columns are to be used, it is a good plan to bore them through from end to end, as it prevents their splitting. -Timbers occasionally laid in mortar, or in any part contiguous to lime, have sometimes been capped with melted pitch as a preserver from the destructive powers of lime; but it has been found to be rather hurtful than otherwise.
(17) For the purpose of preserving timber for mines, Koug packs the timber, cut in proper lengths, in a vertical position in an iron reservoir, provided with a tight-fitting cover. The vessel is then filled to about 3/4 of its capacity with a solution of the car-bolate of soda. Into this he leads live steam, which speedily brings the liquid to the boiling-point. The access of the steam is continued until, by its gradual condensation, it has filled the vessel to its full capacity. The wood is then allowed to remain in the hot liquid some hours; this is drawn off, and the wood washed off with a dry steam jet.
(18) Hock dissolves paraffin in ligroin, so-called petroleum ether, kerosene, or other convenient substances, and immerses the wood to be preserved in the solution, care being taken that the wood is as dry as possible. After impregnation, the saturated wood is heated in a large retort provided with a condensing arrangement, whereby the volatile solvent is expelled and condensed for use over again, whilst the paraffin is left in the pores of the timber. Crude paraffin (containing much liquid hydrocarbons) may be employed.
(19) At Bellagio, on the lake of Como, where olive-wood is used in large quantities for the formation of various articles of turnery, the plan adopted for seasoning the wood is to boil it for about 10 minutes, and then let it dry gradually for months before using it.
(20) The best preservative against dry rot, according to the American ' Journal of Pharmacy/ is the following: - 1 part oil of cassia, 1 wood t,ar, and 1 train-oil; apply 3 coats on the reverse sides and on the ends of planks, floors, etc. In all probability oil of cassia plays the chief role as preservative.
(21) During the excavation of a canal in Berlin the workmen struck upon 12 perfectly preserved coffins, which lay apparently in 4 graves, each containing 3 superimposed coffins. The site of the discovery corresponds with the cemetery that existed even as late as 1620 in connection with the poor-house and pestilent hospital. The corpses must in consequence have been in the earth for at least 260 years. Notwithstanding this long period, the coffins, as well as their contained bones, are in a perfect state of preservation; articles of clothing have even been found still clinging to some of the bones. Prof. Virchow found upon investigation that the coffins were coated on both sides with a thick layer of tar, the wood itself appearing to be young oak, 1 in. in thickness. A silicious crust was likewise found on the inner side of the coffins. The wood is sp hard that axes and saws were broken in the attempt to cut it.
(22) Jacques first impregnates the timber thoroughly with a simple solu tion of soap mixed with an acid - preferably phenic acid. This causes the formation in a few days, within the wood, of a fatty acid, which is insoluble in water, and impregnates the remotest fibres. The reaction of the acid on the soap does not take place until a portion of the water has evaporated. It is claimed that more perfect impregnation can be had in this way than with creosote, and there is no danger of the washing out of the preservative from the exposed surfaces, as when sulphate of copper is used. The Government commission on technical railroad operation in France is said to favour this process.