(23) Card impregnates the wood with a solution of zinc chloride or other antiseptic soluble mineral salt, then dries the outer layers of the wood by heated air currents, and finally saturates with hot creosote-oil. The creosote-oil is to prevent the soluble antiseptic from being washed out.

(24) Richard uses common salt, in a chemically pure crystallized form, as the most efficacious preservative of timber. In combination with alum, absolute incombustibility, it is said, can be ensured by its use. (tierme Indust.)

(25) The well-known methods of preserving posts and wood which are partly embedded in the earth, by charring and coating with tar, are only effective when both are applied. Should the poles only be charred without the subsequent treatment with tar, the charcoal formation on the surface would act as an absorber of the moisture, and, if anything, only hasten the decay. By applying a coating of tar without previously charring, the tar would only form a casing about the wood, nor would it penetrate to the depth which the absorbing properties of the charcoaled surface would ensure. Wood that is exposed to the action of water or let into the ground should first be charred, and then before it has entirely cooled be treated with tar till the wood is thoroughly impregnated. The acetic acid and oils contained in the tar are evaporated by the heat, and only the resin is left behind, which penetrates the pores of the wood and forms an airtight and waterproof envelope. It is important to impregnate the poles a little above the line of exposure, for here it is that the action of decay affects the wood first, and where the break always occurs when removed from the earth or strained in testing, (Ind. Blatt.)

(26) Miiller employs for the preservation of wood the phosphate of baryta formed within the fibre. The wood is first steeped in a solution of the phosphate of soda containing 7 per cent, of the salt. When dry, the wood is again treated with a solution of chloride of barium containing 13 per cent.

(27) Leech takes 1 lb. arsenious acid and dissolves it in 4 gal. water; to this he adds 1 lb. carbonate of soda, stirring the mixture till it is thoroughly dissolved. In a separate vessel he makes a solution of 16 lb. sulphate of copper in 16 gal. water, mixes the solutions together, and places them in a wooden or a lead-lined vat; The timber is placed in this bath, and the solution teated by means of steam to the boiling-point. A few hours' soaking is said to be sufficient, but when heat is not applied the wood must remain for at least 2 or 3 days. These solutions are applicable to wood that is already in permanent position, as telegraph-poles, fences, and gates. In these and similar cases one solution should be painted on and allowed to dry before the other is applied. When possible, they should be laid on hot.

(28) Mewburn's process, so far as oak is concerned, consists simply in boiling the wood in a solution of gallo-tannic acid, the proportions of the respective ingredients being apparently immaterial. The result is the formation of an insoluble substance in the pores of the wood. One solution only is necessary for oak, on account of the tannin naturally present in that wood, the endurance of which in moist situations is proverbial. A consideration of this fact led Hatzfeld to try the effect of impregnating timber with tannin, and afterwards with acetate of iron, a process which is both cheap and useful, and which is at present being tested by a telegraph company in France.

(29) Posts and pier-piles can be rendered nearly indestructible by boring one or more holes, larger or smaller, in the centre of the butt, the whole length if desirable; then fill with boiling coal-tar and close the aperture with a long taper wedge, well driven home, which will give pressure to force the antiseptic into the inner heart pores of the mould. Were posts thus preserved, and the exterior surface dressed with resin-varnish, they would last for centuries. Wood exposed to the air should not be dressed with coal-tar, but Stockholm tar or resinous varnish; the former will rot the fibres when exposed to sun and air. Mark the posts at 6 or 8 in. above the depth they are to be placed in the earth, and bore the hole up to the mark. Then fill in with boiling coal-tar, plug up the hole, and the base of the post will outlast the upper part. The writer has also had occasion to stand posts under floor joists, as a support, when, by making a clay puddled hole, and pouring into it a gallon of boiling coal-tar as a bed for the post to stand in, it would never decay. (Eng. Mech.)

(30) Wood is rendered extremely durable and weather-proof by covering it with hot linseed-oil varnish, several coats being applied, each one after the preceding one is dry; finally, oil colours are applied as required. The drying requires a longer time than the ordinary process of painting. (Dingier's Polytech. Jl.)

(31) The following recipe is said to be a cure for dry rot: - Melt 12 oz. rosin in an iron pot, add 3 gal. train-oil, and 3 or 4 rolls brimstone; when it is thin, add Spanish brown, or red and yellow ochre, or what colour preferred; put on the wood hot and thin with a brush; give two coats.

(32) Villain and Co., of Berlin, manufacture, under the name of mycotha-naton, a product which has the property of destroying dry-rot in houses and other buildings, and preventing its appearance in new ones. It may also be employed with advantage in seasoning railway sleepers, telegraph posts, beams, etc, which it effectually preserves from decay. It is a clear liquid, containing no poisonous or disagreeably smelling substance. Its presence in the atmosphere is good for the health, as it destroys miasma and ferment. Lastly, wood impregnated with it does not easily catch fire, which has been repeatedly proved. It requires boiling in a cast-iron boiler, and in this state is to be spread over the surfaces covered with dry rot by means of a large brush. During the boiling the boiler must be kept carefully closed. Wood which is to be impregnated with it must be first cleaned. The efflorescence of masonry may be prevented by smearing the walls with this liquid. In old buildings the efflorescence should be first scraped, and after a layer of the liquid has been put on, the walls can be restored. (Pract. May.)