ON THE DECAY AND PRESERVATION OP WOOD.

Southland Times, Issue 1576, 10 May 1872, Page 3

ON THE DECAY AND PRESERVATION OP WOOD.

. — .» By Jameß Haitaw. »'• Creosote is now more extensively used to soak the wood in for preservation than the two solutions laat mentioned. It is thought more of, and scantling prepared with it is kept for sale in someof thetimber yards in London. Creosote is a light brown transparent liquid, slightly oily. It is procured by distilling coal tar, and is sold in Melbourne under the name of paraffine oil for lamps. It is also made from a tarry liquid that is collected by a pipe from the bottom of the pits in which charcoal is burned. It is said that it is refined and mixed with a small quantity of turpentine, and then sold as kerosene, in America. Now using this to preserve wood with is only putting into the timber a substance similar to what is already in it, and which is liable to be drawn out both by water and heat. A few drops poured on the hand will speedily evaporate, leaving no oily trace, beyond the smell of tar. So it is with all mineral oils when sublimated ; the inflammable spirit is there, bub no lubricating oil. Something superior to this is required. Dry-rot supervenes when timber, of which the uniting gums are weak, is placed, while still unseasoned or green, in a damp place where the air is excluded. If unseasoned timber is used in building or public works, and painted for ornament, both ends, or one side, the under one if suspended, should be left undone, to allow the moisture to escapo, or else it will have a similar effect. The wood-fly (Cramhyx eedilis, and Qryllus) only attack the posts and rails near a bush from which they emanate, very seldom the timber of a bridge or pier, a few miles off, unless driven in that direction by strong winds when on the wing. In some cases the eggs may be in the bark, before the wood is put in the ground. It is an enormous mistake to coat stationary timber with coal-tar or pitch. These preparations doubly attract the solar heat in midsummer, making fissures in the wood for the next rain to penetrate and be evaporated by the next sun, driving out the very substances that bind the wood together. Instead of being preservatives, they are really destroyers,, and should not be allowed in public works. Our indigenous timbers are all close grained, like the English holly, birch, and lime ; and require no filling up of the pores with plaster-of-paris, previous to being polished, as cabinet-makers find necessary with Australian cedar, or English elm, ash, or oak. When thoroughly dry they are easily stained, with terra sienna, gum dragon, rose-pink, logwood, or iron filings and vinegar for a black stain. They will take a high polish, are admirably suited for all kinds of furniture, and have never been known after being made up, to get worm eaten, like elm or ash. When green or unseasoned, they can be easily bent by steam into any shape required, as for the arms or backs of chairs. I have known cedar panels, that had been saturated with linseed oil mixed with litharge, taken from the body of a family carriage over 150 years old, and exposed to all weathers, perfectly sound when the ash frame had decayed away. I believe that a mixture of two-thirds raw linseed oil, one-third spirits of turpentine, and a quarter of a pound of arsenic to every gallon of oil, is the best solution to dip the wood in, when cut to the required scantling. It should remain in soak for three days. The turpentine is to make the oil thinner and more penetrating ; the arsenic to destroy animal or vegetable life. This is for cold immersion. If the oil is heated in an iron tank, which is by far the best way, the turpentine should be left out, as the oil will penetrate wit.boii.fc it, and the turpentine would be lost by evaporation. The temperature should be kept below boiling poiut, when the wood is in the tank. It should remain for four hours, as nearly as possible at the same heat. It should then be taken out with hooks, fastened to a chaiD, and stood on end in a trough to drain. This method is only for preserving timber for valuable work, which may be exposed to all weathers. I recommend white arsenic, as no other of the metallic or mineral corrosives, such as sulphate of zinc, sugar of lead, litharge, chloride of lime, or patent dryers, will endure against the elements so well as arsenic, as I have proved by trial. It is the cheapest of all when bought wholesale. I have now proved beyond a doubt that the centre of the heart-wood, and not the sap, as erroneously supposed, conveys the nourishment from the roots, and spreads it out all over the whole tree. Therefore the ends of the wood are more porous than the sides, and if one or both are exposed longitudinally to the sun's rays, the gums will quickly be drawn out by the heat, and the wood become faded, rough, fragile, and full of cracks. To remedy this, dip both ends in hot fish oil, melted fat, strained waste, bacon fat, or the fat of any dead horses or other animals might be utilised. Add a$ lb of arsenic to every 12 lbs of fat. This treatment will keep the gums in to solidify, and allow the watery portion to escape from the sides, if the wood is green or fresh cut. Posts for fencing should have the bark

taken off before being put in the ground. About a foot, six inches in the ground and six inches out, should be well heated over a fire, and melted fat put on with a brush. Some should also be put in the j ends of the mortices, and when tf c posts are up, on the tops. The bottom end may be brushed over previously to putting in the ground, and if the postg are all heart-wood, they will last more than three times as long as they would without this treatment. I have done most of my fencing, sluices, the ends of sills, girders, and slabbing of culverts in this manner, using sugar-of-lead instead of arsenic, as I had it by me, instead of purchasing. I have seen arsenic sold by auction at £21 per ton, or about 2£d per Ib. Sugar-of-lead, chloride of zinc, and litharge, cost about Is per lb wholesale. In the framework of bridges, gates, or palisading, the splices, mortices, dovetails, and tenons, should be soaked and well done over with a brush in hot raw linseed oil, mixed with arsenic, before the work is put together. This is far better than white lead, which dries hard without penetrating, flakes off, and allows the rain to soak into the mortices, wljere the sun's rays cannot enter to dry it out. For external coating, if the timber is green, about three months after the erection of the work, lay on the first coat with arsenic as hot as it can be done without burning the brush,having two pots in use. Then finish with two more coats laid on cold, allowing a fortnight between each coat to harden. If in the summer months, omit the arsenic for these two coats only, as the oil will dry without it, and be more durable. In the two last coats yellow ochre with pale yellow chrome may be added. This will give a pleasing tint. My argument goes to prove that when posts are fixed in the ground, there is a capillary conduit through the centre of them upwards, by which the water in the ground passes upwards, and finally evaporates from the top of the post, carrying with it the gums which bind the wood together. In further proof of this, it will be observed that on the top of a post in wet ground a quantity of green mould may generally be found. To stop this waste of essential matter, a coat of fat or oil, laid on hot, or the ends dipped, as above directed, is necessary to fill up the pores of the wood, which, viewed through a microscope, will appear very rough, jagged, and full of small holes. The more the oil penetrates the ends of the wood, the more it will check decay. It will also have the effect of destroying grubs, as they cannot exist and perforate without air. Should both ends of the post be struck hard with a sledge hammer several times, the concussion will sometimes have the desired effect. Black pine or totara, when green, will weigh about 501bs to the cubic foot, more or less according to quality. They will lose one-third of their weight in drying. White or red pine will lose nearly half their weight in seasoning. The proper time to apply any preservative is when the wood is half seasoned, and after being cut into scantling. The pores are then open to receive the liquid application. I do not think it probable that any better or simpler remedy than this can be devised to make wood durable, if properly done ; and, if I am judged rightly, I consider I will be allowed more claim to call my process " Hananizing" than others have to denominate theirs by their own names. The most difficult things seem simple when it is known how they are done. For example, to gullett a circular saw with a hand punch, and take the buckles out ; to make a dozen holes in a twelve-inch circle in the middle of a 4 x 4 ft. quarter- inch plate of iron, with a hand punch, using a common nut-bolster on the anvil ; to make oil paint flow from a pen, making a line one-32nd or one-16th of an inch broad, to dry in twenty minutes, to do on a panel in imitation of cane work ; to take a dint or bulge out of the crook part of a key bugle, or cornet-a-piston. Not one man in twenty millions can do these tkings, simple as they are. Many a mechanic has been discharged from his employment for spoiling the work, through not knowing simple things, like these, in the arts. Many a time have I given information and got no thanks for it — sometimes by the reply, " I knew that, but forgot it." In no place more than in the colonies is there a prevailing desire to " scamp" work, especially piece-work. Most contractors think they have a perfect right to take every advantage they can, ! to slight the work, and get extras for j everything not actually named in the ' specifications. This was beautifully I illustrated lately by a Dunedin brick layer, who said to his laborer, " Here, Jack, hold your back up against the j chimney, to keep it from falling, while I go and draw the money." My informant added that it has not yet fallen, being protected from strong winds by the brow of a hill. Many a time have I seen the grouting poured outside the brick wall, and none put in between the bricks, and ! have also many a time seen stones for the | foundation thrown in so carelessly that the weight was on the mortar, and the rough angles of the stones had no bearing to fit into one another, thus causing settlements or cracks in the wall. Those are only a few of the many thousand cases that could be named, showing the necessity of employing an architect or engineer of sterling magnanimity, free from the influences of " tip," and with a vision that cannot be blinded by gold dust. Had Southland been always so fortunate, she need not have lost her position aa an independent Province. P.S. — In my first letter there is a passage which does not express the meaning I intended to convey. It should have been, " The quicker the growth of the tree the shorter time the wood will endure. The slower, on sandy or poor soil, the wood will be harder and more lasting."

I Cunning, at best, only duz the dirty i work of wisdom, therefore I despize it. — - ' Josh Billings.