ON THE DECAY AND PRESERVATION OF WOOD.

Southland Times, Issue 1565, 19 April 1872, Page 2

ON THE DECAY AND PRESERVATION O F WOOD.

By James Hanat*. The first attempt at preserving wood by impregnation with mineral matter, which was brought into public notice, was thought of by a Mr KLyan. His solution consisted of lib corrosive sublimate in lOgals. of water. So elated was he at his so-called invention that he took out a patent for it, which was purchased by a company, called the " Anti Dry R >t Company," constituted and empowered by special Act of Parliament. A large wooden tank is filled with the solution, and the timber is steeped in it from two to four days, accorJiuo; to size It will peuetrate soft wood | to 1 of an inch, hard wood, such as oak, to -J of aa inch, and pitch pine and fir to only i of an inch. This solution baa long been used to preserve furs, stuffed animals, birds, &c, from the ravages of insects ; and this is ono of the best uses it can be put to. It has the effect of softening and not of hardening the wood to which it is I applied, and keeps it always in a moist ( atitte. Corrosive sublimate is one of the most virulent and penetrating poisons known. Mr Ryan's application of it to .wood cannot rightly be claimed as an invention, nor had he any right to call it after his own name, " Kyanising." I believe the wisest part of it was the sale of it. Professor Farraday and other scientific men gave testimonials and spoke in the strongest manner of the efficacy of this solution for seasoning and preserving wood. Professor Cooley, in his Practical Receipts, a standard book for chemists, recommends the sublimate to be used in varnish to coat over valuable paintings, to preventthein being destroyed by small insects. This is theory without practice, for it would destroy the pointing by turning it black, particularly the lights, which contain carbonate of lead. The beautiful pigment vermillion, also a preparation of mercury, will turn black or russetty if exposed to the sun's rays. What to mis with it to prevent this is only known to chemical artists, and they are few and far between. In ecenepainting, skilful artists use Venetian red, and red oxide of lead, in preference, as gas light does not impair their effect. This by the way. The sleepers on the South Western Railway, in England, were all steeped in Mr Kyan's solution. Eight years after, many of them were found to be rotten, but the engineer said that he did not consider it conclusive evidence against the process a » i a that case it had been hastily performed. A fatal objection I consider is that nails, screws, and bolts of iron, in'coutact with timber prepared with this solution, rust and eat away in a short time. The next attempt was by Sir "William Burnett, M.D., whose process professes, like the foregoing, to preserve timber, canvas, cottons, woollens, felt, and cordage, from mildew, moth, and dry rot, by a solution of 1 lb chloride of zinc in 4 gallons of water, for wood, and in 5 gallons of water for the other articles. The timber is steeped in the mixture two days for every inch in thickness ; — thus timber 3 inches by 9 inches would require sir days. The pieces when taken out are set up on their ends in a shed for periods varying from a fortnight to three months, according to the thickness, after which they are fit for use. At the Navy Dockyards at Portsmouth, the timber is put into a large iron tank in the form of a cylinder, 50 feet long by 6 feeb in diameter, and the solution forced into the wood by hydraulic pressure, to the enormous amount of 150 lbs to the square inch. Under this, process, eight hours is considered sufficient for the largest logs, and it is believed to penetrate the wood more than double as far as when it is merely steeped. This chloride of zinc, or white copperas, is a rank corrosive poison, sometimes used to make paints dry. If articles, such as woollens, cordage, cottons, or canvas be saturated with it, it will make them rotten, unless indeed they are exposed to the rain to wash it out. It might even be attended with fatal consequences should it drain out into human food, or on a man's back during perspiration. It is claimed that it renders the material to which it is

ipplie;! less liable to combustion. I rrant this ; but not to half the extent hit a solution of alum would have, vvhile the alum would not do the slightest harm. It is well known that muslins or cottons impregnated with alum will not : )laze, though they may smoulder away. Both these solutions, being poisons, prevent the wood from beco-ning worm------eaten. In a" dry situation out of the sun they will make the wood last longer. In dimp places t ! ie last ia far the best; but neither of the n will make wood with-sfc.-ind the' elements, and resist fie combined actiou of moisture and heat afc 9.) degrees of Fahrenheit, particularly when the wood is exposed to constant alternations of wet, hea.t, and wind. It is inexplicably strange that so many dubbed with the letters C.8., M D , and B.A , did not know the reason why, which is si:nply this : — lf we dissolve any of the" base metals by sublimating, carbonising, or oxidizing-, they will readily rair with water, aud the constant weu will draw them all out. As the artisan would say, they want some other material to bind them. Hanansvale Mill, Forest Hill, April 2nd, 1872.