Chapter V · ON SEASONING TIMBER BY PATENT PROCESSES, ETC. (continued 2)

We can only spare the space for a few words about this method.

1st. We have seen lead which has formed part of the gutter of a building previous to its being burnt down: lead melts at 612° F.; caoutchouc at 248° F.; therefore caoutchouc would not prevent wood from being destroyed by fire. At 248° caoutchouc is highly inflammable, burns with a white flame and much smoke.

2nd. We are informed by a surgical bandage-maker of high repute, that caoutchouc, when used in elastic kneecaps, &c., will perish, if the articles are left in a drawer for two or three years. When hard, caoutchouc is brittle.

Would it be advisable to interpenetrate oak with a solution of caoutchouc? In 1825, Mr. Hancock proposed a solution of 1½ lb. of caoutchouc in 3 lb. of essential oil, to which was to be added 9 lb. of tar. Mr. Parkes, in 1843, and M. Passez, in 1845, proposed to dissolve caoutchouc in sulphur: painting or immersing the wood. Maconochie, in 1805, after his return from India, proposed distilled teak chips to be injected into fir woods.

Although England has been active in endeavouring to discover the best and cheapest remedy for dry rot, France has also been active in the same direction.

M. le Comte de Chassloup Lambat, Member of the late Imperial Senate of France, considers that, as sulphur is most prejudicial to all species of fungi, there might, perhaps, be some means of making it serviceable in the preservation of timber. We know with what success it is used in medicine. It is also known that coopers burn a sulphur match in old casks before using them—a practice which has evidently for its object the prevention of mustiness, often microscopic, which would impart a bad flavour to the wine.

M. de Lapparent, late Inspector-General of Timber for the French Navy, proposed to prevent the growth of fungi by the use of a paint having flour of sulphur as a basis, and linseed oil as an amalgamater. In 1862 he proposed charring wood; we have referred to this process in our last chapter (p. 96).

The paint was to be composed of:

Flour of sulphur 200 grammes 3,088 grains.

Common linseed oil 135 ” 2,084 ”

Prepared oil of manganese 30 ” 463 ”

He considered that by smearing here and there either the surfaces of the ribs of a ship, or below the ceiling, with this paint, a slightly sulphurous atmosphere will be developed in the hold, which will purify the air by destroying, at least in part, the sporules of the fungi. He has since stated that his anticipations have been fully realized. M. de Lapparent also proposes to prevent the decay of timber by subjecting it to a skilful carbonization with common inflammable coal gas. An experiment was made at Cherbourg, which was stated to be completely successful. The cost is only about 10 cents per square yard of framing and planking.[14] M. de Lapparent’s gas method is useful for burning off old paint. We saw it in practice (April, 1875) at Waterloo Railway Station, London, and it appeared to be effective.

At the suggestion of MM. Le Châtelier (Engineer-in-chief of mines) and Flachat, C.E.’s, M. Ranee, a few years since, injected in a Légé and Fleury cylinder certain pieces of white fir, red fir, and pitch pine with chloride of sodium, which had been deprived of the manganesian salts it contained, to destroy its deliquescent property. Some pieces were injected four times, but the greatest amount of solution injected into pitch pine heart-wood was from 3 to 4 per cent., and very little more was injected into the white and red fir heart-wood. It was also noticed that sapwood, after being injected four times, only gained 8 per cent. in weight in the last three operations. The experiments made to test the relative incombustibility of the injected wood showed that the process was a complete failure; the prepared wood burning as quickly as the unprepared wood.

M. Paschal le Gros, of Paris, has patented his system for preserving all kinds of wood, by means of a double salt of manganese and of zinc, used either alone or with an admixture of creosote. The solution, obtained in either of the two ways, is poured into a trough, and the immersion of the logs or pieces of wood is effected by placing them vertically in the trough in such a manner that they are steeped in the liquid to about three-quarters of their length. The wood is thus subjected to the action of the solution during a length of time varying from twelve to forty-eight hours. The solution rises in the fibres of the wood, and impregnates them by the capillary force alone, without requiring any mechanical action. The timber is said to become incombustible, hard, and very lasting.

M. Fontenay, C.E., in 1832, proposed to act upon the wood with what he designated metallic soap, which could be obtained from the residue in greasing boxes of carriages; also from the acid remains of oil, suet, iron, and brass dust; all being melted together. In 1816 Chapman tried experiments with yellow soap; but to render it sufficiently fluid it required forty times its weight of water, in which the quantity of resinous matter and tallow would scarcely exceed ⅟80th; therefore no greater portion of these substances could be left in the pores of the wood, which could produce little effect.

M. Letellier, in 1837, proposed to use deuto-chloride of mercury as a preservative for wood.

M. Dondeine’s process was formerly used in France and Germany. It is a paint, consisting of many ingredients, the principal being linseed oil, resin, white lead, vermilion, lard, and oxide of iron. All these are to be well mixed, and reduced by boiling to one-tenth, and then applied with a brush. If applied cold, a little varnish or turpentine to be added.

Little is known in England of the inventions which have arisen in foreign countries not already mentioned.

M. Szerelmey, a Hungarian, proposed, in 1868, potassa, lime, sulphuric acid, petroleum, &c., to preserve wood.

In Germany, the following method is sometimes used for the preservation of wood: Mix 40 parts of chalk, 40 parts of resin, 4 of linseed oil; melting them together in an iron pot; then add 1 part of native oxide of copper, and afterwards, carefully, 1 part of sulphuric acid. The mixture is applied while hot to the wood by means of a brush, and it soon becomes very hard.[15]

Mr. Cobley, of Meerholz, Hesse, has patented the following preparation. A strong solution of potash, baryta, lime, strontia, or any of their salts, are forced into the pores of timber in a close iron vessel by a pump. After this operation, the liquid is run off from the timber, and hydro-fluo-silicic acid is forced in, which, uniting with the salts in the timber, forms an insoluble compound capable of rendering the wood uninflammable.

About the year 1800, Neils Nystrom, chemist, Norkopping, recommended a solution of sea salt and copperas, to be laid upon timber as hot as possible, to prevent rottenness or combustion. He also proposed a solution of sulphate of iron, potash, alum, &c., to extinguish fires.

M. Louis Vernet, Buenos Ayres, proposed to preserve timber from fire by the use of the following mixture: Take 1 lb. of arsenic, 6 lb. of alum, and 10 lb. of potash, in 40 gallons of water, and mix with oil, or any suitable tarry matters, and paint the timber with the solution. We have already referred to the conflicting evidence respecting alum and water for wood: we can now state that Chapman’s experiments proved that arsenic afforded no protection against dry rot. Experiments in Cornwall have proved that where arsenical ores have lain on the ground, vegetation will ensue in two or three years after removal of the ore. If, therefore, alum or arsenic have no good effect on timber with respect to the dry rot, we think the use of both of them together would certainly be objectionable.

The last we intend referring to is a composition frequently used in China, for preserving wood. Many buildings in the capital are painted with it. It is called Schoicao, and is made with 3 parts of blood deprived of its febrine, 4 parts of lime and a little alum, and 2 parts of liquid silicate of soda. It is sometimes used in Japan.

It would be practically useless to quote any further remedies, and the reader is recommended to carefully study those quoted in this chapter, and of their utility to judge for himself, bearing in mind those principles which we have referred to before commencing to describe the patent processes. A large number of patents have been taken out in England for the preservation of wood by preservative processes, but only two are now in use,—that is, to any extent,—viz. Bethell’s and Burnett’s. Messrs. Bethell and Co. now impregnate timber with copper, zinc, corrosive sublimate, or creosote; the four best patents.

We insert here a short analysis of different methods proposed for seasoning timber:—

Vacuum and Pressure Processes generally.

Bréant’s.

Bethell’s.

Payne’s.

Perin’s.

Tissier’s.

Vacuum by Condensation of Steam.

Tissier.

Bréant.

Payne.

Renard Perin, 1848.

Brochard and Watteau, 1847.

Separate Condenser.

Tissier.

Employ Sulphate of Copper in closed vessels.

Bethell’s Patent, 11th July, 1838.

Tissier, 22nd October, 1844.

Molin’s Paper, 1853.

Payen’s Pamphlet.

Légé and Fleury’s Pamphlet.

Current of Steam.

Moll’s Patent, 19th January, 1835.

Tissier’s ” 22nd October, 1844.

Payne’s ” 14th Nov., 1846.

Meyer d’Uslaw, 2nd January, 1851.

Payen’s Pamphlet.

Hot Solution.

Tissier’s Patent, 22nd October, 1844.

Knab’s Patent, 8th September, 1846.

Most solutions used are heated.

The following are the chief ingredients which have been recommended, and some of them tried, to prevent the decomposition of timber, and the growth of fungi:—

Acid, Sulphuric.

” Vitriolic.

” of Tar.

Carbonate of Potash.

” Soda.

” Barytes.

Sulphate of Copper.

” Iron.

” Zinc.

” Lime.

” Magnesia.

” Barytes.

” Alumina.

” Soda.

Salt, Neutral.

Salt, Selenites.

Oil, Vegetable.

” Animal.

” Mineral.

Muriate of Soda.

Marcosites, Mundic.

” Barytes.

Nitrate of Potash.

Animal Glue.

” Wax.

Quick Lime.

Resins of different kinds.

Sublimate, Corrosive.

Peat Moss.

For the non-professional reader we find we have three facts:

1st. The most successful patentees have been Bethell and Burnett, in England; and Boucherie, in France: all B’s.

2nd. The most successful patents have been knighted. Payne’s patent was, we believe, used by Sirs R. Smirke and C. Barry; Kyan’s, by Sir R. Smirke; Burnett’s, by Sirs M. Peto, P. Roney, and H. Dryden; while Bethell’s patent can claim Sir I. Brunel, and many other knights. We believe Dr. Boucherie received the Legion of Honour in France.

3rd. There are only at the present time three timber-preserving works in London, and they are owned by Messrs. Bethell and Co., Sir F. Burnett and Co., and Messrs. Burt, Boulton, and Co.: all names commencing with the letter B.

For the professional reader we find we have three hard facts:

The most successful patents may be placed in three classes, and we give the key-note of their success.

1st. One material and one application.—Creosote, Petroleum. Order—Ancient Egyptians, or Bethell’s, Burmese.

2nd. Two materials and one application.—Chloride of zinc and water; sulphate of copper and water; corrosive sublimate and water. Order—Burnett, Boucherie, Kyan.

3rd. Two materials and two applications.—Sulphate of iron and water; afterwards sulphate of lime and water. Payne.

We thus observe there are twice three successful patent processes.

Any inventions which cannot be brought under these three classes have had a short life; at least, we think so.

The same remarks will apply to external applications for wood—for instance, coal-tar, one application, is more used for fencing than any other material.

We are much in want of a valuable series of experiments on the application of various chemicals on wood to resist burning to pieces; without causing it to rot speedily.