are not represented in the Exhibition, and therefore donot come before the Jury, though the machinery eni- tployed by Mr. Payne is exhibited, but without any spcci- :men of impregnated or preserved wood.
Sir AY. Burnett exhibits an interesting'series of speci-mens in illustration of his mode of preserving wood, &c.,and in proof of its efficacy (7, p. 196*). This process,which consists in impregnating it with a solution ofchloride of zinc, was patented in 1836, four years after .the date of Kyan’s patent, in which a solution of corro- !. sive sublimate was employed for the same purpose. Thespecimens shown are highly satisfactory, and clearlyprove the high preserving power of the solution of zinc. :The Jury awarded a Prize Medal for this process.
The specimens shown by Mr. J. Bethkll (21, p. 196*) ,are likewise highly interesting and satisfactory. The jprocess employed in this case, and for which a patent ;was obtained in 1838, consists in thoroughly impreg- jrating the wood with oil of tar containing creosote, and ■a crude solution of acetate of iron, commonly called py- jrolignite of iron. The idea of preserving wood by the iaction of oil of tar, or similar liquids, is by no meansnew. In 1756, Hales recommended that the planks of .ships should be soaked in vegetable oil to prevent theinjury to which wood is subject when alternately exposed ;to wet and dry; and, indeed, many ships were built in <which a hollow place was cut in one end of each beam 1or stern-post, so that it might be constantly kept filled ;with train oil. Among other ships so constructed, the“ Fame,” 74, may be mentioned. When, after someyears, this ship was repaired, it was found that, as far as !the oil had penetrated—namely, from 12 to 18 inchesfrom the end—the wood was quite sound, whilst theother parts were more or less decayed. In 1805, Mr.Maconochie proposed to saturate with resinous and oilymatters inferior woods, and thus render them more last-ing. This proposal was practically carried out in 1811by Mr. Lukin, who constructed a peculiar oven for thepurpose of thus impregnating wood under the influenceof an increased temperature. The scheme, however,had but very partial success, for either the heat was toolow and the wood was not thoroughly aired and sea-soned, or it was too high and the wood was more or lessscorched and burnt. The importance of oil as a pre-serving agent for wood is also shown by the fact thatwhalers, and other ships employed in the oil trade, thetimbers of which become thoroughly saturated with oil |or grease, invariably last longer—and are less subject todecay of any sort—than other vessels. It is also wellknown that the staves of old tallow-casks jnake a morelasting and durable fence than any other sort of wood—an effect entirely due to the protecting influence of theoil with which they have become saturated.
The operation, as conducted by Mr. Bethell, is carriedon in a strong cylindrical vessel connected with a power-ful air-pump, so that in the first instance a vacuumbeing formed, and subsequently a pressure of severalatmospheres applied, the liquid may as much as possible ;be forced into all the pores of the wood. It is statedthat wood thus prepared is not only protected from de- ;cay, and from the attacks of insects, but also that it ;becomes stronger and tougher in consequence of the layerof bituminous matter with which the woody fibre becomes 'encrusted. Among the specimens exhibited are portionsof railway sleepers which have been in use for severalyears, and which are perfectly sound, whilst others from :the same situation, but not prepared, are quite destroyed.Portions of piles which have been four years in The sea inLowestoft harbour, and which are quite sound, are alsoshown. This process has been extensively employed in thepreparation of railway sleepers for more than ten years,and the result of its application appears in every ease to ibe highly satisfactory where the process has been well :and properly conducted. The Jury therefore awardeda Prize Medal for it to Mr. Bethell/ (See p. 153.)
The mere seasoning of wood, though it will not al-together prevent its decaying, nevertheless considerablydiminishes its tendency to do so, and is of the very utmost ,importance in many cases. The value of any process for •seasoning wood depends, of course, to some extent, on the !
time required for its completion. A valuable series ofspecimens is shown by Mr. C. II. Newton (2U, p. 196*) inillustration of Davison and Symington’s patent processfor speedily and effectually seasoning wood by exposing itto the influence of a rapid and continuous current ofheated air, so that it soon becomes thoroughly dry. Thepractical value of this process appears to he satisfactorilyproved, and the Jury accordingly deemed it worthy ofHonourable Mention/
A fine specimen of elm, cut across the grain, and wellseasoned by steeping in water and very slow drying, isshown by Sir AY. Murray, Bart. (137, p. 208*).
A sample of Welch oak, stated to be seasoned by anew process, which renders it better suited to the pur-poses of the cabinet-maker, is exhibited by AY. Evans(9a, p. 196*).
The collection of East Indian woods, exhibited by theHonourable East India Company (p. 884) is by far themost extensive series of woods in the whole Exhibition,and constitutes a very valuable part of the great collec-tion of Indian raw produce. It is remarkable for thelarge number of specimens, the excellence of many ofthem, and the valuable practical information to be gainedby their examination. The collection consists of manyhundred specimens, and includes several minor or localcollections of great interest. Amongst these are thevaluable collections of Drs. Roxburgh and Wallich(884, 885) ; and extensive series of the woods of the Malaypeninsula , Amherst, Tavoy, Tenasserim, Prince of ValesIsland, Assam, Cuddapah, Madras, Orissa , &c.
Considering the extent and importance of Dr. Wal-lich’s collection, the Jury would certainly have awardedto him a medal had not the fact of his being a member ofthe Jury precluded them from doing so. They awarded aPrize Medal to Mr. Commissioner Blundell (p. 885), fora very valuable collection of Amherst woods. They alsoawarded a Prize Medal to Messrs. Almeida of Singapore(p. 890), for fine specimens of Lir.goa-wood and Kayu-buka.
1 he smaller series of woods contributed by Messrs. A.P. Onsi.ow, of Ganjam ; I). Mayne, of Cuddapah (p. 188);Walter Elliott of Yizagapatam; J. K. Chapman;Lieut.-Col. Ti lloch ; The Commissary-Gknkp.al ofMadras; Captain Ogilvie, of Masulipatam : CaptainMaitland, and Major Balfour, of Madras ; Dr. Hunter,of Madras: Dr. Wight, of Coimbatore ; Captain Mar-quart, of Chittagong; and J. K. Colvin, of Moulmein (pp. 888, 891), were also severally deemed worthy of Ho-nourable Mention.
The nature and properties of many of these Indianwoods is very little known: and though, for the mostpart, it is not probable that it would he found worth■while to import them into Europe , yet their importanceto India is every year increasing, and must necessarilycontinue to do so, as the demand for timber in India forrailways and other engineering works increases. Forsuch uses it is desirable, not only that the wood shouldbe strong and not liable to decay from mere exposureto the weather, but, also, that it should work freely,and be able to withstand the ravages of the variousinsects to which wood of all kinds is more or lessexposed in tropical countries. It is true that even themost porous and spongy woods may he rendered tosome extent capable of resisting all such influences, bybeing impregnated with various solutions, as in the pro-cesses just adverted to; but it is obviously far better,when possible, to select such woods as are naturallysaturated with resinous and aromatic substances, as inthis latter case all cost of preparation is saved, besidesthat the preserving matter is far more perfectly disse-minated throughout the whole of the wood than canpossibly be effected by any artificial process after thetree is felled.
1 n examining the comparative value of different sorts ofwood, it is of the first importance to ascertain the natureof the encrusting matter deposited throughout the cellsand tubes of the wood. For all practical purposes, thosewoods appear to be best in which the cells are lined withresinous matter; those filled with hygroscopic gummymatter are, for the most part, of less value: they areseasoned with difficulty, and are always more liable to