PRESERVATION OF TIMBER, &c. 



569 



tended over a period of forty years, we 

 have seen almost every plan for the pre- 

 servation of timber, to a greater or lesser 

 extent, reduced to practice, but with no 

 very satisfactory result. We allude more 

 especially to timber employed in garden 

 buildings. That the timber used many 

 years ago for such purposes lasted longer 

 than it now does, is quite evident, and 

 not difficult to account for ; as in those 

 days the demand was not anything so 

 great, and the purchasers chose the very 

 best in quality for importation. The 

 case changed as the demand increased, 

 and anything in the shape of timber was 

 imported and readily sold. Again, our 

 timber merchants, and more especially 

 those who were to use it, formerly allowed 

 it sufficient time to season before it was 

 wrought up ; but competition and low 

 prices for carpenter work have now in- 

 duced both the wood-merchant and car- 

 penter to work up their material as soon as 

 possible, being unable to lose the interest 

 on their stock ; while the former, to supply 

 the latter with a cheap article, bought also 

 cheap, and took the timber most conve- 

 nient to be procured, and in many cases 

 even such as had been rejected by former 

 importers. We have been told by those 

 engaged in the Baltic wood trade that for- 

 merly every tree felled that appeared of 

 inferior quality was left upon the ground, 

 the good only being squared and shipped. 

 Such is certainly not the case now ; and 

 this accounts in a very great measure for 

 the prevalence of what is called dry rot in 

 buildings. 



Sir William Burnett's preparation. — 

 Amongst the many preventatives for 

 this evil, Burnettising has been recom- 

 mended. This invention has been pa- 

 tented by Sir William Burnett, and con- 

 sists in injecting a solution of chloride of 

 zinc into the timber by the application 

 of mechanical force; whereas Kyans 

 patent was simply steeping the timber 

 in a solution of corrosive sublimate or bi- 

 chloride of mercury, acting, so far as our 

 observation has extended, upon the outer 

 surface only, without penetrating to the 

 centre of the logs, blocks, or planks ; and 

 thus probably locking up the natural 

 sap or imbibed moisture, much in the 

 same way as paint does when applied to 

 the surface before the body is thoroughly 

 dry, and so producing the effect it was 



VOL. I. 



intended to counteract or prevent. Hy- 

 draulic power of great pressure is em- 

 ployed to inject the chloride of zinc 

 through the section, and consequently 

 through the pores of the wood from one 

 end of the tree to the other; and according 

 to the opinion of A. M. Mangin, Inspec- 

 tor of the French Navy, the operation 

 ought to be performed when the trees 

 have been recently felled, "for then all 

 its pores are open, and the sap is more 

 easily drawn from it and replaced by an- 

 other fluid. A very dry wood, of which 

 the pores are so close that in a manner 

 they disappear, would offer great difficul- 

 ties to such a preparation ; and there are 

 other hard woods " (we presume box to be 

 one) " with which it would be impossible." 



Testimonials as to the merits of this 

 invention have been obtained from many 

 of the most scientific men of the age. We 

 deem it sufficient, however, for our pre- 

 sent purpose, to make the following 

 extract from the testimonial of Professor 

 Graham, of University College, London. 

 " The wood appears to be fully and deeply 

 penetrated by the metallic salt. The 

 salt, although very soluble, does not 

 leave the wood easily when exposed to 

 the weather, or buried in dry or damp 

 earth. It does not come to the surface 

 of the wood by efflorescence, like crystal- 

 li sable salts. I have no doubt, from re- 

 peated observations made during several 

 years, of the valuable preservative quali- 

 ties of the solution of chloride of zinc ; 

 and would refer its beneficial action 

 chiefly to the small quantity of the metal- 

 lic salt which is permanently retained by the 

 ligneous fibre in all circumstances of exposure. 

 The oxide of zinc appears to alter and 

 harden the fibre of wood, and destroy 

 the solubility, and prevent the tendency 

 to decomposition, of the azotised principles 

 it contains, by entering into chemical 

 combinations with them." 



The preparation is formed by adding 1 

 lb. of the chloride to 10 gallons of water. 



Sulphate of copper has been recommend- 

 ed by a writer in the " Mechanics' Maga- 

 zine," vol. xxxviii. p. 568, as a preserva- 

 tive of timber, who instances the effects 

 in the mines in Cornwall and Anglesea, 

 where this salt abounds in the mineral 

 waters, the timber immersed in which 

 has been found very durable. This 

 composition is prepared as follows : 24 



4 c 



