Processes for Wood-preservation. 197 



condition of oak long buried. It is claimed to be particularly 

 serviceable for mining timbers and the like, much exposed to moist- 

 ure, and therefore liable to decay. It is understood that this process 

 is being largely adopted by the Eastern lluihvay in France and by 

 the telegraph service, under the co-operation and authority of the 

 Ministry of the Interior. 



780. The Houtln and Bontiymj Process, aims to hermetrically close 

 the ends of the wood, so as to neutralize the property of absorbing 

 moisture. This might be done, either by covering with some hydro- 

 carbon, as, for example, coal oil, or by charring the end, and then 

 plunging it, while hot, in a melted mixture of pitch, tar, and gum- 

 lac, or by covering the whole piece with tar in the usual manner. 



781. Tke Kynnizing Process-. On the 31st of March, 1832, Mr. 

 John H. Kyan took out an English patent fora process for prevent- 

 ing timber from decay, by penetrating the tissues with a solutu n 

 of the bi-chlunilc <>f int'i-riiry, or "corrosive sublimate." 1 This was 

 done by placing the timber in large tanks, so that it could not float, 

 and then submerging it with the solution for about a week. It was 

 afterwards found necessary to apply pressure, equal to about 100 

 pounds to the inch. The .strength of the solution was finallv fixed 

 at about 1 pound to 15 gallons of water, although as strong as 1 

 pound to 2 gallons had been used. 



782. There appear to be still conflicting facts for and against this 

 method, and although formerly much practiced, it is now seldom 

 used. The value of corrosive sublimate as a wash to kill dry-rot, 

 and to prevent insect injuries in wood, had been long known, and it 

 is still employed by botanists for preserving dried specimens from 

 insects. Its agency as an antiseptic was ascribed to the coagulation 

 of albumen in the tissues of the wood, and perhaps the differences iu 

 effect were due to the greater or less abundance of this material in 

 the wood, or in permeability of the pores by which it could be 

 reached. The principal objections against this process were its ex- 

 pense and the exceedingly poisonous nature of the material used, 

 which rendered it dangerous to the health of the workmen em- 

 ployed. 



783. The Margary Process, patented in England iu 1838, consists 

 in immersing in a solution of acetate or sulphate of copper. 



1 This material had been proposed by Knowles and Davy in 1821, but not 

 practically applied. In 1837, Letellier proposed to use it with gelatine. 



