ANTISEPTIC TREATMENT OF WOOD. 511 



corrosive sublimate being a strong poison has also the draw- 

 back of injuring the workmen who are employed in handling 

 it ; it also corrodes iron and is somewhat volatile at ordinary 

 temperatures. Tr.] 



Creosoting with heavy oils from coal-tar is employed chiefly 

 in Britain, and is now being used increasingly in France, 

 Germany and other countries ; although the method of injec- 

 tion now employed is capable of improvement, it is undoubtedly 

 superior to injection by metallic salts. Creosoted wood is 

 hard, tough and black, much less absorptive of moisture than 

 uncreosoted wood, and does not form chemical combinations 

 with metals. On the Emperor Ferdinand Railway, in Austria, 

 a mixture of chloride of zinc and carbolic acid is being used 

 with good results. 



Ely the at Bordeaux injects wood with steam containing 

 tar-oils. [Boulton considers that no good can result from 

 this, the light oils being too volatile to remain long in the 

 timber; on the other hand, the injection of heavy oils in 

 the form of vapour is prevented by their high boiling point 

 ranging from 400 to 760 F., while timber is rendered 

 brittle and unsafe for engineering purposes at a temperature 

 of 250 F. Tr.] 



Stuart Monteith first used milk of lime to fill the pores of 

 timber; this method has been reintroduced by Frank and 

 is useful for preserving furniture and other woodwork under 

 cover, but its utility is doubtful for wood in the open. 



2. Methods of Injection. 



The method of injecting wood by the various substances 

 already referred to is as influential on the result as the anti- 

 septic substance itself. The most important methods are : 

 hydrostatic injection, pneumatic injection, imbibition by 

 immersing or boiling the wood in solutions of the antiseptic 

 substances. 



(a) Hydrostatic injection. At first the antiseptic liquids 

 were absorbed by the natural force of the foliage raising the 

 sap, incisions being made with this object at the base of the 

 stem of a standing tree. This method was abandoned owing to 

 its impracticability [and the fact that the foliage exerts only an 



