ANTISEPTIC TREATMENT OF WOOD. 515 



or by a chemical test, to ascertain when the injection is 

 sufficient. Tr.] 



In order to inject logs satisfactorily by Boucherie's process, 

 a long time (up to 70 hours) and a large timber-yard are 

 required. The injected logs are dried slowly and as thoroughly 

 as possible, then they are barked and converted. 



When freshly felled stems are injected, the bark must be 

 preserved completely or the injecting liquid will escape. If, 

 however, they have been kept for about three months, the pre- 

 servation of the bark is not material, as the sapwood dries for 

 a few centimeters down and becomes impermeable for liquids. 



Another improved method based on that of Boucherie is 

 that carried out by Pfister.* Instead of pressure due to a 

 fall of about 30 feet, Pfister used a portable forcing-pump 

 producing a pressure up to 20 atmospheres, he thus drove 

 the injecting liquid through tubes into the wood, the tubing 

 being arranged so that it can be lengthened at discretion or 

 conducted at the same time to several logs. The advantages 

 of this method are, that the injection is effected more rapidly 

 than by Boucherie, and in the forest immediately after the 

 felling of the trees or poles without an;y necessity for trans- 

 porting them to the injecting works. 



Pfister's apparatus will inject thoroughly a beech-butt 

 10 feet long in about half an hour, it being immaterial 

 whether the bark is damaged or not. He also devised an 

 improved method of enclosing the base of the logs. The 

 apparatus, with several closing pieces of various sizes, costs 

 from 200 to 300. 



(b) Pneumatic injection. Antiseptic substances can be 

 injected into wood more effectually by means of a forcing- 

 pump than by the hydrostatic method, the process being 

 conducted much more rapidly ; at present in Germany 

 pneumatic injection is employed exclusively in the case of 

 chloride of zinc, creosote, acetic acid, etc. 



In this case the wood is converted into beams, scantling, 

 railway-sleepers, etc., and they are placed in large iron 

 cylinders (A, A] containing the injecting fluid, which, at 



* Dimitz und Bohmerle, " Ccntralblatt des gesammten Forslwesens," Vienna, 



L L 2 



