106 



Forest Club Annual 



tried with a number of poles and while a pressure of 15 pounds 

 per square inch was maintained for a short time, this line of 

 experimentation was abandoned because of the high handling 

 charge and because equally good results were obtained by open 

 tank methods. 



The experimental plant consisted of a heavy round iron 

 tank eight feet deep and seven feet in diameter in which to 

 stand the poles ; and two very small galvanized iron tanks for 

 use as cold bath dips, or for special experiments as with crude 

 oil where only a small quantity of the preservative could be 

 used for the bath. There was also a 3,000 gallon storage tank 

 of galvanized iron in which to store the creosote while giving 

 the zinc treatments. The poles were handled by -means of a 

 donkey hoist engine with steel cable and a mast and boom. 



The open tank method of treating timber depends upon the 

 two propositions ( 1 ) that dry wood is a porous material full of 

 air and (2) that air expands and contracts very noticeably when 

 heated and cooled. The propositions are practically applied by 

 heating wood in a hot bath of any liquid preservative, expanding 

 the air contained in the wood until a part of the air escapes and 

 then cooling the wood by a cold bath until the contained air 

 shrinks in volume and draws a quantity of the preservative into 

 the wood. 



Success with this method depends upon the characteristic 

 wood structure of the species handled. Each species presents 

 new problems that must be solved before it can be treated to 

 best advantage, that is, of securing the deepest penetration with 

 the smallest quantity of preservative. Western Yellow Pine can 

 be very effectively treated by this method. 



The first series of runs with the creosote consisted, in treat- 

 ing the poles with a single long hot bath of oil heated at 170 to 

 200. F. for three hours and then allowing the bath to cool to 

 air temperature. This treatment requires from 15 to 24 hours. 

 The results are tabulated below . 



TABLE 5. POLE TREATMENTS WESTERN YELLOW PINE. 

 Creosote Open Tank. 



