CHAPTER XII 

 HOW WOOD IS PRESERVED 



ONE of the greatest drawbacks to the extensive use 

 of wood is that while it is easily worked and the first 

 cost is comparatively slight, it may be expensive in the 

 long run because it is subject to decay, especially when 

 used in contact with the ground. 



Reasons for Decay. Decay in wood as in any sub- 

 stance is due to the action of bacteria and fungi and as 

 a rule timbers containing considerable moisture and 

 sugar are much more subject to disintegration. The 

 agencies causing decay must have food, oxygen, a cer- 

 tain amount of heat and water in order to live and 

 thrive, and if any one of these necessities is removed 

 from the wood, decay can be postponed for a long time 

 or prevented altogether. If a fence post has been thor- 

 oughly seasoned before being put into the ground it will 

 last much longer than one which was used green, as the 

 moisture in the freshly cut stick is favorable to the 

 action of the bacteria and fungi. If air is cut off from 

 timber the agencies causing decay cannot work and that 

 is the reason the oak found in English bogs and the pile 

 foundations of the Swiss lake dwellings are in such a 

 splendid state of preservation. 



Methods of prolonging the life of wood have long 

 been known, for in the earliest times the Ancients 

 succeeded in preventing decay by impregnating timber 

 with cedar oil or coating their statues with oils or by 



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