CHAPTER II: WOOD PRESERVATION 



The tendency of wood to rot when exposed to the weather, 

 and especially when placed in contact with the soil, and when 

 partially submerged in water, fresh or salt, is something every- 

 body knows. Season a stick of timber, then build it into your 

 house where it never gets damp and it is practically imperishable. 

 But lay it in the sill, and unless the foundation is exceptionally 

 high, dampness may creep up and fungous disease attack and 

 ultimately destroy the timbers upon which your house rests. 

 No matter how long the albuminous substance in the cells of sap 

 wood has been dry and inert, moisture softens it and it becomes 

 a favourable soil for wood-destroying fungi. Rot is the result. 

 Every decayed twig in the woods is a menace to the healthy trees. 

 In time it scatters disease far and wide. 



A telegraph pole a few years old breaks off at the ground in a 

 stiff wind storm. It is rotten to the heart. But the wood above 

 ground is sound; so it is below the surface. This is not a marvel. 

 Rot is an organism that breathes while it grows. Oxygen avail- 

 able for growth is not found far below the entrance. Rot is 

 dependent on moisture; the wind keeps the exposed parts of the 

 pole dry. Hence the rot is restricted to a narrow zone the 

 surface of the soil and the broken ends show how far its growth 

 has proceeded. Posts break off at the ground for like cause. 

 Piles in wharves rot off at some point between high and low water 

 mark. Railroad ties and paving blocks suffer a more general 

 decadence. Mine timbers fall a prey to their own particular 

 subterranean fungi. 



Weathering boards turn grey in the alternation of sun and 

 rain, heat and cold. The outer fibres weaken and disintegrate. 

 Oak can be scraped off with the finger nail. Hornets chew it into 

 pulp to build their paper castles. 



The protection and preservation of wood has been one of 

 the problems of civilisation. A vast body of experience has 

 accumulated, and we are nearer to-day to a satisfactory, a trium- 



536 



