Seasoning of Timber. 



249 



starch, sugar, and oils, form the food supply necessary for the 

 growth of fungi. Without oxygen, no fungus growth will take place, 

 and as there is insufficient oxygen in water and in the deeper 

 layers of the soil, wood remains sound for a longtime under such 

 circumstances. The best examples of this necessity for oxygen 

 can be found in the way in which fence posts and telegraph poles 

 decay at points at or immediately below the surface of the 

 ground, where both air and water are present in sufficient quan- 

 tity. For practical purposes water is the most important factor. 

 Without water no fungus growth, and consequently no decay, is 

 possible. Too much water will prevent fungus growth, because 

 it shuts off the supply of air. The amount of water necessary 

 to permit the growth of fungi is very small. Wood freshly cut 

 contains more than enough at all seasons of the year to support 

 fungus growth. 



From the foregoing it will be evident that the removal of 

 water from timber brings about a condition which prevents the 

 growth of wood-destroying fungi. In other words, perfectly dry 

 wood will not decay, or, at most, decay will be very slow. 



Seasoning is ordinarily understood to mean drying. But 

 seasoning, von Schrenk observes, implies other changes besides 

 the evaporation of water. Although we do not yet fully under- 

 stand the difference between seasoned and unseasoned wood, it 

 is very probable that it consists in changes in the albuminous 

 substances in the cells and fibres of the wood, and possibly also 

 in the tannins, resins, and other incrusting and saturating sub- 

 stances. Whether the change in these substances is merely a 

 •drying out, or whether it consists in a partial decomposition, is 

 as yet undetermined. That the change during the seasoning 

 process is a profound one there can be no doubt, because 

 •experience has shown again and again that seasoned wood fibre 

 is very much more permeable, both for liquids and gases, than 

 the living, unseasoned fibre. One can picture the albuminous 

 substance as forming a coating which dries out, and possibly 

 •disintegrates, when the wood dries. The drying out may result 

 in considerable shrinkage, which may make the wood fibre more 

 porous. It is also possible that there are oxidising influences 

 at work within these substances which result in their disintegra- 

 tion. Whatever the exact nature of the process may be, one 



