14 AMERICAN FORBST TREES 



gftHK** Buckeye and red cedar fence posts, situated alike, will not 

 last alike. The buckeye may be expected to fall in two or three years, 

 and the cedar will stand twenty. Timbers light in weight and light in 

 color are, as a class, quick-decaying when exposed to the weather. 



The rule holds in most cases that sapwood decays more quickly 

 than heart when both are subject to similar exposure. The matter 

 of decay is not important when lumber and other products intended for 

 use are in dry situations. Furniture and interior house finish do not 

 decay under ordinary circumstances, no matter what the species of wood 

 may be; but resistance to decay overshadows almost any other consider- 

 ation in choosing mine timbers, crossties, fence posts, and tanks and silos. 



Decay in timber is not simply a chemical process, but is due 

 primarily to the activities of a low order of plants known as fungi, 

 sometimes bacteria. The fungi produce thread-like filaments which 

 penetrate the body of the wood, ramifying in and passing from cell to 

 cell, absorbing certain materials therein, and ultimately breaking down 

 and destroying the structure of the wood. Both air and dampness are 

 essential to the growth of fungus. That is the reason why timbers deep 

 beneath ground or water do not decay. Air is absent, though moisture 

 is abundant; while in the dry Egyptian tombs, air is abundant but 

 moisture is wanting, fungus cannot exist, and consequently decay of the 

 wood does not occur. Nothing is needed to render timber immune to 

 decay except to keep fungus out of the cells. Some of the fungus 

 concerned in wood rotting is microscopic, while other appears in forms 

 and sizes easily seen and recognized. 



Timber may be protected for a time against the agencies of decay 

 by covering the surface with paint, thereby preventing the entrance of 

 fungus. By another process, certain oils or other materials which are 

 poisonous to the insinuating threads of fungus, are forced into the pores 

 of the wood. Creosote is often used for this purpose. Attacks are thus 

 warded off, and decay is hindered. The preservative fluid will not 

 remain permanently in wood exposed to weather conditions, but the 

 period during which it affords protection and immunity extends over 

 some years; but different woods vary greatly in their ability to receive 

 and retain preservative mixtures. 



The better seasoned, the less liable is timber to decay, because it 

 contains less moisture to support fungi. It is generally supposed that 

 Umber cut in the fall of the year is less subject to decay than if felled in 

 summer. If it is so, the reason for it lies in the fact that fungus is inac- 

 tive during winter, and before the coming of warm weather the timber 

 has partly dried near the surface, and fungi cannot pass through the 

 dry outside to reach the interior. Timber cut in warm weather may be 



