CHAPTER II. PRESERVATIVES 



Sedtion 1. Cause of Decay 



181. At ordinary temperatures wood is a stable com- 

 pound. Unless it is acted on by some outside agency it will last 

 forever. When we speak of wood rotting we mean that it 

 has been attacked by a fungus. The fungi have no green 

 leaves and cannot draw their food from the soil and air as 

 trees and other plants with green leaves do. They must 

 feed on the tissues of other plants. It was pointed out at 

 Paragraph 136 that the fungi sometimes feed on standing 

 trees. They also feed on timber when it is cut. 



Sedtion 2. Conditions of Decay. 



182. The fungi must have several conditions to live. 

 First of all the organism itself must be present, either in the 

 form of spores or fragments of a mature plant. An experi- 

 ment running over many years was made by the late Profes- 

 sor W. H. Brewer, of Yale, which proved that wood does not 

 rot no matter how favorable the other conditions are, pro- 

 vided the organism is not transplanted to it. The other con- 

 ditions are air, water, heat, and food^all of which must be 

 present in sufficient quantities or a fungus cannot live and 

 grow after it has been transplanted. Timbers that have 

 been buried where the air could not reach them have lasted 

 for centuries. Timbers used in dry places do not decay; the 

 so-called dry rot is in places where there is some moisture. 

 Timbers kept at low temperatures do not decay; and decay is 

 more rapid in warm climates than in cool climates. And 

 timbers which have been poisoned and rendered unfit for 

 food for the fungi do not decay. 



