190 FARM FORESTRY 



value of woods for different purposes determined. Formerly 

 the knowledge had of woods came from their use alone and 

 often erroneous ideas in regard to woods were held, as for 

 example, the idea that the heartwood of hickory was inferior 

 to the sapwood for use for making wagon spokes. Many 

 woods have been found to be adapted for different uses that 

 were formerly considered worthless, and many new uses have 

 been found for our common woods. 



THE DIFFERENT PROPERTIES OF WOODS 



Weight, hardness, strength, durability, elasticity, tough- 

 ness, heat production, color, odor and taste are some of the 

 properties of woods that make them valuable for use. 



Weight. — The weight of different woods varies greatly. 

 Cork oak of the Southern swamps is lighter than cork, weigh- 

 ing not more than one-fifth as much as water. Ironwood 

 weighs a third more than water. The wood substance itself 

 is heavier than water, weighing one and one-half times as 

 much. In the form of wood, however, because of the large 

 amount of air enclosed in the cells, the weight of a piece of 

 wood is usually much less than the weight of the same volume 

 of water. Most of our commercial woods when dry weigh less 

 than water, weighing from one-half to three-fourths as much. 

 The weight of wood depends on the wood substance itself and 

 the amount of water contained. Only a few of our woods 

 will float when first cut. Most coniferous woods will float 

 when green and a few of the lightest hardwoods, like cotton- 

 wood. This often enables them to be floated or driven down 

 streams to the sawmill. All woods weigh much lighter when 

 dry and seasoned than when green and full of water. Some 

 woods lose over half their weight in drying. 



Woods show a great variation in density, even in the same 

 species of tree and also from the same tree. This variation 

 depends on the rate of growth, quality of the locality in whicli 

 the tree was grown, age of the tree, the part of the tree from 



