HOW WOOD IS PRESERVED 155 



this loss should be decreased. The rapid increase in 

 price due to diminishing supply of the naturally durable 

 woods has forced the consumer of construction timbers 

 to substitute cheaper and less lasting species and this 

 fact alone will inevitably result in increased preserva- 

 tive treatment. 



Costs and Effects of Preservation. When it is realized 

 that at a cost of thirty-five cents for impregnation a 

 railroad tie costing seventy cents will last seventeen 

 years instead of seven, the economy of this practice can 

 be seen and the wisdom of the American wood consumer 

 in reducing the drain upon the nation's forests by the 

 use of preservatives can be highly commended. That 

 timber preservation is on a rapid increase is evident 

 when it is realized that during the past nineteen years 

 the number of plants for the treating of timber increased 

 from fifteen to one hundred and twenty-two. Of the 

 present number one hundred are of the pressure cylin- 

 der variety. 



During the past year nearly 80,000,000 gallons of 

 creosote, 27,000,000 pounds of zinc chloride and 2,500,- 

 000 gallons of other preservatives such as crude oil and 

 coal tar were used. Altogether 160,000,000 cubic feet of 

 timber was preserved which in the form of railroad ties 

 would be sufficient for a new line 1100 miles long. The 

 rapid rise of the preservation industry is a striking ex- 

 ample of the increasing economy which is being prac- 

 ticed regarding the products of the forest. 



