THE FOREST PRODUCTS LABORATORY 

 Wood preservation. Open tank treatment on the left; commercial treating plant in the centre 



wood most effectively with the preserv- 

 atives. 



To study the first class of these prob- 

 lems, the laboratory is provided with a 

 fungus pit, which contains chambers in 

 which the wood can be thoroughly in- 

 oculated with various destructive fungi. 

 The humidity and temperature of the 

 pit can be regulated to produce condi- 

 tions most favorable to fungus growth. 

 Woods treated with different preserva- 

 tives are placed in this pit, where the}- 

 can be isolated in chambers. The ef- 

 ficiency of the preservative is indicated 

 by the ability of the wood treated with 

 it to ward off the attacks of fungi un- 

 der these conditions. 



The second class of problems involv- 

 ing the impregnation of wood are 

 chiefly those of mechanical engineering 

 and the plant of the laboratory is most 

 complete in this respect. It is. in fact, 

 a reproduction of a fully developed 

 commercial plant. The machinery is 

 provided for forcing any required 

 amount of preservative into the species 



and forms of wood which may be 

 tested. This is done under high press- 

 ure, and the treated cylinders are tested 

 for great resistance. The outfit in- 

 cludes one treating cylinder three and 

 one-half feet in diameter and twelve 

 feet in length, which will withstand a 

 working pressure of 300 pounds to the 

 square inch. There is also a small ex- 

 perimental cylinder one and one-half 

 feet in diameter and three feet long, 

 designed to withstand a working press- 

 ure of 600 pounds to the square inch. 

 This apparatus is connected with a sys- 

 tem of tanks, force, air, and vacuum 

 pumps for handling these preservatives 

 and forcing them into the wood. There 

 is also an open tank outfit for the sim- 

 pler treatment of butts of posts and 

 poles, such as is practicable for farmers 

 and others using much of this material 

 but not enough to justify having re- 

 course to a commercial plant. In this 

 connection it may be suggested that 

 time only can tell what and how 

 much superior value the closed tank 



397 



