62 



FORESTRY AND IRRIGATION. 



t'ebruary, 



It will be necessary to test all pre- 

 servatives side by side under similar 

 conditions, in order to determine which 

 one is of the most value. An experi- 

 ment has been started with this end in 

 view in southern Texas, where the de- 

 cay of timber takes place with the greatest 

 rapidity. 



When a suitable method of impreg- 

 nation is found, it will be possible to 

 increase the length of life of many tim- 

 bers several times. The question is one 

 of particular interest to the railroads, 

 as they use such enormous quantities of 

 timber every year. Successful impreg- 

 nation will mean the utilization of infe- 

 rior timbers, which no one wants now 

 because they decay so fast, such as the 

 Tamarack, Loblolh^ Pine, Lodgepole 

 Pine, and Swamp Oak. When they are 

 preserved, these timbers will be as serv- 

 iceable as the scarcer and higher-priced 

 timbers. This will allow of the utiliza- 

 tion of vast amounts of timber which 

 are now not used, and will admit of a 

 more careful exploitation of the scarcer 



.^JliL. 



FIG. 3. THE BROWN PUNK TRAMETES PINI, 

 GROWING ON SHORTLEAF YELLOW PINE. 



The decay of structural timber can 

 be prevented for a considerable period 

 by properly drying lumber before using 

 it. Much is yet to be learned as to the 

 length of time necessary to dry timber, 

 so as to increase its length of life. 



For many years engineers have en- 

 deavored to find some method for pre- 

 venting this decay in structural timber 

 by injecting various substances into the 

 wood. These were put there to kill 

 any fungus which had started to grow 

 in the wood. Those most used are coal- 

 tar oil, zinc chloride, copper sulphate, 

 and mercuric chloride. Varying de- 

 grees of success have been obtained with 

 these materials, depending upon the 

 kind of timber used and the climate 

 where the timber was exposed. We 

 know very little as yet concerning this 

 subject, although there is every pros- 

 pect of success in this research. On 

 some European railroads ties have been 

 made to last thirty years and more. 



FIG. 4. SECTION OF SHORTLEAF YELLOW PINE, 



SHOWING THE WAY IN WHICH THE FUNGUS 



DESTROYS THE WOOD AND THEN GROWS 



OUT THROUGH AN OLD BRANCH. 



