10 



BULLETIN 1231, U. S. DEPARTMENT OF AGRICULTURE. 



of the site, and the geographical situation. Coal-tar creosote and 

 carbolineums have been found to be the most effective preservatives. 

 Several coats of coal-tar creosote brushed on timber will add from 

 2 to 5 years to its life. In the tests at Falls Church, Va., brushing 

 with coal-tar creosote (three coats applied hot) was more effective in 

 preventing attack by termites than was dipping in the hot preserva- 

 tive. As has been stated, much depends upon the preservative. 



/9/2 /9/3 /9/4 /9/5 /9/6 /9/7 /9/8 /9/9' /920 /92/ /S22 

 SUPEPF/C/fiL TXEfiTMEA/TS. 



Fig. 3. — Comparison of the relative resistance to attack by termites of chemical 

 wood preservatives and methods of treatment, Palls Church, Va., 1912-1922. 



Heavy or thick coatings of tar for the bases of poles or posts are 

 not effective and are valueless as preservative treatments. Many 

 patented or proprietary preservatives or methods failed after short 

 periods of test and are not referred to, except in a few cases. 



IMPREGNATION TREATMENTS. 



Methods by which the preservative is more thoroughly impreg- 

 nated into the wood more permanently protect wood from insect at- 

 tack. These methods of course are more expensive. Inspections of 



