FOREST SERVICE. 643 



WOOD PRESERVATION. 



Studies made during the year in wood preservation dealt with (1) 

 the preservative; (2) the wood, its penetrability and resistance to 

 decay; and (3) methods of injection, 



E«sults secured in an experiment with mine timbers in actual 

 service showed that while untreated gangway sets have an average 

 life of only from 1 to 2 years, the same timbers, when brush 

 treated with coal tar, will last from 3 to 4 years, and when im- 

 pregnated with zinc-cldoride solution, or creosote, are, as a rule, en- 

 tirely sound at the end of 4 years. Inspections made during the 

 year of 8 test tracks, laid at various times since 1902 with treated 

 and untreated ties, showed that with one exception all the treat- 

 ments used have increased the durability of the ties over that of 

 similar untreated material. The test tracks have not been in service 

 long enough to permit of definite conclusions as to just how much the 

 natural life of ties can be prolonged by treatment, but that it may in 

 many cases be doubled, or even trebled, seems certain. Untreated 

 loblolly pine and hemlock ties laid in Texas lasted only 1.5 years, 

 while of those treated by the Burnett process over TO per cent are still 

 serviceable after 7 years. 



Many new preservatives are either being proposed or marketed. 

 A number of such preservatives were tested during the year, and 

 their physical, chemical, and fungicidal properties, their penetrative 

 qualities, and the inflammability of wood treated with them de- 

 termined. While many gave little evidence of usefulness, a few 

 were found which prornise to be of value either in reducing the cost 

 of treatment or in increasing its efficiency. 



To determine by a quick method the comparative efficiency of 

 various preservatives in preventing the growth of fungi, tests were 

 made with pure cultures of fungi in specially prepared cultural 

 media. Results so far secured are of special interest in showing 

 for any given preservative the proportion necessary to prevent the 

 growth of fungi. 



Creosotes derived from different sources, or from tars produced 

 by different methods or at different temperatures, vary in their physi- 

 cal and chemical properties and in their efficiency as wood preserva- 

 tives. To study the extent of this variation, an examination of 

 authentic samples of tars collected from various sources was begun. 

 The work involves a great number of precise determinations, and 

 probably another year will elapse before final results are obtained. 

 These are expected to afford a rational basis for classifying creo- 

 sotes in accordance with their cliemical and pliysical i^roperties. 



The study of the relative efficiency of creosote fractions, begun 

 last year, was continued and extended. The tests now comprise 

 determinations of the efficiency of the various fractions in prevent- 

 ing attack by marine organisms, in ])i-eventing decay, and in prevent- 

 ing the absorption of water by paving blocks. A second set of pile 

 sections, treated with lesser amounts of the various fractions than 

 those placed the previous year, were set in the Gulf of Mexico and 

 in San Francisco T?ay. Data on tho volatilization of various frac- 

 tions of creosote after their injection into wood, secured in connection 

 with this experiment, indicate that the creosote, to be of most value, 

 at least for loblolly pine, should contain considerable (juantities of 



