FOREST SERVICE. 409 



(1) The study of different preservatives in order to determine 

 their toxic properties and their relative vakie for the preservative 

 treatment of wood under difi'erent conditions of use. 



(2) Studies of methods of impregnating wood in order to deter- 

 mine the best mechanical method of injecting the required amount 

 of various preservatives into different species of wood. 



(3) The apphcation of wood preservation to permanent improve- 

 ment w^ork on the National Forests, and assistance to outside parties 

 in applying the principles to the commercial treatment of timber. 



(4) The inspection of treated test timbers set to determine their 

 durability under different conditions of use when treated with various 

 chemicals and by different methods of treatment. While logically 

 this would be included under class 1, the amount of time put upon 

 this work and the importance of the results secured make it worthy 

 of special mention. 



In studying preservatives, their chemical and physical properties, 

 the ease with which each kind can be forced into the wood, its toxic 

 properties, its effect upon the strength and other mechanical proper- 

 ties of wood, and its effect upon the inflammability of wood are 

 learned. Very Uttle systematic work of this kind has ever been done, 

 and the results now being obtained are proving of great service in 

 determining the relative value of chfferent preservatives for the treat- 

 ment of wood under different conditions of use. Several pieces of 

 special apparatus have been developed for conducting these tests, 

 the most important of which are the fungus pit and apparatus for 

 studying the manner in wliich preservative fluids penetrate the wood. 

 The fungus pit is a concrete chamber beneath the floor of the labora- 

 tory, 10 feet by 20 feet in size. This chamber is divided into com- 

 partments, in which the temperature and humidity of the atmosphere 

 can be regulated. In the compartments specimens of various kinds 

 are subjected to attack by vigorous growths of wood-destroying fungi. 

 By means of the fungus pit it is possible to secure records of the 

 durabihty of treated and untreated woods in much less time than 

 under natural conditions. Thirty of the most promising wood pre- 

 servatives, including practically all those commercially important at 

 the present time, are now being studied. 



To determine how piling may best be protected against the attack 

 of marine organisms, sections of piles treated with different preserva- 

 tives and protected in various mechanical ways, set in San Francisco 

 Bay and m San Diego Bay, are being examined periodically and 

 notes taken on their condition. These experiments, wliich must 

 continue through at least two or three years, and possibly longer, 

 will be of great assistance to engineers and others concerned with con- 

 struction work in waters affected by the teredo and limnoria. 



An important investigation has been undertaken to determine the 

 relative efficiency of different fractions of creosote. Commorcial 

 creosote is a mixture of a number of different oils, varying widely in 

 their chemical and physical properties, and it is important to know 

 what constituents are most effective in protecting woods from decay 

 and other destructive agencies. A representative commercial creo- 

 sote was distilled into a number of fractions so as to separate the 

 different classes of oils of which it is composed, and specimens of 

 loblolly pine were treated with different quantities oi each. Some of 

 the treated specimens are exposed to the attack of marine organisms, 



