410 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Others to wood-destroying fungi. These test specimens are l^eing 

 inspected in the same way as the treated piles already described. 



Experiments under way in cooperation with the agricultural 

 department of the Uuiversity of Wisconsin, to ascertain whctlier or 

 not treated wood in silos would affect the quality of the silage, indi- 

 cated a probability that treatment can be used to lengthen the life 

 of the wood and to })ermit cheaper woods to take the place of the 

 expensive woods now employed. 



The structure of different species of wood varies widely, some 

 having so many open ducts that it is possible to force fluids into them 

 with great ease, while other species are very resistant to the fluids. 

 A correlation of the structure of woods with the best methods of 

 treating them with different fluids was sought through tests which 

 should also be of value in connection with the wood-pulp investi- 

 gations. 



Experiments in the open-tank treatment of paving blocks were 

 made in cooperation with the University of Washington. Wood 

 paving blocks when properly treated make an excellent pavement for 

 streets. If blocks can be treated by the inexpensive open-tank 

 method, their use for paving might be widely extended, especially in 

 small municipalities distant from commercial treating plants but at 

 the same time having an adequate supply of cheap wood. 



Demonstration work is carried on by the Service to verify experi- 

 mental results on a commercial scale or to assist in the practical 

 application of processes with which the laboratory is thoroughly 

 familiar. It is frequently possible to secure in tliis way important 

 new data. Usually this work is carried on in cooperation with rail- 

 roads or other companies which place their facilities at the disposal 

 of the Service for the experiments and demonstration. Such projects 

 include the treatment of ties in cooperation with the Chicago, Mil- 

 waukee & St. Paul Railroad Co., the application of principles of wood 

 preservation to mining timbers in cooperation with the Anaconda 

 Copper Mining Co., and the installation of 39 sets of test timbers of 

 various kinds, including crossties, piles, poles, paving blocks, and 

 fence posts in cooperation with companies and individuals interested 

 in the problem of wood preservation. 



Wood Distillation. 



The wood-distillation studies of the year were confined to prob- 

 lems bearmg on the distillation of resinous woods, especially southern 

 yellow pine and Douglas fir. Distillation processes successfully 

 applied to these woods would have great economic importance in the 

 utilization of forest and mill waste. The wood-distillation industry 

 has been placed upon a good business basis in the Southeastern States, 

 and to a lesser extent in the Puget Sound region, where sufhcient 

 quantities of cheap wood, such as lightwood, pine knots, etc., are 

 available. The application, however, to the general run of mill and 

 forest waste depends upon the development of apparatus which will 

 greatly cheapen the present cost of production. 



Experiments in steam distillation investigated (1) the minimum 

 amount of steam required for the extraction of the volatile oils from 

 yellow pine and Douglas fir, (2) the size of the chips required to 



