188 ANNUAL REPOETS OF DEPAETMENT OF AGEICULTUEE. 



bleeding, the chief causes for dissatisfaction with wood paving 

 hitherto. Inspections of experiments installed during past years 

 made possible the preparation of the most exhaustive record ever 

 compiled on the durability of various species of timber treated under 

 various methods with different preservative compounds. 



The discovery that sodium fluoride is superior to sodium carbonate 

 in preventing sap stain promises to reduce materially the present 

 estimated annual loss of $7,000,000 from this cause. A fire-testing 

 house constructed during the year duplicating conditions in modern 

 office buildings will permit future tests of great practical value in 

 the fireproofing of wood finish. Other tests on fireproofing com- 

 pounds have given a much more exact measure than has ever before 

 been available of the comparative value of the compounds in the 

 market, and have further resulted in the development of a new com- 

 pound by the laboratory staff which will be patented and dedicated 

 to the public. 



About TO species of hardwoods and 40 species of conifers were 

 tested to show their relative resistance to decay, and about 900 tests 

 were made on the toxic properties of wood preservatives. 



In timber physics the most important work of the year was the 

 further development of methods of kiln drying originally devised by 

 the laboratory staff and the working out of variations adapted to 

 different species, together with the cooperative demonstration of 

 these methods on a commercial scale. The Service method is based 

 upon full control of temperature, moisture, and circulation during 

 the period of drying. Dipping in paraffin was shown to reduce 

 materially the tendency of wood to shrink and swell. 



Improved methods for the manufacture of ground-wood, soda, 

 and sulphate pulps showed the possibility of increasing yields 20 

 per cent under the former and 5 per cent under each of the latter 

 processes, while other methods were worked out for eliminating the 

 " f uzziness " from soda pulp. For the first tim.e methods were de- 

 veloped for making a good kraft paper from longleaf pine stumps 

 from which the turpentine and rosin had previously been extracted. 



INDtrSTEIAL INVESTIGATIONS. 



The collection of statistical data on various forest products was 

 continued. In general, the year was one of overproduction and slack 

 business in the principal lumber manufacturing regions. A report 

 on the amount of wood preservatives used and the amount of timber 

 treated in the United States showed a considerable falling off in the 

 use of the principal preservative (creosote) in 1914 as compared 

 with 1913, due probably to conditions induced by the European war. 



Eeports on the wood-using industries of three States were pub- 

 lished. Thirty-three State reports of this character have now been 

 issued. A final report on the wood-using industries of the United 

 States is in preparation, in which the data collected in the various 

 studies will appear by species and by industries. 



Records of lumber prices for important woods, useful in establish- 

 ing timber-sale prices and in answering inquiries as to the range of 

 price of certain kinds and grades of lumber, were compiled quarterly. 



A wood-waste exchange was established, to bring together manu- 

 facturers of wood products who had waste to dispose of and manu- 



