248 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



A 40-page catalogue of service tests of railroad ties, covering all 

 installations on Avhieli the lal)oratt)ry is keei)ing ins])ection records, 

 was completed and printed in the 1920 proceedings of the American 

 Wood Preservers' Association. This information is of great value to 

 railway engineers and Avood preservers. Service-test records of posts, 

 poles, piling, and other forms of timber were ol)tained and made 

 available to farmers, telephone and electric companies, engineers, and 

 architects. As a result of experiments by the laboratory demon- 

 strating the value of sodium fluoride, two railroad companies and one 

 mining company have decided to use this material for the preserva- 

 tive treatment of railroad ties. 



The effect of different amounts of various chemicals added to 

 hardwoods previous to distillation has been studied. It was found 

 that the addition of a small amount of sodium carbonate increases 

 tlie yield of wood alcoliol by from 50 to GO per cent without seriously 

 affecting the yields of the other valuable products. The method is 

 effective, however, only Avhen the material for distillation is in the 

 form of small pieces of wood or sawdust briquettes. In cooperation 

 with the Bureau of Mines, a study was started to determine the value 

 of different fractions of hardwood tar as flotation oils. The cooper- 

 ators have already reported that certain of the tar-oil fractions show 

 great promise of becoming excellent substitutes for pine oil, which is 

 the most universal and most expensive flotation oil now in use. 



A line of work which may lead to results of far-reaching import- 

 ance was the production of a stock food by a process similar to that 

 develoj^ed for the manufacture of ethyl alcohol from sawdust. In 

 this process the wood cellulose is first converted into a sugar by treat- 

 ing the saAvdust with a dilute solution of sulphuric acid under pres- 

 sure. The acid is then neutralized and the sugar solution after 

 evai^oration to a thick molasses is combined with the dried residue 

 to form a brownish meal somewhat resembling bran. A stock feed 

 prepared in this way showed, on preliminar}^ tests, great promise of 

 being a valuable carbohj'^drate food. 



The study of seasoning southern SAvamp oaks in vehicle sizes repre- 

 sents one of the tAvo most important ncAv investigations in kiln dry- 

 ing undertaken during the year. The other is an iuA^estigation into 

 the operation of commercial kilns of A^arious types, with special ref- 

 erence to drying efficiency, cost of operation, and relatiA^e cost of kiln 

 drying and air drying. luAestigations have been completed at tAVO 

 plants and are under way at a third. The experimental work on 

 the effect of kiln drying on the strength of aircraft Avoods has been 

 nearly completed, only a fcAv kiln runs on cypress still remaining to 

 be done. 



Giving advice to commercial concerns in the solution of their kiln- 

 drying problems is a matter of daily routine. While the majority of 

 the requests for help are handled through the mails, many manu- 

 facturers and engineers visit the laboratory to receiA^e more detailed 

 assistance. The saving in stock, time, and otherwise brought about 

 by the application of this advice has been A^ery great, amounting in 

 at least one case to as much as $300 per day. Forest Service Avater 

 spray kilns have proved so satisfactory in actual operation that they 

 have been installed or are being built not only in the United States 

 but in India, Australia, New Zealand, and Mexico. 



