FOREST SERVICE. 411 



secure the best results, and (3) the relation of the yield of products to 

 the duration of the treatment. 



These experiments yielded many significant results. They will be 

 continued to learn how the process may be profitably apphed to 

 materials givuig much lower yields of products than those now 

 obtained. 



Important results were obtained from a study of the subject of 

 refining and grading the crude products of distillation. The com- 

 mercial success of distillation plants often pivots on the ability 

 of the manufacturer to produce a marketable product. The paint 

 and varnish trades frequently object to wood turpentines, and they 

 are marketed at a great disadvantage as compared with gum tur- 

 pentine. By refining commercial samples from plants using different 

 processes, including destructive and steam distillation and extrac- 

 tion processes, the results showed that, using a continuous-column 

 still with a capacity of 25 gallons of crude oil per hour, it was possible 

 in every case to obtain a marketable turpentine, and in most cases a 

 product free from objectionable odors. Samples of the turpentine pro- 

 duced were sent to different paint and varnish manufacturers, and 

 were tested by them. The tests showed that in general the greatest 

 difference between gum turpentine and wood turpentine affecting 

 the value of the latter is the odor, but that there is also a difference 

 in the solvent power and drying properties. In some cases the wood 

 turpentines were slightly superior to the gum turpentine vath which 

 they were compared, and m other cases not quite as good. To 

 demonstrate the commercial practicability of the apparatus, the 

 experimental still was set up at the plant of the Atlantic Turpentine 

 Co., at Mount Pleasant, Ga., the cooperating company bearmg the 

 entire expense of shipping and instalhng the apparatus. The results 

 showed conclusively that the still could be readily applied to the re- 

 fining of wood turpentine on a commercial scale. As a result of this 

 demonstration several distillation plants have decided to install 

 improved apparatus for the refining of their products. 



Wood Pulp and Paper. 



The pulp and paper studies covered the mechanical grinding 

 process, the chemical processes, and the suitabihty of different woods 

 for both classes of pulp. So far as the immediate needs of the paper 

 trade are concerned, the work with ground pulp is of greater im- 

 portance. The consumption of news and cheap print papers has 

 mcreased verj^ rapidly during the past 20 years, and will doubtless 

 continue to increase. Mechanical pulp is produced almost entirely 

 from spruce. Hundreds of millions of dollars have been invested in 

 mills which are depending upon this species for their raw material. 

 On the other hand, the supply of spruce in the United States is 

 rapidly nearing exhaustion, and it seems probable that the future 

 of the mechanical pulp industry in the United States depends upon 

 its ability to find a substitute. For the manufacture of chemical 

 pulp also new raw materials are required. 



One serious difficulty in the past in connection with the pulp and 

 paper investigations of the Forest Service has been the lack of means 

 for accurately describing the qualities or properties of a pulp. During 

 the year much progress was made in overcoming this difficulty 



