FOREST SERVICE. 413 



manufacture of ground wood pulp. The section of distillation 

 studies the possibility of dcA'eloping valuable chemical by-products 

 of wood by distillation processes. This section should greatly 

 reduce waste by recovery of materials such as alcohol, turpentine, 

 oils, and gums, in which many of our conmiercial woods are ricli. 



The second group, properly called the physical group, contains 

 the sections of wood preservation, pathology, and wood physics. 

 Wood preservation covers the treatment of wood by substances to 

 improve its durability or appearance. The preservative treatment of 

 wood, as an industry, is new in the United States, but of rapi<lly 

 increasing importance, and it is already beginning to work a notice- 

 able reduction in the waste of wood caused by decay, insects, and 

 marine borers. Many of the fundamental problems are yet to be 

 solved, anil on these the section of wood preservation is working. 

 Closely allied with it is the section of pathology, which investigates 

 the diseases of wood. The Bureau of Plant Industry furnishes the 

 personnel of this section and supervises its technical methods. The 

 section of wood pliysics investigates the microscopic structure of 

 wood and the relation between structure and physical properties, 

 such as strength, toughness, and penetrability to liquids. It has 

 many problems awaiting it. 



The third group contains two sections, which rest substantially 

 on mechanical engineering. It may, therefore, be called the engi- 

 neering group. The first is the section of timber tests, which seeks, 

 througli mechanical tests, relial)le data on the relative value of our 

 commercial woods for specific purposes. The second section, that of 

 engineering, has to do mainly with the design of equipment and 

 machines to be used for the discovery and demonstration of metlioils 

 to reduce waste. Efficiency in lessening wood waste will depend 

 in great part upon the efliciency of the machines and equipment 

 designed ror the work. Third in this group is the section of main- 

 tenance, which cares for the upkeep and unimpeded operation of 

 tiie laboratory. 



Progress was made during the year in projects which pertain to 

 the work of these three groups, as follows: 



Chemical Studies. — ^-V revision of gum turpentine specifications 

 was undertaken and is still in progress. As a basis for the revision, 

 flash-point and sjiecific-gravity tests were made on a large number or 

 samples. Approximately 125 moisture-determination tests were 

 made in connection with the strength tests of treated timbers. 

 Study of methods of analysis of turpentine were continued. In 

 the turpentine-refining still built for the Forest Service, as announced 

 in last year's report, several samples of four barrels each of crude 

 wood turpentine were refined. Iliis still is a three-product, con- 

 tinuous-column still of new design. It was found that the proj)or- 

 tion of refined turpentine j)roduced was greater tiian that proiluced 

 by the old methods at the conmiercial jdants from the same crude 

 turpentine; and the feasibility of using a continuous-column still 

 over the old-form still was demonstrated. 



In testing the fiber value of difierent woods for pulp purposes, 

 58 soda cooks were maile on 13 difierent species, ami bleach tests 

 were made on 48 samples. Effort in this ficKl was, however, mainly 

 given to working uj) the investigations of ])revious years and to 

 installing the ecpiipment in the new lal)oraiory. 



