STRENGTH TESTS OF STRUCTURAL TIMBERS. 3 



Longleaf : 



5 treated partially air dry and tested. 



5 tested partially air dry. 



5 treated partially air dry, seasoned, and tested. 



5 seasoned and tested. 

 Loblolly: 



5 treated partially air dry and tested. 



5 tested partially air dry. 



5 treated partially air dry, seasoned, and tested. 



5 seasoned and tested. 



DOUGLAS FIR. 



The material was selected at two western mills. In both cases 

 the test timbers were shipped to the creosoting companies within a 

 few days after they were sawed from logs at the mill, and were treated 

 within a few days after arrival at the creosoting plants. The pieces 

 as selected were 8 inches by 16 inches in section and 32 feet long, 

 and included three grades of material — select, merchantable, and 

 common, as classified by the grading rules of the West Coast Lum- 

 ber Manufacturers' Association. It is customary to use only select 

 and merchantable timbers in permanent structures. These pieces 

 were cut in two just before treatment, so that the test stringers 

 measured 16 feet. Two processes of treatment were used, the "boil- 

 ing" process and the "steaming" process. The material which was 

 seasoned before testing was piled in a shed with open sides. The 

 number of 16-foot test stringers used in studying the effect of the 

 two processes, and their condition when treated and tested, was as 

 follows : 



Boiling process: 



20 treated green and tested. 



20 tested green. 



19 treated green, seasoned, and tested. 



19 seasoned and tested. 

 Steaming process: 



15 treated green and tested. 



15 tested green. 



treated green, air seasoned, and tested. 



seasoned and tested. 



METHODS OF TREATMENT. 



The preservative treatments to which the three species of struc- 

 tural timber were subjected were briefly as follows: 



LOBLOLLY PINE. 1 



Steamed for 4 hours under 29 pounds pressure; vacuum of 26 inches applied for 1 

 hour; cylinder filled with creosote and pressure of 125 pounds applied for 4J hours at 

 a temperature of 140° F.; vacuum of 23J inches applied for \ hour. Absorption of oil, 

 13 \ pounds per cubic foot of wood. 



i Run made Mar. 4, 1908. 



