STRENGTH TESTS OF STRUCTURAL TIMBERS. 11 
and fiber stress at the elastic limit was considerably less in the treated 
material (35 and 36 per cent, respectively), and the stiffness was 
slightly less. 
Table 1 gives the average values of the strength functions shown in 
the diagrams, together with the highest and lowest values and some 
additional data. 
SMALL PIECES CUT FROM STRINGERS. 
Table 2 gives the average strength and stiffness of the small pieces 
cut from the main beams for both treated and natural material of the 
three species under test. The average values of the small pieces cut 
from the outside portions of the main beams and the average values 
of the small pieces cut from the interior portions are also given. No 
moisture determinations were made on the small pieces cut from the 
treated longleaf and loblolly pine timbers. The determinations for 
moisture in various parts of the cross sections of the treated timbers 
of these two species indicate that in general they contained slightly 
more moisture than the natural pieces. The treated sticks are in 
general weaker than the natural sticks, but the difference is slight 
except for partially air-dry loblolly pine. Part of the apparent loss 
in strength of the treated material may be ascribed to its higher 
moisture content. 
In the Douglas fir treated by the boiling process and tested green, 
the average for the outside sticks- shows a decrease in strength over 
the natural, with but little difference in stiffness. As compared with 
the natural sticks the treated sticks cut from the interior of the main 
beams showed a more marked drop in strength and stiffness. The 
air-dry material in all cases showed a decided decrease in the strength 
of the treated sticks. The decrease in stiffness was less marked. 
Part of this decrease may be accounted for by the higher moisture 
content of the treated pieces. 
