6 BULLETIN 286, U. S. DEPARTMENT OF AGRICULTURE. 
RESULTS OF TESTS. 
The results of the bending tests on the natural and treated stringers 
are shown in figures 3 to 7. 
The diagrams were made by first plotting the values for modulus of 
rupture of the natural beams (solid lines) arranged from the highest 
to lowest, beginning with the highest value on the left at the top of 
the figure. The modulus of rupture of the treated half (dotted 
lines) of the test pieces was then plotted in the same vertical line as 
the untreated pieces. The two values are marked to distinguish 
butts (B) from corresponding tops (T). The other values (fiber 
stress at elastic limit and modulus of elasticity) for the same beams 
are plotted in the same vertical lines. 
Conclusions should not be drawn regarding the comparative effect 
of creosoting on the strength of the different woods, since they were 
not treated under similar conditions. It should also be kept in mind 
that the test material was not selected for the purpose of comparing 
the various species. 
LOBLOLLY PINE. 
Figure 3 gives a comparison of the strength and stiffness of natural 
and treated loblolly pine stringers for partially air-dry and seasoned 
material. In drawing conclusions from the diagrams it should be 
kept in mind that butt stringers are naturally stronger than second- 
cut or top stringers. This point was considered when the method of 
selecting the test material was determined upon and butts and tops 
were arranged to alternate in serving as treated and untreated 
material. It will be noted from figure 3 that when the butts were 
treated the breaking strength of the butts and tops fell rather close 
together, while when the tops were treated the breaking strength 
values were much farther apart. This shows an evident weakening 
due to the treatment, even when the lower breaking strength of the 
top stringers is taken into account. The tests are too few to make 
a definite statement as to the amount of weakening for the specific 
treatment under consideration. It is probably not more than 17 
per cent. The fiber strength at elastic limit and the stiffness both 
show a greater weakening due to treatment than does the breaking 
strength. The weakening is more marked in both strength and 
stiffness in the air dry than in the partially air-dry stringers. Both 
the treated and untreated stringers showed a strength about 30 per 
cent greater in the seasoned material than in the partially air-dry 
material. 
LONGLEAP PINE. 
In figure 4 the strength of treated and untreated longleaf pine 
stringers is compared for both partially air-dry and seasoned material. 
It does not appear that the breaking strength was affected by the 
treatment used with these stringers. There is a slight reduction in the 
