During the last few years a quantity of literature has appeared in which
the treatment of timber by preservatives has been discussed. The
properties of timber, both treated and untreated, have been determined
by the Forest Service, United States Department of Agriculture, and
through its researches valuable knowledge has come to engineers who have
to deal with the design of wooden structures. There is very little
information, however, regarding the effect of time on creosoted timber,
and for this reason the results given herewith may prove of interest.
The material tested consisted of southern pine stringers having a
cross-section approximately 6 by 16 in. and a length of 30 ft. For the
purpose of testing, each beam was cut into two parts, each about 15 ft.
long. This material had been in use in a trestle of a railroad near New
Orleans for 26 years. The stringers were chosen at random to determine
the general condition of the trestle. The timber had been exposed to the
weather and subjected to heavy train service from the time it was
treated until it was tested. The annual rainfall at New Orleans is about
60 in., and the humidity of the air is high. In spite of these
conditions, there was no appearance of decay on any of the specimens
tested. The specifications under which the timber was treated were as
follows: