Vilas County news. [volume] (Eagle River, Vilas County, Wis.) 1896-1927, 1905-04-10
poultry of all kinds, for that is the
only kind that pays"
Treatmens that Weaken Timber.

The bureau of forestry had in oper-.
alton at the st. Louis exposition an
experimental plant for testing the in
fluence of preservatives upon the
strength of green and seasoned tim
Der. Most processes involve three
stages-a preliminary treatment to-
! fit the wood for the next one, the ac-
tual introduction of a chemical agent
and an operation which tends to seal
the pores. Thus, steaming is some
times resorted to as a preparatory
measure. The two chemicals to,
which the most attention was given
were creosote and chloride of zinc. A
press bulletin recently issued by the,
bureau gives some details about the,
methods followed in conducting the
inquiry and the conclusions thus far
reached To render the comparisons
as instructive as possible, the 11-foot
timbers with which the experiments
were made were taken from the same
forest.
Because Of fears that defects OF
brittleness of treated timbers might
under slowly-applied loads, provision
was made for both that class Of tests
and others in which there was a sud-
den blow or impact. The test pieces
were subjected to cross-bending strain.
compression along the grain under
both slow pressure and impact condi-
tons. The data taken include the
moisture conditions, specific gravity
and rate of growth. During the treat
ing operations records wer kept of the
temperature to which the timbers
were subjected to all stages. the
amount of water lost or gained, and
of the amount of personalities absorb
ed as indicated by gross weight and
subsequent chemical analyses of the
test pieces.
While this program is not sufficient
ly advanced to allow the drawing OF
final conclusions, yet the preliminary
results are fairly indicative of what
may he expected It is found tha1
the steaming process weakens the
resistance of the wood fiber to both
steady pressure and impact loadings
II may be stated that this diminution
of strength is very nearly in direct
proportion to the length of time that
anv given steam pressure is applied.
The diminution of strength was found
to be Is percent after a pressure OF
20 pounds was applied for 10 hours
tog reen 1oblolly pine and to per cent
when a pressure of 20 pounds was ap-
pie dior four hours. This diminutlon
of strength increased very rapidly
when the pressure rose above 20
pounds, and amounted to about 20
per cent when pressure of SO pounds
was applied for four hours.
It will be easily seen that when the
conditions of time and pressure are
made very severe the conditions pre-
vailing in a pulp mill industry will be
approximated. Evidently it is well to
avoid, when possible, the use OF
these preliminary steaming opera
lions in the wood preserving Industry.
with relation to the effect of pres
ervation themselves, the latter Is DIS
tinct from the preliminary process.
It may be said that the treatment with
zinc chloride does not seem to further
reduce the strength of timber beyond
the effect of the steaming process.
This might have been expected when
it is considered that the strength OF
the solution ordinarily used does NOT
exceed 21h per cent. The strength 81
timber that had been treated with the
21b per cent solution OF zinc CHLORIDE
after having been steamed four hours
at 20 pounds pressure was the same
as that of timber which had been
steamed without the subsequent APP
plication of zinc chloride. The same
statement may be made of timber
treated with an 81b per cent solution
of zinc chloride. 1t may be that SUD
seorently the crystalization OF the
salts will weaken the wood fiber. This
remains to be determined.
The effect of the creosote appears
to be the same as that OF an equal
amount of water in weakening the
fiber. That is to say, the strength OF
creosoted timber is that of green tim
ber The difference is that while green
timber gains strength upon seasoning
the creosote oil remains in the wood
and it appears from analysis OF pile
35 years Old that the oil remains in a
LIQUID condition. Consequently com
parison between seasoned timber and
creosoted timber will always result TO
the disadvantage of the latter as far
as it's strength is concerned. In the
case of creosoted wood. it also re-
mains to determine what changes
in the wood fiber take place throu@h
lapse of time in the presence or creo-
sote oil.