AN IMPROVED METHOD OR PROCESS OF TREATING WOOD TO PREVENT ITS DECAY AND ITS DESTRUCTION BY THE TEREDO NAVALIS OR BY SIMILAR AGENCIES
Year: 1878

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for the Invention of
" AN IMPROVED METHOD OR PROCESS OF TREATING WOOD TO PREVENT ITS
DECAY AND ITS DESTRUCTION BY THE TEREDO NAVALIS OR BY SIMILAR
AGENCIES." A communication from abroad by Waldemar Thilmany, of Cleve-
land, Ohio, United States of America, Civil Engineer.
Sealed the 5th April 1878, and dated the 6th February 1878.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 6th February 1878.
"
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. AN IMPROVED METHOD OR PROCESS OF TREATING
WOOD TO PREVENT ITS DECAY AND ITS DESTRUCTION BY THE TEREDO NAVALIS OR
BY SIMILAR AGENCIES." A communication from abroad by Waldemar Thilmany, of
Cleveland, Ohio, United States of America, Civil Engineer.
This Invention relates to an improved method or process of treating wood to
prevent the decay of the same and to protect it from the attack of the marine
animal termed teredo navalis.
In practising the said Invention the wood may be first steamed in a closed
cylinder or chamber to drive off the sap, moisture, and other matters. After the
wood has been thus steamed a vacuum is created in the said chamber by the action
of a pump; then the wood is charged with a solution of sulphate of zinc and iron,
either combined or separately. The proportion of the solution of sulphate of either
the zinc or iron should be about one pound of the same to one hundred pounds of
water, more or less, depending upon the nature of the wood and the purpose for
which the treated wood is designed. The surplus liquid or residuum is discharged
from the chamber, and then a solution of chloride of barium is forced or charged
into the wood. The proportion of chloride of barium used with the sulphate of zinc
or of iron is about two-thirds by weight of that of sulphate of zinc or of iron in one
hundred pounds of water, that is to say, in case three pounds of sulphate of zinc or

page_text: iron with one hundred pounds of water is used therewith, it would require about two
pounds of the chloride of barium with one hundred pounds of water, depending upon
the circumstances above mentioned, to charge the same wood.
The solution of the chloride of barium may be first used in this process in place
of sulphate of zinc or iron after the wood has been subjected to the action of steam,
as specified, whereby a decomposition of the two soluble salts takes place in the
pores and cells of the wood, forming therein insoluble sulphate of baryta and chloride
of zinc or iron, depending upon which of these metals has been used.
It must be understood that this Invention does not comprise the use of the
chloride of barium or sulphate of zinc or of iron taken separately, but it comprises
for the purposes set forth charging the timber with a solution of the chloride of
barium and a solution of the sulphate of zinc or of iron after the wood has been
steamed, or without steaming the same.
The various steps in the said improved process of treating wood are as follows,
that is to say-The wood or timber is placed in a closed chamber of iron or copper
capable of sustaining the pressure to which it may be subjected by the steam or
otherwise in the process, say five to eight atmospheres, more or less. By these
means the crude sap, moisture, and like matters are vaporized, and the soluble parts
or matter of the wood climinated and drawn off by a vacuum pump, and a vacuum
being formed in the chamber, the wood becomes very readily charged. I now intro-
duce under hydrostatic pressure a solution of either sulphate of iron or sulphate of
zinc, thus filling the cells and pores of the timber therewith. I now draw off the
surplus solution in the chamber, and then introduce a solution of the chloride of
barium under hydrostatic pressure. Then the elective chemical affinity directly
decomposes the soluble zinc or iron salts, forming the insoluble sulphate of baryta
and chloride of zinc or of iron in the cells and tissues of the wood, although the
chlorides of zinc and iron are soluble alone, but when combined with the sulphate of
baryta there is formed (according to the metal used) chloride of zinc or of iron,
which becomes so united in the tissue of the wood that it cannot be washed out
when exposed to the action of water or moisture, and by these means, together with
insoluble sulphate of baryta, the decay of the wood is arrested.
As herein-before stated, it is unimportant which form of salt is first introduced,
the final result will be the same.
The chloride of barium and sulphate of zinc or sulphate of iron are soluble sepa-
rately, but when brought together are by elective chemical affinity decomposed,
forming the insoluble sulphate of baryta and chloride of zinc or of iron which are
active agents in resisting the inroads of parasites and decay.
In treating large timbers, such as piles and pieces for docks, ships, and similar
structures, it may not be convenient to subject such pieces to the action of steam in
a chamber. In such instances it is deemed sufficient to charge such timbers with
the sulphate of zinc or of iron and the chloride of barium without subjecting the
pieces first to the action of steam. These agents may be forced into and through
the structure of the wood by hydrostatic pressure. In this manner the crude sap
and albumen of the wood are driven off, and their place will be taken by the solu-
tions of the chloride of barium and sulphate of zinc or of iron, and the result of this
mode of treatment will be the same as when the wood is first steamed, but such
treatment is only necessary for large timbers, the process being slower than when
the wood is first steamed.
In treating large timber outside of a boiler the bark should be allowed to remain
upon the same to prevent the elimination of the above-named agents from the
wood during the process.
There are connected with the vessel in which the wood is treated the requisite
devices for the proper carrying out of the said process, and the steam is conveyed to
the treating vessel or chamber from the boiler by means of a pipe.
The advantages of using the chloride of zinc or of iron are that the wood may be
treated in either an iron or wood tank or chamber, and these agents, namely, chloride
of zinc or of iron, will not attack the iron and other metal fastenings of a ship and

page_text: other structures when exposed to moisture, or either salt or fresh water; the action
of the said zinc tends to toughen the fibres of the wood; the said process is attended
with little cost comparatively; and the cost of these chemical agents is slight.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that in this process I do not claim separately the use of chloride of barium or of
sulphide of zinc or of iron, but I claim,-
First. The method or process of treating or preparing wood, consisting in sub-
jecting the wood to the action of steam in a cylinder or chamber, and then charging
the pores and fibres thereof with the solution of sulphate of zine or of iron, and
saturating the wood with a solution of the chloride of barium, as above described
and for the purposes set forth.
Second. In the process of preparing timber for the purposes set forth, the treat-
ment of the same, whereby the fibres are charged or combined with a mixture of
sulphate of baryta and chloride of zinc or of iron by hydrostatic pressure, as herein
described.
Third. In the process of treating or preparing wood or timber for the purposes
set forth, charging the wood with sulphate of iron or of zinc and with chloride of
barium either with or without the preparatory treatment by steam, as herein
described.
•
Fourth. In the process of treating or preparing wood to prevent its decay or its
destruction by parasites, the treatment of the same to combine with the woody
fibres the sulphate of zinc and the chloride of barium, as above set forth.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Sixth day of February, in the year of our Lord One
thousand eight hundred and seventy-eight.
W. ROB. LAKE. (L.S.)