IMPROVE- MENTS IN PRESERVING WOOD FROM DECAY
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ARTHUR
HOWE HOLDSWORTH, of Brookhill, in the County of Devon, Esquire, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-first day of January, in the third year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Arthur Howe Holdsworth, Her especial licence, full power, sole privilege and
authority, that I, the said Arthur Howe Holdsworth, my exors, adñiors,
and assigns, or such others as I, the said Arthur Howe Holdsworth, my
exors, adñiors, or assigns, should at any time agree with, and no others, from
time to time and at all times during the term of years therein expressed,
should and lawfully might make, use, exercise, and yend, within England,.
Wales, and the Town of Berwick-upon-Tweed, my Invention of " IMPROVE-
MENTS IN PRESERVING WOOD FROM DECAY;" in which said Letters Patent is:
contained a proviso that I, the said Arthur Howe Holdsworth, shall cause
a particular description of the nature of my said Invention, and in what
manner the same is to be performed, to be inrolled in Her said Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
""
.

page_text: .
NOW KNOW YE, that in compliance with the said proviso, I, the said
Arthur Howe Holdsworth, do hereby declare the nature of my said Invention,
and the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof (that is to say) :-
The object of my Invention is to preserve wood or timber from decay by
immersing in it certain liquids having the following properties, namely, of
receiving a temperature under common atmospheric pressure capable of
charring or searing the surface of wood exposed to their action, and of con-
creting or hardening more or less by subsequent cooling, so as to remain
in those pores into which they have previously entered, as well as to cover the
surface of the wood, and thus preserve it from the injurious effects of air
and moisture.
The substances that may be employed for this purpose are,―
First, natural bitumens, solid or liquid, such as asphaltum or petrolium.
Second, the tarry matter produced in the distillation of coal, whether such
matter is in its usual state of liquidity or in that of its products, where it has
been subsequently inspissated.
Third, common or wood tar, as well as the products into which it is
converted by distillation, namely, common pitch and essential oil of tar.
Fourth, turpentine and the products into which it is converted by distil-
lation, namely, oil of turpentine and common rosin.
Fifth, tallow and other fixed oils, or fats of animal or vegetable origin.
All the above substances, when at their respective boiling temperatures, are
much hotter than. boiling water, and therefore any one of them used by
itself for a sufficient length of time might produce on wood immersed
in it when boiling the searing or charring, which is one of the effects
contemplated by this my Invention. But, as some of them are of too
thick a consistence when melted, and as others (being liquid at common
temperatures) will not concrete sufficiently in the pores of wood, I find it
advantageous to mix them in various suitable proportions. That mixture
which I have found to answer my purpose best is composed in the following
manner I put into an iron pan, or other suitable vessel, one gallon or any
number of gallons of wood tar, and dissolve therein, by the application of a gentle
heat, common, that is, wood pitch, in the proportion of two pounds to every
gallon of tar.
I then add tallow, in the proportion of two pounds to every
gallon of tar, and, when this has likewise been melted and well mixed, I
add coal tar in the proportion of half a gallon for every gallon of wood tar.
The above mixture may be made either in the same vessel as is used for the
subsequent process, or in a separate one; and, when local circumstances will

page_text: permit, I prefer to make the mixture in one vessel, and to apply it to the
wood in another. The shape of the former of these vessels is immaterial,
provided there is a fireplace, by means of which a moderate degree of heat
can be given to the mixture contained in such vessel. The latter vessel, being
that in which the wood is to be placed, is most convenient if made of a
quadrangular form, the proportions of which will depend on the size and
shape of the timber to be operated on. It ought to have bars placed inside,
an inch or two above the bottom, for the timber to rest on. It should have
a convenient fireplace, and a covering with an opening wide enough to allow
the timber to be readily put in and taken out; and should likewise have an
ascending pipe or pipes, for the purpose of conveying away the inflammable.
vapour which rises from the mixture or liquid when heated, in order to
diminish as much as may be the risk of fire, as well as for the purpose of
condensing and collecting (if advisable) such vapour or essential oil. The
timber, which I prefer to be previously in a seasoned or dry state, is, to be
brought to the form in which it is intended to be employed, is to be arranged
on the bars within the boiler, and the liquid mixture above described (if made
in a separate vessel) is then to be poured in, the fire is then to be urged as
quickly as consistent with prudence, and it will be found, as the heat of the
liquid increases, that bubbles arise from the immersed timber; so long as the
temperature is less than that of boiling water such bubbles will be little else than
common air, but as the temperature increases the moisture contained in all timber,
even in that which has been seasoned, will be converted into steam or vapour,
and will thus not only itself escape out of the timber, but will also drive out much
air, and thus allow the preserving mixture to penetrate the deeper. The use
to which the timber is afterwards to be applied, as well as its thickness,
regulates the temperature of the mixture and the length of time during which
the timber is to remain immersed; no specific directions therefore can be
given applicable to all cases, but as a general rule, it may be observed that
those pieces which are required to be flexible (such as the planks of ships'
sides) require a temperature ranging from 212° to 220°, and generally a
shorter time for immersion than those pieces of which the frame of a ship is
composed, which require the mixture to be raised to its boiling point. The
wood, when taken out of the hot liquid, should be placed in a warm stove, to
drain more or less, according to its intended use, and may then either be
employed while still warm, or may be kept until the liquid has hardened on
its surface.
Having thus described the nature of my Invention, and the materials,
apparatus, and method by which I carry it into effect, I expressly disclaim the

page_text: Inrolled the Twenty-first day of July, in the year of our Lord One 1
thousand eight hundred and forty.