AN IMPROVED METHOD OF PRESERVING WOOD FROM THE RAVAGES OF WHITE ANTS AND OTHER INSECTS BY THE APPLICATION OF CERTAIN CHEMICAL SOLUTIONS
Year: 1873

page_text: LETTERS PATENT to William Leech, of the Firm of Johnston,
Farquhar, and Leech, of 65, Moorgate Street, in the City of London,
Solicitors, for the Invention of "AN IMPROVED METHOD OF PRESERVING
WOOD FROM THE RAVAGES OF WHITE ANTS AND OTHER INSECTS BY THE
APPLICATION OF CERTAIN CHEMICAL SOLUTIONS."-A communication from
abroad by William Malpas, of Athelstane, near Adelaide, in the
Province of South Australia, Gentleman.
COMPLETE SPECIFICATION filed by the said William Leech at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 29th July 1878, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
LEECH, of the Firm of Johnston, Farquhar, and Leech, of 65, Moorgate
Street, in the City of London, Solicitors, send greeting.
WHEREAS I am in possession of an Invention for "AN IMPROVED
METHOD OF PRESERVING WOOD FROM THE RAVAGES OF WHITE ANTS AND OTHER

page_text: INSECTS BY THE APPLICATION OF CERTAIN CHEMICAL SOLUTIONS," and have
petitioned Her Majesty to grant unto me, my executors, administrators,
and assigns, Her Royal Letters Patent for the same, and have made
solemn Declaration that the samo has been communicated to me from
abroad by William Malpas, of Athelstane, near Adelaide, in the Province
of South Australia, Gentleman.
NOW KNOW YE, that I, the said William Leech, do hereby declare
that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and in
what manner the same is to be performed, in and by the following
statement, that is to say :-
I find that a solution of sulphate of copper applied to wood is of great
advantage in preventing the attack of white ants and other insects, and
I also find that the beneficial effect of this solution is greatly increased
by the addition thereto of arsenious acid, and for this purpose I mix
together these chemicals in water in the proportions and manner herein-
after specified, but inasmuch as arsenic is only to a small degree soluble
in water, and as the addition of carbonate of soda to the water increases
the proportion of arsenic taken up by it, I add carbonate of soda to the
other constituents and prepare the solution in the following manner :—
I dissolve one pound of arsenious acid in four gallons of boiling water,
to which there has been previously added one pound of carbonate of
soda, and I stir till the arsenic is dissolved. I then dissolve in a
separate vessel sixteen pounds of sulphate of copper in sixteen gallons
of hot or cold water, and I then mix the arsenical solution with the
solution of sulphate of copper.
.
The timber or wood to be operated on should if practicable be placed
in a vat or tank of wood or of wood lined with lead, and the solution
formed as above should be poured in so to cover the wood, and should
be heated by a steam pipe to a boiling point for a short time and then
allowed to cool. The timber can then be taken out and is at once ready
for use.
Where it is not convenient to apply heat the timber should remain in
the vat for two or three days. In cases where it is inconvenient or
impracticable to immerse the timber in a vat, as for instance in the case
of telegraph poles in the interior of a wild country, it will suffice to
apply two coats of this solution with a brush to the timber to be pro-

page_text: tected, care being taken that every part of the wood is covered and that
the second coat is not laid on till the first is dry; it is desirable though
not indispensable that the solution should be heated to boiling point and
applied to the timber in that state.
In some cases however where the appliances are not readily obtainable
for dissolving so large a proportion of arsenio as above mentioned, I
mix together in one gallon of cold water sixteen ounces of sulphate of
copper and one quarter of an ounce of arsenious acid and apply two
coats of this solution with a brush in the manner herein-before described.
This solution also may with advantage be applied at boiling heat though
it is not necessary that it should be.
may
It be noted that these solutions do not in any way depend for
their success upon the impregnation of the wood with the compound by
means of pressure which is the principle of most other known pro-
cesses of preserving wood; and further it may be noted that the
materials used are very cheap and the manner of application so simple
that its cost is much less than that of any other.
In witness whereof, I, the said William Leech, have hereunto set
my hand and seal, this Twenty-ninth day of July, in the year of
our Lord One thousand eight hundred and seventy-three.
W. LEECH. (L.S.)