IMPROVEMENTS IN TREATING STONE, BRICK, WOOD, AND OTHER POROUS BUILDING MATERIALS TO RENDER
Year: 1871

page_text: LETTERS PATENT to Campbell Douglas, Architect, of Glasgow, in
the County of Lanark, North Britain, and David Mathew Watson,
Paper Maker, of Bullionfield, Dundee, in the County of Forfar,
North Britain, for the Invention of "IMPROVEMENTS IN TREATING
STONE, BRICK, WOOD, AND OTHER POROUS BUILDING MATERIALS TO RENDER
Sealed the 13th February 1872, and dated the 16th August 1871.
PROVISIONAL SPECIFICATION left by the said Campbell Douglas and
David Mathew Watson at the Office of the Commissioners of
Patents, with their Petition, on the 16th August 1871.
We, CAMPBELL DOUGLAS, Architect, of Glasgow, in the County of
Lanark, North Britain, and DAVID MATHEW WATSON, Paper Maker, of
Bullionfield, Dundee, in the County of Forfar, North Britain, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN TREATING
STONE, BRICK, WOOD, AND OTHER POROUS BUILDING MATERIALS TO RENDER THEN
IMPERVIOUS AND LESS LIABLE TO DECAY," to be as follows, that is to say :—
This Invention, which has for its object the treating of stone, brick,
wood, and other porous building materials, so as to render them imper-

page_text: vious and less liable to decay, consists in first applying to the surface of
the material as a wash a solution containing rosin or colophony and an
alkali, and then before this first wash dries applying a solution of
alum. By these means an insoluble resinous and aluminous precipitate
is formed on the surface and in the interstices or pores of the building
material, and preserves or protects the material from atmospheric
decaying influences, at the same time rendering the material impervious
to moisture. The solution for the first wash may be conveniently
prepared by thoroughly boiling about five parts by weight of the rosin in
a solution of one part of soda ash.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Campbell Douglas and David Mathew Watson in
the Great Seal Patent Office on the 15th February 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CAMPBELL
DOUGLAS, Architect, of Glasgow, in the County of Lanark, North
Britain, and DAVID MATHEW WATSON, Paper Maker, of Bullionfield,
Dundee, in the County of Forfar, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of August, in the year of
our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Campbell Douglas and David Mathew
Watson, Her special licence, that we, the said Campbell Douglas and
David Mathew Watson, our executors, administrators, and assigns, or
such others as we, the said Campbell Douglas and David Mathew
Watson, our executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN TREATING STONE, BRICK, WOOD, AND OTHER POROUS BUILDING
MATERIALS TO RENDER THEM IMPERVIOUS AND LESS LIABLE TO DECAy,” upon the
condition (amongst others) that we, the said Campbell Douglas and David
Mathew Watson, our executors or administrators, by an instrument in
writing under our, or their, or one of their hands and seals, should par-

page_text: ticularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same to
be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said Campbell Douglas and David
Mathew Watson do hereby declare the nature of our said Invention,
and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement in writing,
that is to say :-
Our said Invention, which has for its object the treating of stone,
brick, wood, and other porous building materials, so as to render them
impervious and less liable to decay, consists in forming on the surface
and to a greater or less depth in the interstices or pores of the building
material a precipitate in which rosin is combined with alumina or other
suitable carth, and which preserves or protects the material from atmos-
pheric decaying influences, at the same time rendering the material
impervious or less pervious to moisture.
In practically carrying out our said Invention the details are sus-
ceptible of various modifications, but in order that the nature of the
said Invention and the manner of performing the same may be properly
understood, we shall proceed to particularly describe the modifications
of our processes which we prefer to employ.
We form a solution containing rosin or colophony by boiling about
five parts by weight of the rosin in a solution containing one part of soda
ash, or its equivalent of soda carbonate or other suitable alkali. This
resinous solution in a sufficiently diluted state to be easily spread or
washed on with a brush is first applied to the building material, and then,
by preference before this first wash is dried, there is applied over it a
solution of alum, or a solution containing alumina or other suitable earth.
The resinous solution, to be of a convenient and suitable strength, should
contain about ten pounds of rosin for overy nine gallons; whilst the
second solution should contain a corresponding proportion of the salt in
it. A reaction takes place between the two washes, the acid of the
second wash combining with the alkali of the first to form a soluble salt,
whilst the earth of the second wash and the resinous matter of the first
are precipitated in a combined or in a mixed state, and adhere to the
stone or other building material. The best results will probably be

page_text: obtained by employing comparatively dilute solutions, and repeating the
treatment twice or oftener; and if this is done the soluble salt formed
in the reaction should be removed by washing with water between each
treatment with the two solutions.
Where cheapness is an object, alumina being the desired earthy |
precipitate, the solution obtained by lixiviating what is known as alum
cake may be employed; but it will be equally if not more economical
to employ calcium chloride, yielding lime or chalk as the carthy
precipitate.
*. Having thus particularly described our said Invention, and the manner 1
of performing the same, we have to state that we do not restrict our-
selves to the precise details herein described or delineated; but that
what we believe to be novel and original, and claim as the Invention
secured to us by the herein-before in part recited Letters Patent is, tho
treating of stone, brick, wood, and other porous building materials with 1
solutions reacting to form a resinous and carthy precipitate upon their
surfaces, and more or less in their interstices or pores, substantially as
herein-before described.
In witness whereof, I, the said Campbell Douglas, on behalf of
myself and the said David Mathew Watson, havo hereunto set 2
my hand and seal, this Fourteenth day of February, in the year
of our Lord One thousand eight hundred and seventy-two.
Witness.
EDMUND HUNT,
Patent Agent,
Glasgow.
CAMPBELL DOUGLAS. (L.S.)