IMPROVEMENTS IN THE MANUFACTURE OF BRICKS, TILES, TERRA-COTTA, AND THE LIKE MATERIALS OR ARTICLES
Year: 1881

page_text: LETTERS PATENT to James Walker, of Leeds, in the County of York, for an
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF BRICKS, TILES,
TERRA-COTTA, AND THE LIKE MATERIALS OR ARTICLES."
PROVISIONAL SPECIFICATION left by the said James Walker at the Office
of the Commissioners of Patents on the 18th May 1881.
JAMES WALKER, of Leeds, in the County of York. "IMPROVEMENTS IN THE
MANUFACTURE OF BRICKS, TILES, TERRA COTTA, AND THE LIKE MATERIALS OR
ARTICLES."
My improvements have reference to the manufacture of vitrified bricks, tiles,
terra cotta ware, and other like materials or articles of an ornamental or ordinary
form, also to preventing such articles or materials from fusion together while in
the kiln.
I take 3 parts of common brick earth, of clay, or other clay earth, or marle used
in the manufacture of the above, ground finely into a semi-plastic or plastic or
other suitable state for moulding, and add thereto one part of waste oxide of iron
pyrites that has previously been used for extracting the sulphur in purifying gas,
and after its being burnt to recover the sulphur. The substance is usually termed
the oxide; or I use the dross of iron pyrites from which the sulphur has been burnt
without having been previously used in the purifying of gas, or any other oxide of
iron, or the refuse from chemical works.
The proportions of the different materials may be varied to suit the colour of the
article to be manufactured, also the required metallic qualities thereof.
I also add manganese, either in solution applied on the surface or mixed with the
material.
In the preparation of the material I pass the oxide into the ordinary grinding
pan or pug mill whilst the clay or other material is being pulverized; the two
substances are thus thoroughly mixed into one uniform mass and made ready for
the moulding operation, after which the material is dried and burned in ordinary
kilns and in the usual way.

page_text: In order to prevent fusion together of the articles or material during the
burning operation, I wall in between each of them a layer of old spent tan, ground
bark, sawdust, spent dye-woods, or other suitable waste vegetable substances which
when burnt leaves a stratum of carbon or charcoal, thus preventing them from
adhering to each other.
The hereinbefore described mixture of the oxide with the clay and other
materials, with suitable heat applied thereto, becomes vitrified, forming a dense
substance and impervious to the weather; consequently the bricks, tiles, terra cotta
ware, and other like materials or articles are especially valuable for cornice
mouldings of buildings, stringings, also for window arches and other purposes.
When additional glaze is required I add a small quantity of salt while the
burning operation is going on in the kiln in the usual way.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Walker in the Great Seal Patent Office on the
15th November 1881.
JAMES WALKER, of Leeds, in the County of York. "IMPROVEMENTS IN THE
MANUFACTURE OF BRICKS, TILES, TERRA-COTTA, AND THE LIKE MATERIALS OR
ARTICLES."
My improvements have reference to the manufacture of blue vitrified metallic
bricks, tiles, terra-cotta, or other articles of an ornamental or ordinary form, also to
prevent fusion together while in the kiln.
I take three parts of brick earth, or clay, fire clay, or marle used in the ordinary
manufacture of the above, and I add thereto one part of burnt oxide of iron which
has previously been used for extracting the sulphur in purifying gas, and after it
has been burnt to recover the sulphur in making sulphuric acid. This substance
is then called "burnt oxide," and has hitherto been cast away as a waste article ;
or I use for the same purpose as above named, and in lieu of the burnt oxide, the
ashes of iron pyrites of the coal measures (which I grind into powder) after the
sulphur has been burnt out for the said purpose of making sulphuric acid without
having previously been used in purifying gas; or I use any other oxide of iron
refuse from chemical or other works ground as, above stated; and as these pyrites
or other oxide of iron may be richer than burnt oxide, I vary the proportions of
the clays, earths, fireclay, or marle, and add thereto from four to six parts to one
part of these oxides, according to the strength or richness of the pyrites or other
oxide of iron then to be used, so as to make as near as possible one equal quality
and colour with the burnt oxide.
I pass the burnt oxide, burnt ground pyrites, or other oxide of iron into the
grinding pan with the proportions of clay, earths, fire clay, or marle to be used,
which has been finely pulverized or ground; or I take clay that has previously
been ground and screened to make it evenly fine throughout (which I prefer), and
work and temper the clay so prepared while in the grinding pan with the burnt
oxide, burnt ground pyrites, or other oxide of iron into a plastic state till the two
substances are thoroughly mixed and amalgamated into one uniform mass, which
is then ready for moulding either by hand or machine (the material is ready for
use when no lumps or grit can be felt in passing it through the fingers), after
which the articles are dried and burned in the usual kilns and in the ordinary
way.
As the brick earths, clays, fire clays, and marles that may be used for the above
are of various strengths and qualities in resisting the action of fire without melting
away, and as a certain heat is requisite to bring out the blue colour and vitrifi-
cation herein described, and in order to fortify and strengthen any brick earth,
clay, or fire clay, or marle that is too weak to stand of itself the requisite amount
of heat for the above described purpose, I add one part of pulverized gannister
rock in the state of finely sifted sand, or calcined flint, gravel put into the same state
of sifted sand, or any other suitable sand, to the one part of burnt oxide, burnt
pyrites, or other oxide of iron, and the two or more parts of brick earth, clay, fire
clay, or marle in hand may require to bring out the blue colour and to vitrify the
substance, and which I work and temper together as before described.
But I prefer to use a fire clay which will stand of itself sufficient heat without
melting the article, forming a dense semi-metallic substance impervious to the
damp or weather; consequently the bricks, tiles, terra-cotta ware, and other like
materials or articles are especially valuable for durability for buildings, bridges,

page_text: culverts, water ways, and for cornice mouldings of buildings, stringings, also for
window arches and other purposes.
When additional glaze on the surface is required I use a small quantity of salt
in the kiln while the burning is going on in the usual way.
In order to prevent the fusing together in the kiln during the burning operation
of the articles above named, I wall between each of them a layer of old spent
tanners' bark (ground fine), saw dust, spent dye woods, turners' dust, or other
suitable waste vegetable substance, to leave a stratum of carbon or charcoal, which
tends to keep them separated when burned.
I would have it understood that I do not limit myself to the exact proportions
given, which are taken as approximate, and the quantity of each ingredient may
be varied in accordance with the nature or quality of the material or article to be
manufactured, but what I claim and desire to be secured to me by Letters
Patent is,―
The combination of the various ingredients and the method employed in the
manufacture of blue vitrified bricks, tiles, terra-cotta, and the like materials or
articles, substantially as and for purposes herein set forth.
In witness whereof, I, the said James Walker, have hereunto set my hand
and seal, this Twelfth day of November, in the year of our Lord One
thousand eight hundred and eighty one.