IMPROVEMENTS IN THE MANUFACTURE OF FIREPROOF CEMENTS AND FIRE-BRICKS
Year: 1873

page_text: LETTERS PATENT to William Thomas Holland, of Llanelly, in the
County of Carmarthen, Earthenware Manufacturer, for the Inven
tion of "IMPROVEMENTS IN THE MANUFACTURE OF FIREPROOF CEMENTS AND
FIRE-BRICKS."
Sealed the 6th March 1874, and dated the 23rd December 1873.
PROVISIONAL SPECIFICATION left by the said William Thomas Holland
at the Office of the Commissioners of Patents, with his Petition, on
the 23rd December 1873.
'I, WILLIAM THOMAS HOLLAND, of Llanelly, in the County of Car-
marthen, Earthenware Manufacturer, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF FIREPROOF
CEMENTS AND FIRE-BRICKS," to be as follows:-
My Invention consists in the manufacture of fireproof cements and
fire-bricks made essentially from a combination of silicious and vitrifiable
materials, substantially as hereafter described.
To manufacture fireproof cements according to my Invention I take

page_text: ingredients or of a combination of the same:--Sandstone or silica,
cribbathstone, millstone grit, fire-stone, ganister, silver sand, white or
native silica and its combinations, quartz, calcined flint stones, fire and
other clays after being fired and pulverized, or other materials possessing
similar qualities, or I employ fired potters' saggers, salt, glazed ware, 5
old fire-brick, and other fired fire-clay articles, and such as made from
Dorset and Devon clays, earthenware, china and parian broken pitchers,
glazed and not glazed (all these having been fired up to a white heat), or
other highly refractory material.
To render these materials of silicious base suitable for the purposes of 1
my Invention they are reduced by pulverizing and grinding by the dry
or wet methods or otherwise to a state of powder by any known and
suitable machines or machinery.
The vitrifiable cements or materials to be used in combination with
the above in or about the approximate proportions hereafter mentioned 1
are, Cornwall china stone, Jersey china stone, Middleton Hill stone,
felspar, pulverized or ground glass, iron ore, pumice stone, boracic acid
and its combinations, or other substances of an equivalent nature.
These vitrifiable cements or materials are reduced to powder by
grinding in the dry or wet way, or otherwise, or to a liquid state before 2
combining them with the silicious base before named.
To make a fireproof cement according to my Invention I take, say
powdered sandstone, and thoroughly mix or incorporate with it from, say
eight to nine per cent. of, say powdered Cornwall china stone, but these
proportions necessarily vary because the quantity must be regulated
according to the fusibility of the particular cementing material used,
which should be added in such proportions as may be necessary to make
the mass combine and set firmly with high heat, but not sufficient to
make it melt or waste away quickly at or with the highest heats.
The next part of my Invention refers to the manufacture of fire-bricks
known as "Dinas" bricks.
"
or
Heretofore it has been customary in the manufacture of "Dinas
("silica") bricks to employ lime as a cementing material in their com-
position, which to a great extent renders them unfit for use in steel or
other furnaces exposed to great heat and subjected to quick cooling, but
by my Invention I am able to manufacture "Dinas or "silica" fire-
"

page_text: bricks without the use of lime, such bricks. being capable of standing
the great heat of steel and glass furnaces better than any other bricks
that are to my knowledge now made, and at the same time they will
stand quick cooling better than bricks known as
"
"Dinas or silica
bricks of ordinary manufacture. For this purpose I take one or other
of the purely silicious materials before mentioned, or I take a purely
silicious material of an equivalent nature to one or other of those before-
named, being reduced to powder as before described, and I mix it with
one or other of the vitrifiable materials before mentioned or an equivalent
vitrifiable material. For instance, if I take ordinary fire-stone, such as
is now generally used in the manufacture of "Dinas" bricks, I should
then mix and incorporate with it in the manner before described with
reference to fire-proof cements, say of or about four per cent. of Jersey
china stone, but this proportion of cementing material must vary
according to the fusibility, as before stated, of the particular cementing
material used. Material thus prepared and properly mixed is subse-
quently made up into bricks of varied shapes and sizes in the ordinary
way generally adopted for the manufacture of bricks known as "Dinas"
bricks.
My Invention further consists in the manufacture of fire-bricks and
other usual fire-clay goods almost entirely from fired fire-clay articles
that have been subjected to a white heat, and earthenware, china and
parian broken pitchers glazed and unglazed, together with Cornwall
china stone, Jersey china stone, Middleton Hill stone, and felspar for
cements as may be requisite, and in this way I am able to utilize old and
heretofore comparatively useless materials, partly the refuse of the
Staffordshire potteries district, and of other china and earthenware
potteries, using white clays and ground flint; for this purpose I pulverize
the pitcher material by grinding or otherwise; I thus frequently by
judicious mixtures of the glazed, unglazed, and vitreous fired materials
dispense with the employment of vitrifiable material other than is con-
tained in the earthenware and china itself wholly, if not nearly so, in
the manufacture of fire-brick by the employment of this pulverized
earthenware, china and parian broken pitchers, in biscuit state as well
as glazed, and at the same time I utilize a material now almost
valueless.

page_text: materials pulverized as aforesaid are made up into bricks with or without
the addition of any vitrifiable cements or adhesive materials by any
approved known means (but by preference by the employment of
pressure in a suitable press, such as in a press known as Bodmer's
Patent hydraulic press) in a dry or semi-dry state by any suitable 5
machinery applicable to the purpose.
In some cases I add to these and "Dinas" brick and fire-proof
cement mixtures a small proportion of china or other clay (but not of
necessity, or exceeding five per cent. in weight of the whole) where it
may be found advisable to make the mass a little more plastic and 1
adhesive to bear handling for the setting in kiln and to stand pressure
during firing, and for the more easily spreading and plastering of
cements.
Where china stone alone is used as the cementing material, or in fact
where any of the bases before named are used alone, or any two 1
together, it may in some cases be found requisite to use a farinaceous
or other mucilage in order to obtain the requisite plasticity or adhesive-
ness for fire-bricks and fire-proof cements.
I sometimes use small portions of manganese in its different states in
mixture for cements for the hearths of mill, re-heating, balling, refinery, 2
reverberatory, Siemen's Patent regenerative gas furnaces, and other
similar iron and steel furnaces; also for the linings of cupolas, ladles,
Bessemer converters, and other like furnaces connected with the manu-
facture of iron and steel for its chemical effect upon certain classes of
iron.
Also with or without any admixture I sometimes use maganese as a
liquid wash or dry powder over cements used for linings, hearths, and
portions of the interior of such furnaces and vessels.
2
Also I occasionally use manganese in the Dinas bricks made without
lime to improve the appearance and colour of the bricks, for instance, 3
when the materials used contain an excess of oxide of iron I use
manganese in the mixture, in dry, or liquid, and ground state, to
counteract to some extent the colouring and spotting caused by the iron
oxide after firing.
I also sometimes mix with these bricks and cements a small portion a

page_text: vitrification with less fire and to render the mass not quite so dense, so
as to bear contraction from sudden cooling better, and also quick
heating without cracking, as for example, from molten iron or steel
poured on.
The silicious bases and vitrifiable materials prepared and combined in
the manner before described are applicable as fire-proof cements for
setting fire-bricks and to all such other purposes where such cements
and fire-clays are now used for lining and repairing furnaces, such as for
example in which fire-bricks are now used, as well as for the hearths of
all kinds of furnaces where fire-bricks or iron arc now used in their
construction.
The cements are also suitable for lining ladles used in the manufacture
of steel and iron, and for the protection of iron and other metals from
the action of fire or heat, as for example, in "Bessemer" converters,
and can be used for repairing effectually in parts where the first applied
material may be worn away without renewing the whole, but are not
intended as a substitute for fire-bricks or fire goods in furnaces, where
any, now used in the building of such furnaces.
My Invention also consists in the manufacture of artificial stone or
fired fire-proof cement from the silicious bases specified, which when
properly prepared and moulded in a dry or wet state by pressure or
otherwise and fired, it will retain the exact shape and sharpness of edge,
as for instance, the same mixture answers the purposo in large bricks or
lumps for hearthstone in blast furnaces to bear high heat; and also for
a durable building stone, and for other purposes for which the mixed
material can be moulded and fired.
Many of the cements I use, as for instance china stone, Middleton
Hill stone, and felspar, have not been previously used to my knowledge
as vitrifiable cements for making fired artificial, stone, which made
properly with these cements will be vitrified and very durable, not dis-
figured by any efflorescence of the cementing materials after exposure
to the weather, as is often the case with artificial sandstones not
fired.
When moulding these articles also Dinas and pitcher or china bricks,
I occasionally use for dusting the moulds and the moulded surfaces a
mixture of fine sand and finely ground or pulverized china stone or

page_text: Middleton Hill stone to assist the withdrawal from moulds and to
improve the surface when fired.
The bricks made according to my Invention from pitcher and other
fired materials, and moulded with pressure by any suitable press such as
by a hydraulic press known as Bodmer's Patent press, as dry pressed
bricks not fired can in some cases be used and set with or without
cement in furnaces without being previously re-fired as bricks, and a
little extra of the cementing material mixed with the dry pressed or
unfired brick and cement will slightly glaze over the surface by the
action of the heat, and as the bricks become gradually fired they will
form a solid mass and wear away slowly, the joints being perfect; and
when the furnace is up to full white heat and empty, I claim to smear
these unfired and also other fired bricks by a salt glaze thrown into the
furnace, whether fixed or rotary.
I sometimes also wash over or dry powder bricks pressed, as specified,
or wet moulded and used for such like furnaces in an unfired state, or
fired with a thin coat of one of the vitrifiable cements named with or
without an admixture of sand throughout the interior of the furnace
when cold or newly set and after repairing and cementing joints; I also
treat similarly in both ways, as above specified, cements used for
linings and protection of metal previous to and after the fixing of such
cements.
My Invention also consists in the use of salt through the fires and
top of kiln during the last stages of the firing kilns of Dinas bricks, to
assist the burning and cementing together of the materials in a shorter :
time, and to improve the colour and appearance of the bricks by it
having a bleaching effect, and of use especially when no lime is used in
the mixture for Dinas bricks.
This salt is also used according to my Invention for glazing through
the fires and at top of kiln in the firing of kilns of pitcher or china
bricks and similar firc-standing goods, especially fired artificial stone
made as specified, and bricks made of mixtures of the other fired fire-
brick and other materials specified, and also of fire-proof stone and clay,
such as used or made at Dinas and ganister brick works, as assisting to
produce a solid and hard sounding brick without continuing the firing so a
long as usual; and I thus economize the consumption of coal besides
improving the colour or surface of the bricks; though as salt glazing

page_text: may have been slightly used or tried at some fire-clay works, for
instance where salt glaze pipes and other such glazed articles are made,
but not to my knowledge; I do not claim this as for use with ordinary
native fire-clay bricks, but for such as have their chief bases or mixture
of fire-stone or silica, say, not exceeding seventy per cent. of silica in
their composition; and also of the fired or other materials specified, I claim
it as my Invention and improvement in the manufacture of such bricks
and fire goods on account either of economy, quality, or better
appearance.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Thomas Holland in the Great Seal Patent
Office on the 23rd June. 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
THOMAS HOLLAND, of Llanelly, in the County of Carmarthen, Earthen-
ware Manufacturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of December, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Thomas Holland, Her special
licence that I, the said William Thomas Holland my executors, admi-
nistrators, and assigns, or such others as I, the said William Thomas
Holland, my 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,
usc, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF FIREPROOF CEMENTS AND FIRE-BRICKS,"
upon the condition (amongst others) that I, the said William Thomas
Holland, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
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 imme-
diately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said William Thomas Holland, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
My Invention consists in the manufacture of fireproof cements and
fire-bricks made essentially from a combination of silicious and vitrifiable
materials, substantially as hereafter described.
To manufacture fireproof cements according to my Invention I take
some silicious material composed of one or other of the following
ingredients, or of a combination of the same:-Sandstone or silica,
cribbathstone, millstone grit, firestone, ganister, silver sand, white or
native silica and its combinations, slate, quartz, calcined flintstones,
fire and other clays after being fired and pulverized, or other materials
possessing similar qualities; or I employ fired potters' saggers, salt
glazed ware, old fire-brick, and other fired fire-clay articles, and such as
made from Dorset and Devon clays, earthenware, china and parian,
broken pitchers, glazed and not glazed (all these having been fired up to
a white heat), or other highly refractory material.
To render these materials of silicious base suitable for thic purpose of
iny Invention they are reduced by pulverizing and grinding by the dry
or wet methods or otherwise to a state of powder by any known and
suitable machines or machinery.
-
The vitrifiable cements or materials to be used in combination with
the above in or about the approximate proportions hereafter mentioned
are: Cornwall china stone, Jersey china stone, Middleton Hill stone, 1
felspar, fluorspar, alkalies, pulverized or ground glass, iron ore, pumice-
stone, boracic acid, and its combinations, artificial and natural or other
substances of an equivalent nature.
These vitrifiable cements or materials are reduced to powder by
grinding in the dry or wet way or otherwise, or to a liquid state before
combining them with the silicious base before-named.
To make a fireproof cement according to my Invention, I take, say,
powdered sandstone and thoroughly mix or incorporate with it from,
say, eight to nine per cent. of, say, powdered Cornwall china stone,
but these proportions necessarily vary because the quantity must be 8
regulated according to the fusibility of the particular cementing material

page_text: used, which should be added in such proportions as may be necessary
to make the mass combine and set firmly with high heat, but not
sufficient to make it melt or waste away quickly at or with the highest
heats.
The next part of my Invention refers to the manufacture of firc-bricks
known as "Dinas" bricks.
"
Heretofore it has been customary in the manufacture of "Dinas" (or
"silica") bricks to employ lime as a cementing material in their com-
position which to a great extent renders them unfit for use in steel or
other furnaces exposed to great heat and subjected to quick cooling, but
by my Invention I am able to manufacture "Dinas" ΟΙ "silica", firc-
bricks without the use of lime, such bricks being capable of standing the
great heat of steel and glass furnaces better than any other bricks that
are to my knowledge now made, and at the same time they will stand
quick cooling better than bricks known as "Dinas or silica bricks of
ordinary manufacture. For this purpose I take one or other of the
purely silicious materials before mentioned; or I take a purely silicious
material of an equivalent nature to one or other of those before-named,
being reduced to powder as before described, and I mix it with one or
other of the vitrifiable material before mentioned, or an equivalent
vitrifiable material. For instrance, if I take ordinary firestone, such as
is now generally used in the manufacture of "Dinas" bricks I should
then mix and incorporate with it in the manner before described with
reference to fireproof cements, say of or about four per cent. of Jersey
china stone, but this proportion of cementing material must vary
according to the fusibility, as before stated, of the particular cementing
material used. Material thus prepared and properly mixed is sub-
sequently made up into bricks of varied shapes and sizes in the ordinary
way generally adopted for the manufacture of bricks known as
" Dinas
bricks.
"
My Invention further consists in the manufacture of fire-bricks and
other usual fire-clay goods almost entirely from fired fire-clay articles.
that have been subjected to a white heat, and earthenware, china and
parian broken pitchers, glazed and unglazed, together with Cornwall
china stone, Jersey china stone, Middleton Hill stone, and felspar for
cements, as may be requisite, and in this way I am able to utilize old
and heretofore comparatively useless materials, partly the refuse of the
.

page_text: Staffordshire potterics district, and of other china and earthenware
potteries using white clays and ground flint.
For this purpose 1
pulverize the pitcher material by grinding or otherwise, I thus frequently,
by judicious mixtures of the glazed, unglazed, and vitreous fired
materials, dispense with the employment of vitrifiable material other
than is contained in the earthenware and china itself, wholly, if not
nearly so, in the manufacture of fire-brick by the employment of this
pulverized earthenware, china and parian broken pitchers, in biscuit
state as well as glazed, and at the same time I utilize a material now
almost valueless.
Sometimes in order to prevent the pulverized material being too
vitreous I am obliged to mix a small quantity of sand with it. These
materials pulverized as aforesaid are made up into bricks, with or
without the addition of any vitrifiable cements or adhesive materials by
any approved known means (but by preference by the employment of
pressure in a suitable press, such as in a press known as Bodmer's
Patent hydrulic press), in a dry or semi-dry state by any suitable
machinery applicable to the purpose.
In some cases I add to these and "Dinas" bricks and fire-proof
cement mixtures a small proportion of china or other clay (but not of
necessity or exceeding five per cent. in weight of the whole), where it
may be found advisable to make the mass a little more plastic and
adhesive to bear handling for the setting-in kiln and to stand pressure
during firing and for the more easily spreading and plastering of
cements.
Where china stone alone is used as the cementing material or in fact
where any of the bases before-named are used alone or any two or more
together, it may in some cases be found requisite to use a farinaceous or
other mucilage in order to obtain the requisite plasticity or adhesiveness
for fire-bricks and fire-proof cements.
2
3
I sometimes use small portions of manganese in its different states in
mixture for cements for the hearths of mill, reheating, balling, refinery,
reverberatory, Siemen's patent regenerative gas furnaces, and other
similar iron and steel furnaces, also for the linings of cupolas, ladles,
Bessemer converters, and other like furnaces connected with the manu- 3
facture of iron and steel for its chemical effect upon certain classes of
iron.

page_text: Also with or without any admixture I sometimes use manganese as a
liquid wash or dry powder over cements used for linings, hearths, and
portions of the interior of such furnaces and vessels.
I also sometimes mix with these bricks and cements a small portion of
finely pulverized anthracite or stone coal or culm to assist the vitrifica-
tion with less fire and to render the mass not quite so dense, so as to
bear contraction from sudden cooling better, and also quick heating,
without cracking as for example from molten iron or steel poured on.
The silicious bases and vitrifiable materials prepared and combined in
the manner before described are applicable as fire-proof cements for
setting fire-bricks, and to all such other purposes where such cements
and fire-clays are now used for lining and repairing furnaces, such as for
example in which fire-bricks are now used as well as for the hearths of
all kinds of furnaces where fire-bricks or iron are now used in their
construction, also in fire-proof buildings.
The cements are also suitable for lining ladles used in the manufacture
of steel and iron, and for the protection of iron and other metals from
the action of fire or heat, as for example, in "Bessemer" converters, and
can be used for repairing effectually in parts where the first applied
material may be worn away without renewing the whole, but are not
intended as a substitute for fire-bricks or fire goods in furnaces, where
any now used in the building of such furnaces.
My Invention also consists in the manufacture of artificial stone or
fired fireproof cement from the silicious bases specified, which when
properly prepared and moulded in a dry or wet state by pressure or
otherwise and fired it will retain the exact shape and sharpness of edge,
as for instance the same mixture answers the purpose in large bricks
or lumps for hearthstone in blast furnaces to bear high heat, and
also for a durable building stone and for other purposes for which the
mixed material can be moulded and fired.
Many of the cements I use, as for instance china stone, Middleton Hill
stone, and felspar have not been previously used to my knowledge as
vitrifiable cements for making fired artificial stone, which made properly
with these cements will be vitrified and very durable, not disfigured by
any efflorescence of the cementing materials after exposure to the
weather as is often the case with artificial sandstones not fired.

page_text: When moulding these articles, also Dinas and pitcher or china bricks,
I occasionally use for dusting the moulds and the moulded surfaces a
mixture of say half fine sand and half finely ground or pulverized china
stone or Middleton Hill stone to assist the withdrawal from moulds and
to improve the surface when fired.
The bricks made according to my Invention from pitcher and other
fired materials, and moulded with pressure by any suitable press, such
as by a hydraulic press, known as Bodmer's Patent press, as dry pressed
bricks not fired can in some cases be used and set with or without
cement in furnaces without being previously re-fired as bricks, and a
little extra of the cementing material mixed with the dry pressed or
unfired brick and cement will slightly glaze over the surface by the
action of the heat, and as the bricks become gradually fired they will
form a solid mass and wear away slowly, the joints being perfect, and
when the furnace is up to full white heat and empty I claim to smear
these unfired and also other fired bricks by a salt glaze thrown into the
furnace, whether fixed or rotary.
I sometimes also wash over or dry powder bricks pressed as specified,
or wet moulded and used for such like furnaces in an unfired state, or
fired with a thin coat of one of the vitrifiablo cements named, with or
without an admixture of sand throughout the interior of the furnace
when cold or newly set, and after repairing and cementing joints.
I also treat similarly in both ways, as above specified, cements used
for linings and protection of metal previous to and after the fixing of
such cements.
My Invention also consists in the use of salt through the fires and top
of kiln during the last stages of the firing of kilns of Dinas bricks to
assist the burning and cementing together of the materials in a shorter
time, and to improve the colour and appearance of the bricks by it,
having a bleaching effect, and of use especially when no lime is used in
the mixture for Dinas bricks.
This salt is also used according to my Invention for glazing through
the fires and at top of kiln in the firing of kilns of pitcher or china
bricks, and similar fire standing goods especially fired, artificial stone
made as specified, and bricks made of mixtures of the other fired fire-
brick and other materials specified, and also of fireproof stone and clay,
such as used or made at Dinas and ganister brickworks, as assisting to

page_text: produce a solid and hard sounding brick without continuing the firing
so long as usual, and I thus economize the consumption of coal, besides
improving the colour or surface of the bricks, though as salt glazing
may have been slightly used or tried at some fire-clay works; for
instance, where salt glaze pipes and other such glazed articles are made,
but not to my knowledge. I do not claim this as for use with ordinary
native fire-clay bricks, but for such as have their chief basis or mixture
of fire-stone or silica, say, exceeding seventy per cent. of silica in their
composition, and also of the fired or other materials specified, I claim
it as my Invention and improvement in the manufacture of such bricks
and fire goods on account either of economy, quality, or better appear-
ancc.
Having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim as my
improvements in the manufacture of fireproof cements and fire-bricks,―
First. The combination of Cornwall (or Devonshire) china stonc,
Jersey china stone, Middleton Hill stone, and felspar, with any or all of
the silicious and fired or unfired materials or substances herein specified
as new and original for the purposes herein named, also as being cheap
vitrifiablo binding cements in the manufacture of fire cements, fired
artificial stone, fire-bricks, and fire goods for high heats, causing such
silicious base materials to cohere with high heat by the admixture of
such named vitrifiable substances in small proportions only so as to
stand well the highest heats.
Second. The combination of various other vitrifiable cements herein
specified, or of an equivalent nature, along with the silicious bases
herein named in the manner and for the purposes substantially as
described.
Third. The manufacture of pitcher or china bricks almost wholly of
previously fired materials, made in the methods described, and the
refiring of them with high heat to bind the materials thoroughly
together; also with or without the addition of silica or of any extra
vitrifiable cement, so that they will afterwards stand like fire-bricks the
highest heats, substantially as described.
Fourth. The employment of china stone and Middleton Hill stone in
mixture with sand or alone as applied to the exterior of the moulded
surfaces previous to firing in the manner and for the purposes described;

page_text: also the coating of bricks fired or not fired, and the interior of furnaces
and linings with these and any of the other vitrifiable cements named
alone or in combination in the manner described as by dry powder or by
a liquid wash.
Fifth. The employment of powdered anthracite coal or culm in the t
manufacture of fireproof cements, and in the Dinas and other classes of
bricks and fire-standing goods herein named only for the purposes
described.
Sixth. The application of manganese to a silicious base in the manu-
facture of fireproof cements for iron and steel furnaces for purposes 1
specified, and also as a liquid wash or dry powder over cements, with or
without mixture, substantially in manner and for the purposes as
described.
Seventh. The employment and application of a salt glaze to the
interior of furnaces, substantially in the manner and for the purposes 1
described.
Eighth. The employment of salt through the fires and top of kiln, or
in any other convenient or equivalent way during the last stage of firing
the kilns of bricks and fire goods, substantially in the manner for the
purposes only as described.
In witness whereof, I, the said William Thomas Holland, have here-
unto set my hand and scal, this Nineteenth day of June, in
the year of our Lord One thousand eight hundred and seventy-
four.
2