AN IMPROVED KILN OB OVEN FOR FIRING PORCELAIN AND OTHER SIMILAR WARE
Year: 1847

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Mechanical Draughtsman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-ninth day of July, in the eleventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alfred Vincent Newton, Her especial licence, full power, sole privilege and
authority, that I, the said Alfred Vincent Newton, my executors, adminis-
trators, and assigns, and such others as I, the said Alfred Vincent Newton,
my executors, administrators, 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 mentioned, should and lawfully might make, use, exercise, and vend,
within England, Wales, the Town of Berwick-upon-Tweed, and in all Her
Majesty's Colonies and Plantations abroad, and in the Islands of Jersey,
Guernsey, Alderney, Sark, and Man, an Invention of "AN IMPROVED KILN OB
OVEN FOR FIRING PORCELAIN AND OTHER SIMILAR WARE," being a communication
from a foreigner residing abroad; in which said Letters Patent is contained a
proviso, obliging me, the said Alfred Vincent Newton, by an instrument in writing
under my hand and seal, particularly to describe and ascertain the naturo
of the said Invention, and in what manner the same is to be performed, and
to cause the same to be inrolled in Her Majesty's High Court of Chanecry

page_text: 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Alfred Vincent Newton, do hereby declare that the nature of the said Inven-
tion, and the manner in which the same is to be performed, is particularly
described and ascertained in and by the following description thereof, reference
being had to the Drawings hereunto annexed, and to the letters and figures
marked thereon (that is to say):-
My foreign correspondent, who has communicated to me the Invention for
which I have obtained Her Majesty's Letters Patent, as aforesaid, precedes
the description of his Invention by the following preliminary observations
explanatory of the ordinary mode of firing or baking hard porcelain, and
the difficulties and objections incident thereto.
A long
The employment of pit-coal as a fuel for firing or baking hard porcelain has
hitherto been thought impossible, or at least subject to almost insuperable
difficulties. It was thought that the hardness and infusibility of the clay
(kaolin), and the high degree of heat necessary to fuse or melt the glaze which
is employed to cover hard porcelain, were insurmountable obstacles.
and sufficiently large or extensive flame to occupy the whole space of the oven
or kiln is indispensable for this kind of manufacture, and the liability of
the matters composing the hard porcelain becoming discolored, rendered this
superabundance of flame absolutely necessary, in order that no smoke might
be allowed to remain in the kiln or oven. It is requisite therefore to cause
pit-coal to develop such an amount of flame as would have the same effect, and
would act within a given time in the same manner as wood.
Before proceeding further, and commencing the description of the accom-
panying Drawings, it will be as well to give some explanation as to the matters
of which hard porcelain is composed, also as to the arrangements or construction
of the ordinary kilns or ovens, as well as to say a few words upon the important
question of the action of the fire.
The bodies or matters of which hard porcelain is composed are divided into
two classes; first, the paste or clay, which is a principal element; and, second,
the glazing or enamelled covering. The paste or clay consists essentially of two
elements; the one is an infusible argillaceous matter, this is kaolin, either alone
or mixed with plastic clay, or with magnesite; the other, an infusible acid, is
given by feldspar or other stony minerals, such as siliceous sand, chalk, or
gypsum, either separately or mixed together in different combinations. The
enamel or glaze eonsists of quartzoze feldspar, sometimes alone and sometimes

page_text: in combination with gypsum, but always without either lead or tin; hard por-
celain must, in fact, be considered as hard, compact, impermeable pottery ware,
which is essentially translucid, and ought not to be confounded either with
stone ware, delph ware, pipe clay, or even with the ordinary tender English
porcelain. The kilns or ovens for firing or baking hard porcelain are generally
eylindrical, and divided into two chambers or laboratories, one placed above
the other. The upper laboratory is supplied with heat from the flame of the
lower laboratory, and serves to warm or heat the articles, which, when taken
from thence, are dipped into the glazing composition, and afterwards exposed
to the great heat in the lower laboratory, which may be properly said to con-
stitute the kiln. The fusion of the glaze or enamel, as is above said, requires
a very high temperature, and it is in the laboratory where this operation is
carried on that the temperature is raised to the highest degree. In both these
laboratories the articles must be enclosed in fire-clay vessels or seggars, which
should be carefully closed, in order to prevent the admission of deleterious
matters. The necessary amount of flame and heat may be obtained by
increasing the number of fire-grates and openings for the flame; thus, a kiln or
oven of six yards in diameter, which, when heated with wood, requires six
openings, must have ten when pit-coal is employed. A kiln or oven five yards
in diameter would require only five fire-grates for wood, but must be furnished
with eight for coal. A kiln or oven of four yards in diameter, heated by wood,
would require four fire-grates and apertures for wood, but must have six for coal.
In order to make the flame sufficiently long and abundant for the requirements
of the manufacture, the combustion ought to be supplied with a double draft or
additional currents of air. Thus, besides the supply furnished between the
fire bars from the surrounding atmosphere in the workshop, air obtained from
outside is conducted by horizontal channels to the fire; that is to say, besides
the ordinary supply of air, an additional quantity obtained from the external
atmosphere is made to act with energy on the fires in the grates. By this
means the kiln is supplied with a very large and superabundant supply of air;
which furnishes the fuel with a much greater quantity of gas to decompose.
The Figures in the accompanying Drawing represent a kiln or oven con-
structed according to the present improvements, and it should be observed that
it is always easy to obtain the necessary quantity of air by taking it from
the atmosphere of the workshop, either by having an aperture or grating at
the end of the ash-pit, or by making openings below the fire bars in the two
side walls of the furnace.
The improved system of firing or baking may be applied to all kilns, what-
ever may be their form or dimensions; and by means of a double roof in the

page_text: upper laboratory, hard and tender porcelain may be fired in the same kiln
simultaneously; (that is to say,) hard porcelain may be baked or fired in the
lower laboratory at the same time that tender porcelain or common earthen-
ware is being fired in the upper laboratory.
Note. It will be evident, therefore, that in those manufactories where at
present the baking of biscuit ware and glazed ware is carried on in separate
kilns, these kilns may, by the application of a double roof, be more advan-
tageously employed in the following manner:-In the biscuit kiln heretofore
employed, delph or earthenware, or unglazed tender porcelain, may be operated
upon in the lower laboratory, while hard porcelain may be dried and heated in
the upper laboratory; and in the other kiln, formerly used for glazing; the hard
porcelain should, on the contrary, be placed in the lower laboratory to be
baked or fired, and glazed delph or earthenware, or tender porcelain, may be
operated upon in the upper laboratory, the heat in which will be found sufficient
for this kind of ware.
The kilns being furnished with the required quantity of fire-places, the com-
bustion must be kept up by supplying an excess or superabundance of air;
obtained either from the external atmosphere or from the workshop, and sup-
plied in some convenient and suitable manner, depending, of course, upon the
situation of the kilns, their peculiar construction, and other circumstances. The
fire should be gradually supplied with fuel, at first at long intervals, then at
short intervals. The state of the fire-place should be looked to carefully, for
it is the rapidity of the combustion of the coal which indicates the quantity of
fuel that is required, and the moment when the charges are to be thrown on
quickly. The fire-places must be well watched for the purpose of levelling the
fuel, so that the fire bars may be suitably and evenly covered, and that air to
support combustion may always find a proper passage. It is also necessary to
rake the fire frequently, in order to clear out the cinders and to prevent the fire
bars from getting foul, and to remove clinkers therefrom, which would otherwise
stop or diminish the combustion.
Holes through the mass of fuel should never be allowed to exist, and the
flame should always be well watched, and the baking or firing operation
always be carried on with a long flame. All these precautions are necessary
in order to obtain very pure and white porcelain, as the defects of the firing
operation arise most frequently from the want of a proper flame.
The above observations are intended for the use of persons conversant with
and experienced in the manufacture of porcelain, and it is almost unnecessary
to add that the dimensions of the flues, heating surfaces, and other parts are
susceptible of considerable modification, depending upon the quantity of the

page_text: coal employed, and the state and temperature of the atmosphere, and other
circumstances.
In the accompanying Drawings, Fig. 1 represents a transverse vertical
section, taken through the centre of a kiln of the improved construction ;
Fig. 2 is a horizontal section or plan of the same; in both these Figures the
same letters denote corresponding parts. A is the outer chimney or flue of the
upper or second laboratory; B is an upper chamber, which may be used for
drying or heating; C, a roof (shewn by dotted lines), which will be required
if it is intended to bake or fire both tender and hard porcelain in the same
kiln; D is the flue of the lower chamber or laboratory; E, E, are passages or
openings, of which there are the same number as there are fire-places in each
kiln; these passages should be placed between the fire-places, and open a com-
munication from the lowerto the upper laboratory; F is the lower laboratory,
where the principal firing or baking operation is carried on; G, G, G, G, are
the fire-places; and H, H, H, H, openings to allow the flame to pass there-
from into the interior of the kiln; I, I, the fire bars; J, J, the fire door,
through which the fire is supplied with fuel; K, the ash-pit; L, L, are pas-
sages communicating with the ash-pit from the external atmosphere, to supply
air to the fire; this object may, however, be effected by making an aperture in
the front wall of the fire-place immediately below the fire-box and grate bars.
N, N, is the floor or hearth of the kiln; O, O, holes covered up in any suitable
manner, but communicating with the ash-pit, and whereby the scoria, cinders,
and clinkers may be removed therefrom. P, P, in Fig. 2, shews another
manner of supplying air to the fire-places, by making openings in the side walls
of the same. Q represents another mode by which air is supplied from the
atmosphere of the workshop through a grating communicating with the
ash-pit.
I would observe that whatever may be the mode adopted for supplying the
air to the fire, the same plan should be invariably adopted in all the fire-places
of the same kiln; thus, if the kiln is supplied with air obtained from the
atmosphere of the workshop, either by means of apertures made in the side
wall, or by means of a grating, as shewn in Fig. 2, all the fire-places of the
same kiln ought to be supplied in the same manner. On the other hand, if the
kiln is supplied with air conveyed through passages communicating with the
5 external atmosphere, all the fire-places must be supplied in the same manner,
and constructed upon the same plan.
Having now described the Invention that has been communicated to me by
my foreign correspondent, as aforesaid, I would observe that I am aware that
coal has been heretofore used for heating the kilns in which common earthen

page_text: or delph ware, and even tender English porcelain, is commonly baked or fired;
I do not, therefore, mean or intend to claim the employment of pit-coal for such
purposes as constituting any part of the present improvements; but that which
I consider to be new, and therefore wish to claim as the Invention secured to
me by the herein-before in part recited Letters, is,―
First, the application of coal for heating the kilns or ovens in which hard
porcelain is submitted to the baking or firing operation.
And, secondly, the arrangement or construction of kilns or ovens, as herein
shewn and described, or any mere modification thereof, whereby I am enabled
to employ pit-coal as the fuel for heating such kilns or ovens for firing or
baking hard porcelain in the place of wood, which has heretofore been employed
for that purpose.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto
set my hand and seal, this Twenty-ninth day of January, in the year
of our Lord One thousand eight hundred and forty-eight.
J. JEFFERSON.
AND BE IT REMEMBERED, that on the same Twenty-ninth day of
January, in the year above mentioned, the aforesaid Alfred Vincent Newton,
came before our Lady the Queen in Her Chancery, and acknowledged the
Specification aforesaid, and all and every thing therein contained, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute in that case made and provided.