IMPROVE- MENTS IN THE MANUFACTURE OF IRON
Year: 1855

page_text: LETTERS PATENT to Henry Bessemer, of Queen Street Place, New.
Cannon Street, in the City of London, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF IRON."
Sealed the 3rd June 1856, and dated the 7th December 1855.
PROVISIONAL SPECIFICATION left by the said Henry Bessemer at
the Office of the Commissioners of Patents, with his Petition, on the
7th December 1855.
I, HENRY BESSEMER, of Queen Street Place, New Cannon Street, in the
City of London, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF IRON " to be as follows:-
In the manufacture of iron, as generally practised in Great Britain, the
ironstone or ore is smelted with coal or coke in a blast furnace, from which
the molten iron is allowed to flow at certain intervals into channels formed in
a bed of sand, and becoming there consolidated forms what is technically
known as pig iron. The iron-so produced is generally mixed with sulphur,
silicia, and other heterogeneous matters, but more especially with carbon, the
quantity of which and its state of combination with the iron forming the chief
characteristic by which the pig iron of commerce is distinguished, and its
qualities classified. The quantity of carbon thus associated with the iron is
found in all cases to interfere with its malleability. It has, therefore, for the

page_text: most part been the practice in the manufacture of bar iron to expose the pig
iron to a refining process in what is known as "the finery," or running out
furnace, where the metal is remelted with coke or charcoal, and a certain
quantity of its carbon and other impurities are driven off, after which it is
allowed to flow into a long iron trough, where it consolidates, and is then
broken by the workmen into pieces of a size suitable for the "puddling"
process which is to follow. Now, the object of the first stage of my improved
process of manufacturing iron consists in refining the iron after it leaves the
blast furnace, and while still in a fluid state.
For this purpose I make a
vessel or ladle, somewhat similar to the ladles used in iron foundries, formed
of stout plate iron, and lined with loam or other suitable slow conductor of
heat. The ladle should be suspended on axes, and be nearly closed at top, or
the upper part may be quite closed, and an opening be made in the side of it.
This vessel should be placed near to the discharge hole of the blast furnace,
and at such a level that the fluid iron may be run direct into it. The vessel
should be of such dimensions as to be nearly filled with a single charge from
the furnace. As soon as the iron is let in I pass a pipe through the opening
into the vessel, and allow the end of it to dip into the metal, a current of
atmospheric air or steam, or both air and steam mixed together, is then to be
forced into the fluid metal, and allowed to bubble up through it. I prefer to
use "hot blast," and that the air should be heated as high as is found
practicable; in either case it will be found that the oxygen thus introduced
into the metal will rapidly combine with and carry off a large portion of
carbon and the impurities. When the workman judges the process has been
carried far enough (which the lessened fluidity of the iron will indicate), he
will turn the vessel on its axes, and discharge the contents of it into a suitable
iron mould, having compartments of such dimensions as will form ingots
suitable for the puddling process. The mould I also mount on axes in order
to facilitate the discharge of the ingots of refined iron therefrom. The vessel
in which this process is carried on may either be used cold, or it may be
previously heated by making a fire therein, or by other convenient means, and
the pipe by which the air or steam is conducted into the metal may be made
of fire clay and kept red hot, or it may be made of iron and coated with
loam. In the process of refining iron by air or steam, as herein described,
without additional fuel, it will be at once perceived that the injurious effects
of mineral coal or coke in the refining process are entirely avoided, while the
iron is rendered fit for the puddling process with less loss of time, labour, and
materials than is necessary in the finery or running-out furnaces at present
employed. For the purpose. of completing the refinement of the iron, I use a

page_text: reverberatory or puddling furnace, similar to those in general use; making the
hearth, however, a little deeper, and on the sides thereof, at any convenient
distance apart, I place hollow fire lumps; having a hole or holes therein;
below the level of the metal from these openings I force hot air into and
among the fluid metal, or in lieu thereof I use one or more pipes, which have
their lower ends inserted into the fluid metal, for the purpose of conducting
streams of air into it. The charge of iron having been put in and piled
up, as is usual in puddling furnaces, is allowed to melt slowly, and run down
on to the hearth; the air from a blowing machine is then turned into branch
pipes leading into the hollow fire lumps, before referred to, or into the pipes
which dip direct into the iron, meanwhile the workman should rake the metal
about with an implement in the manner generally practised until the iron is
in such a condition as will allow the balling operation to be carried on, after
which the squeezing, shingling, or other processes common to the manufacture
of bar iron, may be proceeded with. It will, however, be found that whenever
the puddling process is carried on in a reverberatory furnace, and the products
of combustion are allowed to pass over the metal on their way to the chimney,
that not only will a certain portion of ashes and other extraneous matters
become mechanically mixed with the iron, but sulphur and other volatile
products of the coal will combine with or act on the iron in an injurious
imanner. When it is desired, therefore, to make the iron as free as possible from
such impurities, I construct a puddling furnace, in which I place any con-
venient number of fire-clay retorts; similar in form to the retorts used in the
manufacture of coal gas, suitable openings being made in the ends thereof,
and fitted with doors, both for the purpose of putting in and taking out the
charge of iron by suitable pipes. I conduct a jet or jets of hot air into the
retorts, and either force it down into the fluid metal or pass it over the surface
of it, meanwhile the workman keeps the metal in motion with a rake or other
implement, as is usually practised in puddling iron. After the process is
finished, the iron may be made into puddle balls, and treated as usual, except
as far as regards the reheating thereof; which I prefer to do in fire-clay, retorts
of a suitable form, kept at a high temperature in an oven or furnace, and by
which processes the iron is prevented from coming in contact with the fuel or
gases resulting therefrom throughout each stage of the manufacture through
which it passes after leaving the blast furnace.
In the methods herein-before' described of carrying out my improvements in
the manufacture of iron, I have sought to adapt them to the other processes
of the manufacture as at present generally practised in Great Britain, and
whereby the said improvements may the more readily be brought into

page_text: operation; but I wish it to be understood that, except. in such cases, as the
aforesaid adaptation may be found expedient, I carry out the refinement of
pig or crude iron. by a single process, and cast the same into ingots suitable
for rolling at once into bars. or rods; for which purpose I construct an air-
furnace; in which I place a fire-clay or black-lead crucible; capable of holding.
several hundredweight of iron.. The interior of the furnace I construct of a
circular form, having a number of buttresses or projecting parts. jutting out
from its interior; these projecting parts stand out further at the fire grate than
at the top, and. are of, such a shape as to come in contact with the exterior of
the crucible, and thus form a series of supports to the crucible, and assist in-
preventing the pressure of the metal from bursting it, when it becomes.
softened by the. great heat to which it is exposed. The crucible. I form with
a dome-shaped top; in which one or more openings are made for the supply of
metal to its interior. I also provide a tapping: hole in the: bottom of the
crucible, through. which the refined. iron is run out; the spaces between the.
buttresses are to be occupied with fuel, and the, whole covered. over. with a.
suitable cover, so that a powerful draught may be maintained, and a very high.
degree of heat applied to the crucible. The furnace having been got up to
its full heat, the crucible is to be about three-fourths filled with fluid iron, by
preference.from the blast furnace; a pipe is then lowered into the fluid metal,.
and atmospheric air or steam,, or a mixture of steam and air, is to be forced
into the fluid, metal, until so much of, the carbon and other impurities are
driven off as will render the iron malleable; the heat is then to be raised in
order to. make it more fluid, when the plug is to be drawn out, and the iron-
allowed to flow into an ingot mould; the ingots so produced may then be
rolled or hammered into any of the forms usually given to bar iron. The
ingot I prefer to be of large dimensions, so as to require a considerable
amount of rolling before they are reduced to the required size.. The bar iron
produced by this process will be free from the numerous flaws produced by
the aglomeration of small fragments of puddled iron, while the largeness of
the ingot may avoid the necessity of "piling" to obtain a fibrous texture.
Although I have herein-before described. only the application of my said
Invention to the making of bar iron, I would, nevertheless, have it understood
that the same process, or, a modification thereof, may be used with iron
intended to be founded or cast into various articles.. When refining iron that
is intended to be used for founding, the metal may be entirely deprived of its
carbon, or nearly so, by which castings capable. of. being afterwards forged or
rolled will be produced; but, when castings are required to contain a large
quantity of carbon,. I first refine the metal in the manner described, and

page_text: then either put into the fluid metal some substances, such as wood, bituminous
shale, or other matters capable of supplying the required quantity of carbon
to the metal, or I pass through the metal a stream of any carburetted gaseous
matter. And here I would observe, that in passing air or steam through fluid
iron, I in some cases make use of it as a means of introducing any matters
that may be found to assist in the refinement of the metal. In this way I
blow in the dry powder of carbonate of soda or potash, whereby the separation
of silica is facilitated, and the slag rendered very fluid and easily run off.
The iron may be melted in a cupola or blast furnace, and then be refined
in a ladle or crucible to any desired extent, and be then run into the mould,
or it may be so far refined and deprived of carbon as to render it difficult to
found, in which case an addition of carbon may be made thereto by thrusting
à billett of dried wood or other suitable carbonaceous matter into the melted
metal, which will produce a rapid ebullition, and impart the desired quantity
of carbon to the iron.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Henry Bessemer in the Great Seal Patent Office on
the 7th June 1856.
. TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
BESSEMER, of Queen Street Place, New Cannon Street, in the City of London,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of December, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Henry Bessemer, Her special licence that I, the said Henry
Bessemer, my executors, administrators, and assigns, or such others as I, the
said Henry Bessemer, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there=
after 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 THE
MANUFACTURE OF IRON," upon the condition (amongst others) that I; the said
Henry Bessemer, my executors or administrators, by an instrument in writing
under my, or their; or one of their hands and seals, should particularly

page_text: 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 I, the said Henry Bessemer, do hereby declare.
the nature of the 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:-
!
"In the manufacture of iron as generally practised in: Great Britain,. the
ironstone or ore is smelted with coal or coke in a blast furnace, from which the
molten iron is allowed to flow at certain intervals into channels formed in a
bed of sand, and becoming there consolidated, forms what is technically known
as pig iron. The iron so produced is generally mixed with sulphur, silica, and
other heterogenous matters, but more especially with carbon, the quantity of
which, and its state of combination with the iron, forming the chief characteristic
by which the pig iron of commerce is distinguished and its qualities classified.
The quantity of carbon thus associated with the iron is found in all cases to
interfere with its malleability; it has, therefore, for the most part been the
practice in the manufacture of bar iron to expose the pig iron to a refining
process, in what is known as the "finery" or running out furnace, where the
metal is remelted with coke or charcoal, and a certain quantity of its carbon
and other impurities are driven off, after which it is allowed to flow into a long
iron trough, where it consolidates, and is then broken by the workman into
pieces of a size suitable for the puddling process, which is to follow. Now,
the object of the first stage of my improved process of manufacturing
iron consists in refining the iron after it leaves the blast furnace and while
still in a fluid state. For this purpose I make a vessel or ladle, somewhat
similar to the ladles used in iron foundries, formed of stout plate iron, and
lined with loam or other suitable slow conductor of heat. The ladle should be
suspended on axes and be nearly closed at top, or the upper part may be quite
closed and an opening be made in the side of it.". The shape and dimensions,
as well as the materials employed, in the making of such ladles or vessels, will
be found. greatly to influence the results obtained by their use; I will, therefore,
more particularly describe the peculiar forms which I have found best suited
for this purpose, first premising, as a general rule to be observed in their
construction, that the interior of the vessel should be as nearly spherical.as
may be, or of an egg shape, or of such other. form as will present as little
surface as may be for loss by radiation or absorption of heat by the vessel, in
proportion to the bulk of metal it contains; this point should be specially

page_text: attended to, because the fluid iron, if exposed in a shallow or narrow vessel or
in small quantities, would lose heat too rapidly to allow the crude iron to be
brought into the condition of "finery or plate metal" while still in a fluid
state. The vessel may be made of cast iron or 'other' metal, but I prefer to
'make it of stout plate iron, securely rivitted together; the interior may be
thickly coated with loam, but I prefer to line it with fire bricks, because I
have found such a lining more durable than any other with which I am
acquainted. The combination of such materials as iron and fire brick is rendered
necessary, in consequence of the force exerted on the vessel, not only by the
weight of the metal, but by the violent concussions produced by the agitation
of the fluid mass while under operation. The necessity for preventing loss of
heat, and of preventing any contact between the fluid iron and the iron vessel
in which it is operated upon, renders the fire brick lining peculiarly suitable
for that purpose. And in order that the same may be fully understood, I have
hereunto annexed a Sheet of Drawings, marked A, on which an example is
given of the kind of vessel I have found to answer in practise.
Figure 1 represents a vertical section, and Figure 2 an elevation, of an egg-
shaped modification of the vessel. a is the outer casing, of stout plate iron;
6 shows the internal lining, of loam, sand, clay, or some other slow conductor
of heat, used to protect the vessel; c is an iron frame, for the purpose of
supporting the vessel a on its axis d; and è is a handle attached to the axis, by
means of which the workmen turn round the vessel to discharge the fluid
metal; is a perforated fire tile or cover, laid loosely over the mouth of the
vessel, and which forms also a support for the pipe g.
The spherical form of vessel before mentioned is represented in section at
Figure 3, and in elevation at Figure 4; where h is the outer case or vessel, ;
and i, the lining of fire bricks; it is supported on axes on the frame j, and is
provided with a handle k, by means of which the workmen are enabled to tip
the vessel and pour out its contents. I is an opening made at one side of the
vessel, and which answers the same purpose as the perforations in the tile f;
shewn in Figure 1; namely, the escape of flame, sparks, and other products
of the combustion of the carbon contained in the crude iron. "This vessel
should be placed near to the discharge hole of the blast furnace, and at such a
level that the fluid iron may be run direct into it.. The vessel should be of
such dimensions as to be nearly filled with a single charge from the furnace:
As soon as the iron is let in, I pass a pipe through the opening m into the
vessel, and allow the end. of it to dip into the metal. A current of atmospheric
air
or steam, or both air and steam mixed together, is then to be forced into
the fluid metal and allowed to bubble up through.it. I prefer to use-hot blast;

page_text: and that the air should be heated as high as is found practicable;" or, in lieu
of hot blast, cold air may be used, if desired; "in either case it will be found
that the oxygen thus introduced into the metal will rapidly combine with and
carry off a large portion of carbon and the impurities. When the workman
judges that the process has been carried får enough (which the lessened
fluidity of the iron will indicate), he will turn the vessel on its axis, and dis-
charge the contents of it into a suitable iron mould, having compartments of
such dimensions as will form ingots suitable for the puddling process. The
mould I also mount on axes, in order to facilitate the discharge of the ingots
of refined iron therefrom."
The mode of discharging the fluid metal will be better understood by
reference to Figure 5, Sheet A, of the annexed Drawings, in which the vessel
is turned partly round on its axis, and allows the metal to flow out of the hole
m (from which the pipe n has been withdrawn). The hole m terminates in a
short spout or lip, from which the metal falls into the trough or mould p,-and
in which it is allowed to consolidate, and from which it may be afterwards
removed, by turning the mould p on its axis q into such a position as will
allow the mass to fall out. When the whole of the metal has been poured
from the vessel, it may be again moved into the position shown in Figure 4,
and a loose gutter r, communicating with the tap hole of the furnace from
which the fluid iron is obtained, will convey another charge of metal to the
vessel through the opening m; each charge may thus follow the other with
little loss of time, and thus advantage will be taken of the heated state of the
vessel, which will facilitate the process. In the first instance, "the vessel in
which this process is carried on may either be used cold, or it may be
previously heated, by making a fire therein, or by other convenient means, and
the pipe by which the air or steam is conducted into the metal may be made of
fire clay and kept red hot; or it may be made of iron and coated with loam."
I, however, prefer to use fire clay, or such refractory substances as are
commonly employed in making crucibles, and in all cases where they are used
I previously heat such pipes in an oven, from which they may be taken when
required at a red heat and put into the vessel.
Figure 6, on Sheet A of the annexed Drawings, shews a convenient form of
pipe. s is the part which enters the fluid.metal; t, a boss or collar, which rests
on the edge of the opening into the vessel, and which prevents the pipe from
falling into it; and u is a conical end, by means of which a sufficiently tight
joint is made by bringing the end of the air or steam pipe v on to the cone u.
The pipe v may be united to a piece of flexible pipe, so as to give facility for
its removal when cold air or steam is used; but if very hot air or superheated

page_text: steam be employed, the pipe v should be fitted to a fixed portion of pipe, so as
to slide in or out, in the manner known as a telescopic joint, and thus afford
facility for connecting or disconnecting the clay pipe with the steam or blast
pipes when required. "In the process of refining iron by air or steam, as
herein described, without additional fuel, it will at once be perceived that the
injurious effects of mineral, coal, or coke in the refining process are entirely
avoided, while the iron is rendered fit for the puddling process with less loss of
time, labour, and materials than is necessary in the finery or running-out
furnaces at present employed. For the purpose of completing the refinement
of the iron, I use a reverberatory or puddling furnace, similar to those in general
use, making the hearth, however, a little deeper, and on the sides thereof at
any convenient distance apart I place hollow fire lumps, having a hole or holes
therein below the level of the metal; from these openings I force hot air into
and among the fluid metal; or, in lieu thereof, I use one or more pipes, which
have their lower ends inserted into the fluid metal, for the purpose of con-
ducting streams of air into it. The charge of iron having been put in and
piled up, as is usual in puddling furnaces, is allowed to melt slowly and run
down on to the hearth; the air from a blowing machine is then turned into
branch pipes leading into the hollow fire lumps, before referred to, or into the
pipes which dip direct into the iron, meanwhile the workman should rake the
metal about with an implement in the manner generally practised, until
the iron is in such a condition as will allow the balling operation to be carried
on, after which the squeezing, shingling, or other processes common to the:
manufacture of bar iron, may be proceeded with."
In order that this part of my said Invention may be fully understood, I.
have shewn on Sheet A of the annexed Drawings the peculiar construction
of reverberatory furnace which I consider best adapted for the purpose of
carrying out this part of my said Invention.
Figure 7 represents a vertical cross section thereof, Figure 8 a longitudinal
section, and Figure 9 a side elevation. of the same.. The general arrangements.
of the fire chamber, the fire bars and feed holes, and the reverberatory arch.
and chimney, and also the mode of binding the furnace with iron bars or plates,
may be precisely similar to such parts of the puddling furnaces now in general
use; but I prefer to make the hearth or sole A of less length, and as much.
deeper as will compensate for such reduced length, whereby a greater depth of
metal will be obtained. Into the side walls B.of the furnace I insert several
fire lumps D, having a hole made therein, which I prefer to be of about one-
quarter to one-half of an inch in diameter. On each side of the furnace I fix up,
an air pipe C, in communication with a blast engine; the upper part of this

page_text: pipe passes along the side of the furnace in an horizontal direction, at a leve
higher than the surface of the fluid metal within the furnace E, E. The smal
branch pipes E, E, are fitted with joints to the horizontal pipe C, so that they
may be moved into the position shewn at E*, Figure 7, and thus allow the
holes in the fire lumps D to be cleaned out or removed from the furnace when
required. When the apparatus is in operation, the pipes E have their lower
ends inserted a short distance into the lumps D, the joint being still further
secured by a little soft loam or clay put around the junction, so that several
tuyere holes are thus formed below the surface of the metal on the hearth,
and by means of which, air (or steam) may be forced into and among the par-
ticles of fluid metal, and be allowed to bubble up through the metal so long as
it remains fluid or pasty, and which will also serve for admitting air (or steam)
in among the solid lumps of iron which are formed in the act of puddling, and
thus the process will be facilitated by the action of the oxygen thus introduced
combining with the carbon of the iron, and thereby producing combustion,
and: at the same assisting in the disengagement of the volatile matters and
other impurities contained in the iron. When the workman (who moves the
iron about with a tool as usual) judges, that the iron is sufficiently freed from
its impurities, he may proceed to form it into balls, in the manner now com-
monly practised. Should it be preferred to force air into and below the surface
of the fluid iron by means of pipes, I make openings in the side walls of the
furnace, through which I insert loosely the fire-clay pipes, which may be made;
and connected to the blast pipe in the manner herein-before described, and.
represented at Figure 6, Sheet, A, of the annexed Drawings, so that the pipes
may be put into or taken out of the furnace as required.
"It will, however, be found, that whenever the puddling process is carried
on in a reverberatory furnace, and the products of combustion are allowed to
pass over the metal on their way to the chimney, that not only will a certain,
portion of ashes and other extraneous matters become mechanically mixed with
the iron, but sulphur and other volatile products of the coal will combine with
or act on the iron in an injurious manner. When it is desired, therefore, to:
make the iron as free as possible from such impurities, I construct a puddling:
furnace, in which I place any convenient number of fire clay retorts, similar in:
form to the retorts used in the manufacture of coal gas, suitable openings being.
made in the ends thereof, and fitted with doors, both for the purpose of putting in
and taking out the charge of iron. By suitable pipes I conduct a jet or jets of
hot air into the retorts, and either force it down into the fluid metal or pass it
over the surface of it, meanwhile the workman keeps the metal in motion with
a rake or other implement, as is usually practised in puddling iron. After.

page_text: the process is finished, the iron may be made into puddle balls, and treated
as usual."
In order that the peculiar, construction of the retort furnace (which I con-
sider most suitable for carrying into practical operation this part of my said
Invention) may be fully understood, I have represented the same on Sheet A of
the Drawings hereunto annexed, where Figure 10 is a cross section, Figure 11
a side elevation, and Figure 12 another section, taken on the line A, B, of
Figure 10. G, G, are retorts, made of fire clay, the ends of which rest on the
side walls H of the furnace, and at intervals, on supporting walls I; formed in
the interior thereof; the retorts are each provided with an opening or mouth
at one end, over which a sliding door J is made to move by a chain and
counterweight, in a manner similar to that by which the doors of puddling
furnaces are now generally made to open. In the upper part of each retort
small holes are made at K, K, for the escape of gaseous matters from the inte
rior of them, and at each end of the retorts I make projections L, which have
holes passing through them into the interior of the retort; into these holes a
fire-clay nozzle or tuyere pipe M is placed, and its junction secured by loam or
similar matter, well rammed into the joint; the outer ends of these, tuyere
pipes are flush with the exterior walls of the furnace, and are there united to
the pipes N, the lower elbow of which is made conical, and enters a short dis-,
tance into the clay tuyere pipes. The pipes N, N, are attached to the blast
pipe P by moveable joints, so as to allow of their movement into the position
shewn at N*, whenever it is required to remove or gain access to the tuyere,
pipe. It will thus be seen that currents or jets of air or steam may be forced
into the fluid metal contained in such retorts, whereby the metal will be ren-,
dered more pure and the process of puddling greatly, facilitated. And here I
would observe, that in all cases where air or steam is blown or forced through
tuyere pipes, the orifices of which are situated below the surface of the fluid
iron, that the blast of air or steam must be allowed to issue therefrom previous
to the introduction of the fluid metal into the chamber,, retort; or other vessel
in which they are used, and also that the pressure of such air or steam at the
point of escape must exceed the pressure due to the column of fluid iron
against which such jets are forced, and that such pressure must be in all cases,
continued until after the metal has been run from such vessels or retorts, or has
lost so, much of its fluidity as will prevent it from flowing into the tuyere pipes.
By reference to Sheet A of the Drawings, it will be seen that the fire grate
Qis situated below the centre retort, from which, part the heated matters, find
their way between the walls I, crossing the bottom of the two other retorts,
and escaping upwards into the space above, in the centre of which a row of

page_text: holes R is formed, leading into the horizontal flue S, and thence into the
chimney T, the centre retort having its working hole and door J at the oppo-
site side of the furnace to the other retorts, thus affording ample space for the
workmen who puddle the charge in the two outer retorts, while it also gives
greater space to the workman at the opposite side of the furnace who puddles
the charge contained in the centre retort, and he is thus prevented from standing
in front of the fire door U, which he would have to do if all the retorts opened
on one side.
In puddling iron with the kind of retort furnace just described, crude or
"finery iron may be put into the retort in the form of "pig or plate metal,"
and be remelted therein; or fluid iron may be run or poured therein, after the
manner already practised for supplying fluid iron to puddling furnaces, the
blast of air or steam being turned on previous to the fluid metal rising as high
up as the orifices of the tuyere pipes. When the workmen judge that the
action of the blast upon the metal has brought it to a favourable condition,
they will proceed to rake it about and turn it over in the usual manner; the
high temperature which the metal will acquire, in part by the application of
fire to the retorts, and in part by the combustion going on in and among the
particles of metal, will enable them to work the same into puddle balls, with-
out waiting for any further heating of the mass, as at present. Such fluxes as
salt, or oxide of manganese, iron scales, lime, or other matters heretofore used
in the puddling of iron in the open furnace, may also be used, if desired, in pud-
dling in retorts, and the slags produced may either be scooped out at the
mouth of the retort, or they may be run off at a hole made at the back-end
of the retort, and which hole may be stopped with loam, and opened from
time to time, as required.
I have herein-before mentioned that iron may be puddled in retorts by
forcing jets of air or steam on to instead of into the fluid iron. I will now
proceed to shew in what manner the retort should be made when it is desired
to use this modification of my Invention; I have therefore shown at Figure 13,
Sheet A, of the annexed Drawings, a longitudinal section of a retort suit-
able for this purpose. V is the retort, having a boss or projection W. formed
above the level of the metal; the boss has a tuyere pipe X passing through it,
so as to direct the blast on to the metal in an oblique direction. Any conve-
nient number of blast pipes may thus be directed on to the metal from one or
both ends of the retort during the puddling process, which will not proceed so
rapidly as when the air is forced below the surface of the metal, and for which
reason I prefer the forcing in of the blast, as before described. In either case,
the iron when made into balls may be subjected to the further processes of

page_text: the iron. manufacture as usually practised, "except as far as regards the
reheating thereof, which I prefer to do in fire-clay retorts of a suitable form,
kept at a high temperature in an oven or furnace, and by which processes the
iron is prevented from coming in contact with the fuel or gases resulting there-
from throughout each stage of the manufacture. through which it passes after.
leaving the blast furnace."
The retort. furnace which I use for the purpose of reheating or of retaining
the heat of iron, made according to my said Invention, is represented. on.
Sheet B of the Drawings hereunto annexed,, where Figure 1 is a front eleva-
tion, Figure 2. a cross section,. and. Figure 3 a longitudinal section, of the,
retorts, and furnace. a, a, are the retorts, which I prefer to be made of fire,
clay; the ends of them are supported on the outer walls. b, and the central
parts of them, by the internal. walls c, c;. d is the fire grate, with its door and
fire. bars made in the manner usually employed in similar furnaces;, the retorts.
are provided with openings at each end, which may be stopped with. a. fire
tile e, or by a door, so as to cut off the free access of air to the interior of the
retorts, and thus prevent the rapid oxydation that its presence would cause..
The flame and heated matters from the fire grate pass under the retorts in the
direction shewn. by arrows, and escape into the flue f and chimney g; the
bars or other blocks or masses of metal, represented at h, may be thus reheated.
or retained at an even temperature until. they are required, without being.
exposed. to the injurious effects of the fuel and gaseous products of the furnace,.
or to the oxydation which would follow its exposure for a long period.of.time.
to the free action of the atmosphere..
"In the methods herein-before described of carrying out my improvements
in the manufacture of iron, I have sought to adapt them to the other processes of
the manufacture as at present generally practised in Great Britain, and whereby.
the said improvements may the more readily be brought into operation; but. I
wish it to be understood that, except in such cases as the aforesaid adaptation.
may be found expedient, I carry out the refinement of pig or crude iron. by a.
single process, and cast the same into ingots suitable for rolling at once into
bars or. rods, for which purpose I construct an air furnace, in which a fire-
clay or black lead crucible capable of holding several hundredweight of iron.
The interior of the furnace I construct of a.circular form,. having a number.
of buttresses or projecting parts jutting out from its interior; these projecting
parts stand out further at the fire grate than at the top, and are of such a shape.
as to come in contact with. the exterior of the crucible, and thus form a series.
of supports to the crucible, and assist in preventing the pressure of. the metal.
from bursting it when it becomes softened by the great. heat to which it.is

page_text: exposed. The crucible I form with a dome-shaped top, in which one or more
openings are made for the supply of metal to its interior; I also provide a
tapping hole in the bottom of the crucible, through which the refined iron is
run out; the spaces between the buttresses are to be occupied with fuel, and the
whole covered over with a suitable cover, so that a powerful draught may be
maintained, and at a very high degree of heat applied to the crucible. The
furnace having been got up to its full heat, the crucible is to be about three-
fourths filled with fluid iron (by preference from the blast furnace); a pipe is
then lowered into the fluid metal, and atmospheric air or steam, or a mixture
of steam and air, is to be forced into the fluid metal, until so such much of the
carbon and other impurities are driven off as will render the iron malleable."
The description of furnace which I prefer for carrying into practical opera-
tion the conversion of crude flude iron into a nearly pure and malleable iron
while still in a fluid state, is represented on Sheet B of the Drawings hereunto
annexed, where Figure 4 is a vertical section, Figure 5 a horizontal section,
through the tapping hole of the crucible; Figure 6 is another vertical section,
on the line A, B, of Figure 4; and Figure 7, a plan of the circular cover of the
furnace; details are also shewn at Figures 8 and 9. E is the crucible for
containing the fluid iron, and which I prefer to be made of fire clay, in a
manner well understood and practised in making the large pots used in the
manufacture of glass. The crucible is supported on a stand or mass of fire
clay F, which rests on the fire bars G, two of the fire bars G* being made of
greater strength for the better support of the crucible. At the front side of
the furnace there is a conical opening H, which extends across the space left
at other parts between the crucible and the furnace; the sides and top of the
opening H are formed with fire tiles I, or of a moulded piece of fire clay, so
as to cut off the communication with the annular space which is formed
between the crucible and the cylindrical interior of the furnace. At the bottom
of the crucible I make a hole, which may be stopped with a plug of burned
fire clay, or by soft loam; as shown at K, and by means of which I tap or run
out the fluid iron, in a manner similar to that commonly practised by iron-
founders, to discharge the molten metal from the cupola furnaces which they
employ, access being had at all times when required to the tap hole K by
means of the opening H, without admitting air to or otherwise affecting the
action of the furnace. The upper part of the crucible has a cover L fitted to
it, around which several openings L* are made, for the escape of gaseous
matters from the interior of the crucible; the cover has also a central hole,
through which the fire-clay pipe M is introduced. At N a flue leads from the
furnace into a tall chimney, calculated to afford a powerful draught, so as to

page_text: keep up a vivid combustion in the furnace, in which I use, by preference, good
oven-made coke. The top of the furnace is covered with a stout fire brick
cover P, hooped with iron, and having a central hole for the purpose of putting
in the pipe M when required; it is also provided with openings Q, Q, through
which fuel is supplied to the furnace from time to time. Small tiles R, R, are
used to cover these holes, and prevent the ingress of cold air into the furnace.
To prevent the bulging out of the sides of the crucible, I place several fire
tiles S in a radial position in the fire chamber, against the edges of which the
pot is in contact, while the opposite edge of the tiles are inserted in the walls
of the furnace; the crucible is thus supported and rendered more durable.
Having thus described the various parts of such a furnace as I have found
to answer well in practice, I will now proceed to describe how the same may
be used for the purposes of my Invention.
66
The crucibles to be employed must be "burned or fired" in a
pot arch,"
as well understood and practised by glass makers, and there kept at a red heat
until required; the furnace should have a fire made therein in order to bring
up the heat to a bright red. The cover P is then removed and the crucible
placed into its seat; the cover L must be then placed on it, and the cover P
of the furnace replaced as quickly as possible; more fuel may then be put in
through the openings Q, until the spaces between the supports S are quite filled
up; the workman will then proceed to stop the tapping hole K, after which
the furnace will be in a condition to commence operations, for which purpose
the workman will provide himself with a funnel made of plate iron and lined
with loam, as represented in section at Figure 9, Sheet B, of the annexed
Drawings. This funnel is put through the central hole in the furnace cover P,
on which the upper part of it will rest, while the lower part will enter the top
of the crucible; the workman will then run or pour the fluid iron therein,
whether the same be obtained direct from the ore in a blast or other furnace,
or is obtained by the remelting of pig or refined iron, called "plate metal,"
or waste or scrap cast iron; the funnel is then to be removed, and a fire-clay
tube is to be taken at a red heat from the "pot arch" and inserted in the
crucible, as represented at Figure 4, Sheet B; of the annexed Drawings, and
also at Figure 8 of the same Sheet, where it is shewn in connection with a'
piece of iron tube T, to which a piece of elastic tube U is also attached,
and through which air or steam is to be forced into the fluid metal. The
workman being provided with the moveable piece of tube T and flexible pipe U,
attached to a steam or blast pipe; he will lower the end of the tube T on to
the conical end of the fire-clay tube M, whereby a communication will be
established with the blast of air or steam, whichever he may desire to employ,

page_text: and which must be of such a pressure as will overcome the resistance of the
column of fluid iron and rush in among it, causing a violent ebullition of the
metal, accompanied by sparks and flame, which will find an escape by the holes.
made in the cover L for that purpose. The oxygen of the atmospheric air or
decomposed steam will thus be made to unite with the carbon of the iron and
carry it off, at the same time a portion of the oxygen combining with-the iron
will produce oxide of iron, which rapidly fuses, and combines with other
impurities of the iron; the combustion which is going on among the particles
of iron adds greatly to the temperature of the metal, which as it loses its
carbon requires a much greater heat to maintain it in a fluid state.
The hole in the furnace cover P being larger than the pipe T; the workman
will be enabled to see through the space thus formed, and judge of the
progress which is being made in the operation by the appearance of the flame
and sparks which issue from the holes in the cover L. After the air has
been forced in about fifteen or twenty minutes, a considerable augmentation
of the flame generally takes place, accompanied with a copious discharge of
slag, which discharge lasts generally about five or six minutes, and then
ceases to a great extent; a large body of flame still, however, continuing
to force its way out for a period of about ten minutes, after which it gradually
diminishes, and thus indicates to the workman that the process is com-
pleted, and that the crude metal has been converted into a nearly pure
malleable iron. The workmen will then proceed to unstop the tap hole in
the bottom of the crucible, and allow the fluid iron to flow into an ingot, or
such other mould as he may desire, or he may run the metal into a founder's
ladle, by means of which the moulds may be filled. The tap hole may then be
closed, and the pipe M again removed, so as to allow the workman to run in
another charge of crude iron to be treated in a similar manner, meanwhile.
he will keep up the fire in the furnace by the addition of fuel from time to
time, as may be required..
:
And here I would remark, that the appearance presented by, the flame, sparks
and slag issuing from the upper. part of the crucible will vary with the quality
and quantity of metal treated, and with the temperature obtained, a knowledge.
of which the workman may soon acquire. Those indications which I have
pointed out are pretty uniformly, obtained, and afford a good criterion of the
state of the metal.. I have in no case found the iron pass into the malleable
state and retain its fluidity without first undergoing the violent ebullition before.
mentioned, which sets in spontaneously, and throws off the slags by the rising
or boiling up of the metal.
I would also remark, that I have found that the use of steam in the early,

page_text: part of the process is useful in assisting the removal of sulphur from the iron;
but if it be used alone towards the close of the process, a great difficulty is
experienced in maintaining the requisite heat and fluidity of the iron, which
is apt to assume the pasty condition, and to require an additional degree of
heat before it is fluid enough to run out; I therefore prefer to use steam only
during the first part of the time occupied by the process, completing it by the
use of air, and in some cases using air only, whereby the intense heat required
to maintain malleable iron in a fluid state is more easily obtained, more
especially if the supply of air is copious, and the pressure such as to thoroughly
boil up the metal. However, should 'the metal from any cause have assumed a
somewhat pasty condition, "the heat is then to be raised in order to make it
more fluid, when the plug is to be drawn out and the iron allowed to flow
"into an ingot mould. The ingots so produced may then be rolled or ham-
mered into any
of the forms usually given to bar iron; the ingot I prefer to
"be of large dimensions, so as to require a considerable amount of rolling
"before they are reduced to the required size; the bar iron produced by this
process will be free from the numerous flaws produced by the aglomeration
"of small fragments of puddled iron, while the largeness of the ingot may
"avoid the necessity of piling to obtain a fibrous texture."
seen, that by this process the manipulation of the metal in the puddling
furnace will be entirely dispensed with, the metal passing by a single process,
from the state of crude iron to the condition of pure or nearly pure malleable
iron, which is then cast into moulds of such a size and shape as will be best
suited for the kind of rod, bar, rail, or plate intended to be made from them.
It will also be understood that the whole mass of metal, however large. the
ingot may be, will be generally of the same homogenous quality throughout,
its different particles cohering firmly together, and being entirely free from that
admixture of cinder and other heterogeneous matters that are always more or
less mixed up and worked in with the iron in the process. of puddling.
Thus it will be
"Although I have herein-before described only the application of my said
Invention to the making of bar iron, I would nevertheless have it understood
that the same process, or a modification thereof, may be used with iron intended
to be founded or cast into various articles. When refining iron that is intended
to be used for founding, the metal may be entirely deprived of its carbon, or
nearly so, by which castings, capable of being afterwards forged or rolled, will
be produced; but when castings are required to contain a large quantity of
carbon, I first refine the metal in the manner described, and then either put
into the fluid metal some substances, such as wood, bituminous shale, or
other matters capable of supplying the required quantity carbon, to the
B

page_text: metal, or I pass through the metal a stream of any carburetted gaseous
matter. And here I would observe, that in passing air or steam through fluid
iron, I in some cases make use of it as a means of introducing any matters
that may be found to assist in the refinement of the metal. In this way I
blow in the dry powder of carbonate of soda or potash, whereby the separation
of silica is facilitated, and the slag rendered very fluid and easily run off.
The iron may be melted in a cupola or blast furnace, and then be refined
in a ladle or crucible to any desired extent, and be then run into the mould;
or it may be so far refined and deprived of carbon as to render it difficult
to found, in which case an addition of carbon may be made thereto, by
thrusting a billett of dried wood or other suitable carbonaceous matter into
the melted metal, which will produce a rapid ebullition, and impart the desired
quantity of carbon to the iron."
Whenever the recarbonization of fluid malleable iron is to be effected, I
prefer to carry out this part of my said Invention by using crucibles, as
herein-before described, into which the carbonaceous gases may be forced by
the same kind of apparatus as is employed to force in the air, the same fire-
clay tubes being also employed for the conveyance of the gas into the metal ;
but when it is desired to effect the recarbonization of the fluid iron by the use
of solid carbonaceous substances, it will be necessary to force such substances
down beneath the metal with an iron rod, coated with loam, or otherwise
defended from the action of the metal; in either case a very pure quality of
foundry iron may be thus obtained, for the most part free from that admixture
of silicum, sulphur, and other matters usually associated with crude iron. In
those cases where it is found desirable to flux the metal with soda, potashes,
or other substances in the form of powder, I enclose such matters in a small
chamber in connection with the blast pipe, such chamber having a perforated
bottom, through which the powder may be made to fall, by striking the vessel,
and thus shaking it into the blast pipe, along which it will be carried by the
force of the current, and will thus find its way into the metal.
Having thus described the nature of my Invention, and the manner in
which the same is carried into practical operation, as modified to work in con-
junction with other processes now in daily use in the manufacture of iron,
and having also shewn how my Invention may be worked, irrespective of such
adaptations to the present modes of working, whereby I am enabled to treat
fluid crude iron, or remelted pig or refined iron, or remelted waste or scrap
cast iron, and to change or convert such metal into pure or nearly pure,
malleable iron by a single process, without any manipulation analagous to the
puddling process, and by which such metal is retained in a fluid state during,

page_text: the process of conversion, and until it is cast into ingots or bars of pure or
nearly pure malleable iron, suitable for hammering or rolling into rods, bars,
rails or plates, and for founding various articles; I will (in order that the
nature and extent of my said Invention may be clearly ascertained and its
limits defined) remark, that I am aware that it has before been proposed to
force air or steam or water into fluid crude iron as it flows along gutters
leading to pig beds, and after it has run into pig beds, and thus to prepare
iron for the ordinary process of puddling; and I mention this fact in order
that it may be distinctly understood that I do not claim generally the pre-
paring of crude iron for the process of puddling, by forcing air or steam into
fluid cast iron when flowing in gutters or when in a pig bed, nor do I claim
the use of gutters or pig beds for such a purpose. I will also mention, that I
am also aware that steam has been forced into fluid cast iron when under-
going the puddling process, by a workman using a hollow or tubular "rabble,"
and I am also aware that it has before been proposed to employ a series of
sliding tubes through the upper part of a puddling furnace, for the purpose of
blowing streams of steam in contact with the fluid metal in such furnaces;
and I mention these facts in order to state that I make no claim to the intro-
duction of streams of steam into a puddling furnace where iron is undergoing
the process of puddling; but what I do claim is,
Firstly, constructing and applying vessels, partly of metal and partly of loam,
fire brick, or other refractory slow conductor of heat, and the mounting of such
vessels on axes, when treating fluid iron, by forcing currents of air or steam
below the surface of such fluid metal.
Secondly, I claim forcing air or steam into and below the surface of fluid
iron by means of fire-clay pipes, or through passages or tuyeres formed in
lumps of fire clay, or such mixture of fire clay and other matters as are
generally employed in making crucibles.
Thirdly, I claim forcing air into or below the surface of fluid crude or cast
iron in a puddling furnace through passages, pipes, or tuyeres, the orifices of
which are situated below the surface of the fluid metal.
Fourthly, I claim the puddling of iron in retorts or close chambers, from
which the fuel and vapours of the furnace are excluded, and into which
atmospheric air is forced below or on to the surface of the fluid metal.
Fifthly, I claim reheating or maintaining at a high temperature in retorts
masses of iron that have been treated by forcing currents of air or steam
therein when in a fluid state, so as to protect such iron from the action of the
atmosphere, and from the injurious vapours of the furnace.
Sixthly, I claim the forcing of currents of air or of steam, or of air and

page_text: steam, into and among the particles of molten crude iron, or of remelted pig,
cast, or refined iron, until the metal so treated is thereby converted into
malleable iron whilst still retaining a fluid state, and the running of such fluid
malleable iron into suitable moulds.
Seventhly, I claim the manufacture of rods, bars, rails, and plates of
malleable iron by hammering or rolling, or by hammering and rolling, ingots
or masses of iron that have been rendered into malleable iron, by forcing air
or steam, or air and steam, into and among the particles thereof whilst in a
fluid state.
Eighthly, I claim founding articles in molten malleable iron, obtained by
forcing air or steam or both into fluid crude iron until the same is thereby
rendered malleable.
Lastly, I claim preparing iron for founding purposes, by forcing currents
of air or steam into and below the surface of such iron. while in a fluid
state, and then supplying a quantity of carbon thereto, by forcing into the
same carbonaceous gases, or by carbonaceous matters, in the manner herein
described.
In witness whereof, I, the said Henry Bessemer, have hereunto set my
hand and seal, this Seventh day of June, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
B. GOBEY,
4, Old Square, Lincoln's Inn.
HENRY BESSEMER. (L.S.)