AN IMPROVEMENT OR IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL
Year: 1863

page_text: LETTERS PATENT to Robert Mushet, of Coleford, in the County of
Gloucester, Metallurgist, for the Invention of "AN IMPROVEMENT OR
IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL."
Sealed the 2nd October 1863, and dated the 12th August 1868.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the
12th August 1863.
I, ROBERT MUSHET, of Coleford, in the County of Gloucester, Metal-
lurgist, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT OR IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL," to be as
follows:-
When pig or cast iron is subjected whilst in a melted state to the decar-
bonising process commonly called the pneumatic process, and has been by that
process deprived or nearly deprived of the whole of its carbon, malleable iron
is produced; the malleable iron so produced is commonly called pneumatized
iron. The said malleable pneumatized iron is obtained from coke or charcoal
pig or cast iron by melting the said pig or cast irons, and then forcing air
through the said melted pig or cast irons until the whole or nearly the whole of
the carbon which they contain has been eliminated.

page_text: My Invention consists in adding to melted malleable pneumatized iron a
quantity of melted refined cast iron, by means of which addition the said
pneumatized iron is at once converted into cast steel. Refined cast iron is
cast iron partially decarbonized and purified from silicon, and it may be
prepared by various methods. The usual method of preparing refined iron
or finers' metal, as it is frequently termed, is by melting pig or cast iron in
the hearth of an ordinary refinery furnace, and by blowing air through
tuyeres down upon the surface of the melted pig or cast iron until a con-
siderable portion of the carbon and silicon contained in the said pig or cast
iron has been eliminated. The melted refined iron is then run out and cast
into plates or slabs to be broken up for use. Refined cast iron may likewiso
be prepared by partially decarbonizing pig or cast iron whilst in a melted state
by the pneumatic process, or refined cast iron may be prepared by melting
granulated pig or cast iron mixed with about ten per centum of oxide of iron
in melting pots or crucibles. The refined cast iron which I prefer to employ
for my process is such as has been prepared from good charcoal pig iron, such
as Swedish or Indian pig iron, but refined cast iron prepared from coke pig
iron of good quality and nearly free from sulphur and phosphorous may like-
wise be employed. The quantity of refined cast iron which I prefer to add to
the malleable pneumatised iron is from twenty to fifty pounds of the said
refined cast iron to every one hundred pounds of malleable pneumatised iron.
I do not however confine myself to these relative proportions of the refined
cast iron to the malleable pneumatised iron, for the proportions may be varied
without departing from the nature of my Invention; but the proportions I have
herein given produce most of the varieties of cast steel required in commerce,
and answer exceedingly well. I add the refined cast iron to the pneumatised
malleable iron when both aro in a melted state, so that the said refined cast
iron and the pneumatised malleable iron may become mixed, and form by
their union cast steel. The addition of the melted refined cast iron to the
melted pneumatised malleable iron may be effected in any convenient manner,
as, for example, the refinery furnace, or the pneumatic furnace, or vessel
which contains the refined cast iron may bo tapped, and the refined cast iron
run off at once into the pneumatic converting furnace or vessel containing the
pneumatised malleable iron; or the refined cast iron may be melted in
melting pots or crucibles, and be then poured into the pneumatized malleable
iron contained in the pneumatic furnace or vessel; or both the refined cast
iron and the pneumatized malleable iron may be poured into a heated ladlo or
other heated receptacle, and mixed therein. The cast steel obtained by the

page_text: mixture of the said refined cast iron and the said pneumatised iron may be
poured into ingot or other suitable moulds prepared to receive the said cast
steel. I wish it to be observed that the greater the quantity of refined
cast iron added to a given weight of pneumatized malleable iron the harder
will be the quality of the cast steel obtained by the mixture of these
substances.
The essence of my Invention consists in producing cast steel by adding to
melted pneumatised malleable iron, that is to say, to cast iron which has been
decarbonized and rendered malleable by the pneumatic process, a quantity of
melted refined cast iron, and mixing the said refined cast iron and the said
melted pneumatised malleable iron when both these substances are in a melted
state.
Melted spiegel eisen or melted manganesic pig iron may be added to the
said mixture of refined cast iron and pneumatised malleable iron, but such
addition forms no part of my Invention.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
11th February 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
MUSHET, of Coleford, in the County of Gloucester, Metallurgist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of August, in the year of our Lord Ono
thousand eight hundred and sixty-three, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Robert Mushet, Her special licence that I, the said Robert
Mushet, my executors, administrators, and assigns, or such others as I, the
said Robert Mushet, 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 "AN
IMPROVEMENT OR IMPROVEMENTS IN THE MANUFACTURE OF CAST STEEL," upon
the condition (amongst others) that I, the said Robert Mushet, my executors
or administrators, by an instrument in writing under my, or their, or

page_text: 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 per-
formed, 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 Robert Mushet, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
When pig or cast iron is subjected whilst in a melted state to the decar-
bonising process commonly called the pneumatic process, and has been by
that process deprived or nearly deprived of the whole of its carbon, malleablo
iron is produced; the malleable iron so produced is commonly called
pneumatized iron. The said malleable pneumatized iron is obtained from
coke or charcoal pig or cast iron by melting the said pig or cast irons, and
then forcing air through the said melted pig or cast irons until the whole or
nearly the whole of the carbon which they contain has been eliminated.
My Invention consists in adding to melted malleable pneumatized iron a
quantity of melted refined cast iron, by means of which addition the said
pneumatized iron is at once converted into cast steel. Refined cast iron is
cast iron partially decarbonized and purified from silicon, and it may be
prepared by various methods. The usual method of preparing refined iron or
finers' metal, as it is frequently termed, is by melting pig or cast iron on the
hearth of an ordinary refinery furnace, and blowing air through tuyeres down
upon the surface of the melted pig or cast iron until a considerable portion of
the carbon and silicon contained in the said pig or cast iron has been elimi-
nated by oxidation. The melted refined iron is then run out of the furnace
and cast into plates or slabs to be broken up for use.
Refined cast iron may
likewise be prepared by partially decarbonizing pig or cast iron whilst in a
melted state by the pneumatic process, or iron having the composition and
properties of refined cast iron may be prepared by melting granulated pig or
cast iron mixed with about ten per centum of oxide of iron in melting pots or
crucibles; and I wish it to be understood that by refined cast iron I mean
cast iron which has been so far deprived of part of its carbon or part of its
carbon and silicon as to have the composition of refined iron prepared in an
ordinary refinery furnace irrespective of the processes by which the carbon or
carbon and silicon have been eliminated from the said cast iron. :
The refined cast iron which I prefer to employ for my process is such as bas

page_text: been prepared from good charcoal pig iron, such as Swedish or Indian pig
iron, but refined cast iron prepared from coke pig iron of good quality and
nearly free from sulphur and phosphorous may likewise be employed. The
quantity of refined cast iron which I prefer to add to the malleable
pneumatized iron is from twenty to fifty pounds of the said refined cast iron
to every one hundred pounds of malleable pneumatized iron. I do not, how-
ever, confine myself to these relative proportions of the refined cast iron to the
malleable pneumatized iron, for the proportions may be varied without
departing from the nature of my Invention; but the proportions I have berein
given produce most of the varieties of cast steel required in commerce, and
answer exceedingly well. I add the refined cast iron to the pneumatized
malleable iron when both are in a melted state, so that the said refined cast
iron and the pneumatized malleable iron may become mixed, and form by
their union cast steel. The addition of the melted refined cast iron to the melted
pneumatized malleable iron may be effected in any convenient manner, as, for
example, the refinery furnace, or the pneumatic furnace, or vessel which contains
the refined cast iron may be tapped, and the refined cast iron run off at once
into the pneumatic converting furnace or vessel containing the pneumatized
iron; or the refined cast iron may be melted in melting pots or crucibles,
and be then poured into the pneumatized malleable iron contained in the
pneumatic furnace or vessel; or both the refined cast iron and the pneumatized
malleable iron may be poured into a heated ladle or other heated receptacle,
and mixed therein. The cast steel obtained by the mixture of the said refined
cast iron and the said pneumatized iron may be poured into ingot or other
suitable moulds prepared to receive the said cast steel. I wish it to be
observed that the greater the quantity of refined cast iron added to a given
weight of pneumatized malleable iron the harder will be the quality of the cast
steel obtained by the mixture of these substances.
The furnaces and other appliances which I use in carrying my Invention
into effect are of the kinds well known and commonly employed in the manu-
facture of iron and steel, and I therefore do not consider it necessary to
describe the same. The essence of my Invention consists in manufacturing
cast steel by adding to melted pneumatized malleable iron, that is to say, to
cast iron which has been decarbonized and rendered malleable by the
pneumatic process, a quantity of melted refined cast iron, and mixing the said
melted refined cast iron and the said melted pneumatized malleable iron when
both these substances are in a melted state. Melted spiegel eisen or melted
manganesic pig iron may be added to the said mixture of refined cast iron

page_text: and pneumatized malleable iron, but such addition forms no part of my
Invention.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Second day of February, in the year of our Lord
One thousand eight hundred and sixty-four.
Witnesses,
MARGARET MUSHET,
L. M. MUSПET,
MARY ANN MUSNET,
EDW. M. MUSHET,
B. MUSHET,
Cheltenham.
ROBT. MUSHET. (L.s.)