IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL
Year: 1856

page_text: LETTERS PATENT to Robert Mushet, of Coleford, in the County of
Gloucester, Metallurgist, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF IRON AND STEEL."
Sealed the 24th December 1856, and dated the 22nd September 1856.
PROVISIONAL SPECIFICATION left by the said Robert Mushet at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
September 1856.
I, ROBERT MUSHET, of Coleford, in the County of Gloucester, Mettalurgist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF IRON AND STEEL," to be as follows:-
My said Invention consists of combining purified or decarbonized iron with
metallic maganese, in order to convert it into malleable iron or steel, or to
improve its quality. The iron which I use is purified or decarbonized by
blowing air through it, either in the manner invented by Joseph Gilbert Martien,
or in any other convenient manner. When I intend to produce malleable
iron I purify or decarbonize the iron thoroughly, and then add the metallic
maganese to it. When I intend to produce steel, I either stop the purifying
process before the iron has been deprived of the whole of its carbon, and
whilst it retains a sufficient quantity of carbon to cause it to form cast

page_text: steel, and I then combine the partially decarbonized iron with the metallic
manganese; or I add to iron which has been thoroughly decarbonized, or
nearly so, metallic manganese and also cast iron sufficient to convert the
iron into steel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Mushet in the Great Seal Patent Office on the
21st March 1857.
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 Twenty-second day of September, in the year of our
Lord One thousand eight hundred and fifty-six, in the twentieth 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 thereafter 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 MANU-
FACTURE OF IRON AND 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 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 immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert Mushet, do hereby declare
the nature of my 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:-
When cast iron, whether called grey pig iron, mottled pig iron, white pig
iron, tiger iron, refined iron, or plate metal, which are the names by which
different varieties of cast iron are recognized and distinguished amongst iron
manufacturers, has been purified or decarbonized by blowing or forcing air

page_text: through or amongst its particles when in a melted state, in the manner
described in the Specification of Letters Patent granted to Joseph Gilbert
Martien, dated the Fifteenth day of September, One thousand eight hundred and
fifty-five, or otherwise, it has been found that although the cast iron thus operated
upon is thereby wholly or nearly decarbonized and purified from silicon or its
oxide, yet nevertheless the ingots formed by pouring this decarbonized and
purified cast iron into suitable moulds prove to be in many instances capable
of extension by hammering or rolling at any temperature. In other instances
they may be extended into bars by hammering or rolling; but the bars thus
produced have cracks or flaws along their edges, which render them unfit for
commercial purposes; and in other instances, though the ingots may be extended
by hammering or rolling into tolerably sound bars which can be welded
together, yet these bars are found to be "red short" or "hot short" at certain
temperatures under the welding heat; these bars are also when cold often charac-
terized by being of a crystalline nature, and neither granular nor fibrous in
their structure, and they are therefore what is termed "cold short," that is to
say, brittle when cold. For the purpose of remedying or diminishing as much
as practicable these defects observed in purified cast iron, decarbonized or
partially decarbonized by causing air to pass through it or amongst its particles
whilst in a fluid state, and in order to convert it into iron or steel possessing
such a degree of malleability, ductility, and tenacity as shall render it commer-
cially valuable, I proceed in the manner which I shall now detail.
When I intend to produce malleable iron, I purify the cast iron and decar-
bonize it thoroughly, or nearly so, and I then add to it a quantity of metallic
manganese, varying from one quarter of a pound to two pounds by weight of
such metallic manganese for every one hundred pounds by weight of purified
decarbonized cast iron, and I add the metallic manganese to the molten purified
iron in the following manner, or in any other convenient manner :-I stamp or
crush the metallic manganese to the state of tolerably fine powder in any
convenient manner, and which, as the metallic manganese is exceedingly brittle,
may be readily effected, and I then strew the proper proportion of the metallic
manganese thus pulverized upon or amongst the molten purified cast iron
either when tapped into a ladle or other vessel or furnace from the purifying
furnace; or I place the pulverized metallic manganese in the ladle or vessel or
furnace into which the purified decarbonized cast iron is about to be poured,
and which purified decarbonized cast iron 1 then pour upon the pulverized
metallic manganese, which, by the intense temperature of the said purified
decarbonized cast iron, will be speedily liquified and alloyed therewith, and the

page_text: mixture is then to be poured into suitable moulds and treated in the usual
manner.
I also sometimes add the pulverized metallic manganese to the purified
decarbonized cast iron in the purifying furnace or vessel itself when it is so
constructed that the blast may be conveniently stopped or withdrawn without
the blast openings becoming filled with iron, when the purifying and decar-
bonizing process has been terminated, and before mixing the moltens purified
decarbonized cast iron with the manganese.
When the cast iron contained
in the purifying furnace or vessel has been decarbonized or purified and the
blast of air has been withdrawn, I immediately strew or throw in through
suitable openings in the sides or ends of the furnace or vessel the proper
quantity of metallic manganese, pulverized or broken small, which is intended
to be added to the molten purified and decarbonized cast iron whilst it still
retains its heat and fluidity. The metallic manganese thus falling in small
pieces or particles into the molten purified cast iron is therein liquified by
the intense heat, and is alloyed and incorporated with the mass of molten
purified cast iron, which may then be poured into ingot moulds and afterwards
treated in the usual manner. But I do not here claim the manner of making
the addition of metallic manganeso to purified cast iron, neither do I claim
any peculiar form or construction of the furnace or vessel in which the
mixture or addition is to be made.
When I intend to produce cast steel, I sometimes arrest the purifying
process, so that the cast iron may not be wholly decarbonized, but merely
decarbonized until it shall contain only such a proportion or per centage of
carbon as to constitute cast steel, and I then proceed to add the metallic
manganese to the molten cast steel in the same manner as I have herein-before
described with respect to adding metallic manganese to purified decarbonized
cast iron, in order to obtain malleable iron. Or, in order to produce cast steel,
I add to the purified cast iron, when it has been thoroughly decarbonized or
nearly so, and whilst it is in the molten or fluid state, as much of the best or
purest cast iron obtainable (which contains the usual proportion of carbon as
shall suffice to constitute cast steel when mixed with the said decarbonized
cast iron, and I add this best or purest cast iron when in the molten or fluid
state to the decarbonized purified cast iron (and which is also in the molten
state in any convenient manner, by pouring the fluid cast-iron metal from a
ladle or other suitable vessel into the molten fluid decarbonized cast iron
contained in a ladle, vessel, or furnace, as the case may be, and I add the
metallic manganese in like manner, as I have herein-before described, either

page_text: to the mixture or to the molten decarbonized iron previously to making the
above addition of the molten, best, or purest cast-iron metal; or I add the
metallic manganese to the said best or purest cast iron before mixing the latter
with the molten fluid decarbonized cast iron. The quantity of best or purest
cast-iron metal which I prefer thus to add to the decarbonized iron is from
two pounds to twenty pounds of the best or purest cast iron to every one
hundred pounds by weight of the decarbonized purified cast iron, but these
proportions may be varied, according to the nature of the steel intended to be
produced.
When it is desired to produce a soft quality of steel only a small quantity
of fluid best or purest cast-iron metal must be added to the fluid purified
decarbonized cast iron, and when harder qualities of steel are to be obtained
an increased proportion of fluid best or purest cast-iron metal must be
added to the fluid purified and decarbonized cast iron. The metallic man-
ganese may be conveniently prepared or obtained by smelting the ores of
manganese upon an ordinary blast furnace blown with heated air, and using
a considerable quantity of lime or limestone as a flux for the ores of manga-
nese thus smelted. But I do not, in these Letters Patent, claim any process or
method for procuring or producing metallic manganese. Metallic manganese
is hard, dense, and very brittle, and may be readily pulverized so as to prepare
it for mixture with the molten purified and decarbonized or partially decar-
bonized cast iron, in the manner which I have herein-before set forth, though
I lay no claim to any method of pulverizing or preparing the manganese,
which may be performed in any convenient manner.
Having thus particularly ascertained and described the nature of my said
Invention, and the manner in which the same is to be and may be performed
or carried into effect, I now declare that I do not claim as of my said Inven-
tion the addition of molten or fluid best or purest cast iron to decarbonized
or purified cast iron, or any mixture or combination of those two metallic
substances to which metallic manganese is not added; but what I do
claim is,―
Firstly, the combination of metallic manganese with purified or decarbonized
iron, as above described, for the purpose of converting it into or obtaining
therefrom malleable iron of an improved quality.
Secondly, the combination of metallic manganese with partially decarbonized
purified cast iron, as above described, for the purpose of converting it into or
obtaining steel of an improved quality.
Thirdly, the combination of metallic manganese with a mixture of purified

page_text: and decarbonized cast iron and cast iron pure (or as nearly so as can be
conveniently procured), in the manner above described, for the purpose of
improving the quality of the steel obtained from such purified decarbonized
iron.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Eleventh day of March, in the year of our Lord
One thousand eight hundred and fifty-seven.
Witness,
MAXWELL MUSHET,
Coleford, Gloucestershire.
JOHN LOCKE, Clerk to Mr. Rob' Mushet,
Coleford, Gloucestershire.
ROB MUSHET. (L.S.)