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, Metallurgist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF IRON AND STEEL," to be as follows:-
When cast iron has been purified or decarbonized by blowing air through
it when in a melted stated it is difficult to convert it into malleable iron or
steel. I have discovered that by combining such purified iron in a heated
state with a triple compound or material consisting of or containing iron,
manganese, and carbon, also in a heated state, I can obtain malleable iron or

page_text: steel, and obtain the one or the other of those products by varying or regu-
lating the quantity or proportion of such compound or material which I add
to the purified iron.
The iron may be purified by the action of air, in the manner invented by
Joseph Gilbert Martien, or in any other convenient manner.
The triple
compound or material which I prefer to use is pig or cast iron made from
spathose ore, such ore and the pig or cast iron made from it containing a
proportion of manganese, as well as the iron and carbon of which cast iron is
usually composed.
The compound or mixture of iron, manganese, and carbon may, however,
be produced or made in any other manner which may be found to be more
economical or convenient.
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
TO WHOM THESE PRESENTS SHALL COME, ROBERT
MUSHET, of Coleford, in the County of Gloucester, Metallurgist, sends
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, my executors, administrators, and assigns, 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, adminis-
trators, 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 Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE 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,

page_text: 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
performed, to be particularly described and ascertained in and by the following
statement:-
When cast iron has been purified or decarbonized by the action of air blown.
or forced into, through, or amongst its particles whilst it is in a molten or fluid
state, it has been found that although the cast iron is thereby nearly if not
wholly decarbonized and purified from silicon or its oxide, and some other
matters, yet, nevertheless, it is difficult to convert it into iron or steel, and the
ingots, articles, or picces formed by pouring this purified iron into suitable
moulds in some instances prove to be incapable 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 frequently have cracks or
flaws along their edges, which unfit them for manufacturing purposes, and in
other instances, though ingots of such purified cast iron may be extended by
hammering or rolling into tolerably sound bars capable of being welded
together, yet these bars are often found to be what is termed "red short" or
"hot short." They are also often characterized by being when cold of a
crystalline nature, and neither granular nor fibrous in their fracture, they are,
therefore, what is termed "cold short," that is to say, brittle when cold. Ingots
thus cast from purified cast iron are also generally porous and cellular in their
structure, and when broken exhibit internally a multitude of small cavities,
which not only increase the tendency of the ingots to crack when being rolled
or hammered into bars, but they materially detract from the soundness or
solidity of such bars, whether they be of iron or steel.
For the purpose of remedying these defects in air-purified cast iron, and to
convert it into malleable iron or steel, I add and combine with such purified
cast iron whilst in a melted state a triple compound or material, consisting of
or containing iron, manganese, and carbon, also (by preference) in a heated
state, and I vary or regulate the quantity or proportion of such triple com-
pound or material for the purpose of obtaining one or other of those products,
videlicet, malleable iron or steel.
To the purified cast iron, when it has become wholly decarbonized or nearly
so by the action of air forced into it or among its particles whilst it is in a
molten or fluid state, I add a triple compound alloy or material of or con-

page_text: heated state, so that it may be mixed, alloyed, or incorporated with the fluid
purified cast iron, and which mixture I effect in any suitable furnace, vessel,
or ladle, and then pour the mixture into suitable moulds in any usual or
convenient manner for producing castings, articles, ingots, or pieces of the
desired forms or shapes.
The quantity or proportion of the triple combination or material of or con-
taining iron, carbon, and manganese to be added to the purified cast iron may
be varied, as circumstances may require, (that is to say,) according to the
nature of the purified cast iron, the nature of the material containing iron,
carbon, and manganese, and the effect intended to be produced. I have
found, however, that it is sufficient to add a quantity of the said triple com-
bination or material, amounting (by weight) from about one-fiftieth part to
about one thirty-third part of the weight, (that is to say,) from about two to
three per centum of the decarbonized purified cast iron, when it is intended to
produce wrought iron, and from about one thirty-third part to about one-
twentieth part by weight (that is to say, from about three to five per centum)
of the decarbonized purified cast iron when it is intended to be converted into
semi-steel, and from about one-twentieth to about one-fifth of the weight
(that is to say, from about five to twenty per centum) of the decarbonized
purified cast iron when it is intended to convert it into soft medium or hard
steel, and the softness or hardness of the steel may be regulated by diminish-
ing or increasing the quantity or proportion of the triple combination or
material added to the purified decarbonized cast iron. The triple compound,
or material of or containing iron, carbon, and manganese, may be conveniently
and economically prepared by smelting into pig iron or cast iron metal in the
blast furnace with either coal, coke, or charcoal fuel, such sparry carbonates
of iron termed spathose iron ores or such other ores of iron as contain
besides iron a considerable quantity of manganese, and I prefer to use the
white crystalline cast-iron metal thus obtained, and known in Prussia as
spiegel eisen," for this white cast-iron metal, whilst it contains a large alloy of
manganese, is more free from sulphur, phosphorus, and silicon than the grey
pig iron obtained from smelting spathose manganesic iron ores, and I prefer to
use such varieties of this white crystalline cast-iron metal as are found to
contain a large alloy of manganese; nevertheless such triple compound or
material of or containing iron, carbon, and manganese may be produced in
any other manner which may be found to be convenient and economical, but
I do not claim as of my said Invention the method or manner by which the
6

page_text: triple compound or material of or containing iron, carbon, and manganese is
obtained or produced.
I now proceed to describe the manner in which my Invention may be
practised.
When the cast iron to be operated upon has been so far purified in the
purifying vessel or furnace (that is to say, the vessel or furnace in which the
cast iron is decarbonized,) by forcing air into, through, or amongst it whilst in
the molten or fluid state, or in any other convenient manner, so as to have
become wholly decarbonized, or nearly so, I tap it off and allow it to flow into
a heated furnace, vessel, or ladle containing the requisite proportion of the
triple alloy compound or material containing iron, carbon, and manganese
already heated so as to be also in the molten or fluid state. The purified cast
iron thus falling into the furnace, vessel, or ladle upon such fluid, triple com-
pound or material will become mixed and incorporated with such compound
or material, and the resulting mixture is then to be poured into moulds in any
usual or convenient manner for producing castings, articles, ingots, or pieces
of the desired sizes, forms, and shapes, or the purified cast iron may be tapped
into a heated furnace, vessel, or ladle, and the fluid triple compound or
material of or containing iron, carbon, and manganese then poured upon it or
into it; or the purified cast iron and the fluid triple compound or material
may be poured into the heated furnace, vessel, or ladle simultaneously, or the
purified cast iron and the triple compound or material of or containing iron,
carbon, and manganese may be mixed and incorporated with each other in
any other convenient manner.
The triple compound of or containing iron, carbon, and manganese may be
heated and rendered fluid in any convenient manner either in a crucible, or
in an air furnace or reverberatory furnace, or in a common cupola melting
furnace or otherwise; but I prefer melting it excluded as much as possible
from contact, with sulphury coke or other sulphury fuel. When the triple
compound or material of or containing iron, carbon, and manganese is to be
added to the purified cast iron, and the mixture of them is to be effected in
ladles, I use either fire clay or blacklead crucibles for ladles, heated to a red
or white heat, and held in a pair of pouring tongs with double handles or
otherwise, so that the heated crucibles containing the proper quantity of the
heated fluid compound or material may be held under the end of the spout
or gutter, along which the purified iron flows from the purifying vessel, and
falling into the crucible, ladle, or other receptacle is therein mixed and incor-
porated with the fluid triple compound or material; or when larger quantities.

page_text: are to be operated upon, wrought-iron ladles lined with fire-brick, or any other
non-conducting refractory material, such as blacklead, steel pot composition,
&c. may be used, the interior of these ladles being first thoroughly heated by
filling them with fuel, and if necessary blowing thereon with a blast of air,
or by any other convenient means.
As a triple compound of or containing iron, carbon, and manganese parts
with a portion of its manganese every time it is remelted, I prefer to use that
which has not been previously remelted, and I avoid as much as possible any
repeated remeltings of it.
It may sometimes be necessary to accelerate the mixture of the triple com-
pound or material with the purified cast iron when combined in the same
vessel, and this may be done or promoted by stirring the fluid mass with an
iron rable, or, preferably, by introducing strips of well-dried wood and thrusting
them down to the bottom of the metal, by which means a strong ebullition is
at once excited; but I do not claim the introduction of such pieces or strips
of wood under the fluid metal.
Though I have in this Specification described the addition of the triple
compound or material of or containing iron, carbon, and manganese when
heated so as to be in a molten or fluid state to air-purified cast iron, never-
theless such triple compound or material may, when heated, but not to such
an extent as to become fluid, be added to melted purified iron. This addition
may be made by heating masses, lumps, or particles of the triple compound
or material of or containing iron, carbon, and manganese to a temperature
more or less short of their point of fusion, and then introducing the same into
the molten purified iron, where they may be dissolved or alloyed therewith, but
I prefer to add the triple compound or material when in the molten or fluid
state, as being more convenient and efficacious.
I prefer to operate upon purified and decarbonized iron which has been
obtained from good pig iron, or other cast iron of good quality, as free as
possible from sulphur and phosphorus.
Having thus particularly ascertained and described the nature of my said
Invention, and the manner in which the same is to be performed, I hereby
declare that I do not claim the use of carburet of manganese, or a mixture of
carbonaceous matter and manganese uncombined or unmixed with iron, in the
manufacture of steel; but what I do claim is, the addition of a triple com-
pound or material of or containing iron, carbon, and manganese to cast iron,
which has been purified and decarbonized by the action of air whilst in a
molten or fluid state, or in any convenient manner, so as to become mixed and

page_text: combined in the process of manufacture, in order by the union of these
substances to obtain or produce or improve the qualities of malleable iron and
steel.
In witness whereof, I, the said Robert Mushet, have hereunto set my
hand and seal, this Nineteenth day of March, in the year of our Lord
One thousand eight hundred and fifty-seven.
Witness,
MAXWELL MUSHET,
Coleford, Gloucestershire.
BROOKLYN MUSHET,
Coleford, Gloucestershire.
ROBT. MUSHET. (L.S.)