CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF IRON
Year: 1860

page_text: LETTERS PATENT to George Holcroft, of the City of Manchester, Engineer,
for the Invention of "CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF
IRON."
Sealed the 25th October 1860, and dated the 11th May 1860.
PROVISIONAL SPECIFICATION left by the said George Holcroft at the
Office of the Commissioners of Patents, with his Petition, on the 11th
May 1860.
I, GEORGE HOLCROFT, of the City of Manchester, Engineer, do hereby
declare the nature of the said Invention for "CERTAIN IMPROVEMENTS IN THE
MANUFACTURE OF IRON," to be as follows:-
The first part of my Invention is applicable to blast furnaces, and consists
in forcing carbon in a gaseous state into the lower part of the furnace with
the hot or cold air, or through a separate blast pipe; the carbon thus introduced
combines with the ore and improves the quality of the iron produced.
The second part of my Invention is applicable to the processes of converting
cast iron into bar or wrought iron, and consists in combining charcoal with the
coke or coal used for heating the metal in this process of manufacturing iron.
The third part of my Invention is applicable to the ordinary cupolas in
which pig iron is melted for making iron castings, and consists in forcing
carbon in a gaseous state into the lower part of the cupola.
The fourth part of my Invention consists in mixing various descriptions of

page_text: ores possessing different qualities in certain proportions combined with certain
proportions of fuel and flux so as to obtain very strong pig iron from the blast
furnace, also in mixing various descriptions of pig iron in certain proportions
previous to the refinery processes for the purpose of producing bar or wrought
iron of superior quality. Also in mixing various descriptions of pig iron and
cast iron in certain proportions in the cupola furnaces to produce a stronger
cast iron.
Hematite ores are dvided into two classes, namely, the heavy flinty lumps,
which I call hard hematite ores to distinguish them from the soft or small
hematite ores. In producing foundry iron I take about one-third of the hard
hematite iron ore, and two-thirds of the soft or small hematite ore. To make
puddling iron 1 take four-sevenths of the hard hematite iron ore to three-
sevenths of the soft or small. In producing pig iron from the Yorkshire and
Staffordshire ironstone combined with hematite ore, I take about nineteen
parts of the Yorkshire or Staffordshire ironstone to thirteen parts of a mixture
of the hard and soft hematite iron ores, in the proportion of one-third hard and
two-thirds soft. When the Welsh and Durham ironstone is employed I take
about four-sevenths of the ironstone to three-sevenths of the hematite iron ores
in the proportion of one-third hard and two-thirds soft. It may be found
desirable by further experiments to vary the above proportions and the do-
scriptions of ores.
The last part of my Invention consists in governing the speed of the engine
by which the blowing machine is driven according to the pressure of the blast,
thereby obtaining an uniform pressure on the air for the blast furnace; this
may be accomplished by the action of the air in the blast pipe on a piston or
other equivalent agent which is in communication with the throttle or other
valve of the engine.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Holcroft in the Great Seal Patent Office on the 10th
November 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HOLCROFT, of the City of Manchester, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of May, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-third year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto nie, the said

page_text: George Holcroft, Her special licence that I, the said George Holcroft, my”
executors, administrators, and assigns, or such others as 1, the said George
Holcroft, my executors, administrators, and assigns, should at any time agreo
with, and no others, from time to time, and 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 "CERTAIN IMPROVEMENTS IN THE
MANUFACTURE OF IRON," upon the condition (amongst others) that I, the said
George Holcroft, 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 George Holcroft, 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 (that is to say) :-The nature and particulars of my Invention are
as follows:
The first part of my Invention is applicable to blast furnaces for melting
iron oro and consists in forcing carbon in a gaseous state into the lower
part of the furnace with the hot or cold air or through a separate blast pipe;
the carbon thus introduced combines with the ore and improves the quality
of the iron produced; the proportion of carbon which I have found most
beneficial is about one hundred and twenty cubic feet to one ton of the ore.
The second part of my Invention is applicable to the processes of converting
cast iron into bar or wrought iron, and consists in combining charcoal with
the coke used for heating the metal. When this part of my Invention is
applied to the process of puddling, the fuel I employ is prepared in the
proportion of one part by weight of wood charcoal to four parts of coke,
and in order to obtain a sufficient heat I introduce a blast of air into the
puddling furnace. The quality of iron is considerably improved by introducing
charcoal among the iron in the puddling furnace when the iron is in a molten
state. I find that ten pounds of charcoal to two hundredweights of iron
gives a good result, and this charcoal can be put into the furnace all at once
or at different times. In the heating process the reverberatory furnace may
be dispensed with, and in lieu thereof I make use of a furnace in which the
iron with the fuel are placed on a grate or hearth through which a current
of air or blast is forced to produce the requisite degree of heat. The fuel I

page_text: employ is prepared in the proportion of one part by weight of charcoal to
five parts of coke. Where it is desirable to use the ordinary reverberatory
furnace I employ fuel composed of one part of charcoal to three parts of coke.
In order to produce a strong iron, suitable for railway rails and other purposes,
when coal is employed as fuel in the ordinary manner, I combine bruised
or crushed coke with the iron in the puddling furnace, the said coko being
introduced into the furnace when the iron is in a molten state, in the
proportion of three-quarters of a hundredweight of coke to two hundred-
weights of iron, but when coke is employed as fuel I introduce about one
quarter of a hundredweight of crushed coke to two hundredweights of iron;
in this latter case the heat must be increased by means of a blast.
The third part of my Invention is applicable to the ordinary cupolas in
which pig iron is melted for making iron castings, and consists in forcing
carbon in a gaseous state into the lower part of the cupola in the proporation
of about sixty cubic feet of carbon to one ton of iron melted.
The fourth part of my Invention consists in mixing various descriptions
of ores possessing different qualities in certain proportions so as to obtain
very strong pig iron from the blast furnace.
Hematite ores are divided into two classes, namely, the heavy flinty lumps,
which I call hard hematite ores to distinguish them from the soft or small
hematite ores. In producing foundry iron [ take about one-third of the
bard hematite iron ore and two-thirds of the soft or small hematito ore. Το
make puddling iron I take four-sevenths of the hard hematite iron ore to three-
sevenths of the soft or small ore. In producing pig iron from the Yorkshire
and Staffordshire ironstone combined with hematite ore, I take about nineteen
parts of the Yorkshire or Staffordshire ironstone to thirteen parts of a mix-
ture of the hard and soft hematite iron ores in the proportion of one-third
hard and two-thirds soft. When the Welsh and Durham ironstone is em-
ployed I take about four-sevenths of the ironstone to three-sevenths of tho
hematite iron ores in the proportion of one-third hard and two-thirds soft.
The last part of my Invention consists in governing the speed of the engine
by which the blowing machine is driven according to the pressure of the blast,
in order to obtain an uniform pressure on the air for the blast furnace, this
may be accomplished by the action of the air in the blast pipe on a piston or
other equivalent agent, which is in communication with the throttle or other
valve of the engine. When the speed of the steam engine is increased owing
to a reduction in the pressure of the blast, the ordinary steam engine governor
or other apparatus worked by the engine acting on a throttle valve reduces
the supply of steam until the engine has regained its proper speed.

page_text: Having thus stated the nature of my Invention, and the manner of per-
forming the same, I wish it to be distinctly understood that I do not limit
myself to the details or proportions given, as the same may be varied without
departing from the peculiar character of my Invention, and I declare that [
claim as my improvements in the manufacture of iron,―
First, the application of carbon in a gaseous state to the blast furnaces for
melting iron ore.
Secondly, the combination of charcoal with the coke used in the processes of
converting cast iron into bar or wrought iron.
Thirdly, the combining of charcoal with the molten iron in puddling
furnaces.
Fourthly, the combining of bruised or crushed coke with the molten iron in
puddling furnaces.
Fifthly, the application of carbon in a gaseous state to cupolas used in
melting pig iron.
Sixthly, the various combinations of ores described for producing very strong
pig iron from the blast furnace.
And lastly, the governing the speed of the blowing machine according to
the pressure of the blast as described.
In witness whereof, I, the said George Holcroft, have hereto set my
hand and seal, this Ninth day of November, in the year of our Lord
One thousand eight hundred and sixty.
GEO. HOLCROFT. (S.)