Letters patent No. 143,600, dated Oct. 14, 1873, and granted to
John J. Vinton for an improvement in the manufacture of iron from
blast-furnace slag, are void inasmuch as the process and appliances
described in his specification and claim were known and in common
use before the date of his alleged invention.
The bill of complaint alleged that Hamilton and the other
defendants were infringing certain letters patent, No. 143,600,
dated Oct. 14, 1873, and granted to John J. Vinton, one of the
complainants, for an improvement in the manufacture of iron from
furnace slag, and it prayed for an injunction to restrain them from
further infringement, and for damages and an account of
profits.
The answer denied that Vinton was the original or first inventor
or discoverer of the patented improvement, and it denied
infringement.
Upon final hearing, the bill was dismissed because the process
described in the letters patent was known and in common use before
Vinton's application for them, and the same were therefore null and
void.
The complainants thereupon appealed the case to this Court.
The specification of the letters patent declares as follows:
"My invention relates to the production of cast-iron from the
slag, or refuse of the smelting or blast furnace. Heretofore a
large percentage of good metallic iron has been thrown away with
the slag and become lost to commerce so far as its use as metallic
iron is concerned. This is more particularly the case with rich
ores, such at the Missouri and lake ores, which from their nature
flux imperfectly in the ordinary smelting furnace. When imperfectly
fluxed, the slag assumes a thick consistency, and cools with a
general grayish color, and though the presence of metal in it
cannot be detected by the eye, yet the slag will be found to be of
comparatively great specific gravity, and in fact contains a very
large percentage of good metallic iron, often as great as the
amount of metal reduced from the ore in the process of smelting.
"
Page 104 U. S. 486
"To reduce this metal from the heavy slag of the smelting
furnace, and thereby increase the production of iron from the same
amount of ore, is the object of my invention. To accomplish the
desired result, I employ a cupola furnace, but furnaces specially
adapted to the purpose may be constructed and conveniently used in
connection with the blast furnaces where the iron is smelted."
"The heavy slag is first pulverized or broken up into small
pieces, or it may be made granulous or spongy by passing water or
air through it when in a molten state or in any of the well known
ways. A bed of coke or other suitable material is first placed in
the cupola, and on the top of the coke a small quantity of scrap or
other oxidized iron (preferable scale or black oxide of iron) is
sprinkled."
"The slag to be operated on is then introduced as evenly as
possible on the top of the coke and iron oxide, and on the top of
the slag I sprinkle a small quantity of limestone broken up into
small pieces, then a layer of coke, followed with scrap and scale
slag and lime as before alternately until the whole cupola is
charged."
"The fuel is then ignited, and when the fire is above the
tuyeres, the blast is turned on to the full. Owing to the presence
of the iron oxides, the heat is very great when brought in contact
with the slag, and the latter is speedily reduced, and as the
operation goes on, fresh charges of the materials are supplied from
the top of the cupola, provision being made for the passage of the
remaining slag from the furnace at a point below the tuyeres."
"In this way, it will be seen that the process is continuous,
and the furnace is not permitted to get cool."
"The charge is made up in about the following proportions, but
may be slightly varied as occasion requires: after the furnace is
in operation, first, three bushels of coke; second, fifty pounds
iron oxide (scrap or scale); third, eight hundred pounds slag;
fourth, one-fourth of a bushel of limestone, thrown into the cupola
in succession, and from time to time as required."
"When there is much sulphur in the iron, a small quantity of the
black oxide of manganese may be blown in through the tuyeres, and
salt or litharge, or a mixture of any two or all three of these
ingredients, may be used in this manner with good effect. The iron
thus obtained is run into moulds in the usual way."
"What I claim as my invention and desire to secure by letters
patent is the herein-described method of reducing iron from the
slag or refuse of blast or smelting furnaces, substantially as set
forth. "
Page 104 U. S. 487
Mr. JUSTICE WOODS, after stating the case, delivered the opinion
of the Court.
It is matter of general knowledge that pig-iron is made from
iron ore in a blast or smelting furnace; that to secure this
product, the furnace is charged first, with a layer of coke or
charcoal, then with a layer of iron ore, mixed with broken
limestone, and so on in alternate layers until the proper quantity
of these materials is placed in the furnace. The fuel is then
ignited, and, for the purpose of increasing the heat, streams of
air are forced into the furnace by means of blast-pipes, the
nozzles of which, called tuyeres, are inserted in openings in the
walls of the furnace, usually from four to six feet above its
bottom.
The limestone is used merely as a flux. The ore under this
process undergoes a chemical change, and iron is formed and sinks
in a molten state to the bottom of the hearth, by which is meant
not only the bottom of the furnace, but its sides as high up as the
foot of the boshes. The refuse left after the melted iron has
dropped into the hearth is also in a molten state, and, being
lighter than the iron, floats on its top. This is indifferently
called "cinder" and "slag." About three or four times in every
twenty-four hours the melted iron is drawn from the furnace. This
is accomplished in the following manner: the furnace is constructed
with two holes, one called the iron and the other the cinder notch.
The iron notch is made at the bottom of the hearth. The cinder
notch is higher up the side of the furnace, just below the level of
the tuyeres, so high that the cinder can be drawn through it
without letting off the molten iron. These holes are kept
habitually closed with clay or other similar material. At frequent
intervals, and always just before drawing off the molten iron, or
making a cast, as the ironmongers call it, the cinder notch is
opened, and the cinder or slag is allowed to escape and is carried
away from the furnace in a trough made of moistened sand. The
cinder notch is then closed and the iron notch is opened, and the
molten iron is drawn off through a sand trough and conducted
Page 104 U. S. 488
into moulds made in sand beds, called the sow and pigs, where it
is allowed to cool. The result is the pig-iron of commerce.
In the meantime, the furnace is supplied with constant charges
of fuel and ore, mixed with limestone, in alternate layers, dumped
in from the top; and this process is kept up without cessation for
months and sometimes for years.
The sand trough which connects the pig beds with the iron notch
is usually larger and deeper, but more elevated than the sow or
general gutter which conducts the iron into the moulds or grooves
in the pig beds. When the metal is first let into the trough, it
accumulates so as to fill it nearly to the brim. As the flow from
the iron notch decreases, the iron, and a small quantity of cinder
or slag, which has been chilled by coming in contact with the cold
surface of the trough, adhere to its sides and bottom. When the
molten iron on the hearth is about exhausted, the blast is
increased, and the material left on the hearth is blown out through
the iron notch into the sand trough. This also cools in the trough,
and thus is formed what are known as trough runners, consisting of
iron and slag, which have been forced through the iron notch by
letting on the blast as just mentioned.
A cupola furnace is one used for melting pig-iron for the
purpose of casting it into useful forms and articles. It
constitutes part of the equipment of a foundry. In shape it is
generally a hollow cylinder. The iron is melted by substantially
the same process as the ore in a blast furnace. The cupola furnace
has an iron notch but no cinder notch, because there is generally
so little cinder or slag in pig-iron as to render such an opening
unnecessary.
In order to reach the merits of the controversy, it is necessary
to obtain a definite idea of what, if anything, the appellants are
entitled to under Vinton's patent.
The specifications are ambiguous in respect to the particular
kind of slag which is to be used in the process therein described
-- that is to say, whether it is the slag drawn off through the
cinder notch, or the runners which are left in the trough through
which the molten iron is discharged from the iron notch of a blast
furnace. It appears, however, from the
Page 104 U. S. 489
evidence that the use of the latter only is contemplated, the
former containing such a very inconsiderable quantity of iron as to
be valueless.
We observe, in the first place, that the patent cannot be held
to cover the discovery that the slag, which is to be used in the
process described in the specifications, contains so large a
percentage of good metallic iron that it can be profitably
extracted by again smelting it.
The evidence shows beyond controversy that for many years before
Sept. 18, 1873, the earliest date assigned to the discovery or
invention of Vinton, it had been well and generally known that the
trough runners contained a large proportion of metallic iron, and
they were broken up and re-smelted in blast furnaces. They were
thrown into the furnace with scrap iron and iron ore, and smelted
in the same manner. It was formerly a notion among old-fashioned
furnace men that the use of this material injured the furnace and
deteriorated the quality of the iron produced. But this conceit had
been exploded long before the date of his patent, and the runners
and other heavy slag were used habitually in many blast furnaces as
above stated.
Secondly, the use of a cupola furnace for the purpose of
re-smelting trough runners and heavy slag cannot be claimed as any
part of Vinton's invention. The evidence in the record shows that
as early as the year 1844, at the Jackson furnace in Venango
County, Pennsylvania, which was a blast furnace, a cupola furnace
was erected and used for the purpose of smelting heavy slag, from
which was manufactured plow points and hollow ware, such as
skillets, pots, and Dutch ovens. Sometimes the product was made
into pig-iron. This cupola furnace was thus used for three or four
years. The fact of such use was public; no effort was made to keep
it secret, and it was known, in the language of the witnesses, "all
around the furnace."
The testimony of Robert Paisley, William J. Shaner, and Thomas
W. Kennedy, which is found in the record, shows that the Beaver
Falls Cooperative Foundry Association, in April, 1872, made the
experiment of using slag and runners in their cupola furnace, and
the experiment proving successful, the
Page 104 U. S. 490
runners, as early as August, 1872, were procured by the carload,
and mixed with pig-iron and run into stove plates. In this way,
fifty eight or sixty tons of runners were used prior to Oct. 14,
1873, the date of Vinton's patent.
This use of heavy slag and runners was open and public. No one
was excluded from the foundry where the work was carried on. Anyone
was at liberty to enter and see what was going on, and persons not
interested in the furnace -- among them the witness Thomas W.
Kennedy -- did so. No injunction of secrecy was imposed on them. It
is true the operatives at the furnace, who were all stockholders of
the association, said nothing about the use they were making of
trough runners, because, as they said, if it was a good thing, they
wanted to keep it to themselves; but they took no steps to keep it
a secret, except that they did not talk about it. In fact, it was
at the suggestion of Kennedy that the Beaver Falls Co operative
Foundry Association made the experiment of melting runners and
heavy slag in their cupola furnace.
After the experiment made by the Beaver Falls Cooperative
Foundry Association in April, 1872, had proved successful, Kennedy,
in August, 1873, furnished the defendant, Hamilton, with a quantity
of trough runners to be smelted in his cupola furnace, and before
Oct. 1, 1873, had sold to foundrymen not less than one hundred tons
of the same material to be used for the same purpose.
In fact, the record shows that Kennedy, more than a year before
the date of Vinton's patent, revived the practice of smelting
trough runners and heavy slag in a cupola furnace. As early as the
spring of 1872, he declared to the defendant, Hamilton, Thomas
Struthers, and others the feasibility of the process, and suggested
to Struthers that they ought to take out a patent for it. But
Struthers said that unless they could get up some new way of
extracting the iron, it would not be patentable, and that was the
conclusion they came to after talking the matter over. But Kennedy
at once, in the spring of 1872, commenced buying up the trough
runners from the blast furnaces and selling them to foundrymen for
use in cupola furnaces.
It is therefore abundantly shown in the record that before
Page 104 U. S. 491
the date of Vinton's patent or of his invention, the smelting of
trough runners and other heavy slag in cupola furnaces was
practiced and well known.
Thirdly, the method of making slag granulous or spongy by
passing water or air through it when in a molten state is not new
nor is it claimed to be new. Besides, there is no evidence that
this process is used by the appellees.
Fourthly, the method of charging the cupola furnace and of
smelting the slag as described in the specification of the patent
is as old as the art of making pig-iron, except perhaps the
sprinkling of scale or black oxide of iron on the top of the coke,
and this is not done by the appellees.
Fifthly, the appellants do not claim that Vinton's invention
covers a cupola furnace. A review of the case shows, therefore,
that he did not first discover the value of furnace runners or
heavy slag for re-smelting, that he was not the first to smelt them
and use them for running into pigs or castings, either in a blast
furnace or a cupola furnace, and that there is nothing new in his
process of smelting which is used by the appellees.
All, therefore, that is left for his invention to cover, and
which the appellants can claim as infringed by the appellees, is
the employment of a cinder notch or hole in a cupola furnace to
draw off the cinder when the furnace is employed in smelting
furnace runners or heavy slag. But if the testimony of unimpeached
and uncontradicted witnesses is to be believed, as early as June,
1872, at Beaver Falls, Pennsylvania, a cinder notch was used by the
Beaver Falls Cooperative Association in a cupola furnace when
employed in smelting furnace runners. The notch was put in the
cupola at the suggestion of the witness, Thomas W. Kennedy, who was
not a member of the association but who, being the owner of a blast
furnace, was selling to it furnace runners to be re-smelted and
used for making castings. He testifies to the fact distinctly and
clearly, and designates the part of the cupola where the notch was
placed -- namely "between the tuyeres at the back of the cupola to
draw off the slag." He is fully corroborated by the witness, W. J.
Shaner, a member of the association, whose business was to do the
smelting.
Page 104 U. S. 492
This use of the cinder notch in the cupola was public. No effort
was made to exclude spectators from the foundry or to conceal the
notch. The invention, therefore, of a cinder notch in a cupola
furnace, if it was an invention at all, was made by Thomas W.
Kennedy fifteen months before Vinton, according to his own
testimony, ever conceived the idea, and Kennedy during all that
time allowed it to be used by others without any injunction or
secrecy or any restriction or limitation in a foundry which was
open to all who might choose to visit it, and which was visited by
many spectators not concerned in its operations.
But even if the application of a cinder notch to a cupola
furnace was first made by Vinton, the question remains whether,
standing alone, it implies invention and is patentable.
We think that this question must be answered in the negative.
Neither a cupola furnace nor a cinder notch is new. The use of a
cinder notch for drawing off cinders from a blast furnace is as old
as blast furnaces themselves. The function which the cinder notch
performs in the process covered by Vinton's invention is precisely
the same for which it is used in a blast furnace. In smelting slag
in a cupola furnace, it was found that the molten cinder
accumulated and floated on the top of the molten iron. The
application to a cupola furnace, for the purpose of drawing off the
cinder, of the cinder notch used in the blast furnace to accomplish
the same end would occur to any practical man. When applied to a
cupola furnace, the same function was performed in the same way by
the same means. In making this application, there was no invention.
Pearce v. Mulford, 102 U. S. 112.
We are of opinion, therefore, that the application of a cinder
notch to a cupola furnace for the purpose designated is neither
patentable nor new, and that all the other parts of the process and
appliances covered by Vinton's patent were old and well known long
before the date of his alleged invention and the patent therefor.
He was not the first inventor, either in fact or in law, of the
discovery or invention described in his letters patent. They are
therefore void, and
Page 104 U. S. 493
the decree of the circuit court dismissing the bill was right,
and must be
Affirmed.
MR. JUSTICE MATTHEWS did not sit in this case nor take any part
in its decision.
