AN IMPROVED PROCESS FOR HARDENING CAST IRON
Year: 1863

page_text: LETTERS PATENT to Alfred Vincent Newton, of the Office for Patents,
66; Chancery Lane, in the County of Middlesex, Mechanical Draughts-
man, for the Invention of "AN IMPROVED PROCESS FOR HARDENING CAST
IRON." A communication from abroad by Thomas Allin, of New York,
in the United States of America.
Sealed the 2nd October 1864, and dated the 11th August 1863.
PROVISIONAL SPECIFICATION left by the said Alfred Vincent Newton
at the Office of the Commissioners of Patents, with his Petition, on
the 11th August 1868.
I, ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Mechanical Draughtsman, do hereby declare the
nature of the said Invention for "AN IMPROVED PROCESS FOR HARDENING CAST
IRON," to be as follows:-
The object of this Invention is so to harden articles of cast iron, that it may
be substituted for hardened steel for many purposes in the arts. The cast
iron to be hardened having been cast in the usual or in any other suitable
way, but not chilled, is first finished or worked (when the article requires it)
by turning, filing, or cutting, and then slowly heated in any suitable furnace
or oven until it reaches about a blood-red heat. While at this temperature

page_text: it is plunged in a cold acid bath, composed, by preference, in the proportion of
one pound of sulphuric acid and one ounce of nitric acid to one gallon of
water, and moved about therein until it becomes cold. When taken out it
will be found to have acquired a degree of hardness equal to hardened steel,
and to a sufficient depth for all practical purposes.
By increasing the proportion of acid, the degree of hardness will be
increased and vice versa. When the cast iron is not required to be worked
by turning, cutting, or filing before it is hardened, it can be taken directly
from the mould before it cools down below a cherry-red hent, and in that
condition plunged in the acid bath.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alfred Vincent Newton in the Great Seal Patent Office
on the 11th February 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Mechanical Draughtsman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of August, in the year of our Lord One
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 Alfred Vincent Newton, Iler special license that I, the said Alfred
Vincent Newton, my executors, administrators, and assigns, or such others
as I, the said Alfred Vincent Newton, '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 s
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 IMPROVED PROCESS FOR HARDENING CAST IRON," being a com-
munication from abroad, upon the condition (amongst others) that I, the said
Alfred Vincent Newton, by an instrument in writing under my hand and
scal, 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 Alfred Vincent Newton, do hereby
declare the nature of the said Invention, and in what manner the same is

page_text: to be performed, to be particularly described and ascertained in and by the
following statement (that is to say):-
The object of this Invention, as communicated to me by my foreign cor-
respondent, is so to harden articles of cast iron that they may be substituted
for bardened steel for many purposes in the arts. Although the well known
process of chilling cast iron by running it in the molten state into cold iron
moulds renders it very hard, and for many purposes when so hardened it is
very useful, still the process is not applicable to the production of articles
which require to be made true and with smooth surfaces, for the reason that
it is too hard to be worked after being so chilled. But by the improved
process cast iron is rendered as hard as hardened steel after it has been cast
and suffered to set in the mould or to cool in the ordinary way, and been
worked by turning, filing, or other means to the required form and surface.
The cast iron to be hardened having been cast in the usual or in any other
suitable way, but not chilled, is first finished or worked (when the article
requires it) by turning, filing, or cutting, and then slowly heated in any
suitable furnace or oven until it reaches about a blood-red heat. While at
this temperature it is plunged in a cold acid bath, composed, by preference,
in the proportion of one pound of sulphuric acid and one ounce of nitric acid
to one gallon of water, and moved about therein until it becomes cold. When
taken out it will be found to have acquired a degree of hardness equal to
hardened steel, and to a sufficient depth for all practical purposes, and that
without warping or bending the iron.
By increasing the proportion of acid the degree of hardness will bo
increased and vice versa. Although it is preferred to use sulphuric and nitric
acid, the same result, in kind, will be produced with muriatic acid instead of
sulphuric and nitric acid. It has been stated above that the cast iron should
be heated to a blood-red heat, but this statement is not to be understood as
limiting the claim of Invention to such degree of beat, as a slight variation
will not materially affect the result; and although it has been stated that the
cast iron is taken after it has been removed from the mould, cooled, and heated
to a cherry-red heat, and plunged in the acid bath, the process is so described
because for most purposes it is important to work the cast iron by turning,
cutting, or filing before it is hardened, but when this is not required, the cast
iron can be taken directly from the mould before it cools down below a cherry-
red heat, and in that condition plunged in the acid bath.
Having now set forth the nature of the Invention of "An Improved Process
of Ilardening Cast Iron," and explained the manner of carrying the same into
effect, I wish it to be understood that, under the above in part recited Letters

page_text: Patent, I claim the process, substantially as above described, of hardening cast
iron by plunging it in a bath of acid and water when it is at about a blood-
red heat, substantially as set forth.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto
set my hand and seal, this Eleventh day of February, in the year of 5
our Lord One thousand eight hundred and sixty-four.
A. V. NEWTON. (L.B.)