IMPROVEMENTS IN HARDENING ARTICLES COM- POSED OF IRON;
Year: 1849

page_text: ⚫ TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
DUGDALE, of Brompton, in the County of Middlesex, Engineer, send greeting.
WHEREAS Her present most Excellent Queen Victoria, by Her Royal
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Thirteenth day of January, in the twelfth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said
Richard Dugdale, Her especial license, full power, sole privilege and authority,
that I, the said Richard Dugdale, my exors, adñors, and assigns, and such
others as I, the said Richard Dugdale, my exors, adñiors, or assigns, should
at any time agree with, and no others, from time to time and at all times
during the term of years therein mentioned, should and lawfully might make,
use, exercise, and vend, within England, Wales, and the Town of Berwick-
upon-Tweed, my Invention of "IMPROVEMENTS IN HARDENING ARTICLES COM-
POSED OF IRON;" in which said Letters Patent is contained a proviso, obliging
me, the said Richard Dugdale, by an instrument in writing under my hand
and seal, particularly to describe and ascertain the nature of my said Invention,
and in what manner the same is to be performed, and to cause the same to be
enrolled in Her Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Richard Dugdale, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be. performed, is particularly
described and ascertained in and by the following description thereof (that is
to say):-
My Invention relates to an improved mode of hardening articles composed
of iron, or, in other words, of partially or entirely converting the iron of which
they are composed into steel, so that various articles which are usually made
of steel may now be first made of iron, and when fashioned to the right shape
and form they may be then hardened or converted into steel, or steeled to any
depth, or in any part of the articles where required, leaving the rest of the
iron in its original state of tenacity if required, and without disturbing the
surface of the metal, so that manufactured articles will require very little
finishing afterwards.
The articles intended to be operated upon are to be placed in an iron box,
and each article surrounded with a compound of charcoal, borax, sal-ammoniac,
and saltpetro in their natural state, or as commonly obtained in commerce, but
only pulverized. These ingredients are mixed in the pulverized or granulated
state in about the following proportions:-Of charcoal, one hundredweight;
borax, half a pound; sal-ammoniac, a quarter of a pound; and saltpetro, a
quarter of a pound. For rough and bulky goods I sometimes, instead of the
saltpetre, make use of common salt, employing four times the quantity by
weight as a substitute for the saltpetre.
In effecting the desired object by my improved process, I first cover the
internal surface of the bottom of the box with the above compound, and then
place the iron articles therein upon the bed so prepared, and each article
being surrounded with the hardening compound, the box is closed by a lid or
cover, and made as air-tight as possible by means of sand or other suitable.
material; then the loaded box is placed in an open furnace without a chimney,
and exposed for several hours to a considerable heat, say, between a red and
white heat, the length of time varying from four hours to twenty-four or more,
according to the rough or smooth state and size of the articles, and the depth
of hardening or steeling required. The requisite knowledge for properly.
conducting this part of the process, that is, for regulating the heat and the
length of time the articles are to be exposed to the heat, can only be obtained
by experience. When the articles have been exposed for a sufficient length
of time to the heat they are to be taken from the box and plunged into water
to cool them, after which, if the process has been properly managed according
to the above instructions, they will be found to be rendered very hard, or

page_text: converted into steel partially or entirely, (that is to say,) they will be hardened
or steeled to any certain depth or quite through, according to the time they
have been exposed to the heat surrounded by the pulverized materials above
mentioned.
If the articles do not require to be hardened or steeled in every part, then
the hardening compound must be placed in contact with those parts only.
which it is desired to harden or steel, taking care to cover the other parts
with clay or common sand, so as to protect them from the action of the
hardening compound.
I should here observe that I do not intend to confine myself exclusively to*
the above ingredients, as there may be other materials containing the same
elements which may produce a similar effect, and others not having the same
but equivalent elements which will also produce a similar effect, and may
therefore be employed in place of the above or some of the above mentioned,
of which latter the use of salt in place of saltpetre is an instance; the
common salt, however, tends to make the steel more harsh and less malleable,
but notwithstanding will occasionally bo found useful when rough and large
or bulky articles are to be operated upon. And although other materials
than those mentioned may be found to produce a similar effect, some of them
will deteriorate the quality of the inetal, and others are too expensive for
application, but the materials that form the compound above set forth I have
proved to have no deteriorating or injurious tendency, but, on the contrary,
they have an ameliorating effect on the metal, and are at the same time of
moderate cost; neither do I confine myself rigidly to the above proportions
of the ingredients, as those proportions may be sometimes beneficially varied,
according to circumstances; and as all the ingredients forming the above
compound are such articles as may be casily obtained at very moderate cost,
and have been found to answer the intended purpose when used in about the
above proportions, I prefer to employ them.
I claim, first, the use of the above materials or their equivalents com-
pounded in the manner stated; and, secondly, their application in the manner
described, as together constituting an improved process, and an economical
means of hardening and carbonizing articles mado of iron, or the surface of
iron to any depth, whether in rough bars or manufactured articles.
In witness whereof, I, the said Richard Dugdale, have hereunto set my
hand and seal, this Sixth day of July, in the year of our Lord One
thousand eight hundred and forty-nine.
RICHARD (L.S.) DUGDALE.

page_text: AND BE IT REMEMBERED, that on the Sixth day of July, in the year
of our Lord 1849, the aforesaid Richard Dugdale came before our said Lady.
the Queen in Her Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained and specified, in form above written.
And also the Specification aforesaid was stamped according to the tenor of the
Statute made for that nurnose.
Enrolled the Thirteenth day of July, in the year of our Lord One
thousand eight hundred and forty-nine.