IMPROVEMENTS IN TEMPERING OR INCREASING THE POWER OF RESISTANCE OF ARTICLES OF METAL
Year: 1878

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS
IN TEMPERING OR INCREASING THE POWER OF RESISTANCE OF ARTICLES OF
METAL." A communication from abroad by Auguste Séguin, of Paris, in the
Republic of France.
Sealed the 28th January 1879, and dated the 30th September 1878.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 30th September 1878.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN TEMPERING OR INCREASING THE POWER OF
RESISTANCE OF ARTICLES OF METAL." A communication from abroad by Auguste
Séguin, of Paris, in the Republic of France.
This Invention has for its object enabling the power of resistance of a straight or
curved piece of metal to be augmented by immersing or dipping the same when
hot in certain liquids herein-after mentioned, either entirely or only at that part
which is subject to compression under the strain to which it is destined to be
exposed.
The liquids employed are either sulphuric acid diluted with water, hydrochloric
acid with water or turpentine mixed with say about from five to six times its
volume of water.
When sulphuric acid is employed, the piece of metal after being heated to say a
cherry red heat in a reheating furnace or forge fire, or otherwise is immersed either
wholly or partially in a mixture composed of sulphuric acid, at about 66° Beaumé
and water in equal volumes.
The temperature of the bath should be maintained at say from about 60° to 100°
Prise d

page_text: centigrade, but it has been found by experience that the temperature of the bath
may be elevated to about 200° centigrade without prejudicing its effect.
When turpentine is employed, care is to be taken to agitate the vessel containing
it continually in order to prevent the turpentine from floating on the surface of the
water, and becoming ignited by contact with the heated metal.
In all cases the metal is allowed to remain in the bath until the temperature of
the part immersed is lowered to that of the liquid, after which it is plunged into
cold water.
The process is applicable to pieces of metal of homogeneous composition, or to
articles formed by welding together pieces of iron of different qualities, the said
process having the effect of increasing to a considerable extent the power of
resistance of any article of iron to a tensional transverse or torsional strain by the
complete or partial immersion of such article in one of the liquids mentioned.
It will usually be found sufficient to dip the side of such pieces, which is exposed
to compression in one of the liquids herein-before mentioned when in a heated
condition.
In the case of a piece of metal in the form of a hook (for example), when it is
required to increase its power of resistance to a tensional strain, the back of the
hook only for say about one-third of its thickness is immersed in the bath herein-
before described.
When the piece of metal is of rectangular section supported at one end only, and
carrying a load at the other or acting as a cantilever, the underneath part only is
immersed for say about one-third of the depth or thickness of the piece.
In the case of a solid bar of prismatic section supported at each end and loaded
at the middle, the upper part is to be immersed in the bath.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by.
the said John Henry Johnson in the Great Seal Patent Office on the 20th
March 1879.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN TEMPERING OR INCREASING THE POWER OF
RESISTANCE OF ARTICLES OF METAL." A communication from abroad by Auguste
Séguin, of Paris, in the Republic of France.
The said Invention relates to the tempering of articles of metal 'of either a
straight or curved form, in order to increase their power of resistance by immersing
or dipping them when in a heated condition in certain liquids herein-after
mentioned, either entirely or only at the part or parts subject to compression under
the strain to which the article is destined to be exposed.
The liquids employed are either sulphuric acid diluted with water, dilute
hydrochloric acid or turpentine mixed with say about from five to six times its
volume of water.
When sulphuric acid is employed, the piece of metal after having been heated to
say a cherry red heat in a reheating furnace or forge fire, or otherwise is immersed
either wholly or partially in a mixture composed of sulphuric acid at about
66° Beaumé and water in equal volumes.
The temperature of the bath should be maintained at say from about 60° to 100°
centigrade, but it has been found by experience that the temperature of the bath
may be elevated to about 200° centigrade without prejudicing its effect.
When turpentine is employed, care should be taken to agitate the vessel
containing it continually in order to prevent the turpentine from floating on the
surface of the water, and becoming ignited by contact with the heated metal.
In all cases the metal is allowed to remain in the bath until the temperature of
the part immersed is lowered to that of the liquid, after which it is plunged into
cold water.
The process is applicable to pieces of metal of homogeneous composition, or to
articles formed by welding together pieces of iron of different qualities, but it will
be obvious that the beneficial results of this mode of tempering becomes more
apparent when the process is applied to metal of superior quality, the said process
having the effect of increasing to a considerable extent the power of resistance of
any article of iron to a tensile transverse or torsional strain, by the complete or
partial immersion of such article in one of the liquids herein-before mentioned.
The annexed Drawing illustrates various modes of applying this
process with a
view to augmenting the power of resistance of straight or curved pieces of metal,
by immersing the side of such pieces which is exposed to compression in one of the
liquids herein-before mentioned when in a heated condition.
In the case of a piece of metal in the form of a hook A, Figure 1, when it is
required to increase its power of resistance to a tensile strain, the back a of the
hook only for say about one-third of its thickness is dipped in the bath herein-
before described.
When the piece of metal A is of rectangular section (see Figure 2), supported at
one end b only, and carrying a load B at the other end c or acting as a cantilever,
the under portion a only is immersed to the extent of say about one-third of the
depth or thickness of the piece.
In the case of a solid bar A (Figure 3), of prismatic section supported at each
end b, and loaded at the middle with a weight B, the upper portion a¹ is to be
immersed in the bath.
Although in the examples illustrated in my Drawings and herein-before
described, I have assumed that the process is applied to a portion only of the depth
or mass of the article, it is obvious that the article may be entirely immersed in the
liquid if found advantageous or desirable.
ג

page_text: Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,
and therefore claim as the Invention secured to me by the herein-before in part
recited Letters Patent is,-
The process of tempering or increasing the power of resistance of articles of
metal by immersing or dipping them when in a heated condition in one of the
liquids herein-before mentioned at an elevated temperature, substantially as herein-
before described.
In witness whereof, I, the said John Henry Johnson, have to this my Specifi-
cation set my hand and seal, this Eighteenth day of March, One thousand
eight hundred and seventy-nine.
J. HENRY JOHNSON. (L.S.)