IMPROVEMENTS IN APPARATUS FOR MELTING AND HEATING METALS AND OTHER SUBSTANCES
Year: 1868

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 APPARATUS FOR MELTING AND HEATING METALS
AND OTHER SUBSTANCES."-A communication from abroad by Adolphe
Perrot, of Paris, in the Empire of France, Chemist and Doctor
of Science.
Sealed the 19th June 1868, and dated the 25th January 1868.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 25th January 1868.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN APPARATUS FOR MELTING AND
HEATING METALS AND OTHER SUBSTANCES," (a communication to me from
abroad from Adolphe Perrot, of Paris, in the Empire of France, Chemist
and Doctor of Science) to be as follows, that is to say :-
This Invention relates to certain peculiar apparatus for effecting the
melting and heating of metals and other substances by the aid of

page_text: combustible gas or gases mixed with a suitable proportion of atmospheric
air or of oxygen.
The improved apparatus consists essentially of two parts, namely,
the heating or melting chamber, and the burners or appliances for
introducing and consuming the gas. According to one form of
apparatus intended for effecting the fusion of metals or other substances
in crucibles, the gas, which may be the ordinary gas employed for
illumination, and used at the ordinary pressure, is introduced by a pipe
and regulatory cock provided with an indicating plate and pointer into
an annular chamber provided on the upper surface with any convenient
number of jet nozzles. Each nozzle enters the lower end of an upright
pipe, the upper end of which pipe is curved inwards and enters a ring
situate some distance above the annular chamber herein-before referred
to. On the interior of this ring there are fixed by the aid of pins a
number of mouth pieces curling upwards, into which the ends of the
several pipes open. The requisite supply of air is admitted into the
lower ends of the several pipes by a perforated collar fitted on to
each pipe, a corresponding lateral opening being made in the pipe itself,
so that by turning these collars the air may be either shut off entirely
or its admission regulated according to requirements. The turning of
the several collars is effected simultaneously by the aid of one common
ring turning on a projecting rim on the upper surface of the annular
chamber, such ring carrying a number of projecting arms which actuate
the several collars above referred to. The upper ring into which the
several tubes open rests upon three or more supports and carries in
the centre thereof a vertically adjustible support of fire-clay, upon
which the crucible containing the metal or substance to be fused rests.
Beneath this there is situate a recepticle for collecting the molten
metal in case of fracture of the crucible, and hence there is no risk of
wasting the metal. The crucible is inclosed in a fire-clay muffle open
at the top and bottom, and the gas flame enters this muffle through
the lower opening & surrounds the crucible. The upper and lower
ends of the muffle are curved or rounded inwards, so as to produce a
reverberatory action. The muffle is surrounded by an outer fire-clay
cylinder which communicates with the chimney provided with a regu-
lating valve and indicator, and the whole is enclosed in sheet metal. A
fire-clay cover rests upon the outer fire-clay cylinder, and a central
stoppered opening is made in this cover for the facility of introducing
fresh pieces of metal or other substances into the crucible. No blast is

page_text: required with this apparatus, a chimney of from seven to ten feet in
height being capable of producing sufficient draught for all ordinary
purposes; and as
the apparatus is perfectly portable it may be
conveniently used in any situation.
In many cases it is requisite to protect from the direct action of the
flame articles which are intended to be subjected to an clevated
temperature. For this purpose it is proposed to employ the heating
muffle herein-before described, which will be found to be specially
adapted for enamellers, although the same principle may be applied
to other muffles, or be employed for the heating of ovens for baking
and other purposes. The muffle itself may be of any form according
to the uses to which it is to be applied; its top, bottom, and sides are
surrounded by a fire-clay envelope of a form corresponding to that of
the muffle, but leaving a space all round between the muffle and the
envelope for the passage of the gas flame. The envelope referred to is
enclosed in brick setting, a space being left between the setting and the
envelope for the passage of the flame to the chimney, a number of small
flues being made to communicate between the chimney and the space
last referred to for that purpose. One end of the envelope projects
slightly beyond the front of the setting, and is curved or contracted
at that end, a contracted opening of the shape or contour of the muffle
being also provided at that part, through which the several gas flames
from tubes or burners similar to those herein-before referred to, but
situate horizontally, enter into the envelope. These flames circulate
round the exterior of the muffle, then pass along the exterior of the
envelope, and finally enter the chimney through the several small
flues or passages before referred to. The draught is regulated by an
adjustable valve or damper in the chimney. In the centre of the series
of gas pipes there is situate an adjustable and slightly tapered block
of fire-clay of a cross section corresponding in shape to that of the
opening in the envelope, and by moving this block in or out of the
said opening the amount of air allowed to enter with the flame is
regulated accordingly.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Scal Patent
Office, on the 23rd July 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of January, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-first year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or 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 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 "IMPROVEMENTS IN APPARATUS FOR MELTING AND HEATING METALS AND
OTHER SUBSTANCES," a communication from abroad by Adolphe Perrot,
of Paris, in the Empire of France, Chemist and Doctor of Science,
upon the condition (amongst others) that I, the said John Henry
Johnson, my executors or administrators, by an instrument in writing
under my hand and seal, 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 John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the
accompanying Drawings, and to the letters and figures marked thereon,
that is to say :-
The said Invention relates to certain peculiar constructions, arrange-
ments, and combinations of apparatus for effecting the melting and

page_text: heating of metals and other substances by the aid of combustible gas
or gases mixed with a suitable proportion of atmospheric air or of
oxygen.
The improved melting apparatus consists of two parts, viz., 1st, the
furnace proper; 2ndly, the combustion apparatus or burner, which may
also be applied to heating in general.
The principal advantages of these apparatus are, 1st, the highest
temperature may be obtained without the use of blast engines or
compressed air for melting gold, copper, white or grey cast iron, a
draught obtained by a flue pipe of from 6 to 9 feet in height is quite
sufficient, thus admitting of the erection of the melting apparatus on
the upper floors of ordinary houses without regard to atmospheric
conditions; 2nd, the use of gas at the ordinary pressure adopted for
illumination; 3rd, coal, and consequently cinders, are dispensed with;
4th, the whole of the metal can be saved in the case of the fracture.
of the crucible; 5th, the cast iron may be withdrawn without.
extinguishing the fire; 6th, facility is afforded for the regulation of
the temperature and for maintaining it fixed for any length of time:
by simply adjusting or cutting off the supply of gas to the apparatus.
as may be required; 7th, no attention or feeding are requisite during
melting; 8th, the crucibles not being in contact with coal or cinders
wear only from the interior to the exterior by the reagents, and are
consequently much more durable; 9th, considerable saving in fuel
is effected, the whole of the heat being in the centre of the furnace
itself, and the time required to make the casting is greatly reduced.
The Inventor does not limit himself to the use of illuminating gas as
any combustible gas may be employed, and in lieu of air for the
combustion apparatus pure oxygen or oxygen mixed with any other
gas or with air may be used. In some cases combustible gases may be
introduced separately or in combination under a suitable pressure on
to such portion of the burner or furnace as shall be deemed most
convenient.
And in order that the said Invention may be fully understood I
shall now proceed more particularly to describe the same, and for that
purpose shall refer to the several Figures on the accompanying Sheets.
of Drawings, the same letters of reference indicating corresponding parts
in all the corresponding Figures.

page_text: Figure 1 (of the Drawings) is an elevation of a complete apparatus
arranged for the melting of metals; Figure 2 is a horizontal section
of the same taken on the line 1-2, in Figure 1; Figure 3 is a vertical
section, and Figure 4 a horizontal section taken along the line 3, 4, in
Fig. 3.
The gas is introduced through the tube a, provided with a cock b,
which serves to regulate its supply to the apparatus; the plug of this
cock carries a pointer b' which indicates on a dial the degree of
opening of the cock. The gas passes into the horizontal annular
chamber c provided on the top with any convenient number of gas
jets d, each of which enters the lower end of a curved pipe f, shewn in
full size at Figure 5. These pipes are surrounded by moveable collars F
fitted so as to turn easily round them in order to close more or less
square, round, or oval aperture e, which corresponds to a similar
opening formed in the collar F. By turning this collar a certain
quantity of the external air is caused to enter through the aperture e,
or its supply is entirely intercepted. The pipes f are straight for some
distance, and then bent round so as to enter at an angle of about 45°
the horizontal ring or annular frame h, and each terminates in a mouth
piece g, into which it fits. Through this mouth piece 9 which
is secured by a pin to the ring h, the mixture of air and gas
passes out to be conducted to the melting furnace. The ring /
is supported on feet n, and is provided with a cross piece or bar
which supports the vertical tube k. In the tube k is a cylinder k
terminating in a flange or flat head, on which is placed the block of
refractory clay i intended to support the crucible containing the
materials to be melted. By means of the screw m the height of the
crucible in the furnace may be varied as required. Figures 5 and 6
shew the connection of the pipes f with the ring hand annular
chamber c; Figures 7, 8, and 9, shew the different positions of the
collars F, which regulate the admission of air to the tubes f. On the
annular chamber c is a ring turning easily in a circular direction,
the motion of which is limited by a double stop. This ring is
provided with projections P corresponding in number to the tubes f,
and is turned by means of a handle M; the collars F carry a
horizontal projection or arm u on the side adjacent to the ring N, such
projection or arm being slotted to receive a pin or screw with which
the projections P are provided. It will thus be seen that by turning
the ring N by the aid of the handle M the degree of opening or

page_text: closing of all the apertures e is regulated, by which means the
admission of air into the tube f is mathematically adjusted for its
admixture with the gas.
The melting furnace is composed of a cylindrical muffle o rounded
both at top and bottom, as shewn at p and q, and intended to reflect
the heat on to the crucible, as in a reverbaratory furnace. These
parts are provided with openings p¹ and q¹. The muffle is surrounded
by a cylinder of refractory clay, which is formed with an aperture 7.²
communicating with the chimney y. The muffle and the cylinder "
are supported on an iron base, and surrounded by a sheet-iron
cnvelope communicating with the chimney by the aperture a¹;
the feet support the whole of the melting apparatus. The draught
of the chimney is regulated by the valve y', on the spindle of which
there is fitted a pointer to indicate outside the position of the valve.
A stove may, if desired, be disposed in proximity to the envelope n',
into which the gases may pass before escaping through the chimney,
and which would serve to heat up the crucibles and ingot moulds.
The cylinder is closed by the cover s, which may be removed by the
aid of the handles t; this cover is provided with an opening of about
the same diameter as the aperture p', and which is closed by the plug s¹,
strengthened by a metal collar carrying the handle t. The aperture
in the cover is intended to facilitate the inspection of the melting
operation, and for the feeding of the crucible with materials to be
melted and with reagents. The chamber w is provided for the reception
of any of the molten metal that might escape in the case of the
fracture of the crucible.
In many manufactures it is necessary that the articles which it is
required to expose for a certain length of time to a high temperature
should be preserved from contact with the flame; for this purpose
they are placed in a muffle, the form of which varies according to the
shape of the article it is required to contain. I shall describe the
muffle to be used by enamellers, this description being common to all
furnaces provided with muffles, from those used by the assaying of
gold and silver to the largest kilns for earthenware and porcelain; the
same principle may also be applied to the heating of bakers' and other
ovens.
Figure 10, Sheet 2, is a longitudinal vertical section of a muffle, and
Figure 11 a transverse section of the same taken along the line 5-6.

page_text: (Figure 10). The muffle A, which may be of any form whatever, is
surrounded by a casing o, the opening of which at q is of corresponding
form in cross section to that of the muffle, but the opening q' is of a
reduced size; the envelope » encloses the whole in such a way as to
leave a space between the casing o and the muffle A. The blocks
a and o¹ support the muffle and its casing, and admit of the proportining
of the clear spaces in the part corresponding to the closed end of the
muffle. Orifices x, x¹, x², x³, x*, are provided in the envelope for the
escape of the products of combustion; the position of such orifices will
vary with the form of the muffle, and according as it is required to
heat it uniformly or more or less in a horizontal part. The part 7¹ of
the furnace is of unbaked clay. The aperture which the plug t closes
is provided to facilitate an inspection of the traverse of the flame;
this aperture is formed in the doors which closes the front opening
of the furnace. The casing o which surrounds the muflle from q to q¹
projects from the furnace, as shewn in Figure 10. The combustion
apparatus or burner is of the same construction as that shewn in
Figures 5 to 9 (Sheet 1) for the melting furnaces, its form only being
varied. The tubes f, shewn in red ink, which conduct the mixed
gas, are so arranged that the flames will issue therefrom in a horizontal
or nearly horizontal direction. The form of the block i in cross section
should correspond to that of the opening q', and it is intended to act
as a closing apparatus to regulate the column of air which enters
the furnace with the flames from the burner; its position may be
regulated by turning an adjusting screw which moves it in a horizontal
direction. The muffle may be perforated if required both on its
rounded portion and on its sides; such perforations, by reason of the
draught, only afford an outlet to the products of calcination and to
the air, but not to the ignited gases. The muffle furnaces require a
greater draught than melting furnaces such as shewn on Sheet 1. The
furnace illustrated on Sheet 2 is provided with a chimney y, in which
is mounted the valve or damper z to regulate the draught. The part X
of the furnace may be used as a dryer.
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 peculiar construction, arrangement, and combination

page_text: of apparatus for the purpose of effecting the operations of melting
and heating metals and other substances by the aid of combustible
gas or gases mixed with a suitable proportion of atmospheric air or
oxygen gas, as herein-before described and illustrated by the Drawings
annexed.
In witness whereof, I, the said John Henry Johnson, have
to this my Specification set my hand and seal, the Twenty-
first day of July, in the year of our Lord One thousand eight
hundred and sixty-eight.
J. HENRY JOHNSON. (L.S.)