A NEW MANUFACTURE OF IMPERMEABLE CARBON BRICKS, AND OTHER OBJECTS
Year: 1876

page_text: LETTERS PATENT to Walter Weldon, of Abbey Lodge, Merton, in the County
of Surrey, for the Invention of "A NEW MANUFACTURE OF IMPERMEABLE
CARBON BRICKS, AND OTHER OBJECTS"
Sealed the 24th November 1876, and dated the 28th August 1876.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Cominissioners of Patents on the 28th August 1876.
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey.
MANUFACTURE OF IMPERMEABLE CARBON BRICKS, AND OTHER OBJECTS."
"A NEW
Such carbon bricks, as have hitherto been made, have been obtained by mixing
powdered coke with tar, filling the mixture so produced into cast-iron moulds, and
then subjecting the moulds and their contents to a red heat. Bricks so made have
been employed, I believe, only in a single instance, when they were used for the bed
of a furnace for the manufacture of an alloy of ion. While, however, bricks so
made are not penetrable by molten metal, they are freely pervious to bodies such,
for example, as fused sulphide of sodium, in the manufacture and manipulation of
which they would otherwise be extremely serviceable.
The object of this Invention is the manufacture of impermeable carbon bucks,"
pipes, and other objects, of which it shall be possible to make furnaces, vessels,
tools, conduits, and the like, suitable for containing, treating, conveying, and apply-
ing such fluids and vapours as are equally capable with fused sulphide of sodium
1
and high-pressure steam of penetrating into exceedingly minute interstices.
believe that such bricks and other objects will be found susceptible of many very
important applications.
I accomplish the said object by subjecting the plastic mixture in the moulds,
before the moulds and their contents are heated, to powerful pressure. Into
moulds, nearly filled with the said plastic mixture, I force a block of iron or other
substance exactly fitting the mould, until the contents of the mould are compressed,
and compacted to the necessary degies. I then subject the brick or other object,
which has thus been formed, to such a temperature that the tar in it shall undergo
destructive distillation, the brick or other object being placed during this operation
in such mechanical conditions as to prevent its changing shape or sensibly altering
in dimensions. If, after this operation, it is still too porous, I soak it thoroughly

page_text: in tar, preferably at a high temperature, and then subject such tar, as it may thus
have absorbed, to destructive distillation, under the same conditions as before. This
treatment may be repeated, if need be, several times, and the absorption of the tar
may be promoted by exhausting the air, as far as possible, from the pores of the brick
or other object before immersing it therein.
Any other form of charcoal may be employed instead of coke, and any other of a
number of agglutinating bodies, which leave a residue of solid carbon on being
subjected to destructive distillation may be used instead of tar; but tar and
powdered coke will usually be the cheapest and most convenient.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by 1
the said Walter Weldon in the Great Seal Patent Office on the 26th February
1877.
" A NEW
WALTER WELDON, of Abbey Lodge, Merton, in the County of Surrey.
MANUFACTURE OF IMPERMEABLE CARBON BRICKS, AND OTHER OBJECTS."
Carbon bricks have hitherto been employed only for the beds of furnaces for the :
manufacture of the alloy, known as ferro-manganese. The bricks, so employed,
are made by mixing powdered coke with a small quantity of gas tar, filling the
mixture, so produced, into cast-iron moulds, and then subjecting the moulds and
their contents to a red heat, until the tar in the latter has completely undergone
destructive distillation. While, however, bricks so made are not penetrable by
molten metal, I have found that they are so permeable to such bodies as fused
sulphide of sodium and fused sulphide of potassium, that when these sulphides are
either manufactured, or treated in the state of fusion, in iron furnaces or other
apparatus lined with such carbon bricks, they soon penetrate through the said
carbon lining, and so attack the iron envelope as rapidly to destroy it.
The object of my present Invention is therefore the manufacture of carbon bricks,
blocks, pipes, and other objects, which shall be so impermeable as to be adapted for
lining furnaces and vessels, and as a material for tools, conduits, and the like, for
containing, treating, conveying, and applying sulphide of sodium and sulphide of
potassium in the state of fusion.
I accomplish the said object by subjecting the plastic mixture in the moulds,
before the moulds and their contents are heated, to considerable pressure. Into
moulds, nearly filled with the said plastic mixture, I force a block of iron or other
hard substance, suitably fitting into the mould, until the contents of the mould are
compressed and compacted to the necessary degree. The necessary pressure may be
applied by means of a press or other ordinary appliance to that end, as will be well
understood. If, after having been then heated, until the tar in it has completely
undergone destructive distillation, the brick or other object, so produced, is still too
porous, I soak it thoroughly in tar, preferably boiling, and then heat it again, so as
to subject to destructive distillation the further quantity of tar, which it has thus
been made to absorb. This treatment may be repeated, if need be, several times,
and the absorption of the heated tar may be promoted by exhausting the air, as far
as possible, from the pores of the brick or other object before immersing it therein.
Other forms of carbon may be employed instead of coke, and flour paste, starch,
molten pitch, or other agglutinating body, which leaves a residue of solid carbon on
being subjected to destructive distillation, may be used instead of tar; but tar and
coke will usually be the cheapest, and I believe them to give the most effective
result.
The heating of the bricks or other objects should preferably be performed in a
muffle furnace. During this operation, to prevent them from losing their shape,
or materially altering their dimensions, they must be encased on all sides by
suitably fitting metal plates, or other equivalent appliances, firmly clamped or

page_text: bolted together, after the brick or other object has been placed within them. The
products of the decomposition of the tar or other agglutinating body may escape at
the lines of junction of the said plates, or other appliances, or by special apertures
therein.
Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim as the Invention, to be secured to me by the
herein-before in part recited Letters Patent, the manufacture of impermeable carbon
bricks and other objects, for the applications above set forth, by adding pressure,
and soaking in tar or other agglutinating body, and then re-heating, as above
described, to the means by which carbon bricks have been manufactured hitherto.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand
and seal, this Twenty-ninth day of January, in the year of our Lord One
thousand eight hundred and seventy-seven.
(L.s.) WALTER WELDON.