A CERTAIN PROCESS FOR EXTRACTING ARSENIC FROM ANY OF THE ORES OR OTHER. SUBSTANCES IN WHICH IT IS CONTAINED IN A PURER STATE THAN IT IS AT PRESENT PROCURED IN THIS KINGDOM
Year: 1813

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, RICHARD
EDWARDS, of the Parish of Budock, in the County of Cornwall, Doctor of
Physic, and WILLIAM WILLIAMS, of the Borough of Penryn, in the same
County, Surgeon, send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Fifteenth day of March, in the fifty-third year of His reign, did,
for Himself, His heirs and successors, give and grant unto us, the said
Richard Edwards and William Williams, His especial licence that we, the
said Richard Edwards and William Williams, our exors, admors, and
assigns, or such others as we, the said Richard Edwards and William Williams,
should at any time agree with, and no others, from time to time and at
all times during the term of years therein expressed, should and lawfully
might make, exercise, and vend, within that part of the United Kingdom of
Great Britain and Ireland called England, Wales, and the Town of Berwick-
upon-Tweed, our Invention of." A CERTAIN PROCESS FOR EXTRACTING ARSENIC
FROM ANY OF THE ORES OR OTHER. SUBSTANCES IN WHICH IT IS CONTAINED IN A
PURER STATE THAN IT IS AT PRESENT PROCURED IN THIS KINGDOM;" in which
said Letters Patent there is contained a proviso obliging us, the said Richard
Edwards and William Williams, by an instrument in writing under our hands

page_text: and seals, or under the hand and seal of one of us, particularly to describe and
ascertain the nature of our said Invention, and in what manner the same
is to be performed, and to cause the same to be inrolled in His Majesty's
High Court of Chancery within two calendar months next and immediately
after the date of the said recited Letters Patent, as in and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, and in pur-
suance of the said Statute, we, the said. Richard Edwards and William
Williams, do hereby declare that the following are the principles of our said
Invention (the particular manner by means of which the same are reduced to
practice will be hereafter described and set forth); that is to say :-
We obtain arsenic in a purer state than it has hitherto been produced in these
Kingdoms either from its ores or from the substance collected in the flues of
furnaces for roasting or calcining copper or cobalt ores, or from the condensed
smoke of burning-houses for calcining or roasting tin ore, and which is well
known among workmen and others in Cornwall by the name of burning-house
smoke or poison, or by burning arsenical pyrites, or any mineral or other
substance containing arsenic, by means of coaks, charcoal, culm, cinders, or
any combustible substance that yields little or no smoak, instead of coal, which
is at present universally used for that purpose; by collecting the arsenic in a
condensing house distinct from and having no communication with the fire
that sublimes it, unless that fire is produced by combustible substances which
produce no smoke; by separating the sulphur from it by a gentle heat in a
distinct operation, by mixing it with the black oxyd of manganese (or any
other substance, ore, mineral, or metallic oxyd, that easily parts with its
oxygen) before it is put into the condensing furnace; and, lastly, by reducing
it into a solid state by sublimation in close vessels which we have invented
for the purpose.
Now, as to the manner in which the said principles, by us first invented and
introduced into this country (which we claim and consider as our own peculiar
Invention), are carried into practice, we do hereby declare that the following
contains a full and particular description of our newly-invented process for
preparing arsenic in a purer state than it has been procured in these Kingdoms,
as aforesaid, from the several ores and other substances herein-before set forth,
and of reducing it to a solid form (that is to say) :-
1st. The arsenic collected by roasting the aforesaid minerals containing
ashes, soot, earthy matters, and other impurities with which it accidentally
mixed, and being partly in its metallic state, owing to the coal smoke which
proceeds from the fireplace when that fuel is used, and also combined with. a

page_text: large portion of sulphur, is first carefully dried, and then put into an oven or
common reverberatory furnace, heated in the common way, but by inflammable
substances which produce little or no smoke, or into one which we have
invented for the purpose, and call a condensing furnace, that is connected with
a large condensing house, in which the. arsenic is collected much purer than
in its previous state, being separated from every heterogeneous substance but
the sulphur, a large quantity of which it still contains; a portion of it also pre-
serves its metallic state, which gives it a greyish tint. This furnace, which we
have named a condensing furnace (a Plan, &c., of which is given in the margin
of these Presents), is square, with an arched roof; but it may be made
circular, elliptical, or of any other form. The bottom is made of two layers of
thin tiles, formed of and cemented together with fine clay. The tiles of the
upper layer are placed so as to cover the joints of the under one, to prevent
the arsenic from penetrating and getting into the fireplace; but the bottom
may be formed of cast or wrought iron (if care be taken that too great a heat
be not applied), fire stone, or of any other substance that will bear the heat
which is necessary to sublime the arsenic. The bottom of the furnace we use
measures about twenty-five superficial square feet, but may be constructed of a
larger or smaller size, according to circumstances. The fireplaces are so situated
as to be capable of giving the bottom a uniform heat, and have no connection
with the body of the furnace, one end of which communicates with the con-
densing house, which is a close room about one hundred feet long, thirteen
feet high, and twelve feet wide (but the dimensions may vary according to
circumstances, more particularly according to the size of the condensing
furnace),. with an opening at the end most remote from the furnace, which is
connected with a horizontal flue about two feet square, and two hundred feet
long, at the extremity of which is a large perpendicular chimney thirty feet high,
that is connected with the fireplace of the condensing furnace, by which
means a circulation of air is produced through the horizontal flue. The other
end of the furnace is open, through which aperture it is supplied with arsenic,
and through which a current of air passes into the condensing house, and
carries the volatilized arsenic with it.
2dly. In order to separate the sulphur from the volatilized arsenic it is
spread on the iron bottom of a furnace (of the same construction as that before
mentioned, and which we call a roasting furnace) to the thickness of about a
quarter of an inch, and here exposed to a degree of heat sufficient to evaporate
the sulphur but not to sublime the arsenic, which is known by the white
fumes of arsenic that arise if the furnace be too hot; and if the heat be too
little, the smell of sulphur will not be sensible on the surface of the arsenic.

page_text: When the sulphurous sniell is no longer to be perceived, and it appears but
faintly yellow on the surface, it is to be removed, the purification being
sufficiently perfect with respect to the sulphur. If the whole of the process.
has been carefully conducted, the arsenic, when in the solid state, will be
nearly white like glass, or of a light straw colour; if not, it will be of a dark
yellow, red, or nearly black..
:
3dly. It is now ready for the last operation, which is that of reducing it to
a solid state by sublimation in close vessels. And this we perform in the
following manner-The conical covers v, v, Fig. 4 and 6, (see the annexed
Drawings,) being carefully luted with clay to the kettles t, t, the perpendicular
bars z, Fig. 6, are put into their places, and the weights hung on the ends of
the levers u, U.
The furnace is then heated till the bottoms of the kettles are
uniformly of a low red heat, visible by day in the shade, 1000° Fahr.,
which will make the covers so hot as to. keep the arsenic which is collected
in them in a vitrified state. They are then each of them charged, through the
openings f, with about 10lbs. of the purified arsenic, and the charging holes
closed with the iron stoppers represented in the Drawing. If a regular degree
of heat has been applied, this quantity of arsenic will be sublimed in about an
hour, at the end of which time the stoppers are to be taken out, and the kettles
charged as before. This operation we continue for eighteen and sometimes
for twenty-four hours, and then, in order to cool the kettles, that the covers
may be taken off with safety, that others may be put on, the cover h, Fig. 5,
placed over the opening 9, Fig. 1 and 5, in the center of the furnace, is to be
removed, that the fire may escape into the large chimney y, Fig. 4, and tlie
bricks that close the holes w, w, w, Fig. 4 and 6, are also taken away.. When
a proper degree of heat has been kept up, the whole of the arsenic collected
in the cover will be vitrified and transparent, if not it will be opaque, soft, and
sometimes red. We find that a pressure of nearly 6 cwt. is sometimes
necessary to keep each cover (which is about two feet in diameter in the base,
and made of wrought or cast iron) from being lifted by the expansive force of
the arsenic; it is requisite therefore that the workmen should be very attentive
to the luting of the covers, as a large quantity of arsenic will escape in a short
time through a very small crack, and consequently there will be a great
deficiency in the produce; whenever therefore. a crack is discovered, or the
fumes of arsenic are perceived to arise from the luting, or to proceed from
the charging holes, a painter's brush charged with very wet clay is applied
to those place still the leak is stopped. The workmen must also be very
careful whilst they are luting on the covers or charging the kettles that
the smallest quantity of any inflammable substance does not get into them,

page_text: as it will spoil the arsenic by rendering it black.
Whenever such an accident
happen, (which is soon discovered by the color of the arsenic that collects on
the stopper) the process must be discontinued and the vessels cleaned. Too
much care -cannot be taken in purifying the arsenic (in the manner already
described) before it is put into the kettles, as it will undergo no change in
that respect by sublimation; this circumstance therefore must be particularly
attended to to prevent unnecessary trouble and expence. In order to render
the kettles more durable we place false bottoms in them made of wrought
iron, and we secure the edges with good fire clay, to prevent the arsenic from
penetrating and getting under those bottoms, which would in a short time
destroy the cast iron. These are always examined when the covers are taken
off, and are replaced by new ones when they become defective.
We also consider as our Invention a method which may be used to accelerate
its purification when the arsenic is very impure, that is, when it contains much
sulphur, and when a large proportion of it is in its metallic state. Under
these circumstances a proportion of the black oxyd of manganese (or any
other substance, ore, mineral, or metallic oxyd that easily parts with its oxygen)
is to be mixed with it before it is put into the condensing furnace, the heat
of which being sufficient to disengage. the oxygen from the manganese, it
more readily and effectually separates the sulphur and combines with the
metallic arsenic than common air, by its coming more intimately into, contact
with these substances at the moment of its extrication. The quantity of
manganese necessary for this purpose will depend on the purity of the arsenic;
and can therefore be only ascertained by experience.
"
REFERENCE TO THE ANNEXED DRAWINGS.
The same letters refer to all the Figures.
Fig. 1st, a horizontal section of the furnace through the dotted lines
A, A, A, Fig. 4, 5, 6, and 7.-a, a, hollow pillars which support the cone
and serve as chimnies, and are carried up on the inside of the cone, as in
Fig. 5, 6, and 7; b, b, doors of the fire places; c, c, ashpits; d, d, the bed
of the furnace, formed of cast-iron plates, into the circular holes e, e, e, of
which the cast-iron kettles t, t, Fig. 4 and 6, are placed, with the charging
holes at f; ga circular hole in the centre, stopped whilst the furnace is at
work with the cover h, Fig. 5, which is an iron ring filled with fire clay,
and which is removed before the covers of the kettles are taken off..
i Fig. 2d, section through the lines B, B, B, Fig. 4, 5, 6, and. 7.-h, h, the
penings into the chimnies; i, i, brickwork to support the bed of the furnace,
which is formed of thin bricks k, k, k, Fig. 5, 6, and 7, and covered with cast-

page_text: iron plates, which are seen in Fig. 1, d, d, d; la circular hole through which
the concentrated heat of all the fireplaces passes, and is conveyed by the
openings, s, 8, Fig. 2, 5, 6, and 7, to the six kettles.
Fig. 3d, section through the lines C, C, C, Fig. 4, 5, 6, and 7.-m, m, tho
fireplaces; n, n, flues, through which the fire passes to the centre, and which
are made deep at 0, 0, 0, to give more liberty to the passage of the flame;
p, a circular projection, as well to diminish the cavity as to give a perpendicular
direction to the flame; 9, 9, 7, brickwork to support the bed of the furnace, on
which rest the thin bricks r, r, r, Fig. 5, 6, and 7, that cover the flues.
Fig. 4th, view of the furnace. u, levers about six feet six inches long, to
keep down the covers of the kettles v, v; w, w, openings to admit a current
of air to cool the bottoms of the kettles before the covers are taken off; a. a,
iron ring to strengthen the furnace, just below which is placed a register in
ench flue.
Fig. 5th, a perpendicular section through the dotted lines A, A, A, A,
Fig. 1, 2, and 3.
Fig. 6th, section through the lines B, B, B, B.- a bar of iron which rests
on the top of the cover v, and is pressed upon by the lever u, which is fixed
to a strong piece of iron v that extends across the furnace, and is fixed in the
brick work.
Fig. 7th, a section through the lines C, C, C, C.
The advantages we derive from a furnace of this construction, which we
consider as our own Invention, are the following:-It is capable of producing
a regular degree of heat on account of the number of fireplaces it contains.
If, for instance, one of the fires should go out, or should burn with greater
intensity than is necessary, the loss or increase of heat would be only one
twelfth of the whole. We can at any time, if an accident should happen to
one of the kettles, cool it preparatory to removing it, without interrupting the
process in the others, by opening the hole w, Fig. 4 and 6, and stopping the
fire with a brick at s, Fig. 2, 6, and 7, where it enters from the centre. We
are enabled also to cool all the kettles as much as is necessary to remove the
covers without extinguishing the fires, by taking away the cover in the centre
and opening all the holes at w. Another important advantage attached to
this furnace is, that all the fumes of arsenic which may escape are carried
up through the cone, and do not injure the health of the workmen. The
kettles may be made of an oval shape, square, or cylindrical, or may be
formed of any other substance than cast iron, which is not more casily acted
on or pervaded by the arsenic. They may also be heated by fireplaces placed
immediately under them, as in the common way. of heating boilers, or by

page_text: placing them over flues of furnaces which are used for smelting of metals or
other purposes. But after many trials we prefer kettles of the form we have
represented and the furnace we have described.
In witness whereof, we, the said Richard Edwards and William
Williams, have hereunto set our hands and seals, the Twenty-third
day of April, in the year of our Lord One thousand eight hundred and
thirteen.
RICHARD (L.s.) EDWARDS.
WILL WILLIAMS. (L.s.)
AND BE IT REMEMBERED, that on the Twenty-third day of April, in
the year of our Lord 1813, the aforesaid Richard Edwards and William
Williams came before our said Lord the King in Ilis 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
purpose.
Inrolled the Twenty-eighth day of April, in the year of our Lord One
thousand oight hundred and thirteen