IMPROVEMENTS IN MACHINERY FOR PULVERIZING, GRINDING, AMALGAMATING, AND WASHING ORES
Year: 1854

page_text: LETTERS PATENT to John Mitchell, of the Assay Office, Dunnings Alley,
Bishopsgate Street, in the City of London, Assayer, for the Invention of
"IMPROVEMENTS IN MACHINERY FOR PULVERIZING, GRINDING, AMALGAMATING,
AND WASHING ORES."
Sealed the 10th October 1854, and dated the 11th April 1854.
PROVISIONAL SPECIFICATION left by the said John Mitchell at the
Office of the Commissioners of Patents, with his Petition, on the 11th
April 1854.
I, JOHN MITCHELL, of the Assay Office, Dunnings Alley, Bishopgate Street,
in the City of London, Assayer, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN MACHINERY FOR PULVERIZING, GRINDING, AMALGAMATING,
AND WASHING ORES," to be as follows:-
This Invention has for its object improvements in that class of machinery
where spheres are used in a circular trough; and the improvements consist,
first, of giving motion to such spheres by means of cones which are free on
their axes; or, in place of cones, inclined surfaces are used; by means of
either of which, that tendency of the spheres to move outwards from the centre
of the trough is counteracted, and the inclined pushing or driving surfaces
tend to force the spheres in towards the centre of the trough, by which the
spheres, in addition to a rolling motion round the circular trough, have also a
further rotation; and, secondly, a rake corresponding with the form of the
trough is employed, and connected to one or eacli of the frames or arms which
carry the cones or inclined surfaces.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Mitchell in the Great Seal Patent Office on the 11th
October 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
MITCHELL, of the Assay Office, Dunnings Alley, Bishopsgate Street, in the City
of London, Assayer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of April, in the year of our Lord One
thousand eight hundred and fifty-four, in the seventeenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said John Mitchell, Her special licence that I, the said John Mitchell, my
executors, administrators, and assigns, or such others as I, the said John
Mitchell, my executors, administrators, and 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 MACHINERY
FOR PULVERIZING, GRINDING, AMALGAMATING, AND WASHING ORES," upon the con-
dition (amongst others) that I, the said John Mitchell, 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 sanie was to be per-
formed, 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 Mitchell, 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 thereof (that is to say):—
This Invention has for its object improvements in that class of machinery
where spheres are used in a circular trough; and the improvements consist,
first, of giving motion to such spheres by means of cones which are free on
their axes; or, in place of cones, inclined surfaces are used; by means of either
of which, that tendency of the spheres to move outwards from the centre of the
trough is counteracted, and the inclined pushing or driving surfaces tend to
force the spheres in towards the centre of the trough, by which the spheres, in
addition to a rolling motion round the circular trough, have also a further
rotation; and, secondly, a rake corresponding with the form of the trough is

page_text: employed, and connected to one or each of the frames or arms which carry the
cones or inclined surfaces.
Having thus stated the nature of my said Invention, I will proceed to
describe the best means I am acquainted with for performing the same.
DESCRIPTION OF THE DRAWING.
Figure 1 shows an elevation in section, and Figure 2 shows a plan of a
machine combined, according to my Invention. a, a, is a circular fixed trough,
having outlets covered with wire cloth or perforated metal at b, b, through
which the wash water and matters dissolved or suspended therein may flow off.
c is an outlet, by which the amalgam, gold or silver, or other matters, may be
drawn off. d, d, are spheres in the circular trough, and it is by means of these
spheres being caused to move in the trough a, a, that the process of pulverizing
and grinding is performed, and the matters are at the same time (if mercury
be added) amalgamated by the mercury in the trough, and the matters so
ground or ground and amalgamated are washed off by a flow of water constantly
running into the trough.
I would here state that I am aware that spheres have been before used in
troughs and also in basins, and such is the case in regard to mercury and
water. I do not, therefore, claim the use of such instruments and matters
generally, when crushing, grinding, amalgamating, and washing ores, my
Invention consisting in the peculiar combination of the machinery herein
described for such purposes. c, c', are cones, carried by the frame d', d', which
receives rotatory motion by the upright axis e, put in motion by bevil wheels,
as shewn, or by other convenient means, by a steam engine or other power.
The cones c', c, by being carried round by the frame d', press constantly
against the spheres d, and drive them round in the trough a, a; or, in place of
cones, inclined surfaces may be carried by the frame d', the objects of such
cones or inclines being to counteract thereby the tendency of the spheres to
move off from the centre, and also to move the spheres towards the centre;
and at the same time the cones, in addition to so moving the spheres, also tend
to cause the spheres to rotate as well as roll round in the circular trough;
by which compound motion the spheres. will act with more advantage than
when simply rolling in a trough. f, f, are rakes, carried by the frame which
carries the cones; these rakes are formed to the shape of the bottom of the
trough a, as shewn.
Having thus described the nature of my said Invention, and the manner of
performing the same, I would have it understood that I do not claim any of
the parts separately, nor do I confine myself to the details; but what I claim

page_text: is, the combination of machinery herein described for pulverizing, grinding,
amalgamating and washing ores.
In witness whereof, I, the said John Mitchell, have hereunto set my
hand and seal, this Tenth day of October, in the year of our Lord One
thousand eight hundred and fifty-four.
Witness,
JNO. ALCOCK.
JOHN MITCHELL. (L.S.)