IMPROVEMENTS IN, THE MANUFACTURE OF POTS AND CRUCIBLES, WHEREIN METALS AND OTHER MATERIALS MAY BE HEATED OR MELTED."
Year: 1865

page_text: LETTERS PATENT to George Nimmo, of Jersey City, in the State of New
Jersey, United States of America, for the Invention of "IMPROVEMENTS
IN, THE MANUFACTURE OF POTS AND CRUCIBLES, WHEREIN METALS AND OTHER
MATERIALS MAY BE HEATED OR MELTED."
PROVISIONAL SPECIFICATION left by the said George Nimmo at the
Office of the Commissioners of Patents, with his Petition, on the 19th
July 1865.
I, 'GEORGE NIMMO, of Jersey City, in the State of New Jersey, United
States of America, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF POTS AND CRUCIBLES, WHEREIN METALS
AND OTHER MATERIALS MAY BE HEATED OR MELTED," to be as follows:―
My crucibles or pots are shaped in any suitable mould or apparatus, and for
this purpose the revolving head, mould, and rib may be employed, as men-
tioned in Letters Patent granted to me in Great Britain, March 6th, 1865,
No. 680. The material I employ for forming such crucibles or pots is
plumbago mixed with clay and sand in any usual or desired proportion.
My improvement relates, first, to coating or lining such plumbago crucibles,
the object being to prevent the carbon in the plumbago crucibles injuriously
affecting the steel, or other substances heated or melted in such pots or cru-
cibles, and at the same time to protect the pots from injury internally or
externally, and cheapen the said pots or crucibles. For this lining or coating

page_text: 1 employ clay or glass, or clay mixed with sand or any other silicious sub-
stances, say, in equal proportions, according to the particular use to which the
plumbago pot is to be put. The said pot or crucible is to be moulded as usual,
only rather thinner, then the lining or coating is to be applied or spread evenly
and smoothly upon the surface. The covers for the pots or crucibles may also
be coated in the same manner. I thus obtain the strength and conducting
power of the plumbago pot or crucible, and protect it or its contents from
injury by the one acting on the other.
The second part of my improvement relates to the mode of drying and
burning the crucibles; for this purpose I employ a long horizontal flue, at
one end of which heat is introduced, or a fire provided; at the other end is an
escape for the air and gases. Within this horizontal flue is a travelling plat-
formi or platforms set on rollers that travel on bars or rails, and these platforms
may be side by side, or one over the other, and are moved gradually by power.
The pots or crucibles are placed upon the platform or platforms through a
door at the coolest end of the said horizontal flue, and are gradually moved
towards the hottest end as the platform is moved along, and when the cru-
cibles arrive at or near the hottest end of the horizontal flue they may be
lifted off with suitable-tongs-and-placed directly in the fire; - when sufficiently-
heated or burned they are to be removed. This gradual heating prevents the
crucibles or pots cracking as much as they usually do-in-burning:
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Nimmo in the Great Seal Patent Office on the
16th January 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE' 2!
NIMMO, of Jersey City, in the State of New Jersey, United States of America,.
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters:
Patent, bearing date the Nineteenth day of July, in the year. of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of Her. 30
reign, did, for Herself, Her heirs and successors; give and grant unto me,
the said George Nimmo, Her special license that I, the said George Nimmo,
my executors, administrators, and assigns, or such others as I, thé said!
George Nimmo, my executors, administrators, and assigns, should at.any.
time agree with, and no others, from time to time and at all times there: 3
after during the term therein expressed, should and lawfully might make, 'use,

page_text: exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN.
THE MANUFACTURE OF POTS AND CRUCIBLES, WHEREIN METALS AND OTHER MATERIALS
MAY BE HEATED OR MELTED," upon the condition (amongst others) that I, the
said. George Nimmo, 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 George Nimmo, do hereby declare
the nature of my 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 Drawing hereunto annexed, and to the.
letters and figures marked thereon,(that is to say):
Fig. 1 is a cross section of the chamber for drying and burning the crucibles;
,, 2 is a side view of a portion of the travelling platform sustaining said,
crucibles; and
3 is a plan of part of said platform.
My crucibles or pots are shaped in any suitable mould or apparatus, and,
for, this purpose the revolving head, mould, and rib may be employed, as
mentioned in Letters Patent granted to me in Great Britain, March 6th,
1865, Number 630. The material I employ for forming such crucibles or
pots is plumbago mixed with clay and sand in any usual or desired
proportion.
My improvement relates, first, to coating or lining such plumbago crucibles;
and, second, to the mode of drying and burning the crucibles.
In the manufacture of crucibles from plumbago it is usual to make the.
entire pot or crucible of. black lead, or a mixture of the same with other sub-
stances. Injury often arises to steel melted in said crucibles in consequence,
of the steel-absorbing carbon from the pots, and hence becoming changed in,
its character. The plumbago is indispensable in crucibles subjected to a high,
temperature, in. consequence of its conducting power transmitting the heat,
from the outside to the contents, however in crucibles and pots for melting
brass and other metals requiring but a comparatively low temperature the
principal injury results to the pot from the wear to which it is subjected in
handling.
The said first part of my Invention consists in a crucible or pot of plumbago.
with a lining or coating of clay, or clay and sand, or similar cheap material
free from carbon to prevent injury to the pots, or injury to the contents of

page_text: the pots or crucibles, whereby a cheaper and better pot or crucible is obtained,'
and one that is more durable than those made entirely of plumbago, and no
injury results to the material fused in said pot or crucible. I mould the pot
or crucible in any usual or desired manner of plumbago; only thinner than
those generally made, and I then apply a lining or coating of clay or clay and
sand, or similar cheap substance free from carbon, said lining or coating being?
spread smoothly upon the surface of the plumbago, and of the required thick-
ness; the whole may then be pressed in a mould, dried, burnt, or otherwise
prepared for use. The crucible thus formed with either a lining within or
an external coating, is a compound crucible or pot of two materials, the
plumbgo and the clay in layers, and is a cheaper article, and much better for
some purposes than crucibles entirely of plumbago, or a mixture of plumbago
and other materials. The shape of the crucible and its size may be varied; !
and the covers may also be lined or coated with clay. In drying and burning-
plumbago crucibles there is great risk of cracking them, in consequence of
the unequal expansion, and from the dampness often remaining in the thicker
portions of the pots or crucibles. In order to dry, heat, and burn said pots
very gradually and without injury I make use of a long flue or furnace formed
with a fire at or near -one end.
In the Drawing a represents the fire-place, and 6 the long flue, which may
be of bricks, or of iron plates bolted together; as represented. The crucibles
or pots are entered at the end furthest away from the fire where there is but
little heat, and gradually moved forward towards the fire, and when they.
reach the fire they are placed therein to be reddened or properly burnt.
The crucibles become gradually heated as they are moved along towards
the fire, so that there is but little risk of their cracking. These crucibles
may be moved along in the flue by hand, the workman using a pair
of tongs inserted from the outside through doors in the sides of the flue,
or, for greater convenience, carriages & on rollers e may be employed, said
carriages receiving the crucibles in the position shown by the dotted lines at f.
Two ranges of these carriages may be employed, as shown, the railways on
which they run being extended sufficiently beyond the end of the flue for the
reception of the carriages and' crucibles. When desired to burn the crucibles
but little, they need not be removed from the carriages, or, if otherwise, they
are to be lifted off and placed in the fire. The carriages d might be fitted so
that they could be separately elevated near the fire end of the flue, and run
back gradually on the upper ways in the horizontal flue, so as to become
cooled, and in a condition to handle upon arriving at the delivery end over
the place for introducing the crucibles.

page_text: What I claim and desire to secure by Letters Patent is a crucible or pot of
plumbago with a lining or coating of clay or clay and sand, or similar material
for the purposes and as specified.
I also claim the mode herein specified of drying, baking, or burning
crucibles by gradually moving them from the cool part of the flue towards
the fire, as set forth.
In witness whereof, I, the said George Nimmo, have hereunto set my
hand and seal, this Fourteenth day of December, in the year of our
Lord One thousand eight hundred and sixty-five.
Witnesses,
CHIAS. H. SMITII,
119 & 121, Nassau St.,
N. York.
GEO. D. WALKER,
119 & 121, Nassau St.,
N. York.
GEORGE NIMMO. (L.S.)