IMPROVEMENTS IN THE MANUFACTURE OF SALT
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
FIRMSTONE, late of Newcastle, in the County of Stafford, Coal Master, but now
of Stoney Fields, in the Parish of Stoke, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-fourth day of December, in the third year of Her reign,
did, for Ierself, Her heirs and successors, give and grant unto me, the said
Thomas Firmstone, Her especial licence, full power, sole privilege and autho-
rity, that I, the said Thomas Firmstone, my exors, admors, and assigns, or
such others as I, the said Thomas Firmstone, my exors, adñors, or assigns,
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, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN THE MANUFACTURE
OF SALT;" in which said Letters Patent is contained a proviso, that I, the
said Thomas Firmstone, shall cause a particular description of the nature of
the said Invention, and in what manner the same is to be performed, to be
inrolled in Her said Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto bad, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Firmstone, do hereby declare the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had

page_text: divided into a series of streams, which sweep over the surface of the brine and
thereby evaporate it.
c, c, are
I will now describe the second part of my Invention. Figure 4 represents
a circular pan; and Figure 5 is an elevation in section of the same.
the scrapers, which are set at right angles to the axes f, which receives motion
from a steam engine or by other suitable power; g is a frame which is affixed to
the axis f, and this frame carries the scrapers by means of the chains h,
which allow free play up and down of the scrapers, but keep them properly to
their work at right angles to the shaft or axis. I would remark that tho
scrapers may be connected to the frame by other convenient means, provided
proper play up and down be allowed to them.
i is a pocket or recess from
the centre outwards, across which there are bars to support the scrapers;
and it will be evident, that when the scrapers are caused to move round with
the axis f, the salt formed will be scraped into the pocket i, and from thenco
will readily be removed by the ordinary rakes and shovels, by drawing the
salt from below the cover k; and it should be stated that there is to be a
steam pipe to convey away the steam from under the cover k, and such steam
may be advantageously employed by conveying it under a salt pan in order to
heat the brine therein..
I will now describe the third part of my Invention. Figure 6 shews a
longitudinal section of a salt pan, arranged according to this part of my.
Invention; Figure 7 a plan, and Figure 8 a transverse section of Figure 6;
is a circular pan, having two trunks m proceeding therefrom to the two side
tanks and o, and these two side tanks n and o are connected together by a
trunk or way at the ends of the tanks n, o. In the circular pan there is a
scraper similar to that above described, but in this case it proceeds from both
sides of the axis, and the scrapers are set apart, yet in such manner that in
their revolution the whole surface of the pan will be scraped. p is a paddle
wheel, placed in the tank », which receiving motion from any suitable power
will cause the brine to be drawn out of the circular pan into the tank n, and
to circulate by means of and through the trunk or way before mentioned, into
and through the tank o, and the brine will deposit the salt in such tanks, and
will again pass into the circular pan, which is the only heated part of the
vessels containing the brine under operation. q is a salt pan, which is heated
by the flue of the fire or furnace of the circular pan. I would remark that
although I prefer the use of a paddle wheel for causing the brine to circulate in
a shallow current over the heated surface of the pan, yet it will be evident that
a screw or other convenient means may be resorted to for causing such cir-
culation. I would remark in respect to this part of my Invention, that I am

page_text: aware that it has before been attempted, and a Patent was obtained for a
mode of causing brine to circulate in pans or tanks, but in such case the
vessel wherein the brine was heated was a close vessel, and the wheel employed
was placed in such close vessel.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have it understood that what I claim as my
Invention is,
1
First, the mode of evaporating brine in the manufacture of salt, by means
of blasts of heated air passed over the surface of such brine, as above
described.
Secondly, I claim the mode of constructing circular pans, with pockets i
and scrapers at right angles to the axis of motion, as above described.
And, thirdly, I claim the mode of causing brine to circulate in pans and
vessels in the manufacture of salt, as above described.
In witness whereof, I, the said Thomas Firmstone, have hereunto set my
hand and seal, this Eighteenth day of June, in the year of our Lord
One thousand eight hundred and forty.