IMPROVEMENTS IN MANUFACTURING COMMON SALT
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ROBERTSON ARROTT, Manager of the Union Plate Glass Works, St. Helens, in
the County of Lancaster, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Fifth day of January, in eleventh year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Robertson Arrott, Her especial licence, full power, sole privilege
and authority, that I, the said Alexander Robertson Arrott, my executors,
administrators, and assigns, and such others as I, the said Alexander Robert-
son Arrott, my executors, administrators, 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 mentioned, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed,
my Invention of "IMPROVEMENTS IN MANUFACTURING COMMON SALT;" in which
said Letters Patent is contained a proviso obliging me, the said Alexander
Robertson Arrott, by an instrument in writing under my hand and seal,
particularly to describe and ascertain the nature of my said Invention, and
in what the same is to be performed, and to cause the same to be enrolled
in Her Majesty's High Court of Chancery within six calendar months next

page_text: and immediately after the date of the said in part 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, I, the said
Alexander Robertson Arrott, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, is particu-
larly described and ascertained in and by the following description thereof,
reference being had to the Drawings hereunto annexed, and to the letters
and figures marked thereon (that is to say):-
My Invention of Improvements in Manufacturing Common Salt consists,
firstly, in an improved method of manufacturing common salt from brine
by mixing muriate of lime (chloride of calcium) or muriate of magnesia
(chloride of magnesium) with such brine, and thereby producing such a
solution containing common salt as may be concentrated to a considerable
extent without deposition of salt taking place, and by transferring such solu-
tion containing common salt, when so concentrated, into a vessel wherein
common salt becomes deposited by cooling such concentrated solution, and by
which use of muriate of lime or muriate of magnesia I am enabled to con-
centrate such solations in closed boilers without deposition of salt therein;
and I thereby obtain great facilities in collecting (for the purpose of applying
to heating purposes) the steam evolved from the solution during such concen-
trating process.
And my Invention consists, secondly, in manufacturing common salt by the
use of a heated solution of muriate of lime or of muriate of magnesia, for the
purpose of dissolving common salt from rock salt, and thereby producing a
solution from which I obtain common salt by cooling such solution.
I will further explain my Invention by describing the apparatus which
I prefer to employ for effecting its objects, and the manner in which I
manufacture common salt by means of my Invention, reference being had
to the Drawings hereunto annexed, and the figures and letters marked
thereon.
Sheet I. exhibits such an apparatus as I prefer to use for manufacturing
common salt from brine. In this Sheet, Fig 1 is a plan view; Fig. 2 is a
vertical longitudinal section of such apparatus; Fig. 4 is a vertical section on
an enlarged scale of that part of the apparatus which is herein-after called a
condenser; and Fig. 3 is a plan view of the upper part of this condenser with
its cover removed. In these several Figures the same letters of reference are
used to indicate similar parts. A is a closed boiler similar to those used for
generating steam for steam engines. B, B*, are two open vessels which I con-

page_text: struct of wood, and in which the deposition of salt takes place. C is a vessel
which I call a condenser. This vessel consists of a steam-tight casing marked
b, b, having two tube plates c, c, affixed thereto, into which a number of open
tubes a, a, are fitted steam-tight; these tubes communicate at one end with
a chamber forming part of the condenser C, and marked p, and at the other
end with a chamber q. f is a tube proceeding through the middle of the
condenser C, and communicating at its upper end with the open vessel B*,
and at its lower end with the chamber q; g is a tube connecting the chamber p
with the boiler A; h is a tube for conducting steam from the boiler A into
the condenser C, between the tube plates c, c, and among the tubes a, a,
which are filled with brine. The tube h should be of a size sufficient to take
off the whole steam generated in the boiler A, without causing a sensible
pressure therein, or a pressure not exceeding two inches of water. m is a
tube provided for the escape of condensed steam from the condenser C; n is a
tube communicating from the vessel K to the chamber g, and having a tap i
for regulating the supply of brine to the apparatus. The brine before it enters
the chamber q should be as warm as the liquor is when it leaves the vessel
B by the pipef, and if the heat from the condensed steam is not sufficient
to do this, the brine before entering the chamber q should pass through a
small heating apparatus similar to the condenser C, or of any convenient
form, having a branch from the steam pipe h. The hot water flowing from the
condenser C is caused to pass in pipes through the vessel K, and thereby to
transfer heat to the brine; e is a tube connecting the boiler A with the open
vessel B; d is a tube connecting the open vessel B with the other open
vessel B. I commence the manufacturing of common salt by means of this
apparatus by filling it up to the dotted line r, s, with brine, to which I pre-
viously add such a proportion of muriate of lime or muriate of magnesia as
is herein-after described. I apply fire to the boiler A, so as to cause the
solution contained therein to boil, when steam will pass through the tube h
into the condenser C, and coming into contact with the tubes a, a, transfers
heat to the solution contained in these tubes, and thereby causes a flow of the
solution from the vessel B* through the said tubes and the chamber P
into the boiler A, and consequently a flow of heated solution from the
boiler A into the open vessel B, and from thence to the open vessel B*,
thereby occasioning a circulation of the solution through the whole apparatus.
As the solution contained in the boiler A evolves its water in the form of
steam, this solution becomes concentrated so as to contain a larger propor-
tionate quantity of common salt, and such concentrated solution being trans-
ferred by circulation into the open vessels B and B, a further evaporation of

page_text: water takes place, occasioning a reduction of the temperature of the concen-
trated solution, and a consequent deposition of common salt in the open
vessels B and B*, without any deposition of common salt in the boiler A. I
supply brine to the apparatus through the vessel K in such quantity as may be
equivalent to the quantity of common salt manufactured, and it will be
perceived that this supply of brine, together with the cooled solution flowing
from the open vessel B*, passing through the tubes a, a, of the condenser C,
will absorb heat from the steam passing through the said condenser. I prefer,
when working, to have such a proportion of muriate of lime or muriate of
magnesia with the brine in my apparatus as will cause the solution, as it
passes from the condenser C to the boiler A, to have a specific gravity of
1230 at the temperature of ninety degrees of Fahrenheit's thermometer, water
as 1000 at sixty degrees, and I keep the liquor at this strength during the
process; and if a sample of the liquor taken from the tube has a specific
gravity at 90° of more than 1230, I admit more brine into the apparatus ;
but if less than this number, I diminish the supply of brine accordingly, pro-
vided that this can be done without reducing too much the whole quantity of
liquor in the apparatus; but if it cannot be done without too much reducing
the quantity of liquor, the specific gravity must be increased by adding a fresh
portion of muriate of lime or muriate of magnesia.
In Sheet II. is represented the apparatus which I prefer to use for obtaining
common salt from rock salt. Figure 1 is a plan view and Figure 2 a
sectional elevation of the apparatus; and in these views the same letters are
used to indicate similar parts. A is a vessel for heating the solution. It is
similar to a common steam boiler, and is set in the same manner. B, B*,
are two open vessels in which the salt is to be deposited from the solution
after being beated in the vessel A; C is a circular wooden vessel close, at the
bottom and open at the top, and having a false or perforated bottom a, fixed
about a foot from the true bottom; b is a tube connecting the open vessel B*
with the chamber g, between the false and true bottom of the vessel C; d is a
tube connecting the open vessels B and B* together; and e is a tube connecting
the open vessel B with the heating vessel A. I commence the manufacturo
of common salt with this apparatus by filling the vessel C with rock salt in
small pieces, the salt resting on the false bottom a, and leaving the chamber g
free. I then close the tubes at and e by means of plugs, and fill the heating
vessel A with a solution of muriate of lime or muriate of magnesia of such a
strength that when saturated with common salt, and at the temperature
of 90°, it will have a specific gravity of 1230, and I fill the open vessel B, B,
and C with a similar solution saturated with common salt. I then apply fire

page_text: under the heating vessel A, and so soon as the liquor has attained the tem-
perature of 224°, I remove the plugs from the tubes a+ and e, and a circulation
will then take place through the apparatus in the direction of the arrows. The
hot liquor from the vessel A, which should, during the working, be always
maintained at the above temperature, will flow into the vessel C, and descend
into the chamber g, and having become charged with common salt by passing
through the rock salt contained in the vessel C, from the chamber g of this
vessel it flows up the tube 6 into the open vessel B*, and from thence by the
tube d into the other open vessel B, and then returns to the heating vessel A
by the tube e, and while flowing through the open vessels B, B*, the liquor
will have become reduced in temperature, and have deposited in the open
vessels B*, B, the common salt which it had dissolved from the rock salt in
the vessel C, a portion of the water of the solution being carried off by
evaporation in the open vessels B, B*, and a quantity of water or brine
equivalent to this evaporation is added to the liquor in the heating vessel by
the tube f. I prefer to use a liquor of the strength here mentioned, but a
great variation may be made in the strength without materially affecting the
process, and the supply of water or brine, to make up the loss by evaporation,
may be regulated with sufficient accuracy by means of a float in the heating
vessel, so as to keep the liquor at the same level. In order to obtain the
different qualities of salt by either of the above processes, the open vessels
B and B*, may be divided into different sections by means of divisions j, j‹‚Ì‚Ì‹
placed across them; and these divisions should have their upper edge above the
surface of the liquor, and their lower edge within a few inches of the bottom
of the vessel. The finest grained salt will be deposited in the section where the
solution is hottest, that is, in the section nearest to the place where the liquor
enters the open vessel B or B*, and the coarsest grained salt will be made in
the section nearest to the exit from the open vessel B or B*, or where the
solution is coldest. The number and size of these sections will vary with the
qualities of grain required. The salt as drawn from the open vessels B, B*,
may, if required, be freed in a great measure from the small quantity of
muriate of lime which adheres to it, by placing the salt where the solution can
drain from it, and pouring fresh brine upon the salt, and thus washing out the
muriate of lime.
Having now described my Invention, and also the arrangement of appa-
ratus which I consider to be the most suitable for carrying the same into
effect, I would observe, in conclusion, that althugh I have mentioned certain
proportionate quantities of muriate of lime [chloride of calcium] or of muriate
of magnesia [chloride of magnesium] (as indicated by the specific gravity of

page_text: the solution) which I prefer to use, yet I do not intend to confine myself to
the exact proportionate quantities of the said muriates [chlorides] above
mentioned, nor to the precise arrangement of apparatus herein shewn and
described, as these may be varied to a considerable extent without departing
from the nature and object of my Invention; and I would also observe that I
am aware that native brine contains some minute proportion of muriate of
lime and muriate of magnesia. I do not therefore claim the manufacturing
of common salt from solutions containing naturally some proportion of muriate
of lime or muriate of magnesia, unless these solutions are concentrated and
operated upon in order to so far increase the proportion of muriate of lime or
muriate of magnesia as to admit of the said solution (containing common salt
in conjunction with muriate of lime or muriate of magnesia) being concen-
trated to a considerable extent in a covered or close boiler, without allowing
the common salt to become deposited therefrom in the boiler, but which
common salt may be obtained from the contentrated solution by allowing
the same to cool in open vessels. That which I consider to be new in the
above-described processes and apparatus, and therefore wish to claim as
the Invention secured to me by the herein-before in part recited Letters
Patent, is,―
Firstly, the use (in the manufacture of common salt) of such a proportion
of muriate of lime (chloride of calcium) or muriate of magnesia (chloride of
magnesium) in mixture with brine as will provide for the solution being con-
centrated to a considerable extent in a closed boiler or heating vessel without
depositing common salt therein.
I claim also the concentration of such solutions in a close or covered boiler
and the production of common salt therefrom by transferring such concen-
trated solution from such closed boiler or heating vessel to proper open
vessels or pans, and there allowing the concentrated solution to cool, and
thereby deposit the common salt. And,
Secondly, I claim the use of heated solutions of muriate of lime (chloride
of calcium) or muriate of magnesia (chloride of magnesium), or solutions
containing these or either of these matters, for dissolving common salt
from rock salt, and obtaining common salt by cooling the solutions thereby
obtained.
In witness whereof, I, the said Alexander Robertson Arrott, have here-
unto set my hand and seal, this Fifth day of July, in the year of our
Lord One thousand eight hundred and forty-eight.
(L.S.) A. R. ARROTT.

page_text: AND BE IT REMEMBERED, that on the same Fifth day of July, in
the year above mentioned, the aforesaid Alexander Robertson Arrott came
before our Lady the Queen in Her Chancery, and acknowledged the Specifi-
cation aforesaid, and all and every thing therein contained, in form above
written. And also the Specification aforesaid was stamped according to the
tenor of the Statute in that case made and provided.
Inrolled the same Fifth day of July, in the year above written.