IMPROVEMENTS IN THE MANUFACTURE OF EPSOM SALTS AND CARBONATE OF LIME, COMMONLY CALLED PRECIPITATED CHALK, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES
Year: 1845

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BRUMWELL GREGSOs, of Dunston, in the County of Durham, Manufacturing
Chemist, 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 Ninth day of February, in the eighth year of Her reign, did, for
Herself, er heirs and successors, give and grant unto me, the said John
Brumwell Gregson, my exors, adñiors, and assigns, Ter especial licence, full
power, sole privilege and authority, that I, the said John Brumwell Gregson,
my exors, adiiors, and assigns, and such others as 1, the said John Brumwell
Gregson, my exors, adñiors, and 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
that part of the United Kingdom of Great Britain and Ireland called England,
Iler Dominion of Wales, Town of Berwick-upon-Tweed, the Islands of Guern-
sey, Jersey, Alderney, Sark, and Man, and in all Her Majesty's Colonies and
Plantations abroad, my Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
EPSOM SALTS AND CARBONATE OF LIME, COMMONLY CALLED PRECIPITATED CHALK,
PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER PURPOSES;" in which said
Letters Patent there is contained a proviso, that I, the said John Brumwell
Gregsou, shall cause a particular description of the nature of my said Inven

page_text: tion, and in what manner the same is to be performed, under my hand and
seal, 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 had, will
more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Brumwell Gregson, hereby declare that the nature of my said Invention,
and in what manner the same is to be performed, are fully set forth and
described in and by the present Specification, that is to say:
My improvements in the manufacture of Epsom salts consist, first, in the
application of sulphuric acid to dolomite or magnesian limestone in its raw or
uncalcined state; and second, in the application of muriate of ammonia or
salammoniac to remove the lime from the mixed hydrates of lime and mag-
nesia, obtained by thoroughly calcining and slaking dolomite or magnesian
limestone.
And first, with regard to the application of raw or uncalcined dolomite or
magnesian limestone to the manufacture of Epsom salts, I proceed as follows:-
I reduce the dolomite to a fine powder, and then make it into a paste with
water in a large shallow vessel lined with 'lead. I then add sulphuric acid, of
about the specific gravity of 1.500, in the proportion of about three hundred
and fifty pounds weight of the acid to two hundred pounds weight of the
dolomite, and during the addition of tlic acid I keep constantly stirring the
mixture. The sulphuric acid rapidly decomposes the dolomite (much heat
being evolved during the operation), carbonic acid gas is liberated, and when
the effervescènce ceases a solid mixed sulphate of lime and magnesia remains;
the sulphate of lime may be then separated from the sulphate of magnesia by
.diffusing the solid residuum in water, allowing the sulphate of lime to subside
and drawing off the supernatant liquor, which is sulphate of magnesia (Epsom
salts) in a state of solution; but containing a small quantity of sulphate of iron,
from which it may be freed by means of caustic lime or magnesia. The
purified solution is finally evaporated and crystallized in the usual manner,
forming in that state the Epsom salts of commerce. Or instead of following
the preceding process, the mixed sulphates may be calcined in a reverberatory
furnace for three or four hours, or until the whole of the iron is peroxidized,
after which the sulphate of magnesia or Epsom salts may be dissolved out of
the mass, and the 'clear solution boiled down and crystallized as before. In
the preceding process the carbonic acid gas; which is liberated by the action
of the sulphuric acid on the dolomite is allowed to go to waste; but where this
acid can be applied to any useful purpose, it may be collected for use by per-

page_text: forming the operation of mixing the sulphuric acid and dolomite in a close
vessel.
.
Second, with regard to the application of muriate of ammonia or sal-
ammoniac to the removal of the lime from the mixed hydrates of lime and
magnesia, I proceed as follows:-I dissolve by heat in an iron boiler two
hundred pounds weight of muriate of ammonia in about one hundred gallons
of water, and allow the solution to cool. I also take two hundred pounds
weight of. thoroughly calcined dolomite or magnesian limestone, and slake the
same with water. I then introduce the slaked line and magnesia into an iron
still (capable of holding from three to four hundred gallons), connected with a
Woolf's apparatus containing water. I then put into the.still the solution of sal-
ammoniac, close the apparatus, and apply a gentle heat to expel the ammonia,
which is then condensed in the Woolf's apparatus and stored for future and
separate use. When all the ammonia has come over, I withdraw the residuumi
from the still, and thoroughly wash the hydrate of magnesia, to free it from
muriate of lime. 1 then saturate the remaining magnesia with sulphuric acid,
throw down the iron it contains by means of a little caustic lime or magnesia,
and evaporate and crystallize the clear solution.
My improvements in the manufacture of carbonate of lime, commonly called
precipitated chalk, consist, first, in the application in such manufacture of
carbonic acid gas to a solution of caustic ammonia and muriate of lime,
and in the recovery of the muriate of ammonia for subsequent use; and
second; in adding a solution of carbonate of ammonia (obtained by satura-
ting a solution of caustic ammonia with carbonic acid gas) to a solution of
muriate of lime. The mode of eflecting the first of these improvements is as
follows: I take one hundred pounds weight of muriate of ammonia and
dissolve it in one hundred gallons of water and allow the solution to cool. I
then take about seventy pounds of well burnt lime and slake it with water, and
when cold I add it to the solution of muriate of ammonia in an earthenware
vessel, stirring this. solution well during the addition of the lime;' mutual
decomposition immediately takes place, and muriate of lime and caustic
ammonia are formed in the liquid. Now, in order to convert this solution into
carbonate of lime I transfer it to a cylindrical vessel of wood or iron lined with
lead and containing an agitator with arms reaching nearly to the circumference
of the cylinder and also covered with Jead, which cylinder is placed horizontally
with one end. of-the agitator resting in a footstep, and the other prolonged
through a stuffing box, so that a handle may be attached to turn the agitator
round. I then force into the solution carbonic acid gas. by means of a force
pump attached to a pipe connected with the bottom of the cylinder, and keep

page_text: constantly turning the agitator. until the solution is entirely decomposed, which
will be known by the cessation of all smell of ammonia. A milky fluid will
now be found remaining in the cylinder composed of carbonate of lime and a
solution of muriate of ammonia. This fluid is removed from the cylinder and
allowed to settle, after which the clear solution of muriate of ammonia is
decanted off, and the precipitated chalk well washed and dried. The solution
of muriate of ammonia may be again used. by treating.it with lime as before.
The mode of effecting the second of my improvements relating to car-
bonate of lime, or precipitated chalk, is as follows:-Into a cylinder of the
same kind as that last herein-before described; and capable of holding about
one hundred and twenty gallons, I introduce one hundred gallons of a solution
of caustic ammonia of about the specific gravity of 0.970; I then by means of
a force pump force in carbonic acid gas, and convert the solution of caustic.
ammonia into a solution of bicarbonate of ammonia; and when this has been
effected I run the solution out of the cylinder into a cistern containing about
one hundred gallons of a solution of caustic ammonia of the same specific
gravity as that previously used in the cylinder, and when the two solutions are
thoroughly mixed the result is a solution of carbonate of ammonia of about the
specific gravity 1.050. I then mix this solution of carbonate of ammonia with
a solution of muriate of lime of about the specific gravity 1.200, in the pro-
portion of two parts of the former to one of the latter; decomposition
immediately takes place; the whole becomes a gelatinous mass which must
be constantly-stirred until the carbonate of lime assumes the solid form. The
mass is then allowed to subside, the clear solution of salammoniac is drawn off,
and the precipitated chalk thoroughly washed and dryed as before.
Having now described the nature of my said Invention, and the manner in
which the same is to be performed, I declare that in the directions I have
given as to the quantities and strengths of each of the ingredients employed, I
intend the same to be considered as average quantities and strengths only, and
do not restrict myself to these precise quantities and strengths as they may be
varied one or other, or the whole of them; without any material departure from
the processes described; and I declare that what I claim is :-
:
First, the application of sulphuric acid to raw or uncalcined dolomite or
magnesian limestone for the purpose of making sulphate of magnesia, or
Epsom salts, and the modification of the process in order to the obtaining also
therefrom a quantity of carbonic acid gas available for other purposes, both as
before described.
Second, the employment in the manufacture of Epsom salts of muriate of
ammonia, or salammoniae, to remove the lime from the mixed hydrates of lime

page_text: and magnesia, and the recovery, as aforesaid, of the ammonia by distillation
and separation thereby of the lime from the magnesia contained in magnesian
limestone, whether the residual magnesia is applied to the manufacture of
Epsom salts, or of any other salt.
Third, the manufacture of carbonate of lime, or precipitated chalk, by the
application of carbonic acid gas to a solution of caustic ammonia and muriate
of lime, and the recovery of the muriate of ammonia for subsequent use, as
before described.
And, fourth, the application in the manufacture of carbonate of lime or
precipitated chalk of a solution of carbonate of ammonia (obtained by satu-
rating a solution of caustic ammonia with carbonic acid gas) to a solution of
muriate of lime, as also before described.
In witness whereof, I have hereunto set my hand and seal, this Fifth
day of August, One thousand eight hundred and forty-five.
JOHN BRUMWELL (L.S.) GREGSON.
AND BE IT REMEMBERED, that on the Fifth day of August, in the
year of our Lord 1845, the aforesaid John Brumwell Gregson came before
our said Lady the Queen in Her Chancery, and acknowledged the Speci-
fication 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.
Enrolled the Ninth day of August, in the year of our Lord One thousand
eight hundred and forty-five.