CERTAIN IMPROVEMENTS IN THE PRO- CESS OF DECOMPOSING MURIATE OF SODA FOR THE MANUFACTURE OF MINERAL. ALKALI AND OTHER VALUABLE PRODUCTS
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, OGLE-
THORPE WAKELIN BARRATT, of Birmingham, in the County of Warwick,
Metal Gilder, 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 Nineteenth day of January, One thousand eight hundred
and thirty-nine, did, for Herself, Her heirs and successors, give and grant
unto me, the said Oglethorpe Wakelin Barratt, Her especial licence, full
power, sole privilege and authority, that I, the said Oglethorpe Wakelin
Barratt, my executors, administrators, and assigns, or such others as I, the
said Oglethorpe Wakelin Barratt, 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 "CERTAIN IMPROVEMENTS IN THE PRO-
CESS OF DECOMPOSING MURIATE OF SODA FOR THE MANUFACTURE OF MINERAL.
ALKALI AND OTHER VALUABLE PRODUCTS;" in which said Letters Patent is con-
tained a proviso obliging me, the said Oglethorpe Wakelin Barratt, by an
instrument in writing under my hand and seal, particularly to describe and'
ascertain the nature of the said Invention, and in what manner the same is
to be performed, and to cause the same to be inrolled in Her 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
reference being thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Oglethorpe Wakelin Barratt, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, are par-
ticularly described and ascertained in and by the following description thereof
(that is to say):-
In the common method of manufacturing sulphate of soda by decomposing
muriate of soda or common salt with sulphuric acid, and exposing the mixture
to a strong heat in a furnace, muriatic acid .gas is disengaged, and is with
difficulty condensed.
Now, the objects of my improvements in the said manufacture are the
following (that is to say) :--
Firstly, to effect the decomposition of the common salt without the appli-
cation of heat, and without the escape of muriatic acid gas, and which im-
provements I effect in the following manner:-To about one hundred and
thirty parts by weight of common salt, dissolved in four hundred parts of
water, I add one hundred parts of concentrated sulphuric acid, and to this
mixture I put in sixty parts of metallic zinc in pieces of moderate size. On-
adding the zinc, hydrogen gas evolved or given off, which gas I collect in
the usual way in any of the well-known apparatus for collecting and burning
gases. The hydrogen gas so collected I burn, and apply to the purposes of
evaporation, or to any other purpose where light or heat is required. When
the zinc is dissolved, and time allowed for the sulphate of soda to form or
crystallize, I draw off the clear supernatant solution, which contains chloride
of zinc and a portion of sulphate of soda; I then subject the solution to the
action of heat, and by evaporation and cooling, the remaining portion of
sulphate of soda crystallizes, which I then add to the first crop. I then wash
the sulphate of soda in a hot saturated solution of common salt, which sepa-
rates any chloride of zinc which may have remained mixed with the sulphate
of soda.
In the above process it is evident that no heat is employed in the decom-
position of the common salt, and that no muriatic acid gas escapes during such
operation.
The object of my next or other process is to collect a portion of muriatic
acid gas evolved from the mixture of muriate of soda and sulphuric acid,
when first brought together in a cold state, and then to finish off the charge
or complete the decomposition of the salt, and form the sulphate of soda by
continuing or carrying out the process herein-before described. In this second
process or operation I employ any apparatus suitable for the purpose; that
known by the name of Woulfe's apparatus will answer very well.
To one

page_text: hundred and thirty parts of common salt I add one hundred parts of con-
centrated sulphuric acid. The vessel containing the salt and acid must be so
constructed as to admit of the mixture being occasionally stirred with any
convenient instrument or agitator, as a rake, to facilitate the decomposition of
the common salt, that portion of muriatic acid gas which I wish to collect
being taken up by the water in the Woulfe's apparatus in the form of liquid
muriatic acid. When muriatic acid gas ceases to evolve, and before the
vessels are unluted, I add to the charge of salt and acid four hundred parts'
of water. I then remove the vessels containing the liquid muriatic acid, and
I add to the charge sufficient zinc to complete the decomposition of the
common salt. The quantity of zinc required for this purpose will be found to
be about one-third less than in my first process, and I collect and apply the
hydrogen gas evolved from the mixture or charge, and I crystallize the sulphate
of soda, and proceed as already described. The solution of chloride of zinc
obtained in the above-described processes I decompose by means of any con-
venient agent, so as to separate the oxide of zinc, and I have found lime to
answer this purpose with the greatest economy. Sixty-four parts of zinc
dissolved will require for this purpose about fixty-six parts of lime of the best:
quality, and reduced to the state of cream of lime by slacking and mixing
with water, but if after the addition of this proportion of lime the solution
should by the well-known tests appear to contain excess of acid, more limė
must be used till it ceases to do so. The oxide of zinc thus precipitated I
wash with a large quantity of water, to free it as perfectly as possible from:
chloride of calcium, and I then use it instead of metallic zinc for the purpose
of decomposing fresh portions of common salt.
And I would remark, that the oxide precipitated from the solution of chloride
of zinc containing sixty-four parts of the metal being used, instead of the same
quantity of metallic zinc, a little allowance should be made for the loss un-
avoidable in the process. Or the oxide may be employed as a pigment, or in
the manufacture of glass, or for any other purpose to which it is applicable.
It will be evident that the native carbonate of zinc, and also sulphate of zinc,
may be used, instead of metallic zinc and the above-described oxide of zinc,
but I have not found them to be so advantageous under common circumstances,
but I still claim their use as part of my Invention.
Having now described my Invention, and the manner of carrying the same
into effect, I wish it to be understood that I do not confine myself to the use
of any particular apparatus herein-before mentioned, nor do I claim any privi-
lege with respect to such apparatus, nor the preparation of the muriatic acid.
And further, I do not claim lime as a precipitant of zinc, nor the producing

page_text: hydrogen gas from the decomposition of water. But what I claim as my
Invention, secured to me by the above in part recited Letters Patent, is, the
use and application of zinc in any form in the decomposition of common salt,
in the manufacture of sulphate of soda.
I also claim as my Invention the producing of hydrogen gas during the
decomposition of muriate of soda.
And, lastly, I claim as my Invention the chloride of zinc as produced during
the decomposition of muriate of soda.
And in conclusion I would remark that I do not confine myself to the
proportions here stated, as other proportions may be used, but not with such
advantage.
In witness whereof, I, the said Oglethorpe Wakelin Barratt, have
hereunto set my hand and seal, this Nineteenth day of July, in the
T