IMPROVEMENTS IN THE MANUFACTURE OF SODA, POTASH, HYDROCHLORIC ACID, AND CHLORINE
Year: 1872

page_text: COMPLETE SPECIFICATION filed by Walter Weldon at the Office of
the Commissioners of Patents, with his Petition and Declaration,
on the 21st May 1872, pursuant to the 9th Section of the Patent
Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
WELDON, of 29, The Cedars, Putney, in the County of Surrey, send
grecting.
•
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF SODA, POTASH, HYDROCHLORIC ACID, AND CHLORINE," and
have petitioned Her Majesty to grant unto me, my executors, adminis-
trators, and assigns, Her Royal Letters Patent for the same, and have
made solemn Declaration that I am the true and first Inventor thereof,
and that the same is not in use by any other person or persons to the
best of my knowledge and belief.
NOW KNOW YE, that I, the said Walter Weldon, do hereby declare
that the following Complete Specification, under my hand and seal,
fully describes and ascertains the nature of the said Invention, and in

page_text: what manner the same is to be performed, in and by the following
statement:-
Soda and potash are sometimes manufactured by decomposing
chloride of sodium or chloride of potassium by bicarbonate of
ammonia. There are thus produced bicarbonate of soda, or bicarbonate
of potash, and chloride of ammonium, from which last bicarbonate
of ammonia is reproduced for use again by decomposing it by lime
and then causing the ammonia thereby set free to combine anew with
carbonic acid. This process is the simplest for the purpose in question
which has yet been devised; but it has the disadvantage of not yielding
in any useful form the chlorine of the chloride of sodium or chloride of
potassium which are treated by it. It yields their chlorine as chloride
of calcium, which compound only rarely has any value and has usually
to be thrown away.
The object of the present Invention is to avoid this disadvantage and
enable the said chlorine to be obtained either as hydrochloric acid or
in the free state. To this end, instead of decomposing by lime, as has
been the practice hitherto, the chloride of ammonium produced in the
manufacture of soda or potash by means of bicarbonate of ammonia,
or otherwise by the united agency of ammonia and carbonic acid, I
decompose such chloride of ammonium by either magnesia, oxide of
zinc, oxide of copper, or oxide of lead, (of which four oxides however
I believe magnesia to be on the whole the most advantageous,) and I
then decompose the resulting metallic chloride by heating it with access
of air if I desire to obtain its chlorine in the free state, or by heating it
with access of steam if I desire to obtain its chlorine as hydrochloric
acid. The same operation regenerates the magnesia or other oxide,
which I thus make serve for the decomposition of chloride of ammonium
an indefinite number of times.
The manner of treating the chloride of ammonium by any of the
oxides which my present Invention substitutes for the lime which has
been employed hitherto for the decomposition of the chloride of
ammonium produced in the manufacture of soda and potash by the
agency of ammonia and carbonic acid, may be the same as that followed
hitherto in treating such chloride of ammonium by lime. The resulting
solution of metallic chloride may be evaporated in an open vessel down
to nearly the point at which the chloride in it would begin to decompose,
and may then be run into a brick furnace wherein its evaporation may

page_text: be continued to dryness, and the residue then heated with access of air
or of steam, as the case may be. The furnace employed may be either
a reverberatory furnace or a muffle furnace, but I prefer the latter
The chloride will sometimes give off in the furnace, neither chlorine
only nor hydrochloric acid only, but a mixture of both, In such cases
the hydrochloric acid can be separated by condensation as is well
understood.
Having now described and ascertained the nature of my said Invention
and in what manner the same is to be performed, I would point out in
conclusion that what I believe to be new and original, and therefore
claim as the Invention secured to me by the herein-before in part recited
Letters Patent is, the above described modifications of the manufacture
of soda and potash by the agency of ammonia and carbonic acid, by
which modifications I am enabled to obtain in an useful form the
chlorine of the chloride of sodium or chloride of potassium with which
that manufacture commences, and am also enabled to make the same
oxide serve continually over and over again for the decomposition of
the chloride of ammonium produced intermediately therein.
In witness whereof, I, the said Walter Weldon, have hereunto set
my hand and seal, this Sixteenth day of May, in the year of
our Lord One thousand eight hundred and seventy-two.