CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF THE HYDRATE AND CARBONATE OF SODA FROM THE CHLORIDE OF SODIUM, APPLICABLE TO THE MAKING OF SOAP GLASS, AND OTHER USEFUL PURPOSES
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WATT, of Manchester, in the County of Lancaster, Lecturer on Chemistry,
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 Eleventh day of January, in the first year of Her reign, and
in the year of our Lord One thousand eight hundred and thirty-eight, did, for
Herself, Her heirs and successors, give and grant unto me, the said Charles
Watt and Thomas Rainforth Tebbutt, also of Manchester, in the County of
Lancaster, Merchant, Her especial license, full power, sole privilege and
authority, that we, the said Charles Watt and Thomas Rainforth Tebbutt, our
executors, administrators, and assigns, and such others as we, the said Charles
Watt aud Thomas Rainforth Tebbutt, our 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, our Invention of "CERTAIN IMPROVEMENTS IN THE
MANUFACTURE OF THE HYDRATE AND CARBONATE OF SODA FROM THE CHLORIDE OF
SODIUM, APPLICABLE TO THE MAKING OF SOAP, GLASS, AND OTHER USEFUL PURPOSES;"
in which said Letters Patent is contained a proviso, obliging us, the said
Charles Watt and Thomas Rainforth Tebbutt, by an instrument in writing
under our hands and seals, or under the hand and seal of ono of us, particularly
to describe and ascertain the nature of our said Invention, and in what manner

page_text: 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 imme-
diately 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
Charles Watt, (on behalf of myself and of the said Thomas Rainforth Tebbutt,)
do hereby declare that the nature of our said Invention, and the manner in
which the same is to be performed, aro particularly described and ascer-
tained in and by the following description thereof (that is to say) :-
Our Invention or improvements consist in converting chloride of sodium
(common salt) into oxide or hydrate of sodium (soda) as well as into carbonate
and bicarbonate of soda by the aid of nitric acid, or the nitrates of lead,
chrome, manganese, barytes, lime, &c., and also in the use and application in
the said process of converting common salt into soda of pure barytes and pro-
toxide of lead, prepared or manufactured in the peculiar manner, method, or
process hercin-after described (that is to say), in the preparations of baryta and
protoxide of lead, by disengaging the chlorine of these two bodies, in order to
prepare them for repeated operations of converting the chloride of sodium into
soda or oxide of sodium. And as we propose to operate with the various sub-
stances above stated, we shall proceed to describe the processes which we
prefer, together with the apparatus we employ in the various stages of manipu-
lation, especially as adapted to each particular substance employed.
Firstly, in operating in the above process with nitric acid we take about one
hundredweight of chloride of sodium (common salt), and place it in a closed
retort or vessel composed of earthenware or any other other substance which is not
readily acted upon by chlorine and nitric acid. A cast-iron retort formed like
those used in gas works, and heated by any convenient means, will answer the
purpose of a chamber, or furnace, or oven constructed of fire-brick, and pro-
perly heated and secured, to prevent the egress of the chlorine except through
a pipe of any suitable substance, as clay, iron, &c., which pipe is used for the
purpose of conducting off the chlorine into its receivers, which may be the
common Woulfu's apparatus, or such as is commonly used in forming tho
chlorides. To the above chloride of sodium we put about one-fourth of its
weight of nitric acid or nitrous acid, in their simple states, or mixed with their
equal weight of peroxide of manganese, lead, or chromic acid, the latter being
obtained by decomposing the chromate of lead or potassa by sulphuric acid,
and removing any uncombined sulphuric acid by a small quantity of nitrato or
muriate of baryta. The retort or chamber being properly charged with the
chloride and acid, or acid and peroxide, or chromic acid, a gentle heat will be

page_text: sufficient to liberate the chlorine from the common salt, which will come over
in great quantity, the charge of materials being occasionally stirred or agitated
by a rake or any suitable instrument. And whenever it is desired to learn the
state of the operation, it may be done by taking out a small portion of the
material and dissolving it in water into which is put a few drops of dilute
solution of nitrate of silver; if any white precipitate is evident, the process is
not complete, and more nitric acid and peroxide of manganese, lead, or chromic
acid must be added, until a sample taken out and thus dissolved or tested
ceases to give a white precipitate with the nitrate of silver. If any nitric acid
is retained in the soda it may be removed by combining the soda with a littlo
charcoal, heating it to red heat. The nitric acid used as above stated may be
diluted with as much as three times its quantity of water, but then the operation
takes longer time and is more troublesome to the manufacturer, as the water
must be evaporated and the soda brought to a state of dryness, and therefore
much more time and fuel are uselessly expended; and further, when dilute
nitric acid is used an iron retort or chamber will not answer, as the acid will
act too rapidly upon this material.
Secondly, when operating in the process of decomposing common salt
by means of the nitrates of barytes, lead, &c., we use no dilution and
prefer heated retorts or ovens and apparatus, such as mentioned in the
first of our processes. The proportions used in this process or operation
are about half a hundredweight of nitrate to the one hundredweight of
chloride of sodium united with about one-fourth of the weight of the nitrato
of the following agents or materials (viz'), of peroxide of lead, red lead,
manganese, or chromic acid, the latter prepared as already named. The heat
applied to the retorts or ovens in this case (viz.), when nitrates are employed,
must be increased gradually, and the materials or chloride and nitrate must
be occasionally stirred and tested by nitrate of silver, as before, and if tho
operation is not completed, more of each of the decomposing agents (viz.),
nitrate and oxide or chromic acid must be continually added until the test
indicates that no chlorine remains in the soda, no white precipitate being
formed when nitrate of silver is dropped into the solution. The chloride of
sodium being now perfectly decomposed, the soda is to be taken out of the
retort or chamber and cleared of all extraneous matters by dissolving it in
water. The oxides of lead, manganese, &c., will easily separate and subside
when the soda is dissolved, but the chromic acid will combine with the soda,
from which it may easily be removed by slacked lime or pure barytes added,
until the liquid becomes quite colourless, which liquid is caustic soda in solu-
tion, and
may be evaporated to dryness; or, the soda may be converted in a.

page_text: carbonate or bicarbonate by passing into or through it a stream of carbonic
acid gas, in the manner commonly used in converting acetate of lend into car-
bonate of lead, or atmospheric air may be used which contains carbonic acid.
The fact of soda being converted into carbonate or bicarbonate is known by its
effervescing with acids and losing its caustic taste.
Thirdly. Our next process is as follows:-We put one hundredweight of
chloride of sodium into a vessel of iron or wood, or other suitable material, and
licat the same by fire or steam; we then add water to dissolve the salt, or it may
be dissolved before placing in the vessel. The solution is then made to boil,
and when boiling we put in about an equal weight of protoxide of lead or
hydrated protoxide of lead (if finely levigated the better), and boil it with the
solution till all the chlorine is removed from the salt; this is ascertained by
testing it with nitrate of silver as in the former processes. If any white
precipitate is formed, more oxideo of lead is to be boiled with the solution until
no white precipitate is formed with the nitrate of silver. Whon this is the case
the liquid soda, which is now perfectly caustic, may be removed, and the
water evaporated, and the soda dried or carbonated as already named in the
formed process.
Our fourth or next process is the following:-We put one hundredweight
of chloride of sodium into a vessel, as named in the process, when operating
with protoxide of lead, and add water to dissolve the salt; we then take pure
barytes, in quantity about two-thirds of the weight of the chloride of sodium,
and continually stir or agitate the same until the salt has lost its chlorine,
adding more barytes if any chlorine is evident on using the test already
described; but as by this process we have chloride of barium with the pure
soda, it is necessary to allow the materials to subside when the chloride of
barium settles down as a white powder, or precipitate while the pure soda
remains in solution. This solution of caustic soda may be removed from the
precipitate and evaporated to dryness, or combined with carbonic acid as
before described. And further, we reproduce or form our protoxide of lead used
in the said processes of converting common salt into soda, in a very convenient
and economical manner, from the chloride of lead (obtained by the common
process), by boiling the protoxide or hydrate of protoxide of lead in chloride of
sodium; or we form direct & chloride of lead in the following manner (that is to
say): We obtain a chlorile of lead by putting nitro muriatic acid (in the pro-
portion of one part of nitric acid to two parts of muriatic) into finely granulated
metallic lead, and applying a gentle heat thereto, continuing the process and
adding this compound 2:id as long as any metallic lead remains. The chloride
thus formed, as well as that above named, we decompose by putting them mixed

page_text: with one-third their weight of deutoxide of lead or peroxide of lead, and about
the same quantity of good sulphuric acid, and adding these agents and con-
tinuing the process as long as any chlorine escapes. A retort with Woulfe's
apparatus will effect this purpose. We then remove the sulphate of lead thus
formed, and place it in a wooden or other vessel, and add sufficient water
thereto to cover it; we then remove the sulphuric acid therefrom by combining
it with alumine or magnesia, which earths form soluble salts with sulphuric
acid, and which salts we remove by ablutions with water. The lead is now
what is termed a white hydrate. This hydrate of protoxide, if boiled again
in fresh chloride of sodium, will again become a chloride, leaving the soda
pure and fit for use, thus re-obtaining the protoxide over and over again
through a number of operations.
.
And, lastly, we prepare or reproduce pure barytes used in the said process
of converting common salt into soda from the chloride obtained by mixing or
boiling it with chloride of sodium, to render the latter free from chlorine.
The chloride of barium thus formed, we again boil with water in a vessel
containing protoxide of lead, about equal in quantity to the barytes originally
used, and continue the boiling and adding protoxide of lead until the barytes
when tested with nitrate of silver, ceases to give any white precipitate, and
the lead is converted into a chloride; we then deprive the lead of its chlorine
as before described (that is to say), we put the chloride of lead with one-third
of its weight of red lead or peroxide of lead, and the same quantity of sulphuric
acid into an iron or other vessel having a neck of earthenware, and connected
with a suitable apparatus for making the chlorides, and we continue the
operation, adding more acid until the process is completed. We prepare our
peroxide of lead used in the said process by allowing the chlorine formed by
the decomposition of the chloride of lead obtained by boiling the protoxide
with chloride of sodium or barium, which process has been already sufficiently
described, to pass into the protoxide or deutoxide of lead instead of passing off
into a Woulfe's apparatus, or being used for the production of chloride as in
common; by this means and by thus forming or re-obtaining the various
compounds employed, we are enabled to work up all the substances used in
the various operations, which occasions much saving, and by transferring the
chlorine to the lead and the ease of decomposing it again, much less fuel is
used than in common, as little or no heat is required to disengage it.
Having now described and ascertained our said improvements, we wish it to
be understood that we do not claim as our Invention or improvements in the
said processes of converting common salt into soda, the use of the oxide of
lead or pure barytes, as usually formed or obtained for depriving the chloride of

page_text: sodium of chlorine, or any particular apparatus used in the above processes or
operations, but we claim the use of nitric acid singly and combined with
the oxides of lead, &c., and also the nitrates particularly as combined with the
peroxides of lead, mangenese, and chromic acid. We also claim, in the said
process of converting common salt into soda, the use of pure barytes prepared
as above stated by the novel process of boiling the chloride in protoxide of
lead, by which means the barytes can be used over and over again for
a number of times for the same purpose, and the chloride of lead again
converted into protoxide and peroxide. We also claim in the said processes
the production of protoxide of lead, by saturating the sulphate of lead formed
by the decomposition of the chloride with alumine and magnesia, for use and
application to the above purposes herein stated. We likewise claim in the
above processes the use of peroxide of lead, manganese, and chromic acid, used
as described in the various parts of this our Specification.
In witness whereof, I, the said Charles Watt, have hereunto set. my
hand and seal, this Eleventh day of July, in the year of our Lord One
thousand eight hundred and thirty-eight
CHARLES (Ls.) WATT.
AND BE IT REMEMBERED, that on the Eleventh day of July, in the second
year of the reign of Her Majesty Queen Victoria, the said Charles Watt came
before our said Lady the Queen in Her Chancery, and acknowledged the
instrument aforesaid, and all and every thing therein contained and specified,
in form above written. And also the instrument aforesaid was stamped
according to the tenor of the Statute made in the fifty-fifth year of the reign of
of His late Majesty King George the Third.