A CERTAIN IMPROVEMENT OR IMPROVEMENTS IN MANU- FACTURING OR PURIFYING SODA
Year: 1833

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
ATTWOOD, of Whickham, near Gateshead, in the County of Durham, Glass
Manufacturer, send greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Nineteenth day of October, in the fourth year of His reign,
did, for Himself, His heirs and successors, give and grant unto me, the said
Charles Attwood, His especial licence, full power, sole privilege and authority,
that I, the said Charles Attwood, my executors, admors, and assigns, or such
others as I, the said Charles Attwood, my exors, adññors, 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 expressed, should and lawfully might make, use,
exercise, and vend, within England, Wales, and the Town of Berwick-upon-
Tweed, my Invention of "A CERTAIN IMPROVEMENT OR IMPROVEMENTS IN MANU-
FACTURING OR PURIFYING SODA;" in which said Letters Patent is contained a
proviso, that I, the said Charles Attwood, shall cause a particular description
of the nature of my said Invention, and in what manner the same is to be
performed, to be inrolled in His 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
Charles Attwood, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are particularly described
and ascertained as follows (that is to say):-

page_text: I do declare the said Invention to consist in the purification of such soda
as is contained in the substances usually known or met with in commerce
under the name or names of soda, barilla, natron, mineral alkali or kelp, or
English or artificial soda or barilla or soda balls or lumps, whether such soda
may exist in such substances in a state of combination with earthy or other
more or less insoluble substances, or whether separate from such earthy or
insoluble substances, and whether in solution or otherwise, or under what-
soever name or names the various articles of which soda in either a caustic
state or state of combination with carbonic acid may be manufactured or
produced or be found in trade or commerce in so far as the same may require
or beneficially admit of such purification as aforesaid. And I do further
declare that the impurity from which I do profess to purify such soda by my
said Invention is such sulphur as may exist in a state of chemical combination
with a part thereof, in such substances so manufactured or produced or so
inet with in trade or commerce as aforesaid, or such sulphur as through or by
means of any subsequent lixiviation of other operation on such substances
may enter into chemical combination with a part of such soda; such combina-
tions of sulphur with soda forming the compounds which are included in
common language under the general names of sulphurets or hydro-sulphurets
of soda, my said Invention being by no means applicable to the separation of
sulphur from soda in the combinations which are called respectively the
sulphate and 'the sulphite of soda. And I do further declare that the manner
and means in and by which I do 'effect the purification of such soda are as
follows (that is to say):-I do precipitate such sulphur from such combination
with the soda by adding to a solution of the latter some one or other of the
berein-after mentioned salts of iron or of manganese, which salts may also be
the most conveniently and advantageously applied in a state of aqueous solution;
and on such addition being made the sulphur separates from its combination
with the soda and precipitates in union with the base of such metallic salt or
salts, in the state of a metallic sulphuret 'or sulphurets of a black or brown
colour respectively, according as salts with a base of iron or of manganese
may have been employed. And I do further declare that in adding such
salt or salts 'the operator may be guided as to the proper and necessary
quantities by observing that in proportion as the effect intended advances
towards completion the operation proceeds 'more slowly, and the changes to
black or brown 'respectively in the colour of the precipitates from such metallic
salts take place visibly more gradually, until at length, upon the application of
a suitable test, such as any soluble salt of lead or silver, to a small portion of
the solution in a test glass, the base of such salt is precipitated in a visibly

page_text: mixed state, cousisting in part only of metallic sulphuret of the usual well-
known colour, and in part of such precipitate and of such colour as such salt
produces in solutions of pure caustic or pure carbonated soda, at which period
of the process it become adviseable to proceed with correspondent caution and
by only small successive additions of such salts of iron or of manganese to
purify such soda, not only in order to avoid all waste thereof, but also to
prevent the conversion of part of the pure caustic or carbonated soda into
neutral salts of soda by combination with the acid or acids of such metallic
And I do
salts, which happens in case of the addition of such salts in excess.
further declare, that it is not difficult so to regulate the quantity of such
metallic salts as aforesaid, so as to complete the operation of precipitating all
such sulphur as the solution operated on may contain in the state of sulphuret
or hydro-sulphuret, as before said, without any or any material excess of the
metallic salts, by due attention to the circumstances which have been already
mentioned, and by waiting before each later addition of such salts of iron or
of manganese with intervening agitation of the alkaline solution, until all or
nearly all such metallic precipitates as may have fallen in another state than
that of sulphurets shall have passed into the latter state by absorption of
sulphur from the liquor. And I do further declare, that when the whole of
the sulphur shall have been perfectly precipitated, or as perfectly as for the
purposes such soda is intended for may be deemed necessary, I do separate
such precipitate from such solution either by subsidence or filtration, or partly
by both or by any other of such well-known methods in such cases as may be
convenient. And I do hereby further declare, that when the entire preci-
pitation of such sulphur shall have taken place, the alkaline solution, which is
usually previously of a yellow or greenish-yellow colour, will have become.
nearly entirely colourless and limpid, and will no longer produce nor will the
soda it contains produce, if separated, any of the injurious effects which it or
they would previously have produced in discolouring such metallic matters,..
dyes, pigments, or mordants, as it or they would previously have discoloured,
and will no longer act in such manner upon the surface or substance of metallic
vessels, apparatus, or implements, as it or they would previously have done,.
or discolour or injure the quality of such soap as may be made by means of it
or them. And I do further declare, that my aforesaid Invention of a certain.
improvement or improvements in manufacturing or purifying soda is capable
of being used, not only by manufacturers of soda in their works or manu-
factories, but also by themselves or other persons out of or on other premises
than such works or manufactories, apart therefrom, and as a separate process
of purification distinct from manufacture, so as to be applicable to the puri-

page_text: fication of previously manufactured or of imported soda, or substances con-
taining either caustic or carbonated soda, whether manufactured by themselves
or others, and either for their own use or for the use of others, and that on
this account I do claim the applications of such Invention, not only as a
process of manufacture but also as a process of purification, capable of being
so used as aforesaid not only by manufacturers of soda but also by dealers in
the same or by consumers thereof, for any use or purpose of trade or manufac-
ture. And I do further declare, that all the following metallic substances
may be more or less advantageously employed for the purification of soda as
aforesaid, that is to say, in the first place and preferably, all such salts of iron
as that metal forms in combination with sulphuric, muriatic, nitric, or acetic
acids, preferring such as may be most cheaply and conveniently obtained
by purchase or manufacture, or as occasional residual products in certain
manufactures; and, secondly, but less eligibly, all such salts of manganese
as that metal also forms with the aforesaid acids; but I do give preference
to the salts of iron, because no perceptible portion if any of that metal or
of its precipitate is so acted on so as to be dissolved, held, or retained
in the solution or in combination with the soda or the salts of soda;
whereas a small part of the manganese is sometimes if not always so retained,
so as to constitute in some cases an objection to the use of its aforesaid salts,
where perfect freedom of the soda from metallic impregnation is desireable.
And I do also further declare that it is merely a question of economy, to be
determined according to circumstances, what are the limits of the proportions
between sulphuretted soda and soda free from sulphur, whether in a caustic
or carbonated state, in any alkaline compound which determine the direct
application of my said Invention to such compounds without preparatory
process to be economically beneficial, or adviseable, but, speaking generally,
the less the proportion of sulphuretted soda may be the more advantageously
may such invention be so directly and without preparatory process applied to
the purification of such compound; and, in cases where the proportion of such
sulphuretted soda approaches to near one-fourth the total quantity of soda free
from sulphur in such compound, it will in most cases be advantageous,
especially for manufacturers of soda, who usually possess the requisite facilities,
to previously subject such compound of soda, with sulphuretted soda, to some
of the usual carbonating processes as they are called, and which are in common
use, in order to get rid thereby of the greater part of such contaminating sul-
phur, and afterwards to operate on the product, which is usually still contami-
nated with more or less sulphuret of soda, by means of my process of purifica-
tion. And, speaking generally for the guidance of manufacturers of soda, I do

page_text: declare that I consider that the three or the four first runnings from what is
usually called by manufacturers of soda a tank or vat of soda balls, or lumps
under the process of lixiviation, may be advantageously purified by the direct
application of my Invention, such first runnings usually containing very little
sulphuretted soda; but that, with regard to all the subsequent runnings from
such tank or vat, after such third or fourth, it will be usually economical to
boil the salt in solution down to dryness, and to carbonate the same in the car-
bonating furnace, or otherwise to carbonate the same by some known process in
the liquid state without such boiling down, and afterwards to purify, by the
application of my Invention, such in so far carbonated soda from such portion
of sulphur as it usually still remains contaminated with, even after the applica-
tion of such carbonating process or processes. But I do not mean or intend
hereby to claim as my Invention any process herein mentioned, which may be
already known or in use; but I do hereby claim the improvement or improve-
ments in manufacturing or purifying soda by the process or method herein-
before described of precipitating the sulphur by means of such aforementioned
salts of iron, and of manganese, from such sulphuretted soda as is usually found
in mixture or in combination with caustic or carbonated soda, or with both, in
the greater part of those articles or substances as found in commerce, of or
to which such caustic or carbonated soda constitutes or gives the value, and
which are much deteriorated by such sulphuretted soda.
In witness whereof, I, the said Charles Attwood, have hereunto set my
hand and seal, this Sixteenth day of April, in the year of our Lord