IMPROVEMENTS IN THE MANUFACTURE OF CHLORINE
Year: 1866

page_text: LETTERS PATENT to Walter Weldon, of Park Villa, West Hill, Highgate,
Middlesex, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
CHLORINE."
Sealed the 22nd January 1867, and dated the 26th July 1866.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents, with his Petition, on the
26th July 1866.
I, WALTER WELDON, of Park Villa, West Hill, Highgate, Middlesex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF CHLORINE," to be as follows:-
In the process by which chlorine is at present ordinarily obtained for use
in the manufacture of bleaching powder, chlorates, and other compounds,
there is a constant consumption of peroxide of manganese, and a constant
very large waste of hydrochloric acid, the reaction upon which the process
is based being that which is represented by the equation―
2HC1+Hn02=2HO+HnCl+Cl;
even if the peroxide of manganese employed were absolutely pure only one
half of the chlorine in the hydrochloric acid used would be obtained in the
free state, the other half entering into combination with the metallic base of

page_text: the peroxide, forming therewith chloride of manganese which is usually
thrown away. The peroxide of manganese used, however, almost invariably
contains a large per-centage of impurities which consume hydrochloric acid
to no purpose, so that in actual practice the manufacturers of bleaching
powder and of other compounds for the production of which free chlorine is
required do not obtain in the free state much more than one-third of the
chlorine contained in the hydrochloric acid they consume, while for every
ton of chlorine which they obtain they have to use from one to three tons of
commercial peroxide of manganese, according to its richness in real peroxide,
the cost of this peroxide of manganese forming by far the largest part of the
total cost of the chlorine obtained.
My present Invention, when the first and second parts of it are used
together, enables the whole of the chlorine contained in the hydrochloric acid
employed instead of only about a third of it as at present, to be obtained in
the free state, and further substitutes a very slight expense for labour and
fuel for the exceedingly heavy expense which is at present incurred for
peroxide of manganese. The cost of this labour and fuel being more than
covered by the value of the increased yield of chlorine obtained by tlie
combination of the first part of my Invention with the second part of it.
My Invention may be regarded as saving, when the first and second parts of
it are used togother, the entire cost of the peroxide of manganese at present
employed. A similar result is obtained when the first part of my Invention
is practised in connexion with one of the processes constituting the third
part of it. When only the first part of my Invention is used the whole of
the cost of the peroxide is not saved, but the chlorine is nevertheless obtained
very much more economically than by the present peroxide process. Previous
to the present Invention it had been proposed to substitute for the peroxide
'of manganese employed in the chlorine manufacture sesquioxide of manganese
obtained by precipitating protoxide of manganese by means of lime from
the solution of chloride of manganese, which is one of the results of
the action of hydrochloric acid upon any oxide of that metal, and then
subjecting this protoxide to atmospheric oxidation; this plan, however, in
the form in which attempts were made to carry it into practise was found
not to answer for reasons which may be readily explained. Whereas an
equivalent of pure peroxide of manganese yields an equivalent of free chlorine
when treated with two equivalents of hydrochloric acid an equivalent of
sesquioxide of manganese requires to be treated with three equivalents of
hydrochloric acid in order to the production of an equivalent of free chlorine;
even, therefore, if the conversion of the protoxide of manganese into

page_text: sesquioxide by the method referred to had been quite complete this process
would have doubled the loss of hydrochloric acid incurred by the peroxide
process, besides involving the consumption, per equivalent of chlorine obtained,
of two equivalents of lime. The method followed, however, did not completely
convert the protoxide into sesquioxide, and hence the loss of hydrochloric
acid and the consumption of lime were so considerable, not to speak of other
disadvantages, that the process was found to be the reverse of economical.
In my process I use sesquioxide of manganese to oxidize some of the
hydrogen of hydrochloric acid, in order to the liberation of free chlorine; I
obtain this sesquioxide by oxidizing protoxide, obtained by precipitation from
the solution of protochloride of manganese, which remains in the stills after
the completion of the reaction between the sesquioxide and hydrochloric acid,
and when using either only the first part of my Invention, or the first part
of it combined with one of the processes constituting the third part of it,
I obtain this protoxide by means of lime, but I convert the protoxide
completely into sesquioxide, and when using both the first and the second
parts of my Invention I obtain the protoxide by means of an agent which I
can use over and over again continually, and from which I can readily recover
all the chlorine, which in the first instance I employ it to abstract from the
chloride of manganese, I therefore, when using the first and second parts of
my Invention together, besides having no expense corresponding to that
which was incurred for lime in the sesquioxide process to which I have
referred, not only obtain very much more chlorine than was obtained by that
process, but actually obtain very much more than is obtained in the ordinary
peroxide process; I get, in fact, all the chlorine contained in the hydrochloric
acid employed, being about three times as much as is usually got, and I make
the same oxide of manganese (as I do also when using only the first part of
my Invention) serve over and over again continually at an expense for
regeneration so small that I believe it is considerably more than covered
by the value of the extra yield of chlorine obtained when the second part of
my Invention, or any of the processes constituting the third part of it. are
combined with the first. When the first part of my Invention is used by
itself I still enable the manufacturer of chlorine to effect an economy which I
calculate to be equal to fully four-fifths of the present cost to him of peroxide
of manganese.
The first part of my Invention consists of a new method of converting
protoxide of manganese into sesquioxide. I find that if air be blown through
water or other neutral liquid having protoxide. of, manganese admixed with or
suspended in it; the protoxide. is thereby oxidized with great rapidity, and

page_text: The
may be completely converted into sesquioxide in an exceedingly short space
of time. The method of taking advantage of this fact which I prefer, though
not the only means of practising my Invention which could be employed,
consists in putting the mixture of peroxide of manganese and water or other
liquid into a vessel having a false bottom pierced with numerous holes and
blowing air into the space between the real bottom and this false one.
air then rises through the holes in the false bottom, and thence through the
liquid above, violently agitating the liquid and speedily oxidizing every particle
of protoxide contained in it. The air may either be supplied by a pump, a
fan, or any other kind of blowing machine, or it may be forced in by means
of a jet of steam, as in the apparatus introduced by Mr. James Hargreaves
for oxidizing the sulphide of sodium in crude soda liquors. The former, however,
is the plan I prefer.
The second part of my Invention consists in the use, instead of lime, for
the precipitation of protoxide of manganese from a solution of chloride of
magnesia or any other oxide which will precipitate manganese at the same
time that the chloride of its base admits of being readily decomposed by heat;
I regard magnesia as the most convenient agent, the use of which, when
combined with the first part of my Invention, thus constitutes the second part
of it. By boiling for a very short time with an equivalent of magnesia chloride
of manganese is completely decomposed, the resulting products being chloride
of magnesium, which dissolves as formed and remains in solution, and
protoxide of manganese, which is insoluble and so subsides when the whole
is left still. By evaporating its solution to dryness and heating the residue
the chloride of magnesium is decomposed, the results of the decomposition
being magnesia ready for use over again, and hydrochloric acid which flies off
as vapour, and, after being condensed in the usual way can be employed in
just the same way as the hydrochloric acid obtained directly from the salt
ovens.
When chlorine is manufactured by my process the still liquors after the
first time contain nothing but chloride of manganese and a little free hydro-
chloric acid, being quite free from the chloride of iron, chloride of calcium, etc.,
Lusually contained in them when peroxide of manganese is used, and they
therefore require no treatment before boiling with magnesia or lime, as the
case may be, but may be run directly from the still into the vessel in which
that operation is to take place, that is to say, when this operatiou is not
performed in the still itself. The vessel should at any rate be the same as
that in which the oxidizing process is conducted, and should thus be furnished
with the false bottom spoken of above. The boiling, which is not absolutely

page_text: necessary when the precipitating agent is lime, can be most conveniently
effected by means of steam. When the boiling has continued long enough
the injection of air can be at once commenced, the presence of the chloride of
magnesium or chloride of calcium, as the case may be, which has been formed
by the decomposition not interfering with the oxidation process; when that
is complete, as will be known by the colour of the mixture of sesquioxide of
manganese with solution of chloride of magnesium or calcium, as the case
may be, must be allowed to settle either in the same vessel or in another, as may
be preferred, and the supernatant solution of chloride must then be decanted
in any convenient way. The last portion of liquid may be separated by means
of a centrifugal machine, and the sesquioxide be thus obtained almost entirely
free from adherent liquid, but if the hydrochloric acid upon which the
sesquioxide is to react in the chlorine stills be sufficiently concentrated this
separation of the last portions of liquid need not necessarily take place. I
prefer, when convenient, to make the stills of very considerable size, and
to perform all the operations above described in the stills themselves, so that
the manganese need never be removed from the vessel into which it is originally
put, but may be transformed from sesquioxide into chloride, from chloride into
protoxide, and then from protoxide into sesquioxide again, again to undergo
the same series of transformations (these transformations being repeated in
their due order continually) in one and the same vessel, to the contents of
which first hydrochloric acid, and afterwards lime, magnesia, or other oxide
(the magnesia, when that is the oxide used, being preferably always the same
magnesia used constantly over and over again) are continually added, but from
which nothing is ever drawn off except gaseous chlorine and solution of chloride
of calcium, chloride of magnesium, or chloride of some other metal whose
oxide has been employed for the decomposition of the chloride of manganese.
In this case each still must have a false bottom and a moveable top,
which last can be readily made to fit quite tightly while chlorine is being
evolved, but can afterwards be easily removed. The proper quantity of
sesquioxide of manganese having been placed in this still hydrochloric acid is
added, and the temperature is raised by means of steam to the point at which
the chlorine is given off, a much lower temperature being sufficient than when
peroxide of manganese is used. When chlorine ceases to be evolved the cover
is removed two equivalents of the oxide employed as precipitating agent
(there having been two equivalents of protochloride of manganese formed) are
put into the still with such additional quantity as may be necessary to neutralize
any free hydrochloric acid present, and the whole is then caused to boil by
means of steam; when the boiling has been continued long enough the steam

page_text: is shut off, and air is blown through the contents of the still until all the oxide
of manganese present has been converted into sesquioxide; the injection of
air is then stopped and the contents of the still allowed to remain undisturbed
until the sesquioxide has all settled; the supernatant solution is then drawn
off, and the still is then ready to have its cover placed on again, and to receive
a fresh charge of hydrochloric acid, from which point the round of operations
is repeated as before, this repetition going on continually.
The third part of iny Invention consists in a method of utilizing the chlorides
obtained by the decomposition of chlorides of manganese, as above, by a
method differing from that which is above described. This further method
consists in either decomposing the chlorides in question by sulphuric acid, so
as to obtain hydrochloric acid and a useful sulphate, such as sulphate of
calcium available as paper makers' ".
"pearl hardener," and for other
purposes, or sulphate of magnesium available as "Epsom salts," or for various
chemical applications, as for the generation of sulphurous acid by ignition
with charcoal or by treating them with any saline compound by double
decomposition with which a useful product or useful products can be obtained.
Thus, for example, when tho chloride concerned is chloride of calcium treated
with sulphate of magnesium as obtained as the residue of some one of my
soda processes or otherwise it will yield insoluble sulphate of calcium, useful
as aforesaid, and chloride of magnesium, which can be decomposed by heat
into magnesia and hydrochloric acid. Similarly waste or other sulphate of
zine would yield sulphate of calcium and chloride of zinc, both useful salts, and
waste or other sulphate of iron would yield sulphate of calcium and chloride of
iron.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Walter Weldon in the Great Seal Patent Office on the 23rd
January 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
WELDON, of Park Villa, West Hill, Highgate, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of July, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Walter Weldon Her special licence that I, the said Walter

page_text: Weldon, my executors, administrators, and assigns, or such others as. I, the
said Walter Weldon, my executors, administrators, and assigns, should at.
any time agree with,, and no others, from time to time and at all times.
thereafter during the term therein expressed,, should and lawfully might.
make, use,, exercise,, and vend, within the United Kingdom of Great Britain.
and Ireland, the Channel Islands, and Isle of Man,, an Invention for "IMPROVE-.
MENTS IN THE MANUFACTURE OF CHLORINE," upon the condition (amongst,
others) that I, the said Walter Weldon, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands. and seals,.
should particularly describe and ascertain the nature of the said Invention,,
and in what manner the same was to. be performed, and cause the same.
to be filed in the Great Seal Patent Office within six calendar months next.
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Walter Weldon, do hereby declare.
the nature of my said Invention, and in what manner the same is to be:
performed, to be particularly described, and ascertained in and by the following:
statement:
The object of my said Invention is to diminish the very heavy expense-
which the manufacturer of chlorine has at present to incur for oxide of
manganese, and at the same time to enable him to obtain from a given'
quantity of hydrochloric acid a larger yield of chlorine than it has hitherto
been practicable for him to obtain therefrom.
'
The first and most important part of my Invention consists in a new method
or process whereby I can convert protoxide of manganese obtained by decom-
posing by means of any suitable oxide of other metal the chloride of manganese,
which is one of the results of the reaction between any oxide of manganese;
and hydrochloric acid, into a higher oxide capable of liberating free chlorine
when treated with the acid just mentioned, and in the use in the manufacture
of chlorine of the artificial higher oxide so produced. For the purposes of:
this Specification I shall bereafter call this artificial higher oxide. "sesqui-
oxide;" but I am not certain that it is absolutely such in the strictly chemical
sense. It may be either simply sesquioxide, or a mixture of sesquioxide with:
either a lower oxide or a higher oxide, or with both, or a mixture of a higher
and a lower oxide only; but when the oxidation of the protoxide by my:
process is carried to the point to which I prefer to carry it, the resulting higher.
oxide is practically equivalent to sesquioxide, liberating exactly the amount of
chlorine which, according to theory, a pure sesquioxide would.
In carrying out my Invention I may begin either with that residue of the,
chlorine manufacture as at present conducted, which is technically known as

page_text: "still liquor," or with chloride of manganese obtained in any other way.
When beginning, as will usually be the case with ordinary still liquor, it is
not absolutely essential to separate the iron contained therein, but I greatly
prefer that the iron be got rid of, as may be done by any one of several
methods, each so well known as to render any description of it here
unnecessary. The iron having been separated the still liquor contains in
solution in important quantity no heavy metal excepting manganese, and is now
therefore in the condition in which I prefer it should be when subjected to the
first essential part of my process, this first essential part consisting in the
decomposition of the chloride of manganese contained in the still liquor or
other solution of the said chloride by means of either lime or soda, or any
other oxide which will precipitate protoxide of manganese from a solution of
protochloride of that metal. When either lime or soda is the oxide employed
for this purpose, the said oxide and the said chloride may be either boiled
together or not at the option of the operator, the decomposition of chloride of
manganese by either lime or soda not requiring a boiling heat, but taking
place at any ordinary temperature; but when the oxide used is the one of which
more will be said when treating of the second part of my Invention, if boiling
be not in all cases absolutely essential it is at least greatly to be preferred.
The boiling may be effected either by means of steam, or by the application of
furnace heat to the outside of the vessel employed, as may be most convenient.
The obtainment in the manner thus described of protoxide of manganese,
preferably unmixed with oxide of iron, though not absolutely essentially so,
and whether obtained from the residue of the process of manufacturing
chlorine as at present practised, or from chloride of manganese produced in
any other way, is essentially the first step of my process, but is not in itself
novel, and is consequently no part of my Invention, except as combined with
the method of oxidizing the said protoxide, which I shall now proceed to
describe.
This process of oxidation, constituting the first and most important part of
my Invention, consists in the conversion of protoxide of manganese, obtained
as above described, into sesquioxide, defined as above, by blowing air through
water or other liquid holding the protoxide in admixture or suspension, which
simple method I have found to convert protoxide of manganese into sesqui-
oxide, both completely and with extreme readiness. In carrying out this
process of oxidation I prefer, though it is by no means the only manner in
which the conversion of protoxide of manganese into sesquioxide can bo
effected essentially by the method constituting the first part of my Invention
to place the mixture of protoxide of manganese with water or other neutral

page_text: liquid in a vessel having a false bottom pierced with numerous holes, and to
blow air into the space between this false bottom and the real one. The air
so blown into the space between the real and the false bottom rises through
the holes in the latter and then through the liquid above, thereby violently
agitating the liquid and coming into contact with and rapidly oxidizing every-
particle of the protoxide which it finds admixed with or suspended therein.
The air may be supplied either by a pump or a fan, or may be injected by
means of a jet of steam; but I prefer that it be supplied by a blowing engine,
such as is used for supplying the blast to furnaces for smelting iron. The
period during which the blowing must be continued in any particular instance
will depend of course upon the quantity of protoxide which is being operated
upon at once, and the rate at which the air is blown into the liquid with or
in which the protoxide is admixed or suspended. I have frequently known
the protoxide completely converted into sesquioxide within less than one hour,
but in such cases a considerable excess of air was blown through the liquid
containing it. The cheapest plan is to blow the air at such rate that as
nearly as possible the whole of the oxygen of the injected air shall be absorbed
and nitrogen only emerge from the liquid; but when this plan is adopted the
completion of the oxidation takes a proportionately longer time than I have
named. At first, until he shall have ascertained by experience exactly low
long a period is required, at the rate at which his particular blowing apparatus
supplies air, to convert a given quantity of protoxide into sesquioxide, the
operator must judge, as he readily may, of the progress and completion of the
oxidation of the protoxide by the colour of the resulting mixture of higher
oxide or various oxides with water or other liquid; and to assist him in doing.
this it will be well that he should provide himself with a small quantity of
artificial sesquioxide known to be of accurate composition, which may be
prepared by any convenient method, and should be mixed with as nearly as
possible the same proportion of water or other liquid as the large mass, of
oxide he is operating upon is mixed with. I prefer that the blowing should
be continued until the protoxide is completely converted into sesquioxide, or
the practical equivalent thereof; but of course, if the operator chooses, he
may stop the process of oxidation before that point is attained, through he will
scarcely find any advantage in so doing. When the oxidation is completed I
either leave the resulting mixture of sesquioxide with water or other liquid at
rest for a time until the sesquioxide has subsided, and then decant as far as
possible the supernatant water or other liquid; or I place the mixture in
suitable filtering vessels or upon suitable filter beds, and so separate the
greater part of the liquid from the sesquioxide by filtration. By whichever

page_text: method I may have separated the sesquioxide from the greater part of the
liquid in which it was formed, the further portion of liquid which remains
adherent to or admixed with it can, for the most part, be separated if.
required by means of a centrifugal hydro-extractor; but I have scarcely ever
found this separation of the last portions of liquid to be at all necessary.
The artificial sesquioxide of manganese obtained as above described I use
instead of native peroxide of manganese, which is the agent ordinarily
employed for this purpose to liberate chlorine from hydrochloric acid, and
when I have thus by the reaction upon each other of hydrochloric acid and.
my artificial sesquioxide of manganese obtained free chlorine and reproduced
chloride of manganese I proceed with the said chloride of manganese exactly
as I proceeded with the solution of chloride of manganese with which I
commenced operations, except that the latter may have required a preliminary
purification from iron, which the former, not containing any iron, does not
require. I first decompose the chloride by means of lime or other suitable
oxide, and so obtain protoxide of manganese; I then oxidise this protoxide
by the method described above into sesquioxide; by the reaction on hydro-
chloric acid of the sesquioxide so produced I then obtain a further portion of
free chlorine, at the same time reproducing the same quantity that I had
before of chloride of manganese, and I repeat this series of transformations in
due order any required number of times. Instead of having to purchase a
fresh quantity of oxide of manganese for every fresh portion of chlorine I
desire to liberate, which is what the manufacturer of chlorine has to do at
present, I thus make the same manganese serve over and over again
continually, thereby converting it from a raw material of the chlorine
manufacture, which it may be regarded as being at present, into simply an
instrument thereof, the function of the said instrument (which function it can
perform any desired number of successive times) being to act as a carrier of
oxygen between the atmosphere and the hydrogen of a portion of the hydro-
chloric acid. I thus substitute for the very serious expense which the
manufacturer of chlorine has at present to incur for that native peroxide of
manganese, which is by far the most costly material he has to buy, the
comparatively very slight cost of the two simple operations of firstly
decomposing chloride of manganese so as to obtain protoxide of manganese,
and, secondly, of oxidizing this protoxide into sesquioxide by the inexpensive
method above described. Besides this, however, there are two other very
important economics which are effected by my process, these further
economics being due to the facts that my artificial sesquioxide of manganese,
unlike the native peroxide, contains no impurities which consume hydro-

page_text: chloric acid without generating chlorine, and that like all hydrated artificial
oxides it dissolves in acids much more readily than a hard and anhydrous
native oxide. A quite pure peroxide of manganese would liberate as much
chlorine from two parts of hydrochloric acid as an equally pure sesquioxide
could liberate from three parts of acid, but nevertheless so contaminated with
oxides of other metals are even the best qualities of such native peroxide of
manganese as is ordinarily used in the chlorine manufacture, and so great an
excess of acid has to be employed to effect the decomposition of such
peroxide that my artificial sesquioxide being practically quite pure and
requiring for its ready solution no more than an exact equivalent of hydro-
chloric acid not only does not consume more hydrochloric acid per given
amount of chlorine liberated than is required for the production of the same.
quantity of free chlorine by means of an ordinary quality of native peroxide
but will actually enable a given quantity of hydrocliloric acid to yield nearly
two-thirds more free chlorine than it is usually made to yield by the system
of manufacture which prevails at present. Moreover, owing to the superiority.
as regards facilty of solution in acids of a hydrated artificial oxide over an
anhydrous native oxide the reaction between hydrochloric acid and my.
artificial sesquioxide requires alike considerably less time and considerably
less fuel than are requisite to completely accomplish the reaction between.
hydrochloric acid and any native peroxide. These two additional economics
are together so much greater in amount than the cost of the two operations
by which I produce sesquioxide of manganese from the chloride thereof that.
my process as described above saves altogether considerably more than the
whole cost of the peroxide of manganese at present used in the manufacture
to which it refers.
The second part of my Invention relates to a means of effecting a still
further economy in that manufacture, additional to those above set forth.:
Of the two oxides, lime and soda, which are mentioned above as being
intrinsically suitable. for the decomposition of chloride of manganese only the
former, on account of the so much greater cost of the latter, is at present at
all likely to be used for the purpose indicated. Both, however, are subject
to the disadvantage, as regards their use for the purpose in question, that.
when they are employed to decompose chloride of manganese the chlorine.
which they abstract from that compound cannot be recovered except by the
use of powerful reagents, owing to the extreme stability of both chloride of
calcium and chloride of sodium. . It is true that the quantity of chlorine,
locked up in one or the other of these two compounds when lime or soda, as.

page_text: the case may be, is used for the decomposition of chloride of manganese in
my process as described above is very much less than the quantity contained
in combination with various bases in that residue of the chlorine manufacture
as at present conducted, which is now ordinarily thrown away; but I have
desired to obtain in an available condition the whole of the chlorine contained
in the hydrochloric acid used in that manufacture, and to allow none of it to
form useless compounds, and hence the second part of my Invention consists
in the combination with the method of oxidation which forms the first part of
it, and with the general combination of processes described above of the use
for the decomposition of the chloride of manganese of the oxide of some
metal whose hydrated chloride admits of being decomposed by heat, and
which could thus be readily and cheaply made to give up its chlorine in the
shape of hydrochloric acid, while the operation by which its chlorine should
be thus recovered should reproduce the oxide for use over again. Magnesia
at first seemed to me to answer all requirements, but I ha ve since found that
magnesia from different sources, as was already well known to be the case
with lime from different sources, differs greatly in chemical activity and
energy, and I have been unable to obtain a second supply of magnesia like
that with which my first experiments were performed, and an equivalent of
which completely decomposed a full equivalent of chloride of manganese
when only boiled therewith for a minute or two. To enable other samples of
magnesia to decompose completely an equivalent of chloride of manganese
more or less prolonged boiling is required, while some samples will effect
that object only when aided by a more or less considerable degree of pressure.
In most cases the use of an excess of magnesia considerably facilitates the
decomposition of the chloride of manganese, but the use of any considerable
excess of magnesia is of course attended with obvious disadvantages. I
cannot therefore recommend this part of my Invention except to manu-
facturers who may have command of a specially suitable magnesia, the
Such
source whence which may be obtained I am unable to indicate.
manufacturers, however, will find a great advantage in decomposing their
chloride of manganese by means of magnesia, and in then decomposing the
resulting chloride of magnesium by evaporating its solution to dryness and
then heating the residue in a current of steam. They will thus obtain
magnesia for use over again, and hydrochloric acid, which will fly off as
vapour, and after having been condensed in the usual way may be employed
for the generation of chlorine or for any other purpose just like hydrochloric
acid obtained by the ordinary method.

page_text: A third part of my Invention consists in another method which will some-
times be available of utilizing the chloride of other metal obtained by the
reaction upon chloride of manganese of whatever oxide may in my process be
employed to decompose that compound. This further method consists in
either decomposing the said chloride by means of sulphuric acid, so as to
obtain hydrochloric acid and a useful sulphate (as sulphate of calcium available
for use in paper making and for other purposes, or sulphate of magnesium
available both for medicinal use and for various chemical applications) or in
treating it with any saline compound by double decomposition with which a
useful product or useful products can be obtained. For example, when the
chloride is chloride of calcium treated with refuse or other sulphate of magnesium
it would form insoluble sulphate of calcium, useful as above stated, and chloride
of magnesium admitting of being readily decomposed into magnesia and
hydrochloric acid. With refuse or other sulphate of zinc or sulphate of iron
it would similarly react, and so in a great many other instances, alike with
sulphates and with other salts. The reaction between hydrochloric acid and the
artificial sesquioxide of manganese obtained by my process as above described
may either take place in the same stills that are used at present for the
reaction between hydrochloric acid and native peroxide of manganese, the
chloride of manganese which remains in state of solution when the reaction is
completed being then run off, and its transformation into sesquioxide effected
in another vessel or vessels; or the stills used may be made such as to permit
of the whole series of operations being performed in the stills themselves, so
that the manganese need never be removed from the vessel into which it is
originally put, but may be transformed from sesquioxide into chloride, from
chloride into protoxide, and then from protoxide into sesquioxide again, again
to undergo the same series of transformations (these transformations being
repeated in their due order continually) in one and the same vessel, to the
contents of which first hydrochloric acid and subsequently either lime or other
oxide are continually added, but from which nothing is ever drawn off except
gaseous chlorine and solution of chloride of calcium or other metal, as the
case may be. To this end the stills should preferably be made much larger
than they are usually made at present, though this is not absolutely essential,
and should each be provided with a false bottom, as described above, or with
some equivalent contrivance for diffusing the blast of air required in my process
through all parts of the liquid contents of the still. Any one of a great
number of simple contrivances, such, for example, as a tube dipping down
into the vessel and terminating near the bottom of the vessel in a number of

page_text: perforated radial arms will answer the required end, but on the whole I prefer
the false bottom arrangement. The still should morcover have a moveable
cover which can be readily made to fit quite closely while chlorine is being
evolved, but can afterwards be easily removed. This cover need have only a
small proportion of the superfices of the bottom or other largest area of the
still, but to the sides of the opening into which it fits must be attached either
so as to be removeable from time to time or not, as may be preferred, a long tube
or funnel or other vertical continuation of the sides of the opening in question,
the office of which tubular or other continuation shall be to collect and cause
to fall back into the still such portion of the contents of the still as the blast
passing through the still during the oxidation process would otherwise carry
off as spray. The proper quantity of sesquioxide of manganese having been
placed in this still hydrochloric acid is added, the moveable cover is fitted on,
and the temperature is then raised by means of steam or otherwise, sufficiently
to determine the evolution of chlorine. When chlorine ceases to be evolved
the cover is removed, sufficient lime or other oxide is added to decompose the
chloride of manganese which has been formed and to neutralize any free
hydrochloric acid which may be present with it, and the whole is then boiled
or not, acording to the nature of the oxide used and the option of the operator.
When either lime or soda is the oxide used the boiling as I have said may he
dispensed with. When the chloride of manganese has thus been decomposed
whether by boiling or without, the resulting protoxide of manganese and
solution of chloride of other metal may be separated by subsidence and
decantation, water being then added to the protoxide, and the blast of air
which is to oxidize the protoxide being then injected into the resulting mixture
of protoxide and water, or the blast may be injected directly into the original
mixture of protoxide of manganese with solution of chloride of other metal.
In either case, when the protoxide has been completely converted into sesqui-
oxide, the sesquioxide must be separated by subsidence and decantation from
the greater part of the liquid in which it was formed, and when the separation
has been effected the still is ready to receive another charge of hydrochloric
acid, from which point the round of operations can be repeated as before, this
repetition proceeding continually.
I desire here to add that although when I drew up my Provisional Specifi-
cation I believed that an attempt had been already made to use in the manu-
facture of chlorine sesquioxide of manganese obtained by atmospheric
oxidation of the protoxide of manganese resulting from double decomposition
between chloride of manganese and an oxide of other metal, and that this

page_text: attempt failed in consequence of the method of oxidation adopted, oxidizing
the protoxide only exceedingly imperfectly. I have since found that I had
been incorrectly informed on this point. Further inquiry has convinced me
that no attempt to carry any such process into practice was ever made, nor
can I find either in the records of the Patent Office or in any of the books
treating of the chemical industries any mention of any such process ever
having been even suggested. Many utterly hopeless proposals for modifica-
tions of the process by which chlorine has hitherto been manufactured have
been patented, but all experiments previous to my own with respect to the use
for the liberation of chlorine of artificial sesquioxide of manganese, supposing
any such experiments to have been made, have clearly been so little en-
couraging to those who have made them as to have precluded their either
seeking to obtain the protection of a Patent for any process based on the
results of such experiments, or even placing those results on public record in
any way whatever.
Having thus fully declared, ascertained, and described the nature of my
Invention, and the manner in which the same is to be performed, I wish it to
be understood that what I claim as my Invention, and desire to be secured to
me by the herein in part recited Letters Patent is,―
Firstly. The use in the manufacture of chlorine of an artificial sesquioxide
of manganese, or of any practical equivalent thereof, or of any oxide or
mixture of oxides inferior to sesquioxide, but yet capable of liberating chlorine
when such oxide or mixture of oxides is obtained, substantially by the method
I have above described.
Secondly. The conversion of protoixde of manganese into the said higher
oxide or mixture of oxides by injecting atmospheric air into a mixture of the
said protoxide with water or other neutral liquid.
Thirdly. The general combination of operations by which I make the same
manganese serve for the liberation of chlorine over and over again continually,
and the combination of arrangements by which I am enabled to perform all
the operations of my process in one vessel.
Fourthly. The use in conjunction with the said combinations of operations
and arrangements of magnesia for the decomposition of chloride of manganese
coupled with the subsequent decomposition of the resulting chloride of
magnesium into magnesia and hydrochloric acid.
And, fifthly. The combination with the use in the manufacture of chlorine of
the artificial sesquioxide of manganese, obtained substantially by the process
I have above described, of the utilization of the chloride of other metal

page_text: obtained in that process as a result of the decomposition of chloride of man-
ganese by a suitable oxide, either by treatment with an acid or by double
decomposition with a saline compound.
In witness whereof, I, the said Walter Weldon, have hereunto set my
hand and seal, this Seventeenth day of January, in the year of our
Lord One thousand eight hundred and sixty-seven.
WALTER WELDON. (L.S.)