IMPROVEMENTS RELATING PRIMARILY TO THE MANUFACTURE OF CHLORINE BY MEANS OF REGENERATED OXIDES OF MANGANESE, BUT PARTLY APPLICABLE ALSO TO OTHER PURPOSES, BEING IMPROVEMENTS IN THE DECOMPOSITION OF CHLORINE RESIDUES, IN THE PEROXIDATION OF OXIDE OF MANGANESE RECOVERED THEREFROM, IN THE TREATMENT OF A BYE PRODUCT OF THE DECOMPOSITION OF THOSE RESIDUES, IN THE SEPARATION OF SULPHURIC ACID AND OTHER IMPURITIES FROM THE HYDROCHLORIC ACID EMPLOYED, AND IN APPARATUS AND ARRANGEMENTS FOR SOME OF THESE PURPOSES
Year: 1868

page_text: ETTERS PATENT to Walter Weldon, of Park Villa, West Hill,
Highgate, in the County of Middlesex, for the Invention of
"IMPROVEMENTS RELATING PRIMARILY TO THE MANUFACTURE OF CHLORINE
BY MEANS OF REGENERATED OXIDES OF MANGANESE, BUT PARTLY APPLICABLE
ALSO TO OTHER PURPOSES, BEING IMPROVEMENTS IN THE DECOMPOSITION OF
CHLORINE RESIDUES, IN THE PEROXIDATION OF OXIDE OF MANGANESE
RECOVERED THEREFROM, IN THE TREATMENT OF A BYE PRODUCT OF THE
DECOMPOSITION OF THOSE RESIDUES, IN THE SEPARATION OF SULPHURIC
ACID AND OTHER IMPURITIES FROM THE HYDROCHLORIC ACID EMPLOYED, AND
IN APPARATUS AND ARRANGEMENTS FOR SOME OF THESE PURPOSES."
Sealed the 7th August 1868, and dated the 20th February 1868.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at
the Office of the Commissioners of Patents, with his Petition, on
the 20th February 1868.
I, WALTER WELDON, of Park Villa, West Hill, Highgate, in the
3 County of Middlesex, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS RELATING PRIMARILY TO THE MANUFACTURE OF
CHLORINE BY MEANS OF REGENERATED OXIDES OF MANGANESE, BUT PARTLY
APPLICABLE ALSO TO OTHER PURPOSES, BEING IMPROVEMENTS IN THE DECOM-
POSITION OF CHLORINE RESIDUES, IN THE PEROXIDATION OF OXIDES OF MANGA-

page_text: NESE RECOVERED THEREFROM, IN THE TREATMENT OF A BYE PRODUCT OF THE
DECOMPOSITION OF THOSE RESIDUES, IN THE SEPARATION OF SULPHURIC ACID
AND OTHER IMPURITIES FROM THE HYDROCHLORIC ACID EMPLOYED, AND IN
APPARATUS AND ARRANGEMENTS FOR SOME OF THESE PURPOSES," to be as
follows:-
I. This Invention consists in certain improvements relating primarily
to the manufacture of chlorine by means of artificial oxides of man-
ganese regenerated from what are known as "chlorine residues." The
said improvements have reference to the decomposition of those residues,
to the treatment of a bye product of their decomposition, to the peroxi-
dation of oxides of manganese recovered from them, to the separation
of carbonic acid from atmospheric air used for this purpose, to the
purification of the hydrochloric acid employed to dissolve the regenerated
oxides, and to the apparatus and arrangements for accomplishing these
objects. Some of the improvements collectively constituting this
Invention can be applied also to other purposes, namely, to the
manufacture of alkalies; to the manufacture of magnesia for use for
other purposes than for the decomposition of chlorine residues; to the
purification of hydrochloric acid used otherwise than in the manufacture
of chlorine, by means of regenerated oxides of manganese; and to the
utilization of the sulphuric and sulphurous acids with which the hydro-
chloric acid produced in the manufacture of alkalies is almost invariably
contaminated. In so far as it relates to artificial oxides of manganese
(which are its principal and essential subject) the Invention has
reference chiefly to oxides regenerated and peroxidized by the wet way,
and more, especially to oxides regenerated and peroxidized by the method
for the Invention of which Her Majesty's Letters Patent, numbered 1948,
were granted to me on the Twenty-sixth day of July, in the year of our
Lord One thousand eight hundred and sixty-six, and for successive
improvements upon which further Letters Patent, dated respectively the
Eighteenth day of January and the Fourth day of September, both in
the year of our Lord One thousand eight hundred and sixty-seven, and
numbered respectively 133 and 2501, have also been granted to me.
-
II. In order to the manufacture of chlorine by means of oxides of
manganese regenerated from chlorine residues, the first step is the
decomposition of those residues, or, rather, the decomposition of the
chloride of manganese which is their chief and only essential constituent
Hitherto chloride of manganese has never been decomposed on a manu

page_text: facturing scale except by means of either lime or carbonate of lime, but
when either of those bodies is the agent employed to decompose chloride
of manganese such agent can be used only once, and the chlorine
which it is employed to abstract from the chloride of manganese is
practically lost, inasmuch as that chlorine forms with the calcium of
the lime an exceedingly stable compound, which has but few uses in
the arts, and no method of economically decomposing which has yet
been devised. I have desired to save the chlorine, which, when lime or
carbonate of lime is employed to decompose chloride of manganese,
thus forms with the metallic base of those bodies a compound which
can but rarely be turned to any useful account; and hence one part
of the Invention for which Her Majesty's Letters Patent, numbered 1948,
and bearing date the Twenty-sixth day of July One thousand eight
hundred and sixty-six, were granted to me as aforesaid, consists in a
certain employment of magnesia instead of lime for the decomposition
of chloride of manganese, in order to the recovery therefrom of oxides
of manganese available for the manufacture of chlorine; the advantage
of the use of magnesia for this purpose being due to the readiness
with which the resulting hydrated chloride of magnesium can be
resolved by the action of heat into magnesia and hydrochloric acid,
so as virtually to enable the same magnesia to be used over and over
again continually, and all the chlorine of the chloride of manganese
to be recovered in a practically available form. In the Final Specifica-
tion of that Invention, however, I was obliged to point out that in the
interval between the preparation of the said Final Specification and that
of the Provisional Specification of the said Invention, I had found that
none but magnesia of a special quality would decompose chloride of
manganese, equivalent for equivalent, when treating the chloride of
manganese with the magnesia, and otherwise proceeding by the method
which that Specification describes. "I have since found," I say in that
Final Specification, "that magnesia from different sources, as was already
"known to be the case with lime from different sources, differs greatly
"in chemical activity, 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 an
equivalent of chloride of manganese when only boiled therewith for a
"minute or two "; and I afterwards proceed to remark that "I cannot
"therefore recommend this part of my Invention, except to manufacturers
"who may have command of a specially suitable magnesia, the sourcė
"
"

page_text: "whence which may be obtained I am unable to indicate." I have
now to record certain new discoveries, by taking advantage of which
magnesia from any source whatever may be rendered available for the
decomposition of chlorine residues, so that any manufacturer of chlorine
may now command the advantages resulting from the decomposition of
his chloride of manganese by means of magnesia.
III. One important fact which has not been hitherto known, and
which, though exceedingly simple, is of itself sufficient to render almost
any kind of magnesia available for the purpose in question, is that if
hydrated chloride of magnesium have chloride of manganese associated
with it within certain limits, the subjection to a suitable heat of the
chloride of magnesium so associated with chloride of manganese results
in the decomposition not only of the chloride of magnesium, but of the
chloride of manganese as well, the chlorine of both compounds flying off
as hydrochloric acid, and a mixture of magnesia with oxide of manganese
containing a very large proportion of oxygen remaining behind. It
follows that a chlorine manufacturer employing magnesia to decompose
his chloride of manganese may be content not to obtain a complete
decomposition in the wet way, by boiling together magnesia and chloride
or manganese or otherwise, but to permit a portion of undecomposed
chloride of manganese to pass on with the chloride of magnesium
resulting from a partial decomposition in the wet way. This plan,
which constitutes an important feature of the present Invention, involves
no loss of materials, seeing that, as already explained, both elements of
the chloride of manganese, as well as of the chloride of magnesium, come
safely round, the chlorine as hydrochloric acid and the manganese as a
more or less rich oxide,
IV. By taking advantage, however, of another fact, not hitherto
known, a complete decomposition of chloride of manganese by means of
magnesia of any quality which I have yet met with, provided only that
it have not been excessively heated, may be readily affected in the wet
way. I have discovered, what has not till now been know to chemists,
that whereas on the one hand magnesia can decompose chloride of
manganese with production of chloride of magnesium and protoxide
of manganese, on the other hand protoxide of manganese can decompose
chloride of magnesium with production of chloride of manganese and
protoxide of magnesium (or magnesia). When chloride of manganese,
in solution in water, is treated, completely out of contact with air or

page_text: other oxidizing agent, with an equivalent, or even with a certain con-
siderable excess over an equivalent, of magnesia, a partial reaction at
once takes place, a portion of the magnesia decomposing a portion of the
chloride of manganese; but this reaction does not become complete, and
I have found that the cause of its not proceeding further is the presence
of the protoxide of manganese resulting from the said partial reaction
between the magnesia and the chloride of manganese, and the power of
such protoxide of manganese to decompose chloride of magnesium. The
decomposition of the chloride of manganese by the magnesia proceeds
to a certain point, and the decomposition of more chloride of manganese
is then prevented by the power of protoxide of manganese and chloride
of magnesium to reproduce chloride of manganese and magnesia.
Hence, in order to enable an equivalent of magnesia, of ordinary
chemical activity, to decompose an equivalent of chloride of manganese
in the wet way, the protoxide of manganese, which is one of the products
of the double decomposition of these two bodies, must be practically
removed from the sphere of action as it is formed, and this removal of
the protoxide of manganese from the sphere of action can be effected,
more readily, I believe, than by any other means by oxidizing the said
protoxide into a higher oxide not possessing the power of decomposing
chloride of magnesium. A part of the present Invention accordingly
consists in treating with air or other suitable oxidizing agent a mixture
of magnesia with chloride of manganese, or of magnesia with oxide of
manganese, chloride of manganese, and chloride of magnesium (the two
chlorides being in solution in water) whereby I speedily decompose the
whole of the chloride of manganese without needing to use much, if any,
excess of magnesia.
V. When proceeding as just described, as also, usually at least, when
seeking to decompose chloride of manganese by means of magnesia
without simultaneously oxidizing the resulting protoxide of manganese,
I prefer to operate at temperatures higher than the ordinary temperature
of the atmosphere. I have found that the desired reaction between
magnesia and chloride of manganese is greatly facilitated by such higher
temperatures, the more especially when the magnesia employed has been
obtained by the decomposition of chloride of magnesium at a high
temperature, or from any other cause has been subjected to considerable
heat; indeed, it may be taken as a rule that the greater the heat to
which the magnesia has been submitted the higher will be the tem-
perature which it will be desirable to use during the treatment together of

page_text: the magnesia and chloride of manganese. Magnesia which has only been
very slightly heated can be made to decompose chloride of manganese
completely in the cold, but magnesia which has been very much heated
will scarcely decompose chloride of manganese in the cold at all. The
temperature at which it will be best to treat together the magnesia and
the chloride of manganese in any given case will thus tend to be the
higher the greater the degree of heat to which the magnesia shall have
'been previously exposed; but it is of extreme importance that in fixing
⚫the temperature to be employed in any given instance regard should be
'had, not simply to the temperature at which the particular magnesia used
'will react upon chloride of manganese most readily (I say "most readily,"
because it will often be found that a magnesia which at some high
'temperature will decompose chloride of manganese in some short period
will also decompose it at a much lower temperature if a sufficiently
longer time of treatment be allowed), but also to certain laws relating
to the influence of temperature and other circumstances upon the
peroxidation in the wet way of artificial protoxide of manganese, which
I found to have a most important bearing upon the peroxidation in the
wet way of such protoxide, whether the said protoxide have been
'obtained by means of magnesia or by means of lime, and due regard for
which is therefore very material to the carrying out in the most
economical manner of almost any modification of the process to which
this Invention mainly relates, and accordingly constitutes an important
part of this Invention. The laws of which I speak (and which have
hitherto been unknown to chemists) are, firstly, that what may be
called the inferior peroxides of manganese, namely, red oxide or Mn³ O*
and sesqui-oxide or Mn³ O³, are never formed directly, so to say, when
obtained in the wet way, but are always the result of the combination
of previouly formed particles of peroxide or Mn O2 with particles of
protoxide or Mn O, every act of peroxidation of protoxide of manganese,
however rich or poor the ultimate result may be, being really always
an act of the formation of particles of MnO2; secondly, that whether
each newly formed particle of peroxide or Mn O' combines immediately
on its formation with two particles of protoxide or MnO to form
therewith a particle of red oxide or Mn³ O', or with only one particle
of MnO to form therewith a particle of sesqui-oxide or Mn³ O³, or
declines to combine with any protoxide at all, depends mainly upon the
degree of chemical activity which the newly formed particle of Mn O
possesses at the instant after its formation; thirdly, that the degree of

page_text: chemical activity which characterizes a newly formed particle of MnO*
depends mainly upon the temperature at which the particle is formed,
being usually the greater the higher that temperature; fourthly, that
the presence of an excess of lime materially promotes the peroxidation of
protoxide of manganese (probably by the formation of either oxychloride
or peroxide of calcium which then acts as a carrier of oxygen) in such
wise as not only to be very useful and important when working with lime.
at low temperatures, but also to render practicable the production of rich
oxides at temperatures at which only much poorer oxides could be
obtained otherwise; and, fifthly, that the presence of excess of magnesia
seems to have an effect in some respects the exact reverse of that
produced by the presence of excess of lime, tending to the production
of poor oxides even at temperatures at which much richer oxides could-
be obtained in the absence of excess of magnesia. It follows that;
whereas an excess of lime is always desirable, a material excess of
magnesia should never be used when it can be avoided; that, whether
working with magnesia or with lime, there are certain limits as to
temperature above which only Mu³O' can be obtained, while between
that limit and a lower one Mn 0³ can be produced, and below that
lower limit the obtainment of still richer peroxides is possible; and
finally, that while these limits are not absolutely fixed but vary with.
circumstances, they are always much lower when working with magnesiá
than when working with lime. With lime I have got excellent results;
both as regards richness and rapidity of obtainment, at temperatures.
between 150 and 180 degrees Fahrenheit; but with magnesia, although
perhaps the most rapid, results are got at températures above 150
degrees. I believe that to obtain the richest possible results tem-
peratures below or not greatly exceeding 100 degrees are best;
whether a poor oxide rapidly obtained or a richer oxide more slowly
obtained be the most economical will depend on circumstances.
VI. Before adding the magnesia to the mass of the chloride of
manganese I prefer to grind or triturate it as finely as possible, either
with water or with a portion of the chloride of manganese solution itself.
VII. I have already mentioned that the reaction between magnesia
and chloride of manganese requires a higher temperature the more
highly the magnesia itself has been previously heated. If however the
magnesia have been heated excessively the decomposition of chloride
of manganese by means of it becomes very difficult to accomplish, even

page_text: by the help of heat, and as the magnesia to be used for the decomposition
of the chloride of manganese produced in the manufacture of chlorine
must practically be obtained nearly, if not quite always, by the decom-
position of hydrated chloride of magnesium, either by heat alone or by
heat aided by steam; an important feature of the present Invention
consists in effecting such decomposition at much lower temperatures
than have hitherto been used or prescribed for the decomposition of
that compound. The resolution of hydrated chloride of magnesium into
magnesia and hydrochloric acid by evaporating a solution thereof to
dryness and then heating the residue, preferably in an atmosphere or
current of steam, has long been practised in France, and has several
times been proposed as a part of various suggested processes by
Inventors in this and other countries; but this decomposition of chloride
of magnesium as hitherto practised and proposed has invariably involved
the subjection of the resulting magnesia to a bright red heat, whereas I
have found that magnesia which has not been heated above dull redness
decomposes chloride of manganese much more readily at those tem-
peratures which are most conveniently attainable than magnesia
which has been heated above that point, and that the lower and the
farther below even dull redness be the temperature at which chloride of
magnesium has been decomposed, the more readily does the resulting
magnesia react upon chloride of manganese. In fact, for such purposes
as the decomposition of chloride of manganese, magnesia which has
not been heated beyond a point considerably below dull redness is
practically another substance possessed of far greater chemical activity
than magnesia which has been subjected to the temperatures hitherto
employed and proposed for the decomposition of chloride of magnesium.
VIII. There is another point relating to the resolution into magnesia
and hydrochloric acid of hydrated chloride of magnesium with respect
to which it will frequently be advantageous to depart from what has
invariably been the practice and suggestion hitherto. The practice and
suggestion to which I now refer have always been to decompose each
charge of chloride of magnesium as completely as possible; but when
aiming at the production of a magnesia capable of acting readily at
low temperatures, and therefore decomposing the chloride of magnesium
at the low temperatures which are best adapted to that end, it is a
good plan not to carry the decomposition of each charge of chloride
of magnesium to completeness, but to decompose each charge only

page_text: partiany, and let the unaccomposed portion (WHICH can De dissolveu
out from the magnesia resulting from the decomposition of the
decomposed part, either with water or with a previous non-saturated
solution of chloride of magnesium) form either part or the whole of a
subsequent charge. The mixture of magnesia and chloride of magnesium
which constitutes a but partially decomposed charge can be used for
the decomposition of chloride of manganese without first dissolving out
the undecomposed chloride of magnesium; but this is not a good
plan, since the presence of excess of chloride of magnesium has a
tendency to hinder the decomposition of chloride of manganese by
magnesia.
IX. With respect to apparatus and arrangements which I prefer to
employ for the decomposition of chloride of magnesium, whether
associated or not with chloride of manganese, it will be sufficient now
to say that those features of the said apparatus and arrangements
which are novel, and which therefore constitute parts of the present
Invention, consist, firstly, in the use for the purpose indicated of
"close" or "blind" furnaces, similar to the "blind roasters" used by
alkali makers for roasting salt cake; secondly, in making the furnaces
employed, whether they be close furnaces or open reverberatory furnaces,
of considerable length, divided or not into several beds, and passing
each charge gradually from one end to the other of the furnace in
which it is treated; thirdly, in arranging, when the chloride of
magnesium solution is concentrated in open pans or other vessels,
that such pans or vessels shall be heated by the waste heat from the
decomposing furnaces; fourthly, in making the beds of the decomposing
furnaces of cast iron, and, applying heat only at the upper part of
such furnaces; fifthly, in employing for the purpose in question what
are known as "rotary" or "revolving" furnaces; sixthly, in adding
to solution of chloride of manganese which is undergoing concentration,
when such concentration is performed in open vessels, partially
decomposed charges from the decomposing furnaces, and then "fishing
out the magnesia contained in such partially decomposed charges;
seventhly, in concentrating the solution of chloride of magnesium in
close boilers, taking care not to carry its concentration therein far
enough to determine the evolution of hydrochloric acid, and using the
steam which is given off as a source either of heat or of motive power,
as may be most convenient or advantageous in each particular case;
"

page_text: eightly, in so arranging such boilers that they need never be completely
emptied, but so providing that weak solution shall be more or less
constantly entering them, and concentrated solution be more or less
constantly being withdrawn from them; and, ninthly, in applying the
heat required for the decomposition of concentrated chloride of
magnesium either solely or mainly by means of more or less highly
superheated steam..
X. So far I have treated mainly of the decomposition in the wet
way of chloride of manganese by means of magnesia, resulting in the
production of oxide of manganese and solution of chloride of magnesium,
and of the treatment of this solution of chloride of magnesium so as to
obtain its chlorine as hydrochloric acid and its magnesium as magnesia
fit for use over again. The next point to be considered is the per-
oxidation. of the recovered oxide of manganese. I do not consider it
at all a good method of proceeding, as the result is rarely, if ever, richer
than what is known to chemists as manganoso-manganic oxide or
Mu³ O', and is frequently not even so rich as that; but an oxide capable
of liberating chlorine from hydrochloric acid can be got by simply
boiling in more or less shallow vessels, more or less freely exposed to air,
either a mixture of protoxide or other low oxide of mangancse with
water or other suitable liquid or the mixture which is obtained when
magnesia is added to solution of chloride of manganese. The exposure
to the atmosphere of the largest possible surface of liquid is very
desirable when performing the peroxidation by this method.
The
peroxidation is also greatly facilitated by constantly stirring or
otherwise agitating the liquid during the process.
XI. The method of peroxidation in the wet way which I greatly
prefer is that by the injection of atmospheric air, ozonized or not, into
and more or less through mixture of oxide or oxides of manganese
with water or suitable solutions, which is one of the main subjects of
the three former Inventions, the dates of the Letters Patent for which
are given in the first paragraph above. A very important part of the
present Invention accordingly consists in the combination of that
method of peroxidizing recovered oxides of manganese with methods
of recovering such oxides, based upon the facts set forth in paragraphs
III., IV., and V. of the present Provisional Specification, with the
decomposition into magnesia and hydrochloric acid of the hydrated
chloride of magnesium obtained as a bye product of such processes of

page_text: recovery, with the plan of allowing a portion of chloride of manganese
to pass round and be decomposed together with such chloride of
magnesium and with the arrangements. and methods of proceedure to
be described below.
XII. I can also peroxidize in the wet way oxide or oxides of
manganese recovered by means of magnesia by agitating in contact
with air any mixture of such oxide or oxides with a suitable liquid,
or, in fact, by any method of bringing as completely as possible all
parts of such mixture into intimate contact with atmospheric oxygen.
No one before me having produced or suggested the production of such
oxides,. I can claim not only particular forms of that general method
of treating them, which happens to be a method susceptible of almost
countless modifications, having no substantial difference one from
another), but the general method or process itself which consists in
peroxidizing such oxides by bringing atmospheric air into as intimate
contact as possible with all parts of a mixture of them with either
water or any more convenient suitable liquid.
XIII. I have found. that oxides of manganese recovered in the wet
way subside more rapidly when chloride of manganese is present with
the solution or mixture of solutions in which they are required to settle
than when it is absent therefrom, and also that they settle better in
slightly acid liquors than in neutral ones. From what has been
explained above it will be seen that these facts can be taken advantage
of when recovering oxides of manganese by means of magnesia, without
any loss either of acid or of manganese.
XIV. The peroxidation of oxides, of manganese recovered under the
present Invention by means of magnesia can be performed either in
the stills in which the peroxidized oxides are afterwards to react with
hydrochloric acid, in order to the liberation of free chlorine therefrom,
and in which the chloride of manganese from which the oxides are
recovered is thereby formed, or the recovery and peroxidation processes
may be performed in vessels distinct from the stills, the chloride of man-
ganese being removed from the latter at every operation. I prefer to
perform the recovery and peroxidation processes in the stills themselves,
and to this end it is a good plan, effecting much economy alike of time
and of size and number of stills, to boil together the "still liquor" and
an equivalent or nearly an equivalent of magnesia until the greater
part of the manganese has been thrown down, then to allow the oxide

page_text: formed to settle, which it will do very rapidly in presence of the chloride
of manganese left undecomposed, then to draw off the clear mixed
solution of chloride of magnesium and chloride of manganese, and
then when that mixed solution has been sufficiently removed to
commence the injection of the oxidizing blast. On this plan when
the right quantity of magnesia has been added at starting, there will
always remain with the oxide of manganese after subsidence enough
magnesia to decompose the chloride of manganese contained in the
liquor remaining with the oxide, and such chloride of manganese will
be decomposed by such magnesia almost immediately after the injection
of the blast has been commenced. The oxide may, if need be, be allowed
to settle again after peroxidation, and more solution of chloride of
magnesium be then drawn off. Usually, however, this will not be
necessary, but acid may be run in upon the mixture of peroxidized
oxide and solution of chloride of magnesium immediately upon the
cessation of the blast.
XV. The absence of all need for the oxide to be allowed to settle after
peroxidation, when the method of procedure is that described in the
paragraph next preceding this, may be secured in all cases by making
the oxidising blast hot instead of cold. This tends in two ways to
prevent it being necessary to allow the oxide to settle after peroxidation,
inasmuch as it not only prevents any necessity for the injection of steam
during the peroxidation, in order to keep the oxide at the temperature
at which it most readily absorbs oxygen, which injection of steam adds
considerably to the bulk of the liquor associated with the oxide, but
making the blast hot also greatly increases the evaporation going on
from that liquor during the peroxidation, thereby diminishing the bulk of
the liquor to much less than it would be after peroxidation by a cold
blast, even if no steam were injected during the peroxidation thereby.
XVII. The hydrochloric acid used by manufacturers of chlorine almost
invariably contains more or less sulphuric acid, and often contains in
addition a small quantity of sulphurous acid which becomes converted
into sulphuric acid in the chlorine stills. I shall propose below certain
methods of removing these acids from hydrochloric acid before the
latter is used in the manufacture of chlorine, but when employing in the
manufacture of chlorine by means of artificial oxides of manganese,
recovered by means of magnesia, hydrochloric acid containing sulphuric
and sulphurous acids, or either one of them, sulphate of magnesium, or

page_text: Epsom salts, is formed in the stills, and accompanies the solution,
whether of chloride of magnesium alone or of chloride of magnesium and
chloride of manganese, which at each operation is drawn out therefrom.
When that solution has been boiled down and the residue decomposed by
heat, the sulphate of magnesium, which suffers no change at temperatures
at which hydrated chloride of magnesium becomes completely decom-
posed, remains behind with the resulting magnesia or mixture of magnesia
and oxide of manganese, from which it can then be readily separated by
being simply dissolved out.
XVIII. The exact methods of proceedure to be adopted, for the
separation of the sulphate of magnesium formed in the chlorine stills
when working under the conditions just stated will depend mainly
upon how far the decomposition of each charge of chloride of magnesium
is carried. If each charge of chloride of magnesium be decomposed
completely, the sulphate of magnesium will be the only soluble substance
remaining with the resulting magnesia, in which case it will be found
a good plan to grind the magnesia with water, and then before adding
the resulting milk or paste of magnesia to the chloride of manganese
which it is to decompose to let the magnesia settle as far as it will, and
then run off from it the supernatant solution of sulphate of magnesium.
If cach charge of chloride of magnesium be decomposed, though not
completely yet nearly so, a solution thus run off from the ground
magnesia will consist of sulphate of magnesium mixed with perhaps
not much more than an equal quantity of chloride of magnesium. In
the former case the solution will only need to be suitably concentrated
in order to yield crystallized sulphate of magnesium, which is a salt
in commercial demand, but in the latter case the mixed solution must
be evaporated down, and then the residue heated until the chloride of
magnesium in it has been completely decomposed, whereupon, as in the
former case, a pure solution of sulphate of magnesium will be got by
treating what remains with water. When the plan followed is that of
decomposing each ordinary charge of chloride of magnesium only very
partially, it will be found to be an advantageous method to take each
day, or, if not cach day, at any longer but regular interval, as much
of the chloride of magnesium solution from each still as will contain,
in the state of sulphate of magnesium, the quantity of sulphuric acid
which goes into the still during the period fixed upon, and to make
of this portion of solution from each still a special charge the chloride

page_text: of magnesium in which shall be decomposed completely. It will come
to the same thing if the total solution from cach still, while being
usually decomposed only partially, be decomposed completely, as regards
the chloride or chlorides in it, once every certain number of times, the
frequency of this occasional complete decomposition depending in each
case upon the amount of sulphuric and sulphurous acids in the hydro-
chloric acid employed. Whichever plan be followed, a quantity of fresh
magnesia equivalent to the sulphate of magnesium formed must of
course be added from time to time to that resulting from the decom-
position of the chloride of magnesium.
XIX. Although the plan just described turns to useful account the
sulphuric and sulphurous acids contained in the hydrochloric acid
employed, I nevertheless greatly prefer to separate such acids before
the hydrochloric acid goes into the stills. I can effect such separation
by passing the hydrochloric acid gas before it, reaches the condensers
used at present through any suitable intermediate condenser, the special
function of which shall be to condense or otherwise abstract the sul-
phuric acid, together with certain other contaminating bodies, while
condensing as little hydrochloric acid as possible. If I desire to obtain
the sulphuric acid in the free state, I either feed this condenser as nearly
as I can with no more water than will suffice to condense the sulphuric
acid and a minimum of hydrochloric acid, allowing the great bulk of the
hydrochloric acid to pass on, or, if feeding it with a larger quantity of
liquor, I pump the liquor which runs from it back again a considerable
number of times, whereby I eventually obtain it as a pretty strong sul-
phuric acid, containing only a small per-centage of other bodics. Instead
of thus obtaining the sulphuric acid in the free state I can obtain it as
a useful sulphate by feeding the condenser instead of with water simply
with solution of a metallic chloride, as chloride of iron, chloride of
magnesium, or chloride of sodium, etc. When the hydrochloric acid
contains and I desire to separate sulphurous as well as sulphuric acid,
I feed the condenser either partially or entirely with solution of
perchloride of iron, whereby the sulphurous acid is oxidized, and there
is produced a protosulphate of iron, which last tends to still further
purify the hydrochloric acid by destroying any nilrous vapours, and
also any free chlorine which it may contain. These methods are of
course applicable also to the purification of hydrochloric acid for use
for other purposes than for the manufacture of chlorine, and also to the

page_text: purification of hydrochloric acid for use in the manufacture of chlorine
otherwise than by means of artificial oxides of manganese.
XX. These methods of purifying hydrochloric acid from sulphuric
and sulphurous acids remove the only difficulty which has been met
with in practising on the large scale the manufacture of chlorine by
means of oxides of manganese recovered by means of lime, and peroxi
dized in the wet way under my former Inventions already referred to.
The sulphate of calcium formed when working with lime and using a
hydrochloric acid containing either sulphuric acid or sulphurous acid, or
both, not only rapidly accumulates, and so tends to choke the stills,
but acts also very prejudicially in other ways. It seems to retard and
partially prevent the peroxidation of the recovered oxide (probably by
crystallizing upon the particles of oxide, and so to some extent pre-
venting the access of air to them); it seems similarly to retard the
solution of the regenerated oxide; and dissolving each time that hydro
chloric acid is added, and when the hydrochloric acid is neutralized
resuming the state of a pulpy mass of light feathery crystals, it most
materially retards the subsidence of the regenerated oxide. Now, how-
ever, that the formation of sulphate of calcium when working with
lime in the process aforesaid for the manufacture of chlorine by means
of oxides of manganese regenerated in the wet way can be avoided, it
will doubtless be the case that certain conveniences which attend the
use of lime in that process will sometimes be found to outweigh the
advantage in point of quantity of chlorine obtained from a given
quantity of hydrochloric acid, which results from the use of magnesia
therein. Parts of the present Invention therefore consist in improve-
ments. which are as applicable when that process is performed by
means of lime as when it is performed by means of magnesia, and
of such are the use for the peroxidation of low oxides of manganese
in the wet way of oxygen gas (which I believe will shortly be producible
cheaply enough to admit economically of such application of it), either
instead of atmospheric air or in. conjunction therewith, and in aid
thereof; the similar employment of gaseous oxides of nitrogen; the
use of the air or oxidizing gas or mixture of gases under pressure;.
the performance of the peroxidation by drawing instead of injecting the
air or other gaseous oxidizing body into or through the mixture of oxide
and liquid; the use of heat to facilitate the peroxidation when effecting
it in the wet way, by any method other than that of injecting air into or

page_text: through the liquid mixture containing the oxide; the performance of
the peroxidation by injecting the air or other gaseous oxidizing body,
instead of into the mixture of oxide and liquid, on to the surface of the
mixture, such mixture being at the same time agitated or not by means
of mechanical agitaters; and the exposure of the mixture of oxide and
liquid to intimate contact with air or other gaseous oxidizing body by
applying the air or other body by means of a large apparatus on the
same principle as that of the little instrument known as the " spray
diffuser." When oxygen gas is used for the peroxidation of oxides of
manganese by the wet way it can either be ozonozed or not, and when
the air or other gaseous body is applied under pressure the said air or
other body may either simply issue into the vessel containing the
mixture of oxide and liquid under a greater pressure than that due only
to the depth and density of the liquid mixture, no pressure above that
being maintained in such vessel itself; or the vessel containing the
mixture of oxide and liquid may be a closed vessel, from which no air
or gas can escape except by lifting a loaded valve.
XXI. When the agent employed to peroxodize low oxides of man-
ganese by the wet way is atmospheric air, I like, before using the air for
that purpose, to separate its carbonic acid from it as completely as
possible. When carbonic acid is contained in the air so employed,
such carbonic acid is apt to form carbonates with any free portion of the
lime, magnesia, or other oxide employed to decompose the chloride of
manganese, and not only is that oxide thereby rendered to that extent
incapable of acting upon any undecomposed chloride of manganese
which may be present, but the carbonates so produced remain with the
peroxidized oxide of manganese, and when the latter is treated with
hydrochloric acid they give off their carbonic acid, which mixes with the
chlorine liberated from the hydrochloric acid by the oxide of manganese,
often greatly to the prejudice of the product which the chlorine is
required to form. This formation of carbonates is prevented by depriving
the air, before it comes in contact with the mixture of oxide of manganese
and other substances, of the carbonic acid contained in it, and this
separation of carbonic acid can be readily effected by causing the air to
be either drawn or forced through or otherwise brought into intimate
contact with any liquid, such as milk of lime or an alkaline solution,
which will sufficiently readily absorb carbonic acid gas, or else to be
either drawn or forced through a chamber, tower, or other apparatus
containing any solid substance capable of serving the same end.

page_text: XXII. It is the custom of some alkali makers to inject air into their
crude soda liquors, or to pass them through towers through which air is
drawn, in order to oxidize the sulphides contained in them, and it is
also sometimes the custom to similarly treat these liquors with carbonic
acid gas in order to convert any caustic alkali which they may contain
into carbonate. I believe it would be a good plan to pass the air useḍ
to peroxidize low oxides of manganese first through such crude soda or
potash liquors, whereby, while the sulphides in those liquors would be
oxidized without materially impoverishing the air of oxygen and so
lossening its power to act upon the oxides of manganese, the air would
not only be deprived of its carbonic acid, but the separation of the
carbonic acid from it would be effected without incurring any cost
specially for that purpose, and its carbonic acid would moreover be
turned to account.
23. When working, as it will sometimes be most convenient to
do, at once with lime and with hydrochloric acid which has not been
purified from sulphuric acid, I take advantage for the separation of
the sulphate of calcium formed under such circumstances of the facts that
whereas sulphate of calcium is very considerably soluble both in free
hydrochloric acid and in hot solution of chloride of manganese, it is
but slightly soluble in solution of chloride of manganese when such
solution is both cold and neutral. By neutralizing any free acid
which may be associated with the chloride of manganese and letting
the solution cool, I can therefore cause the greater part of the sulphate
of calcium to crystallize out. It can then be readily eliminated, either
by filtration, or by subsidence and decantation, or by a combination of
both methods.
24. When working with lime, whether or not under circumstances
under which sulphate of calcium is formed, there will always be
impurities derived from the lime itself which will require removal from
time to time. These will be chiefly silica and alumina, which last
will go into solution as sesqui-chloride of aluminium. The addition to
the still liquor of enough lime or other suitable agent (over and above
the quantity required to neutralize the free acid in it, if any), to
decompose the chloride of aluminium will enable both these impurities
to be got rid of in the same way as sulphate of calcium and at the

page_text: :25. As hydrochloric acid produced in the manufacture of alkalies
invariably contains iron, that element, alike when working with
magnesia and when working with lime, will accumulate in the still
.liquor.unless occasionally removed. It will always exist therein mainly
¡if.not exclusively as sesqui-chloride of iron, which should be treated
precisely in the same way as the chloride of aluminium.
"
:26. The methods to be adopted for the systematic separation of
the impurities spoken of in the last three foregoing paragraphs will
depend upon whether the decomposition of the chloride of manganese
and the peroxidation of the resulting oxide are performed in the stills
or in separate vessels. When these operations are performed in the
stills I like to remove from each still at every operation (after the
first half-dozen or so, more or less, according to the amount of the
impurities entering the still or formed within it at each working), such
a proportion of the still liquor as shall contain a quantity of the
impurities to be eliminated as nearly as possible equal to the quantity
added to the still liquor during each operation, cach time replacing
the quantity so removed by an equivalent quantity of pure liquor.
Suppose, for example, that I am working ten stills, that I produce
in each about a thousand cubic feet of still liquor at each operation,
that I have got accumulated in each still the impurities resulting from
ten operations, and that I now desire that impurities shall not
accumulate any further; I run off one hundred cubic feet of liquor
from each still, and run in a like quantity of previously prepared pure
liquor. The impure liquor thus run off I purify while the next operation
in the stills is being performed, and at the end of that operation I again
run off one hundred cubic feet of liquor from each still, this time
replacing the liquor run off by the now purified liquor run off at the
end of the preceding operation. Thenceforth I proceed in this way
continually, at the end of every operation running off a portion of
impure liquor from each still and putting in its place a corresponding
quantity of the liquor which was run off at the end of the last preceding
operation, but which has in the meantime been purified. The purification
on this plan may, of course, be performed less often than at the end
of every operation, but I prefer to perform it after every operation,
excepting the first few, so that, after the first few times, the still liquor
with which operations are commenced shall be always in as nearly as
possible the same condition.

page_text: 27. When purifying the still liquor on the plan thus set forth, I
provide a reservoir called a "purifier," into which I send the impure
liquor from every still. I prefer to place this purifier below the stills
so that the impure liquor may run from the stills into it, but where
this is not convenient it may be placed above the stills, and the impure
Liquor be pumped or otherwise lifted into it. Where the number of
stills is considerable it may be necessary to have more purifiers than
one, but the mode of proceeding will of course be just the same as
when only one is employed. In the purifier the impure liquor is
treated with either magnesia or carbonate of magnesia, or else with
either lime or carbonate of lime, in just sufficient quantity to neutralize
the free acid in it (if any)-and to decompose what chloride of iron and
chloride of aluminium it may contain. It is then either left at rest
so that its impurities may subside and the clear liquor be then run off
or otherwise decanted into a second reservoir or "cleared liquor tank,"
or, which I believe to be the preferable plan, it is run on to a filter
bed, and the clear liquor separated by filtration. Whichever of these
methods be adopted, the cleared liquor is lastly pumped up into a
tank or reservoir suitably placed above the level of the stills, and
suitably connected with each still, so that the cleared or purified
liquor can be run therefrom into the stills as required.
28. When the working of my process is conducted with proper
.care, the liquor in each still will always, after each operation, be at
the same level, almost exactly. Each still should have a tap at that
level, and another tap at the level to which impure liquor is to be
run off each time, and the instructions to the workmen should be to
open the lower of these taps the moment the still has ceased to give
off chlorine, and when this tap has ceased running to close it and let.
liquor run in from the upper reservoir of cleared liquor to the level
of the upper of these two taps. The running off of the right quantity
of impure liquor and the running in of the right quantity of purified
liquor can thus be confided to unskilled workman, with but little risk
of any mistake being made.
29. When the decomposition of the chloride of manganese and
the peroxidation of the resulting oxide are performed in vessels other
than the stills, the purification of the still liquor should be effected in
apparatus placed intermediately between the stills and the vessels in
which the recovery and peroxidation processes are thus conducted.

page_text: This apparatus may conveniently consist of three reservoirs, into one
of which liquor from the stills shall be constantly entering for a given
period, in another of which such liquor shall be treated with a suitable
quantity of lime or magnesia or carbonates thereof and then be left at
rest for the same period, and into the third of which the clear liquor
contained in the second reservoir, after all solid impurities have
subsided therein, shall be pumped, run, syphoned, or otherwise decanted,
the vessel or vessels in which the recovery of oxide of manganese
from the purified liquor is effected being then supplied from this third
reservoir.
30. In this case, however, equally as when performing the recovery
and peroxidation processes in the stills themselves, it is perhaps better
to effect the separation of the solid impurities contained in the liquor
after it has been treated with lime or magnesia, or carbonate thereof,
as aforesaid, by filtration instead of by subsidence. In either casc
if the whole of the liquor be not filtered the sediment left after
decantation of the clear liquor in the reservoir in which the impurities
subside should be thrown on suitable filter beds, and there allowed to
drain thoroughly, the drainings running into the cleard liquor reservoir.
This sediment will usually be so retentive of liquid that much manganese
would otherwise be thrown away with it.
XXXI. Or, instead of filtering the sediment in question, all associated
liquor may be separated from it by means of centrifugal hydro-
⚫extractors.
XXXII. When using filters it will be found advantageous to so
arrange that there shall be no communication while the filtration is
.going on between the cleared liquor reservoir and the atmosphere,
excepting through the pores of the filter, and to keep a partial
vacuum in the said reservoir by means of an exhaust pump. This
plan, however, need be adopted only when the filtration is required
to be effected more rapidly than it will usually be necessary to
perform it.
XXXIII. The three reservoirs to be used, as described in para-
graph XXIX., should, when convenient, be placed at successively
lower levels, so that the liquor may run from the first of them into
the second, and from the second into the third. The number of
reservoirs may be other than three, but three will usually be found
most advantageous. I prefer that the vessel or vessels in which the

page_text: liquor from the third or other final reservoir is decomposed' and: the
resulting oxide peroxidized should be situated at a much higher-level;
so that while the liquor from this "cleared liquor reservoir."" will
require pumping up into such vessel or vessels, the mixture of per-
oxidized oxide of manganese and solution of chloride of other metal
formed in such vessel or vessels may run from it or them to the level
of the stills, and so a single pumping be made to suffice. A single
pumping, however, will be equally sufficient if the regeneration of
the oxide be effected at or below the level of the cleared liquor reservoir,
and the mixture of oxide of manganese with either water or solution
of chloride of magnesium, chlorido of calcium, or chloride of any other
metal be pumped. therefrom to such higher level as may be necessary.
XXXIV. The separation of the peroxidized oxide from as much as
it may be necessary to remove of the liquor in which it was formed
should be effected when the oxide is regenerated in vessels other than
the stills, in vessels specially devoted to the purpose of such separation.
A good plan is to place at the back of or otherwise associate with
each still a reservoir (which may be of wood, iron, or any other con-
venient material) capable of holding as much mixture of regenerated
oxide of manganese and liquor in which it was formed as shall contain
oxide enough for one charge of the stills, and to run or pump or
otherwise propel or convey into each such reservoir such quantity of
mixture of oxide and liquor directly from the vessel or vessels in
which the oxide is formed, allowing one charge to settle in each
such reservoir while another charge is being worked in its associated
still.
XXXV. Another plan is to run or pump or otherwise convey the
mixture of oxide and liquor from the vessel or vessels in which it is
formed into a large tank to allow it to settle therein, to then decant
off the clear liquor, and to then run or pump or otherwise convey
the oxide to the stills in the state of the thick mud, which is. the
state in which the oxide remains after it has subsided as far as it will,
and the clear liquor has then been decanted from above it.. When
adopting this plan it is well to have three such tanks or reservoirs, into
one of which mixture of oxide and liquor can be constantly being put
for some suitable period; in a second, of which the mixture of oxido
and liquor can be left at rest for the same period; and from the third.
of which during the same period oxide can be supplied to the stills..

page_text: XXXVI. Other methods of separating the oxide from the proportion
of associated liquor which it is necessary to remove from it consist in
running the mixture of oxide and liquor on to filter beds, or into pits,
on or in which it may remain untill drained nearly or quite dry. Or
with or without previous washing it may be dried more or less completely
by the direct application of heat.
.
XXXVII. When it is desired to wash the oxide, either as a pre-
liminary to drying it or otherwise, the washing may be performed
either on filter beds or in tanks or other vessels. In the last case
water may be kept constantly running in at the bottom of the vessel
and constantly running out at the top at such rate as not to carry
with it any oxide; or a hollow filter may be forced down into thie
mixture of oxide and liquor and be kept constantly nearly empty by
means of a fixed syphon, while water is run into the vessel containing
the mixture of oxide and liquor in proportion as liquor is removed by
the syphon from inside the hollow filter.
XXXVIII. The stills used for the manufacture of chlorine from
hydrochloric acid by means of native oxides of manganese, and also
those used for the manufacture of chlorine by means of such artificial
oxides as have hitherto been in use, have invariably been more or less
shallow, either their width or their length, when not both their width
and their length also, being greater than their depth. Such stills,
however, are not convenient when working with artificial oxides
regenerated in the stills themselves. In that method of working it is
better for obvious reasons to employ stills whose depth is greater than
either their length or their width.
XXXIX. When thus employing stills whose depth is their greatest
dimension it is a good plan to sink them into the ground so far that
the lowest point to which it shall be necessary, in ordinary working,
to draw off liquor from them shall be just at the level of the ground,
or thereabouts. When the stills cannot be thus sunk in the ground,
I recommend that they be partially buried in artificial embankments.
XL. It will sometimes be found convenient to use stills only the lower
part of which shall be of stone or other substance not readily acted
upon by either hydrochloric acid or free chlorine, the upper part being
of iron or any other suitable material not specially capable of resisting
corrosion by acids. In such cases the arrangements must be such that
the contents of the still, when acid, shall never rise above the upper

page_text: Timit of the stone portion of the still, the function of the portion above
that limit, and made of other material, being simply to afford space for
any liquor which, in the particular system of working; followed, it may
be necessary to add to the "still liquor" proper, after the evolution of
chlorine therefrom has ceased, and for whatever froth or spray may be
formed during the subsequent blowing. Stills of this kind should have
a movable cover or lid, admitting of being readily fixed in its place just
before running in acid upon the recovered oxide, and of being as readily
lifted out after the completion of the reaction between the acid and
oxide. The place of such movable cover should be at or just below the
upper limit of the lower portion of the still.
XLI. Hitherto the pipe by which the oxidizing blast has been
injected into stills in which oxide of manganese has been recovered
from chlorine residues by my method has always been of iron, and
so has had to be removed before the running in of acid each time,
and to be afterwards replaced before the commencement of each
peroxidizing operation. It is far better to make this pipe of either
stone, or earthenware, or ebonite, or other convenient substance,
not readily attacked by either chlorine or hydrochloric acid, so that
it shall not need, as hitherto, to be removed and replaced in the
course of every operation.
XLII. It is sometimes a good plan to so arrange that the steam
required to be injected at one stage or other of the operations conducted
in the still shall enter by the same pipe as the oxodizing blast.
"
XLIII. A very serviceable pipe by which to inject into the stills
cither the steam required, or the oxidizing blast, may be made
by placing an earthenware or "mug pipe of the required bore
inside another of larger bore, making the joints in each pipe with
lead, and either filling the whole space between the outer pipe and
the inner pipe with lead, protected by a coating of "black cement"
at any point at which it would otherwise come in contact with either
chlorine or acid, or else attaching the two pipes together by means
of lead only at the joints in each, and filling the rest of the space:
between them with any other substance that may be preferred.
XLIV. Good pipes for the purposes in question may also be made
by boring longitudinal blocks of red sandstone, or other available
silicious stone. It is possible that suitable pipes could likewise be
made of some varieties of artificial stone..

page_text: XLV. Experience has shown that stills in which oxide of manganese
is recovered and peroxidized by my method need not have false
bottoms to distribute the blast, provided that the blast be injected
with sufficient vigour. I sometimes prefer, however, to make the
bottom of the still of the shape of an inverted truncated cone, and
to place a small false bottom in the centre, at the lower part of such
inverted truncated cone; and if I make such or any other false
bottom used in my process of stone or earthenware slabs, I prefer
to make the holes in it conical, cach hole being much wider at the
under than at the upper side of the false bottom.
XLVI. It will sometimes be desirable, when working with lime,
to take advantage, as follows, of the fact stated in paragraph XII.,
together with the further fact of the solubility of sulphate of calcium
in hydrochloric acid. Suppose that a peroxidizing operation has just
been completed in a given still, and that it is desired that the oxide
produced shall be caused to subside with the utmost possible rapidity;
let hydrochloric acid be immediately added to the contents of the
still, but in quantity insufficient to dissolve any peroxide of manganese.
If the peroxidized oxide be quite up to a hundred per cent. strength,
which will probably happen only very rarely, dilute hydrochloric acid
will not dissolve any of it, though it will very materially increase the
rapidity with which it will settle. The clear acid solution in such case
remaining above the subsided oxide may either be thrown away, or its
free acid may be evaporated off and condensed for use, or be turned to
account in any other convenient manner. If, however, the peroxidized
oxide be at a lower strength than a hundred per cent., the dilute
hydrochloric acid will dissolve protoxide from it, and the quantity of
hydrochloric acid used may easily be so regulated as to leave only
peroxide of a hundred per cent. undissolved. In such cases, when the
peroxide from which all or part of the protoxide at first associated with
it has been dissolved out has subsided, the supernatant solution will
contain more or less chloride of manganese, and so must not be thrown
away until such chloride of manganese shall have been decomposed.
The mixed solution containing this chloride of manganese should
accordingly be run into a supplementary vessel associated with the
still, and be there treated with a quantity of lime equivalent to the
chloride of manganese contained in it. The resulting protoxide of
manganese should then be allowed to settle, and the supernatant

page_text: solution be then drawn off from it; all which can be done while the
oxide in the still is being digested with hydrochloric acid. Then,
on the cover of the still being removed for the addition of lime and
the commencement of a new recovery operation, the protoxide in the
supplementary vessel (which protoxide will now be in the state of thick
mud) should be pumped into the still, there to undergo peroxidation
together with the protoxide resulting from the decomposition of the
chloride of manganese formed by the reaction together of the oxide
which was left in the still and the hydrochloric acid from which that
oxide has liberated chlorine.
XLVII. The plan just described is equally available when working
with magnesia, in which case also another similar plan will sometimes
be useful. Thus, when a quantity of still liquor has been boiled in a
still or other vessel with an equivalent of magnesia until the greater
portion but not the whole of the chloride of manganese in such
liquor has been decomposed, and the resulting oxide of manganese has
been allowed to subside, and the supernatant mixed solution of chloride
of magnesium and chloride of manganese has been drawn off from it,
instead of treating that mixed solution as described in paragraph III.,
it may be run into a supplementary vessel and boiled therein with an
excess of magnesia until the chloride of manganese contained in it
has been all decomposed. The contents of such supplementary vessel
will then consist of a mixture of magnesia, protoxide of manganese,
and solution of chloride of magnesium. The latter having been more
or less completely removed, either by filtration or by subsidence and
decantation, the remaining mixture of magnesia and protoxide of
manganese can be used, instead of magnesia only, in the next recovery.
operation in the still, and so on continually.
:
XLVIII. As regards everything that has to be run off from the
stills, it will be well always to work by fixed taps in the sides of the
stills, upon the plan suggested in paragraph XXVIII. It will be a good
plan, also, at least in some modes of working, to measure the acid
put into the stills by running it in from the level of one tap to that of
another.
XLXIX. When recovering the oxide in the stills and working a
number of stills, it will usually be most economical to so arrange a
system of alternate working that the blowing engine shall be kept going
constantly.

page_text: L. It will sometimes be advisable, when not convenient to, separate
the sulphuric acid contained in the hydrochloric acid employed by
the methods described in paragraph XIX., to separate it, either in the
stills or before the acid enters therein, as sulphate of barium.
LI. Under some circumstances it will be advantageous to use
ammonia, instead of either lime or magnesia, as the agent for the
decomposition of the chloride of manganese.
LII. Lastly, the method of peroxidation described in paragraph X. is
available, so far as it is available at all, whatever the agent by which
the chloride of manganese is decomposed.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
.filed by the said Walter Weldon in the Great Scal Patent Office
on the 18th August 1868.
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 Twentieth day of February, in the
year of our Lord One thousand eight hundred and sixty-cight, in the
thirty-first 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 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 "IMPROVEMENTS
RELATING PRIMARILY TO THE MANUFACTURE OF CHLORINE BY MEANS OF
ARTIFICIAL OXIDES OF MANGANESE, BUT PARTLY APPLICABLE ALSO TO OTHER
PURPOSES, BEING IMPROVEMENTS IN THE DECOMPOSITION OF CHLORINE RESIDUES,
IN THE PEROXIDATION OF OXIDES OF MANGANESE RECOVERED THEREFROM, IN THE
TREATMENT OF A BYE PRODUCT OF THE DECOMPOSITION OF THOSE RESIDUES, IN
THE SEPARATION OF SULPHURIC ACID AND OTHER IMPURITIES FROM THE HYDRO-

page_text: CHLORIC ACID EMPLOYED, AND IN APPARATUS AND ARRANGEMENTS FOR SOME OF
THESE PURPOSES," upon the condition (amongst others) that I, the
said Walter Weldon, my executors or administrators, by an instru-
iment 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 the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in
and by the following statement (that is to say) :-
1. This Invention consists in certain improvements relating primarily
to the manufacture of chlorine by means of artificial oxides of man*
ganese regenerated from the chloride of manganese, which is a residual
product of the manufacture of chlorine whenever that manufacture is
conducted, as it is invariably in this country, and nearly if not quite
so in all other countries likewise, by causing previously generated
hydrochloric acid and a suitable oxide of manganese to react directly.
upon each other. The said improvements have reference, principally
and essentially, firstly, to the decomposition of the residual chloride
of manganese aforesaid, in order to the transformation of the base of
that compound from its state of combination with chlorine to a state
of combination with oxygen; secondly, to the treatment of a bye
product of such decomposition of chloride of manganese; thirdly, to
the peroxidation of oxides of manganese obtained from chloride of
manganese, and to the separation of carbonic acid from atmospheric
air used, for that purpose; fourthly, to the purification of the hydro-
chloric acid employed to react with and dissolve the regenerated oxide;
and, fifthly, to the apparatus and arrangements for accomplishing some
of the objects. Incidentally and subordinately, the said improvements
have reference also to the manufacture of alkalies; to the manufacture
from chloride of magnesium of magnesia for use for other
than
purposes
for the decomposition of chloride of manganese; to the purification of
hydrochloric acid used otherwise than in the manufacture of chlorine
by means of artificial oxides of manganese regenerated in the wet
way; and to the utilization of the sulphuric and sulphurous acids with

page_text: which the hydrochloric acid produced in the manufacture of alkalics by
the ordinary or Leblanc process is almost invariably contaminated.
2. The manufacture of chlorine by means of regenerated oxides of
manganese has hitherto been practised only with oxides peroxidized in
the dry way, and its manufacture by means of such oxides has been
found to be attended with so little advantage that in Great Britain
it has never extended beyond a single fium of manufacturers, while on
the Continent, owing mainly to the greater costliness of fuel there than
in this country, the use in the manufacture of chlorine of artificial
oxides of manganese regenerated by any process having the recovery
of oxides of manganese for its sole or main object, and capable of
regenerating them in any considerable quantity, has never proved
commercially practicable at all. At one continental factory, that at
Dienze, in France, artificial oxides of manganese are now being used
in the manufacture in question, but only to a very insignificant extent,
the artificial oxides there employed being obtained, not directly and
as the product for which the process by which they are regenerated is
chicfly practised, but indirectly, as a bye product of a process for the
regeneration of sulphur from alkali waste. A detailed statement of
the results of the first six months' working of that sulphur-recovery
process was published, by authority, in the number of the 15th of March
last of the "Moniteur Scientifique," from which it appears that during
the six months in question (being the last six months of 1867), whereas
no less than forty cubic mètres of alkali waste were treated per day, the
treatment thereof occupying forty workmen, and yielding, during the
six months, enough recovered sulphur for the production of 787,352
kilogrammes of sulphuric acid of sixty degrees Beaume, the total yield
of recovered oxide of manganese during the same period was only
18,432 kilogrammes, or but slightly over eighteen English tons. So far
as I can ascertain, the one factory in which is practised the sulphur-
recovery process which thus yields as a bye product so small a pro-
portion of recovered oxides of manganese is the only factory on the
Continent in which such oxides are produced at all; while the one
firm of manufacturers in this country, who are thus the only manu-
facturers in the world who produce chlorine in any considerable
quantity by means of recovered oxides of manganese, do not find it
commercially practicable to manufacture more than a portion of their
total production of chlorine by means of oxides regenerated and

page_text: peroxidized by the method which they employ. The chlorine manu-
factured at present by means of artificial oxides of manganese thus
amounts only to a very small per-centage of the total quantity
manufactured, and does not cost appreciably less than the chlorine
manufactured in the ordinary way, which is by means of native oxides
of manganese. The oxides, whether native or artificial, which are at
present used by manufacturers of chlorine, cost, on an average, at
least five pounds, and often considerably more than five pounds, per
quantity of chlorine required to make a ton of bleaching powder;
but for the last two years I have been engaged in working out a
process for the perpetual regeneration of the oxides of manganese
employed for the liberation of chlorine from hydrochloric acid, which
experience has already proved to be capable of regenerating at
a cost not exceeding one pound the quantity of oxide required for
the liberation of the quantity of chlorine necessary to the production
of a ton of bleaching powder, while the said process will moreover
enable the manufacturer to obtain, from a given quantity of hydro-.
chloric acid, from one-and-a-half times to twice as much chlorine,
when the process is performed by means of lime, and from five times
to six times as much chlorine, when the process is performed by means
of magnesia, as can be practically obtained from such quantity of acid
by means of the oxides in use now. Whereas, as already mentioned,
such recovered oxides of manganese as have been used hitherto have
invariably been peroxidized in the dry way, the new process of which
I speak is performed wholly in the wet way; the said new process, in
its original form, consisting, essentially, in first decomposing chloride
of manganese in solution by means of any suitable oxide of other
metal, but more especially by means of either lime or magnesia, so as to
obtain therefrom a low hydrated oxide of manganese, and in then
peroxidizing such low hydrated oxide by injecting air into a mixture of
such oxide with a suitable liquid. For the first form of this process
Her Majesty's Letters Patent. were granted to me on the Twenty-sixth
day of July, in the year of our Lord One thousand eight hundred and
sixty-six, and for various improvements upon the original form of
it two subsequent grants of Letters Patent, dated respectively the
Eigthteenth day of January and the Fourth day of September, both
in the year of our Lord One thousand eight hundred and sixty-seven,
have likewise been made to me. The improvements constituting the
present Invention are for the most part further improvements of the

page_text: just named.
3. One of the most important of those of the improvements
'collectively constituting the present Invention which relate to the use
of magnesia for the regeneration of oxide of manganese in the wet
way has reference to the decomposition by means of that agent of
the chloride of manganese which is the essential constituent of what
are known as "chlorine residues," being "the mixture of various
chlorides (in which, however, chloride of manganese usually greatly
predominates) which remains in the stills used for the generation of
chlorine after hydrochloric acid and peroxide of manganese have
reacted upon each other therein. Chloride of manganese when in
'solution in water, which is the state in which it exists in the residues
in question, is decomposed extremely readily, at all ordinary tem-
-pératures, alike by lime, baryta, soda, and potash; but of these four
bodies the last three are at present far to costly to be used to effect
that decomposition on the large scale. Lime is the only one of these
four reagents which is at present available for the decomposition of
chloride of manganese as a manufacturing operation, and it shares
with the three others the disadvantage that the chloride which is formed
by double decomposition between it and chloride of manganese is an
exceedingly stable compound, not susceptible, so far as is at present
-known, of being decomposed by any method cheap enough for practical
-use in connexion with the manufacture of chlorine. Hence, when lime
is the agent employed to transform into the protoxide the chloride of
manganese produced in that manufacture, not only can such agent
be used only once, but the chlorine which it is employed to abstract
from the chloride of manganese is practically lost, since it forms with
the metallic base of the lime a compound which has at present but
very few uses in the arts, and which, as has already been said, cannot,
by any yet known method, be economically decomposed. It is true
that, when chlorine is manufactured by means of artificial oxides of
-manganese regenerated and peroxidized by my process as described in
'paragraph 2, there is obtained, even when lime is used for the decom-
-position of the chloride of manganese, and notwithstanding the just
-mentioned loss of chlorine as chloride of calcium which then takes
place, a very much larger yield of chlorine, per given quantity of
hydrochloric acid, than is obtained in the ordinary process of manu-

page_text: facturing chlorine by means of native oxides of manganese, or than
in the manufacture of chlorine by means of any such recovered oxide's
of manganese as have been used hitherto; but I have desired not
only to greatly reduce the very heavy cost which manufacturers of
chlorine have always hitherto had to incur for oxides of manganese,
but also to render the whole of the chlorine in their hydrochloric
acid economically obtainable, either wholly as free chlorine, or partly as
free chlorine and partly in some form of combination in which it is
more useful than when locked up in a neutral and highly stable
compound like chloride of calcium. Accordingly, one part of the
"Improvements in the Manufacture of Chlorine," for which Her
Majesty's Letters Patent, numbered 1948, and dated the Twenty-sixth
day of July, in the year of our Lord One thousand eight hundred and
sixty-six, were granted to me as aforesaid, consists in a certain employ-
ment of magnesia for the decomposition of chloride of manganese, in
order to the recovery therefrom of oxides of manganese available for
use in the manufacture of chlorine; the advantage which the use of
magnesia for this purpose possesses over the similar use of lime being
due to the readiness with which the resulting hydrated chloride of
magnesium can be decomposed, by the simple action of heat, into
magnesia and hydrochloric acid, so as virtually to enable the same
magnesia to be used over and over again continually, and the chlorine
which it removes from the chloride of manganese to be recovered in
a practically available form. In the Final Specification filed in pur-
suance of the conditions of the said Letters Patent, however, I was
obliged to point out that in the interval which had elapsed, when
that Final Specification was drawn up, since the preparation of the
Provisional Specification of the improvements to which it referred, I
had found that ordinary qualities of magnesia would not decompose
chloride of manganese completely, when using only an equivalent
proportion of the magnesia and treating the two bodies together by
the method which those Specifications describe. "I have since found,"
I explain in the said Final Specification, "that magnesia from different
sources, as was already known to be the case with lime from different
sources, differs greatly in chemical activity, 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 an equivalent of chloride of manganese when only boiled
"therewith for a minute two;" and I afterwards proceed to remark that
"

page_text: "the source whence which may be procured I am unable to indicate."
I have now to record certain new discoveries, by taking advantage of
which magnesia from any source whatever may be rendered available
for the decomposition of the chloride of manganese in chlorine residues,
so that any manufacturer of chlorine may now command the advantages
resulting from the decomposition of his chloride of manganese by means
of magnesia.
4. One important fact which has not been hitherto known, but which
I have found by experience, and which is of itself sufficient to render
almost any kind of magnesia available for the purpose under con-
.sideration, is that if hydrated chloride of magnesium have a portion of
chloride of manganese associated with it, the subjection of the chloride
of magnesium so associated with chloride of manganese to a heat
suitable to effect, the decomposition of the chloride of magnesium results
in the decomposition, not alone of the chloride of magnesium, but of
the chloride of manganese as well, the chlorine of both compounds flying
off either wholly or chiefly as hydrochloric acid, and a mixture of
magnesia with an oxide of manganese containing at least as much
oxygen as is contained in sesqui-oxide or Mn2Os remaining behind. The
manganese is yielded as sexqui-oxide even when the chloride of mag-
.nesium and chloride of manganese are associated. together in the
proportion of equivalent per equivalent, and however high the tem-
perature which may be used for the decomposition of the mixed
chlorides; but when the proportion of the chloride of manganese to
the chloride of magnesium is only small, and the temperature at which
the mixed chlorides are decomposed is below full redness, the oxide of
manganese in the resulting mixture of oxide of manganese and magnesia
is in a higher state of oxidation than sesqui-oxide. It follows that a
chlorine manufacturer desirous of decomposing his chloride of manganese
by means of magnesia in the wet way, and of then decomposing the
resulting hydrated chloride of magnesium into magnesia, for use over
again, and hydrocholic acid, for application to any purpose for which he
may require it, need not be anxious to obtain a complete decomposition
in the wet way of his chloride of manganese by his magnesia, but may
be content to let a moderate portion of his chloride of manganese remain
unacted upon in the wet way, and to allow this portion, or as much of

page_text: it as may be convenient to pass round with the chloride of magnesium
resulting from an incomplete decomposition by magnesia in the wet way
of the mass of his chloride of manganese. By so doing he will incur no
loss of materials, seeing that as just explained both elements of such
portion of the chloride of manganese as may thus be submitted to the
same treatment as the chloride of magnesium came safely round, the
chlorine either entirely as hydrochloric acid, or mainly as hydrochloric
acid and partially as free chlorine, and the manganese as a valuable
oxide. When, in the Final Specification, quoted above, of my Patent
of the Twenty-sixth of July One thousand eight hundred and sixty-six,
I said that I could "not recommend" the use of magnesia in my
process therein described, except to manufacturers having command
of a special quality of magnesia, it was because I then considered it
essential that a complete decomposition of the chloride of manganese
should be effected before the operation of peroxidizing the resulting
protoxide of manganese began, and I then knew of no method of causing
magnesia to decompose chloride of manganese except that of boiling
the magnesia with the chloride of manganese in solution, and I had
just found that ordinary qualities of magnesia, unless used in imprac-
ticable excess, would not completely decompose chloride of manganese,
when simply boiled therewith, under any conditions which I had then
tried; wherefore it seemed to me that ordinary qualities of magnesia
could not be used in the process in question with sufficient advantage.
Now, however, that I have discovered that chloride of manganese, when
associated with hydrated chloride of magnesium subjected to decom-
position by heat, itself undergoes decomposition as above set forth, the
fact that ordinary qualities of magnesia will not completely decompose
chloride of manganese by being boiled therewitli in simply equivalent
proportions is no longer an objection to the use of such qualities of.
magnesia for the regeneration of oxides of manganese in the wet way:
This discovery renders it no longer essential to the economical use of
magnesia for the decomposition in the wet way of the chloride of
manganese in chlorine residues that the magnésia should be of a quality
capable of effecting, by simple boiling therewith in the proportion of
equivalent to equivalent, that complete decomposition of the chloride
of manganese which is prescribed in the Specifications aforesaid, and
the use of a quality of magnesia capable of effecting which by the
treatment described I regarded, at the dates of those Specifications, as
essential to the advantageous use of magnesia for that purpose at all.

page_text: As all ordinary qualities of magnesia, provided only that they have not
been excessively heated, will decompose chloride of manganese, on being
boiled therewith in equivalent proportions, though not completely, yet
sufficiently nearly so for all practical purposes, in view of the newly
discovered fact set forth in the present paragraph, what I regard as a
very important part of the present Invention is the plan or process or
metliod of proceedure for the decomposition of the chloride of manganese
in chlorine residues which consists in boiling or otherwise treating
together in the wet way the said chloride of manganese with magnesia
until the major part but not the whole of the chloride of manganese
has been decomposed, and then submitting to decomposition by heat
in the dry way, in admixture with the chloride of magnesium resulting
from the reaction of the magnesia upon such portion of the chloride of
manganese as it decomposes during such boiling or other treatment
therewith, that portion of the chloride of manganese which the said
both boiling or other treatment in the wet way leaves unacted upon.
5. I have further discovered, however, certain other facts not hitherto
known to chemists, by taking advantage of which a complete decom-
position of chloride of manganese by means of magnesia from any
source whatever (provided only that the magnesia have not been too
highly heated on which point more will be said below) may be readily
effected in the wet way without the use of any appreciable excess
of magnesia without any boiling. In the first place I have found
that whereas on the one hand magnesia possesses the power of decom-
posing chloride of manganese with formation of chloride of magnesium
and protoxide of manganese, on the other hand protoxide of manganese
can decompose chloride of magnesium with formation of chloride of
manganese and protoxide of magnesium or magnesia. I consider that it
is in consequence of this power of protoxide of manganese to decompose
chloride of magnesium that the boiling together out of contact with
air or other oxidizing agent of magnesia and chloride of manganese
fails to result in a complete decomposition of the chloride of manganese
unless the magnesia be in enormous excess (in which case what is
known as the action of mass probably comes into play). It seems to
me that the case is exactly parallel to that of the decomposition on the
one hand of sulphate of barium by carbonate of potassium, and on the
other of sulphate of potassium by carbonate of barium. When chloride
of manganese in solution in water is boiled out of contact with air with
an equivalent or even with a considerable excess above an equivalent

page_text: of magnesia a partial reaction at once takes place, a portion of the
magnesia decomposing a portion of the chloride of manganesc, but this
reaction between the chloride of manganese and the magnesia does not
become complete, and I consider that what prevents its becoming so is
the presence of the protoxide of manganese resulting from the said
partial reaction and the power of such protoxide of manganese to
decompose chloride of magnesium. The decomposition of the chloride
of manganese by the magnesia proceeds to a certain point with
production of chloride of magnesium and protoxide of manganese, and
I conceive that the decomposition of more chloride of manganese is
then prevented by the power of protoxide of manganese and chloride of
magnesium to reproduce chloride of manganese and magnesia. Whether,
however, this method of accounting for the incompleteness of the
decomposition of chloride of manganese by magnesia be correct or not,
what is certain, and not only certain but both very curious and very
important is that any magnesia which has not been excessively heated:
will decompose chloride of manganese quite completely in the wet way
and without the magnesia requiring to be used in more than very slight
excess, if the protoxide of manganese which is one of the results of the
reaction of these two bodies upon each other be to a certain extent
peroxidized as it is formed. By being so peroxidized the protoxide is
continually removed, so to say, from the sphere of action secing that
the higher oxides of manganese possess no power to decompose chloride
of magnesium; that by oxidizing the portion of protoxide of manganese
which is first formed when chloride of manganese in solution is treated
with an equivalent of magnesia more of the magnesia is enabled to act
upon more of the chloride of manganese, and that by oxidizing the
further portion of protoxide then produced a further action between a
part of the remainder of the magnesia and a part of the remainder of
the chloride of manganese is both rendered practicable and caused to
take place, and that by proceeding in this way continually any magnesia,
which has not been too highly heated, can be made to decompose.
chloride of manganese quite completely without appreciably more
magucsia than actually takes part in the reaction being used may be
seen by boiling a solution of chloride of manganese with an equivalent,
or only very barely more than an equivalent, of magnesia in an open
shallow dish freely exposed to the atmosphere; whereas exceedingly
prolonged boiling out of contact with air would not enable magnesia.
of any ordinary quality, unless used in large excess, to completely

page_text: decompose chloride of manganese by boiling only an equivalent of
such magnesia with chloride of manganese in an open vessel so that
the protoxide of manganese formed can be oxidized as the decomposition
proceeds, the chloride of manganese can be decomposed absolutely
completely. Boiling, moreover, is by no means essential to the complete
decomposition of chloride of manganese by magnesia in the wet way
when the protoxide of manganese resulting from such decomposition is
oxidized as the decomposition goes on. If to solution of chloride of
manganese an equivalent or only very little more than an equivalent
of magnesia be added, and air be then injected into the resulting
mixture, the chloride of manganese will be completely decomposed after
a time, even if the operation be conducted at no higher a temperature
than that of the atmosphere, provided only that the magnesia have been
heated only moderately. Another important part of the present Inven-
tion accordingly consists in treating with air or other gaseous oxidizing
agent or mixture of magnesia with chloride of manganese, or of magnesia
with oxide of manganese, chloride of manganese, and chloride of
magnesium, the two chlorides being in solution in water, or the mixture,
whatever its nature at any stage of the operation (for it is conceivable
that oxychlorides and other compounds may be temporarily formed at
some stages of it) which is obtained by adding magnesia to solution of
chloride of manganese, mixed or not with other substances and
proceeding as described. This treatment with air or other oxidizing
agent of a mixture thereof with chloride of manganese, or with chloride
of manganese and other substances as aforesaid, will enable mágnesia
from any source whatever to decompose a full equivalent of chloride
of manganese, not only without being boiled therewith, but at tem-
peratures which if the magnesia have not been too highly heated, of
which more presently, need not necessarily be much, if at all, above the
temperature of the atmosphero.
6. Allusion has been several times made above to the circumstance
that the extent to which the magnesia used has been previously
heated materially influences its power of decomposing chloride of
manganese. Such experience as I have had on this point would seem
to show, firstly, that the power of magnesia to react upon chloride of
manganese in the wet way at ordinary temperatures is greatest when
the magnesia has not been heated above a point which, I believe to lie
between 450 and 550 degrees Fahrenheit, but which may be somewhat
lower than 450 degrees. Secondly, that the power of magnesia to react

page_text: upon chloride of manganese in the wet way at ordinary temperatures
diminishes in proportion as the magnesia is heated above that point
(especially if the heating be somewhat prolonged), until if the magnesia
have been exposed to a dull red heat, for so long a time as will usually
be the case with magnesia obtained by decomposing chloride of
magnesium thereat, it will scarcely react upon chloride of manganese
at ordinary temperatures at all. Thirdly, that while both magnesia
which has, and magnesia which has not, been highly heated alike react
upon chloride of manganese, in the wet way, far more readily at high
temperatures than at low ones, this is more particularly the case with
magnesia which has been highly heated, the difference between the
activity of such magnesia, as regards chloride of manganesc, at high
temperatures and at low temperatures respectively, being much greater
than the similar difference in the case of magnesia which has not been
highly heated (magnesia, for example, which has been obtained by
decomposing chloride of magnesium at a temperature only a little below.
dull redness reacting upon chloride of manganese, on being boiled
therewith, nearly if not quite as readily, and nearly if not quite to the
same extent, is magnesia which has not been heated above 500 degrees
Fahrenheit, although, while the latter magnesia will react upon chloride
of manganese at ordinary temperatures only a little less readily, and
only to a slightly less extent than at the temperature of ebullition, the
former magnesia can act upon chloride of manganese at ordinary
temperatures only to a very slight extent indeed) and being the greater
the more intense and the more prolonged the heat to which the
magnesia has been subjected. And, fourthly, that magnesia which has
been heated much above dull redness for more than a very brief period
shorter than would be required for the complete decomposition of a
large charge of chloride of magnesium at such temperature,, or even only.
to or below dull redness if the heating have been very long continued,
not only cannot react appreciably on chloride of manganese at ordinary
temperatures, but is practically unavailable for the decomposition of
chloride of manganese in the wet way at any temperatures which would
be conveniently attainable on the large scale. It follows, firstly, that
when the chloride of manganese is to be treated with the magnesia by
the method which is described above in paragraph 4, the magnesia may-
without material disadvantage be heated much more highly than is
permissible in the case of magnesia which is required to decompose,
chloride of manganese at a low temperature by treatment therewith by-

page_text: the method described above in paragraph 5; and, secondly, that when
proceeding by the method described in the paragraph last mentioned
the temperature which will be required to enable the magnesia to
decompose the chloride of manganese will be the more clevated the
higher the heat to which the magnesia shall have been previously
exposed. When proceeding by the method described above in para-
graph 4 I have obtained very good results with magnesia which had
been heated for twenty-four. hours to a point very closely bordering on
dull redness; but magnesia which has been heated as much as that
will usually be found suitable for application by the other method
described above only (for reasons which will be explained below when
treating of the peroxidation in the wet way of recovered oxides of
manganese), when a comparatively poor peroxide, quickly obtained, is
considered more advantageous than a richer peroxide obtained more
slowly, I think, however, that in all cases, or very nearly all, it will
be found best to use magnesia which has not been nearly so much
heated as that just named; while when proceeding by the method
described above in paragraph 5, and desiring to obtain (not the quickest,
but) the richest result which that method is capable of yielding, it will
certainly always be safest to use magnesia which has been subjected
only to the very smallest amount of heating practicable. It may be
added that, while I greatly prefer that a point somewhat below dull
redness should be regarded in practice as a limit beyond which the
heating of magnesia which is to be used for the decomposition of
chloride of manganese in the wet way should never be carried, I do
not wish to convey the idea that magnesia which has been much more
highly heated is absolutely incapable of decomposing chloride of
manganese in the wet way. So far from that being the case, I have
decomposed chloride of manganese by means of magnesia which had
been heated to bright redness, and have found that magnesia which
has been so heated, provided that the heating have been only for a
short time, will act upon chloride of manganese, more or less completely,
not only on being boiled therewith, but even also, sometimes, on being
treated therewith by the method set forth in the paragraph last
preceding this at temperatures below that of ebullition; but a tem-
perature somewhat below dull redness is the highest after exposure to
which for such period as magnesia obtained by decomposing chloride
of magnesium at that temperature will usually have been subjected
thereto can be quite safely relied upon to act completely upon chloride

page_text: of manganese in the wet way, under any conditions sufficiently readily
obtainable in practical working under ordinary circumstances.
7. Seeing that the magnesia to be used by manufacturers of chlorine
for the decomposition of chloride of manganese in the wet way on the
large scale must practically be obtained, nearly if not quite always, after
the first time, for the most part by decomposing by means either of heat
alone or of heat and steam, the hydrated chloride of magnesium which
is one of the results of the decomposition of chloride of manganese by
means of magnesia, and that it is of great practical importance that the
magnesia to be so used should not have undergone too much exposure to
heat, a further important part of the present Invention consists in com-
bining with the use of magnesia for the decomposition in the wet way of
the chloride of manganese produced in the manufacture of chlorine, the
use for the decomposition of the resulting hydrated chloride of magnesium
of much lower temperatures than that employed in the only instance in
which the decomposition of chloride of magnesium in such wise that the
products of such decomposition shall be magnesia and hydrochloric acid
either is now or has been at any time hitherto actually practised as a
manufacturing operation. A number of processes, usually relating to
the manufacture of alkalics, of which processes, if they were practicable,
hydrated chloride of magnesium would be a secondary product, have
been proposed from time to time, and in several instances it has been
suggested that the chloride of magnesium which such processes were
expected to yield should be decomposed by heating it in a current
of steam; but most of these suggested processes are purely visionary,
being based on supposed chemical reactions which do not really take
place, or which only take place partially, and of those of them which
are not thus essentially impracticable not one has possessed merit
enough to enable it to command adoption to even the most limited
extent. The only instance of which I am aware in which the decom-
position of chloride of magnesium into magnesia and hydrochloric acid
has hitherto been practically carried out is therefore that of the chloride
of magnesium obtained in certain salt works in the south of France
from the mother liquors left after the extraction of potash and soda
salts from sea water. According to Watts and Richardson's "Chemical
Technology," vol. 1, part 3, pages 543 and 544, the said mother liquors
"were at one time thrown into the sea, but are now boiled up to 44° B.
in iron pans and become solid on cooling," forming a cystalline mass
of chloride of magnesium which "is then exposed to a red heat in clay

page_text: retorts through which a current of superheated steam is passed." I
greatly prefer, however, in all cases when the resulting magnesia is to
be used again for the decomposition of chloride of manganese in, the
wet way that the decomposition of the chloride of magnesium produced
in my process should take place at a temperature not only below what
is known as "a red heat," but not exceeding a point somewhat below
dull redness, and I am moreover strongly of opinion, as already stated,
that it will usually be found best that magnesia which is required to
react upon chloride of manganese in the wet way should not have been
heated beyond, and consequently that the decomposition of the chloride
of magnesium from which such magnesia is obtained should be per-
formed at a temperature not only below, but very considerably below,
that somewhat lower than a dull red heat which I have indicated above
as being the maximum temperature after moderately prolonged exposure
to which magnesia can be relied upon to act completely upon chloride
of manganese in the wet way, when suitably treated therewith; while in
many cases, when proceeding by the method described above in para-
graph 5, it will be desirable, for reasons which will be set forth lower
down, that the magnesia used should have been obtained by decom-
posing the chloride of magnesium yielding it at the nearest attainable
approximation to the very lowest temparature at which the decomposition
of that compound can possibly be effected.
8. The claim just made, in the paragraph last preceding this, is a
smaller claim than is made under the same head in my Provisional
Specification of the present Invention. When I drew up that Speci-
fication I believed that I could claim, not only so far as combined with
the use of magnesia for the decomposition of chloride of manganese
produced in the manufacture of chlorine, but quite absolutely, without
reference to any particular process of which it might form part, the use
for what is therein spoken of as "such decomposition," immediately
after reference having been made to "the decomposition of hydrated
chloride of magnesium either by heat alone or by heat aided by steam,"
not only of much lower temperatures than had hitherto been ". used,"
but of much lower temperatures than had hitherto been either "used or
prescribed for that purpose. I have since found, however, that in the
Specification of a Patent granted to Dr. Christian Gustav Clemm on the
Fifteenth of July One thousand eight hundred and sixty-three, and
numbered 1776, in which Specification is described a process (which
however has not yet come into use) for the decomposition of chloride
"

page_text: of sodium by means of the native sulphate of magnesium known as
kieserit," it is proposed to treat the chloride of magnesium which
would result from that decomposition "by subjecting it to the action
of steam," and it is stated that "a moderate heat of 390° to 570° F.
suffices to expel completely the hydrochloric acid." I cannot therefore
claim, as I supposed I could, the decomposition of chloride of magnesium
at low temperatures when the chloride of magnesium so subjected to
decomposition is treated with steam, except so far as such decomposition
of the chloride of magnesium is combined with the use of the resulting
magnesia for the decomposition in the wet way of the chloride of man-
ganesc in chlorine residues, in order to the obtainment therefrom of oxides
of manganese available for use again in the manufacture of chlorine; but
I believe that I can claim, not only as in such combination, but abso-
lutely, the decomposition of hydrated chloride of magnesium by heat
alone, unaided by steam, at temperatures between a point about 310°
Fahrenheit (which is somewhere about the lowest point at which
hydrated chloride of magnesium begins to give off acid) and dull redness,
the decomposition of chloride of magnesium by heat alone, unaided by
steam, at any temperatures whatever, not having hitherto, so far as
I can learn, been either practised or even only proposed. And it is to
be noted that whereas I have not found that the use of steam at all
appreciably facilitates the decomposition of chloride of magnesium, when
such, chloride is in that state of hydration in which it will always be
obtained under the present Invention, and in which it can never fail
to have associated with it considerably more water than the quantity
required to supply hydrogen to one of its elements and oxygen to the
other, the use of steam is positively prejudicial in one respect, by so
diluting the vapour of hydrochloric acid which is given off during the
decomposition as to render practically impossible (at least on the large
scale) the condensation of a strong liquid acid therefrom.
9. There is one other point relating to this matter of the resolution
into magnesia and hydrochloric acid of hydrated chloride of magnesia
with respect to which also I believe that it will generally be found to be
advantageous. In the case of chloride of magnesium required to yield
magnesia for use for the decomposition of chloride of manganese, to
depart from what has been both the practice and the suggestion hitherto,
it is and has been the practice in the one only instance, more particularly
referred to above, in which the decomposition of chloride of magnesium
into magnesia and hydrochloric acid is or has been conducted as a

page_text: practical manufacturing operation, and in all cases in which such
decomposition of chloride of magnesium has been proposed it has
invariably been the suggestion, that each charge of chloride of mag-
nesium should be decomposed as completely as possible; but in
decomposing chloride of magnesium produced under the Invention
now being described, and more especially when aiming at the production
of a magnesia capable of acting readily upon chloride of manganese
at low temperatures, it will always, I think, be best not to carry the
decomposition of each charge of chloride of magnesium to completeness,
but to decompose cach charge only partially, and let the undecomposed
portion of one charge form either part or the whole of a subsequent
charge. The decomposition of hydrated chloride of magnesium by heat
proceeds so much more rapidly at the earlier than at the subsequent
stages of the operation, that two charges may each be half decomposed
in very much less time than is required for the decomposition of one
charge quite completely. It follows, firstly, that the plan of decomposing
cach charge only partially is cheaper than the plan of decomposing cach
charge completely; secondly, that the former plan, by reason of its
subjecting the resulting magnesia to so much less prolonged exposure
to the heat employed than the greater portion of the magnesia obtained
by decomposing a charge of chloride of magnesium to completeness
must necessarily go, yields, at whatever temperature it may be con-
ducted, a much more highly active magnesia than can be obtained by
working at the same temperature on the latter place; and, thirdly, that
it is therefore the case, not only as already indicated, that when working
in both instances at the same temperature,.a given quantity of magnesia
can be obtained in much less time by half decomposing two charges of
chloride of magnesium than by completely decomposing one charge,
but also that for the decomposition of chloride of magnesium so as to
obtain therefrom magnesia of a given degree of chemical activity, one
may use much higher temperatures when decomposing each charge
only partially than when decomposing each charge completely, thereby
effecting a still further economy alike of time, fuel, and apparatus. The
chloride of magnesium in the mixture of chloride of magnesium and
magnesia which constitutes a partially decomposed charge can be dis-
solved out from the associated magnesia, either with water or with a
previous non-saturated solution of chloride of magnesium; or such mixture
of chloride of magnesium and magnesia can be used for the decomposition
of chloride of manganese without first dissolving out the chloride of

page_text: magnesium. The latter however I do not consider to be a good plan,
inasmuch as I believe that the presence of excess of chloride of magnesium
tends to hinder the decomposition of chloride of manganese by magnesia.
10. The chloride of magnesium resulting from the reaction of
magnesia upon the chloride of manganese produced in the manufacture
of chlorine will always be obtained as a more or less dilute solution
in water, which solution may be used to dissolve out the undecomposed
portion of a partially decomposed previous charge of chloride of mag-
nesium, and whether first so used or not will require to be concentrated
by evaporation before the decomposition of the chloride of magnesium
in it can commence. The evaporation of this solution may be conducted
in either an open or a closed iron pan, which it will generally be found
advantageous to heat by the waste heat from the decomposing furnace.
If the pan used be an open one, when the boiling down has proceeded
so far that the temperature of the solution has risen to about 310°
Fahrenheit, which is about the point at which acid will begin to be given
off, it must be run therefrom into the decomposing furnace; but if the
evaporating pan be domed over with brick, or be otherwise covered in
with a material not readily acted upon by hydrochloric acid vapour,
and at the same time be duly connected with a suitable condensing
apparatus, the concentration of the solution therein may be carried
further than the point just named. The decomposing furnace may very
conveniently be a "close" or "blind" furnace, similar to the "blind
roasters" used by alkali makers for roasting salt cake; but it is a good
plan to make the furnace very much longer than salt cake furnaces
ordinarily are, and to pass each charge gradually from one end of tho
furnace to the other. The temperature to be maintained in the decom-
posing furnace must depend entirely upon the manner in which the
magnesia which is to result from the decomposition to be performed in
it is to be applied, due regard being had, on the one hand, to the facts
stated above in paragraph 4, and, on the other hand, to what will be
found set forth below in paragraphs 11 and 12. It need hardly be added
that the decomposing furnace should communicate with apparatus for
the condensation of the hydrochloric acid evolved during the decom-
position of the chloride of magnesium, and that the arrangements and
method of procedure may be just the same whether the chloride of
magnesium have or have not chloride of manganese associated with it.
11. It has already been pointed out that the decomposition of chloride

page_text: of manganese by magnesia requires a higher temperature the more
highly the magnesia has been previously heated; and it has now to
.be added that the peroxidation in the wet way of artificial protoxido
of manganese, and more especially of protoxide of manganese obtained
by means of magnesia, cannot (other things being equal) be carried so
far at high temperatures as at low ones. I have found the results
obtained by treating with air or other gaseous oxidizing agent or mixture
of artificial hydrated protoxide of manganese with a suitable liquid are
materially influenced by the temperature at which such treatment is
conducted, the laws which govern this matter, so far as I have been
able to ascertain them, apparently being, firstly, that what may be
called the inferior peroxides of manganese, such as "red oxide," or
Mn O, and "sesquioxide, or Mn 20³, are never formed directly, so
to speak, but are always formed by the combination of previously
formed particles of binoxide, or Mn O³, with particles of protoxide, or
Mn O; secondly, that every act of oxidation of protoxide of manganese is
an act of the formation of particles of binoxide, or Mn O; thirdly, that
whether each newly formed particle of binoxide, or Mn O*, combines
immediately on its formation, with two particles of protoxide or Mn O,
to form therewith a particle of "red oxide," or Mn ³O', or with only
one particle of protoxide to form therewith a particle of "sesquioxide,"
or Mn 20³, or combines with some smaller proportion of protoxide, or
declines to combine with any protoxide at all, depends mainly upon the
degree of chemical activity which the newly formed particle of binoxide,
or Mn O³, possesses at the instant after its formation; and, fourthly, that
the degree of chemical activity which characterises a newly formed
particle of binoxide, or Mn O², depends greatly upon the temperature
at which the particle is formed, being the greater in proportion as that
tempcrature is high. It follows that there are certain limits of tem-
perature, by operating above which by the method in question, protoxide
of manganese cannot be peroxidized more highly than to the red oxide,
or Mn '0', point; which by operating at lower temperatures richer
results may be obtained. Hence it is that ariscs the necessity, more
than once alluded to above, that when proceeding by the method of
treating with air or other gaseous oxidizing agent a mixture of magnesia
with solution of chloride of manganese so as to peroxidize the resulting
protoxide of manganese as it is formed, and at the same time desiring
to produce the richest protoxide possible to be produced by that method,
the magnesia employed should have undergone only the least possible

page_text: amount of exposure to heat, so as to be in the highest degree capable of
reacting upon chloride of manganese at ordinary temperatures.
12. While there is no doubt that the limit of temperature above which
protoxide of manganese cannot be peroxidized in the wet way to any-
thing higher than red oxide, or Mn ³O', is the same in all cases in which
all the conditions under which the peroxidation is performed are the
same, and that below that limit there are similarly definite zones of
temperature, to each of which correspond a peroxide of manganese of
definite strength, which peroxide is the richest that can be obtained
in the wet way within the limits of such zone of temperature, under
some particular set of conditions, yet all such limits of temperature vary
very considerably with circumstances, being usually very much higher,
for example, in the case of protoxide of manganese precipitated by
lime than in the case of protoxide of manganese precipitated by magnesia.
In the case of protoxide of manganese precipitated by magnesia, such
minute variations in the conditions of working influence the result so
very materially, and to so much greater an extent than in the case
of protoxide of manganese precipitated by any other agent, that it is
exceedingly and very specially difficult to name limits of temperature
within which it shall always be found that a given degree of peroxidation
may be attained. I have several times obtained a peroxide of manganesc
containing 55 5 per cent. of binoxide, being the proportion of binoxide
contained in sesquioxide or Mn 20" by injecting air into a mixture of
solution of chloride of manganese with magnesia which had been heated
to nearly dull redness, such mixture being kept at temperatures between
100° and 150° Fahrenlicit, and I have several times obtained a peroxide
containing the proportion of binoxide which may be supposed to be
contained in the hypothethical compound Mn '07 when working with a
similar mixture at temperatures about 170° F., while I have once or
twice obtained a peroxide containing as much as 65 per cent. of binoxide
by working with a similar mixture at a temperature not below 180° F.;
but in the great majority of instances I have failed to obtain a richer
peroxide than one containing about 38 per cent. of binoxide, being the
proportion contained in red oxide, or, Mn 'O', by working with the same
magnesia (under precisely the same conditions, so far as I could find, as in
the experiments yielding the richest results) either at those temperatures
or at any others at which I could make such magnesia react upon
chloride of manganese. When working by the same method, at tem-.

page_text: peratures about 100° F., with magnesia which had been previously
subjected to only a minimum amount of heating, I have only
occasionally failed to obtain a peroxide as rich in binoxide as sesqui-
oxide, or Mn "0"; but as I have failed to do so in some instances,
when all the conditions seemed to me exactly the same as in the
more successful experiments, I cannot lay it down as a rule that a
peroxide of Mn 203 strength may always be so obtained, I have had
similarly non-accordant experiences when operating on protoxide
obtained by the method described above in paragraph 4, and cannot
but conclude that there are some conditions which influence the results
of my process, as performed by means of magnesia, which as yet have
escaped my observation. As regards the regeneration from chloride
of manganese, in the wet way, by means of magnesia, of peroxides of
manganese richer than red oxide, the only instructions which I can
give, with a certainty that obedience to them will ensure the required
result, are therefore, firstly, that when it is desired to transform into
such peroxide richer than Mn *O* protoxide obtained by boiling together
magnesia and chloride of manganese, the magnesia employed should not
contain much peroxide of manganese and should not have been heated
above a point below dull redness, and the protoxide resulting from its
decomposition of the chloride of manganese, or, rather, the resulting
mixture of protoxide of manganese with certain solutions, should be
allowed to cool down to the temperature of the atmosphere before the
peroxidation process be commenced; and, secondly, that when the
required peroxide is to be obtained without boiling the magnesia with
the chloride of manganese, but by simply treating with air or other
oxidizing agent a mixture of solution of chloride of manganese and
magnesia, the magnesia used should be one capable, as several times
already aforesaid, of reacting on chloride of manganese at ordinary
temperatures, and the whole operation of decomposition and peroxidation
should be performed without the assistance of heat. By duly observing
these rules, peroxides containing about the same proportion of binoxide
as is contained in sesquioxide, or Mn 20³, may always be obtained, by
either of the two methods referred to. I cannot doubt, from my ex-
perience recorded above, that it will eventually be found that obedience
to the whole of these rules is not essential to the obtainment of richer
peroxides than Mn 'O', and that a little further experience will so far
reveal the nature of the conditions necessary to be observed in order
to that end as to render certain the obtainment at all times of peroxides

page_text: at least as rich as Mn 'O' when using higher temperatures and other
qualities of magnesia than these rules prescribe. Meanwhile, although
I know that in certain instances I have obtained peroxide richer than
Mn 'O' without obeying these rules I do not know how the obtainment
of such richer peroxides can be unfailingly secured otherwise than by
careful attention to them.
. 13. I am not at all sure, however, that in regenerating in the wet
way, by means of magnesia, peroxides of manganese for use in the
manufacture of chlorine, there is any advantage in aiming at the pro-
duction of peroxides richer than Mn 'O'. Of course, manufacturers of
chlorine accustomed to the use of native peroxides containing from
60 to 80 per cent. of binoxide will be apt, at first blush, to regard with
disfavor a proposal that they should use a peroxide containing only
38 per cent. of binoxide, but a little consideration and experience will
make clear to them that, owing mainly to the extreme facility, duc to
their being hydrated oxides in an exceedingly fine state of division,
with which such oxides as are produced by my process dissolve (their
complete solution being readily practicable without the use of the
slightest excess of acid), an artificial oxide of only 38 per cent. produced
as indicated will liberate more chlorine from a given quantity of hydro-
chloric acid than is ordinarily liberated therefrom by the much richer
native peroxides in use at present, even without taking into account
the recovery of acid, as well as of oxide, which is effected by my process
as performed by means of magnesia; while, by reason of that recovery
of acid as well as of oxide, the use of artificial peroxides regenerated
by means of magnesia, whatever the per-centage strength of such per-
oxides, whether 38 or 60, or 100, or only 10, will enable manufacturers
of chlorine to obtain from a given supply of acid from five to six times as
much chlorine as they obtain therefrom on an average now. The com-
parison, however, really lies not between an artificial peroxide of 38 per
cent. and any native peroxides, but between an artificial peroxide of
38 per cent. and such richer artificial peroxides as are obtainable by my
process as performed by means of magnesia, let us say, between artificial
Mn O, so obtained, and similarly obtained artificial Mn 20%. When
using in the manufacture of chlorine perpetually recovered Mn 'O³,
regenerated by means of perpetually recovered magnesia, there is of
course less chloride of magnesium to decompose, per given quantity
of chlorine obtained, than when similarly using Mn ³O'. For every 35.5

page_text: parts of chlorine liberated from hydrochloric acid by means of Mn³O*
there are produced 189.0 parts of chloride of manganese, the decom-
position of which by magnesia produces 142 5 parts of chloride of
magnesium; whereas for every 35 5 parts of chlorine liberated by
means of Mn 20 there are formed only 126.0 parts of chloride of
manganese, the decomposition of which by magnesia produces only 95.0
parts of chloride of magnesium, being only two-thirds of the quantity
produced in the former case. The use of Mn 20%, therefore, in the manu-
facture of chlorine as indicated, would be cheaper than the similar use
of Mn ³O', if an equivalent of the former peroxide could be regenerated
by means of magnesia as readily and inexpensively as an equivalent of
the latter, but I have not yet found that it can be so. The regeneration
of Mn 20³ by means of magnesia under any conditions under which I
have yet succeeded in effecting it, takes a much longer time than the
regeneration, by means of the same re-agent, of an equivalent quantity
of Mn ³O', so that when manufacturing chlorine by means of Mn 20³ thus
regenerated the regeneration of the Mn 20³ will require much more
extensive apparatus and much more labour and attention than are
sufficient for the regeneration of the quantity of Mn 'O' which will liberate
the same quantity of chlorine; while although when working with
Mn O' there is half as much again chloride of magnesium to decompose,
per given quantity of chlorine produced as when working with Mn Os
yet the magnesia to be used for the regeneration of Mn "O' may have
been so much more highly heated than at present seems to be per-
missible in the case of magnesia to be used for the regeneration of
Mn Os, that I believe that the larger quantity of chloride of magnesium
produced when working with the less' rich peroxide may be decomposed
in fewer furnaces and at less expense than the smaller quantity of
chloride of magnesium produced when working with the richer peroxide.
It is a matter depending very much on circumstances, and which must
be decided by each manufacturer for himself; but I incline to think, for
the reasons given, that when manufacturing chlorine by means of
artificial oxides of manganese regenerated by means of magnesia and
peroxidized in the wet way it will usually be best to be content with
the obtainment of a peroxide of about the strength of Mn 'O'.
14. The regeneration and peroxidation in the wet way of oxides of
manganese recovered from chloride of manganese by means of magnesia

page_text: peroxidation, will have to react upon hydrochloric acid, in order to the
liberation of chlorine therefrom, and in which the chloride of manganese
from which they are recovered each time is produced, as one of the
results of the reaction by which they liberate chlorine; or the recovery
and peroxidation processes may be conducted in vessels distinct from
the stills, the chloride of manganese being removed from the stills into
such other vessels at every operation. That of recovering and perox-
idizing the oxides in the stills in which they have afterwards to be
dissolved is the neatest plan, and the one which involves the least
manipulation of the materials treated; but that of performing the
operations of recovery and peroxidation in vessels other than the stills
has the advantage of employing somewhat the cheaper apparatus.
Stills for use for the generation of chlorine on the large scale must
necessarily be somewhat costly vessels, the only really suitable material
for them being certain not very abundant kinds of silicious stone, and
the difficulty of constructing of such material very large vessels, the joints
of which shall be perfectly tight without containing any cement capable
of being rapidly acted upon by either hydrochloric acid or free chlorine,
being somewhat considerable; and for every, say, three or four stills
which will be required when the plan first mentioned above is followed,
there will suffice, when proceeding by the last-mentioned plan, say, one
still and two or three very much cheaper wooden or iron vessels.
15. The peroxidation in the wet way of oxides of manganese recovered
from chloride of manganese by means of magnesia under the present
Invention may be effected either by injecting air or other gaseous
oxidizing agent into a mixture of such oxides with whatever liquid in
admixture with or in suspension in which it may be convenient so to
treat them, or by any other method of bringing air or other gaseous
oxidizing agent into intimate contract with all parts of such mixture.
Among the methods, other than that of injection, by which I have found
it practicable to successfully apply the air or other gaseous oxidizing
agent used, are, firstly, that of simply boiling in contact with such
gaseous oxidizing agent the mixture containing the oxide or oxides to
be peroxidized; secondly, that of mechanically agitating such mixture
in contact with such oxidizing agent; and, thirdly, that of repeatedly
lifting such mixture from one level to a higher one, and then letting
it fall back through a column of air or other atmosphere of oxidizing
gas. It is obvious that many. modifications, alike of these last-mentioned

page_text: methods and of the method of injection, and also many combinations
of two or more of such last-mentioned methods, or of one or more of
such last-mentioned methods with the method of injection, are possible,
and likewise that, when the method of injection is followed, the injection
may be effected by means of any one of a considerable number of
different kinds of apparatus; but I believe that more especially when,
as will ordinarily be the case, atmospheric air is the oxidizing agent
employed, it will almost invariably be found, firstly, that the best
method of applying such agent is that of injecting it into the liquid
.mixture containing the oxide or oxides to be peroxidized; and, secondly,
that such injection can be effected most conveniently and economically
iby means of a blowing machine similar in principle to those which are
used to supply the blast to furnaces for smelting iron.
16. I prefer that magnesia which has been obtained by the decomposition
of chloride of magnesium, and which is to be used for the decomposition
of chloride of manganese, before being added to the mass of the solution
the chloride of manganese in which it is required to decompose, should
be first ground or triturated, either with a portion of that solution itself,
or with water, or with other suitable liquid, until it shall have been
reduced to the very finest possible state of division, and that it be thus
added to the solution of chloride of manganese, or to the greater
part thereof, in the state of milk, or paste, or more or less thick mud.
17. The method of proceeding in order to the regeneration of oxide
of manganese from chloride of manganese by means of magnesia and
the peroxidation of the oxide of manganese so regenerated, both in the
wet way, which I will first describe, consists in boiling the "still
liquor" (meaning thereby that solution, essentially of chloride of
manganese, which remains in chlorine stills after any peroxide of
manganese has reacted upon hydrochloric acid therein) with an
equivalent or slightly more than an equivalent of magnesia until the
greater portion of the chloride of manganese at first contained in the
said liquor has been decomposed; then allowing the protoxide of
manganese which has been so formed to settle until there shall have
become separated from it a quantity of clear solution (which will be
solution of chloride of magnesium mixed with chloride of manganese)
equal in bulk to the volume of the hydrochloric acid which will be
required to dissolve the oxide after it shall have been peroxidized,
combined with that of the water which will be condensed in the still

page_text: in which the oxide will be so dissolved if steam be used to heat together
therein the oxide and the acide which is to dissolve it, and that of the
milk, or paste, or mud of magnesia which will afterwards require to be
added to the solution of chloride of manganese which by the recovered
oxide being thus dissolved in hydrochloric acid will be reproduced;
then drawing off the said quantity of the said clear solution from above
the settled protoxide, unless, which is a better plan, the decantation
of this clear solution be conducted simultaneously with the subsidence
of the protoxide, the clear solution being drawn off little by little as
it forms; and then, when the required quantity of mixed solution of
chloride of magnesium and chloride of manganése has been removed,
commencing the injection of the oxidizing blast. If, before the boiling
(which boiling may conveniently be effected by injection of steam), a
sufficient quantity of magnesia have been put into the still or other
vessel in which the operations now being described are performed, there
will remain with the protoxide of manganese, after removal of the clear
solution as aforesaid, enough magnesia to decompose the portion of
chloride of manganese contained in the liquor remaining with the
protoxide, and such chloride of manganese will be decomposed by such
magnesia almost immediately after the injection of the blast has been
commenced. The oxide may, if need be, be allowed to settle again,
after peroxidation, and more solution (which will now consist of chloride
of magnesium only) be then run off from it. Usually, however, this
will not be necessary, but the oxide, immediately upon the cessation of
the blast, may have acid run in upon it, if it have been regenerated and
peroxidized in a still, or may itself, in the state of more or less thin
mud in which it will be at this stage, be at once run into a still, if it
have been recovered and peroxidized in another vessel.
18. When the plan described in the paragraph immediately preceding
this is followed exactly as it is there set forth, inasmuch as protoxide
of manganese subsides with extreme rapidity in a hot solution of chloride
of magnesium which contains also chloride of manganese, the mixture
into which the blast is injected will be so hot that I do not guarantee:
that the resulting peroxide shall be richer than Mn³O'. I have obtained
richer peroxides than Mn'O' under the like circumstances, but only in
minority of instances, so that it will be safest to count upon the
product being simply of that strength. The transformation of the
chloride of manganese in such peroxide will be performed, however,

page_text: with such rapidity, especially if, as I recommend, the temperature of
the mixture into which the blast is injected be kept up during the
injection of the blast by the simultaneous injection of steam also, that
a single charge of manganese may be made to generate chlorine
three times, or even four times, per twenty-four hours. Experiments
performed in a large still, of square horizontal section, ten feet deep by
six feet eight inches in diameter each way have convinced me that,
when proceeding on the large scale by the method now being considered,
two hours for the boiling together of the chloride of manganese and
magnesia, two hours for the subsidence of the resulting protoxide of
manganese and the decantation from it of the required quantity of
mixed solution of chloride of magnesium and chloride of manganese,
two hours for the injection of the oxidizing blast, and two hours for the
reaction of the resulting peroxide upon an equivalent of hydrochloric
acid, are periods so abundantly sufficient that each of them could
probably be abridged by one fourth. Certainly, however, the whole
round of operations can be performed with ease in eight hours, or threc
times per day. I requires about one ton and a quarter of Mn³O*
for the liberation of chlorine enough for the production of a ton of
bleaching powder, and my experience with the still the dimensions of
which are stated above goes to show that a still or other vessel having
an internal capacity of about six hundred cubic feet would be large
enough for the working of a charge of that size by the method described
in paragraph 17. Hence, when proceeding by that method, a still of
the capacity just mentioned would suffice for all the operations involved
in the manufacture, by means of Mn³O* regenerated from chloride of
manganese by means of magnesia under the present Invention, of
chlorine enough for the production of certainly three and probably four
tons of bleaching powder per day of twenty-four hours, saving only the
one operation of the decomposition of the chloride of magnesium which
is formed in the course of the process of regenerating the oxide of
manganese. A plant for the manufacture by this method of chlorine
enough for from twelve to sixteen tons of bleaching powder per day
might thus consist simply (in addition to the necessary apparatus for
the decomposition of the chloride of magnesium) of one blowing engine
and either three or four stills, or of one blowing engine, one still, and
two or three other vessels of a cheaper kind than stills.

page_text: mencing the injection of the oxidizing. blast immediately upon the
cessation of the ebullition, and leaving the separation from the oxide
of the required portion of the solution with which it is mixed until. after
the peroxidation of the oxide.. In this case the solution which will
be drawn off from the subsided oxide will not contain any. chloride
of manganese. I believe that this plan yields to some extent even
still more rapid results: than the plan described in paragraph 17;
but on the other hand,, it requires for the treatment of a given quantity.
of material at one operation, stills or other vessels of larger capacity
than will suffice for the treatment of the same quantity of material at
one operation by the method first described, owing to the necessity that
in the vessel in which the peroxidation is performed, there should be a
certain amount of free space above the liquid mixture into which the
blast is injected, and to this mixture having a larger volume per given
quantity of oxide containcl in it, when the portion of solution to be-
separated from the recovered oxide before the treatment thereof with.
acid is not removed until after the acide has been peroxidized than.
when such solution is removed before the operation of peroxidation is
performed.
20. Perhaps, however, the most rapid results of all are got by adding.
to the still liquor an equivalent of magnesia, or slightly more than an
equivalent, then injecting steam until the resulting mixture has been.
brought very nearly to the boiling point, and then at once commencing.
the injection of the blast without waiting. for any actual ebullition..
By this method, especially if the injection of steam be continued
during the injection of the blast, chloride of manganese is transformed
into Mn'O' with most remarkable rapidity; but this method, like that
described in paragraph 19, requires larger stills or other vessels per
given quantity of oxide recovered in them at once than are required
when working by the method described in paragraph 17. This
method further resembles that described in paragraph 17 in yielding.
a solution of chloride of magnesium not containing chloride of man-
ganese.
21. When proceeding by whichever of the methods described. in.
paragraphs 17, 19, and 20, I believe that it will be found that a
blast engine having a double action air cylinder about twenty inches...
in diameter and from twenty-four to thirty inches long, and being.
capable of making seventy or eighty strokes per minute, will suffice.

page_text: for the peroxidation up to Mn'O' of about a ton and a quarter of oxide
of manganese in from one to two hours. I state this, however, only
by way of affording a general indication of the amount of work which
in my process for the regeneration of oxides of manganese by means
of magnesia in the wet way, or rather, in those forms of it which
are described in the paragraphs cited, a blast engine of a given size
may be expected to do, as I have not yet had sufficient experience
on this point to enable me to give particulars with respect to it which
I can guarantee to be absolutely accurate.
22. When proceeding by either of the methods described in para-
graphs 17, 19, and 20, a temperature only a little below dull redness
may be used for the decomposition of the chloride of magnesium pro-
duced, provided only that the resulting magnesia be not subjected to
too prolonged exposure to such temperature.
23. As has already been explained in paragraph 12, when it is desired
to obtain from chloride of manganese by means of magnesia in the
wet way peroxides of manganese containing a larger proportion of
binoxide than is contained in Mn³O', I recommend that the operation
of peroxidation be performed at the temperature of the atmosphere
only, or thereabout, though I would prepare the operator to expect
that he will be able to obtain such richer peroxides at temperatures
as high as 100° Fahrenheit, or even higher. The method of proceedure
in order to the obtainment of such richer peroxides may consist either
in boiling together the magnesia and chloride of manganese and letting
the resulting mixture cool before commencing the oxidizing treatment,
or in effecting the decomposition of the chloride of manganese and
the peroxidation of the resulting protoxide of manganese simultaneously
from the beginning, the peroxidizing operation being commenced
immediately upon the addition of the magnesia to the chloride of
manganese, and so without the magnesia and chloride of manganese
being first boiled together. When the former is the method followed,
I prefer that the solution to be separated until after the peroxidation
of such oxide, for the reason that such solution would otherwise
contain chloride of manganese, which would cause the magnesia
obtained by the decomposition of the chloride of magnesium in such
solution to have peroxide of manganese associated with it, and I
have found (as a rule, but not however invariably) that when chloride

page_text: of manganese is boiled with magnesia containing much peroxide of man--
ganesc, it is difficult to peroxidize the resulting recovered oxide above the
MnO point, at however low a temperature the operation of peroxidation
may be performed.. When the latter method is the one chosen, the point
requiring the most care is that of the decomposition of the chloride of
magnesium which should be effected at the lowest possible temperature
(I have frequently effected it at a temperature not exceeding from 400°
to 450° Fahrenheit), so that the resulting magnesia may be obtained'
in the highest possible state of chemical activity. Both methods will
be found to require a very much longer time than suffices for the trans-.
formation of chloride of manganese into Mn³O' by the methods described
in paragraphs 17, 19, and 20, and both will be found to require about
the same time; that is, at least, if in the method without boiling a
magnesia of nearly maximum activity be used,, for otherwise that method
will require very much more time than the method with boiling, if
indeed it be not rendered impracticable altogether.. The method without
boiling perhaps yields the richer results,. but the method with boiling:
is somewhat the cheaper of the two, both because the magnesia used
in the method with boiling may have been more highly heated than
is allowable for magnesia which is to be used in the method without
boiling, wherefore the chloride of magnesium. produced when proceeding:
by the former method may be decomposed by means of less extensive.
apparatus than will be required for the decomposition. of the same:
quantity of chloride of magnesium when proceeding by the latter method,.
and because when proceeding by the former method the oxidizing
treatment is required during only a part of the operation, whereas when
proceeding by the latter method the oxidizing treatment is required:
during the whole of it.

page_text: manganese, which is obtained in the course of the process of regenera-
ting the said artificial oxides by the method indicated. It is obvious
that this sulphate of magnesium must be removed from time to time,
and to this end advantage may conveniently be taken of the circumstance
that sulphate of magnesium is not affected by such temperatures as the
chloride of magnesium resulting from the decomposition by means of
magnesia of chloride of manganese produced in the manufacture of
chlorine, will usually be decomposed at. If a charge of such chloride
of magnesium associated or not with chloride of manganese be decom-
posed in the manner indicated above, and its decomposition be carried
to completeness, any sulphate of magnesium which was associated with
such charge of chloride of magnesium or of chloride of magnesium mixed
with chloride of manganese will remain behind with the resulting
magnesia, or mixture of magnesia and oxide of manganese, and can
then be readily separated therefrom by being simply dissolved out.
When the decomposition of a charge of chloride of magnesium or of
chloride of magnesium mixed with chloride of manganese is thus
carried to completeness, the sulphate of magnesium which accompanied
such charge will be the only soluble substance remaining with the
magnesia or mixture of magnesia and oxide of manganese resulting
from the decomposition of that charge, in which case it will be
sufficient to first grind with water such magnesia, or mixture of
magnesia and oxide of manganese, and then before adding the resulting
milk or paste to the chloride of manganese which the magnesia in such
milk or paste is required to decompose, to let the magnesia or mixture
of magnesia and oxide of manganese settle as far as it will, and then
run off from it the supernatant clear solution of sulphate of magnesium.
If the charge of chloride of magnesium or of chloride of magnesium and
chloride of manganese be decomposed, though not quite completely
yet nearly so, a solution thus run off from the ground magnesia or
mixture of magnesia and oxide of manganese will consist of sulphate
of magnesium associated with more or less chloride of magnesium.
In the former case the solution run off from the ground magnesia or
mixture of magnesia and oxide of manganese will only need to be
suitably concentrated in order to yield crystals of sulphate of magnesium
which is a salt in constant commercial use and demand; but in the
latter case the mixed solution should be evaporated down, and the
residue heated until the chloride of magnesium in it has been com-
pletely decomposed, whereupon a pure solution of sulphate of magnesium

page_text: will be got as before by simply treating what remains with water.
When the plan followed is that of decomposing each ordinary charge
of chloride of magnesium, or of chloride of magnesium and chloride
of manganese only very partially, it will be found a convenient method
to take each day, after a certain number of operations shall have been
performed without any removal of sulphate of magnesium, or if not
cach day, regularly at such other intervals as may be preferred, as much
of the solution of chloride of magnesium produced per day or other
period fixed upon as shall contain in the state of sulphate of magnesium
the quantity of sulphuric acid which goes into the stills together with
that, if any, which is formed therein from sulphurous acid during the
same period, and to make of this portion of such solution a special
charge the chloride of magnesium in which shall be decomposed
completely. It will come to nearly though not quite the same thing
if, while usually decomposing each charge of chloride of magnesium,
or of chloride of magnesium mixed with chloride of manganese, only
partially once every certain number of times the decomposition be
carried to completeness as regards the chlorides in the charge, the
frequency of these occasional complete decompositions depending in
each case upon the amount of the sulphuric and sulphurous acids
contained in the hydrochloric acid employed. I prefer, however, the
first-mentioned of these two plans, because when it is followed this
quantity of sulphate of magnesium present with the materials treated
is always the same after the first few operations, and any influence
upon the final result which the presence of such sulphate of mag-
nesium may have is then exerted to the same extent every time.
Whichever plan be followed, however, a quantity of fresh magnesia
equivalent to the quantity of sulphate of magnesium formed must
be regularly added to the magnesia resulting from the decomposition
of the chloride of magnesium.
25. Although the plans just described collect or recover in a useful
form the sulphuric and sulphurous acids contained in the hydrochloric
acid employed in the manufacture of chlorine, when the re-agents
employed to liberate chlorine therefrom are artificial oxides of manganese
regenerated by means of magnesia, I nevertheless greatly prefer to
separate such acids from the hydrochloric acid before using the latter
in the manufacture of chlorine, whatever the re-agent or re-agents
by which the chlorine is to be liberated from it, saving only when
one of such reagents is sulphuric acid itself. The hydrochloric acid
.

page_text: which is chicfly in question is that which is produced by manufacturers:
of soda, and which is evolved in the state of hot vapour from the
furnaces in which chloride of sodium is decomposed by means of
sulphuric acid. I have found that when such hot vapour of hydro-
chloric acid has sulphuric and sulphurous acids, one or both,
mechanically or otherwise associated with it, I can separate those acids
by passing the said vapour (first cooling it or not, as may be preferred),
before it reaches the condensers used at present, through an intermediate
condenser, or other apparatus, the special function of which shall be
to condense or otherwise intercept and abstract the said sulphuric
and sulphurous acids, one or both, while allowing all or nearly all
the hydrochloric acid to pass on. This intermediate condenser may
conveniently be exactly similar to the condensing towers which arc
now almost universally used by alkali makers for the condensation
of their hydrochloric acid, and to which the mass of their vapour
of hydrochloric acid would still proceed after passing through my
intermediate apparatus; but the latter may conveniently, though
it need not necessarily, be very much smaller than the present
condensing towers. When the only contaminating acid is sulphuric
acid, and I desire to obtain such sulphuric acid in the free state, I
cither feed the intermediate condenser with no more water than
will suffice for the condensation of the sulphuric acid only, so what
shall run from the intermediate condenser shall be sulphuric acid
associated with only a minimum of hydrochloric acid; or, if feeding
it at first with a larger quantity of water, I pump the acid liquor
which runs from it back again a sufficient number of times, until
at last such liquor is a pretty strong sulphuric acid, containing only
Instead of thus
very little hydrochloric acid as in the former case.
obtaining the sulphuric acid in the free state, I can obtain it as a
useful sulphate by supplying the intermediate condenser or other
intercepting apparatus with solution of a suitable metallic chloride,
as, for example, chloride of iron, chloride of zinc, chloride of magnesium,
or chloride of sodium. Chloride of barium and chloride of calcium
can also be used, but they will only rarely, I think, be found so suitable
as the other chlorides mentioned. When the hydrochloric acid contains,
and I desire to separate, sulphurous as well as sulphuric acid, I supply
the intermediate condenser either wholly or partially with solution
of perchloride of iron, or other suitable per-salt, whereby the sulphurous
acid is oxidized with sulphuric acid, and so prevented from passing on.

page_text: I have said that the intermediate condensing or purifying apparatus
to be used as thus described may conveniently resemble the condensing
towers in use at present, but it need not necessarily be modelled
thereupon; all that is essential is, that it should be apparatus capable
of bringing the vapour passing through it into sufficient contact with
some substance which can then abstract the sulphuric and sulphurous
acids which may be associated with such vapour. I believe, however,
that apparatus precisely similar in construction and mode of working
to the condensing towers referred to will be found to answer this
purpose best.
26. When atmospheric air is the agent employed to peroxidize in
the wet way artificial oxides of manganese recovered from chloride of
manganese, whether by means of magnesia or by means of lime, I
prefer, before so employing the air, to separate its carbonic acid from
it as completely as possible. When this is not done, the carbonic
acid in the air forms carbonates with more or less of whatever free
magnesia or free lime may be contained in the mixture to which the
air is applied, and not only is the magnesia or lime which is thus
converted into carbonate thereby prevented from fulfilling the function
for the performance of which it is present in such mixture, but the
carbonate so formed remains with the peroxidized oxide of manganese,
and when the latter is treated with hydrochloric acid gives off its
carbonic acid in the state of gas, which mixes with the chlorine which
the action of the oxide of manganese liberates from the hydrochloric acid
much to the prejudice of such chlorine, at least as regards its application
to the manufacture of bleaching powder. This formation of carbonates
is prevented by depriving the air, before it comes in contact with the
mixture of oxide of manganese and other substances, of the carbonic
acid contained in it, and this can very readily be done by causing the
air to be cither drawn or forced through, or otherwise brought into
intimate contact with any liquid, such as milk of lime, or a solution
of an alkali, which will sufficiently readily absord carbonic acid gas,
or else to be either drawn or forced through a chamber, tower, or
other apparatus containing any solid substance capable of serving the
same end.
27. It is the custom of some alkali makers to inject air into their
crude liquors, or to pass these liquors through a tower through which
air is drawn, in order to oxidize the sulphides contained in them;

page_text: and it is also sometimes the custom to similarly treat these liquors
with carbonic acid gas, in order to convert any caustic alkali which
they may contain into carbonate. I believe that it would be a
good plan to pass the air to peroxidize artificial oxides of manganesc
in the wet way first through such crude soda or potash liquors,
whereby, while the sulphides in those liquors would be oxidized,
without materially impoverishing the air of its oxygen, and so lessening
its power to peroxidize the oxides of manganese,. the air would be
deprived of its carbonic acid, such carbonic acid being moreover turned
to useful account, and its separation from the air being effected without
incurring any cost specially for that purpose.
28. I now come to those of the improvements collectively constituting
the present Invention, which have reference to the regeneration of oxides
of manganese from chloride of manganese in the wet way, when the
chloride of manganese is decomposed by means of lime. I believe that
at first lime will be used in the process to which the present Invention
refers much more frequently than magnesia will be, and I believe this
for two reasons, one of which is that although the employment in the
manufacture of chlorine, when that manufacture is so conducted that
its residual product is chloride of manganese, of oxides of manganese
regenerated from such residual chloride of manganese by means of
magnesia, coupled with the decomposition of the resulting chloride of
magnesium into magnesia and hydrochloric acid, effects a much greater
economy of hydrochloric acid than can be effected by the similar
employment of oxides of manganese recovered from chloride of man-
ganese by means of lime; yet the use in the manufacture of chlorine,
conducted as just said, of oxides of manganese obtained by that form
of my process of regeneration in the wet way in which lime is the agent
used to decompose the chloride of manganese, effects such an economy.
of hydrochloric acid as will be found abundantly sufficient in the first
instance. By the use in the manufacture of chlorine, conducted as just
indicated, of oxides of manganese regenerated by means of magnesia,
combined with the recovery of hydrochloric acid from the resulting
chloride of magnesium, there may be obtained in the free state
absolutely the whole of the chlorine contained in the hydrochloric acid
employed; whereas when using in the same way oxides of manganese
regenerated from chloride of manganesc by means of lime the yield of
free chlorine is only from about one-third to two-fifths of the total

page_text: quantity contained in the. hydrochloric used.
Inasmuch, however,
as manufacturers of chlorine do not at present obtain on an average
more than one-fifth (and I believe that the proportion is really nearer
one-sixth only) of the total chlorine contained in the hydrochloric acid
they consume, to enable them to obtain from one-third to two-fifths
thereof is to enable them either to double their present production of
chlorine, their supply of hydrochloric acid remaining as at present, or
clse while maintaining their production of chlorine at its present
aniount, to have one-half of the quantity of acid which they now
consume in the manufacture of that quantity of chlorine left free for
application to other purposes. While, however, I believe that it will
be found that manufacturers of chlorine will have no alternative but
to begin immediately to employ my methods of regenerating oxides of
manganese from the residues of their manufacture, by reason of oxides
so regenerated being so very much cheaper than the oxides which they
use now; it is unquestionable that, at first, until they shall have had
time to make arrangements for its application either to the manufacture
of moro chlorine or. to other useful purposes, the hydrochloric acid
which they will save by doing so will be rather an embarassment to
them than otherwise. Eventually, without doubt; manufacturers of
alkalies (who are the chief producers of hydrochloric acid, and almost
the sole manufacturers of chlorine) will find it essential that they should
turn every particle of their hydrochloric acid to useful account, allowing.
none whatever of it to form compounds which can only be thrown away;
but considerable developments of various kinds must have taken place
before they can have become able thus to utilize the whole of their
produce of this intrinsically most valuable commodity, and in the mean-
time the greater number of them will doubtless be content with such
economy of it as they will effect by using for the manufacture of chlorine,
oxide of manganese regenerated in the wet way by means of lime, and
only very few of them will desire, at first, that still greater economy
of hydrochloric acid, to effect which is the only object of using magnesia
instead of lime for the decomposition of the chloride of manganese
produced as a residual product of that manufacture. Add to this the
other of the two reasons spoken of above, which is, that the manufacture
of chlorine by means of oxides of manganese regenerated from chlorido
of manganese in the wet way by means of magnesia requires a much
more extensive plant than will suffice for all the operations involved in
the manufacture of the same quantity of chlorine by means of oxides of

page_text: manganese similarly regenerated by means of lime, seeing that a plant
for working with magnesia must include apparatus for the decomposition
of the chloride of magnesium produced at each operation, nothing
corresponding to which is required in a plant for working with lime,
while, moreover, a plant for working with lime will not require altering,
but will merely require adding to, when it shall be desired to pass from
the method of working with lime to that of working with magnesia, and
it will be quite clear that the practice of my process of regeneration in
the wet way, as performed by means of magnesia, is sure to be preceded
by the practice of the said process as performed by means of lime.
29. A fact of the utmost practical importance in reference to the
regeneration of oxides of manganese in the wet way by means of lime,
which I have discovered in the course of my endeavours to work out
on the large scale the said process of regeneration as described in the
Specifications of my former Patents cited above, is that of the remarkable
power possessed by lime to promote the peroxidation of protoxide of
manganese in the wet way. Thus, if to a solution of chloride of man-
ganese there be added only júst an equivalent of lime, and the resulting
mixture of protoxide of manganese with solution of chloride of calcium
be then treated with air, by injection thereof or otherwise, the protoxide
of manganese in such mixture will peroxidize only very slowly indeed,
and will require exceedingly prolonged treatment with air to raise it to
a higher state of oxidation than that of Mn2 Os; but if to a similar
solution there be added more than an equivalent of lime, and the
resulting mixture of protoxide of manganese, free lime, and solution
of chloride of calcium be similarly treated with air, the protoxide of
manganese in the latter mixture will peroxidize very rapidly indeed,
and may be caused to very speedily attain a much higher state of
oxidation than that of Mn O³, the state of oxidation to which it will
be raised by a given amount of treatment with air being the higher
the larger the proportion of free lime in the mixture in which it is
formed. A very important part of the present Invention therefore
consists in peroxidizing the protoxide of manganese contained in a
mixture of such protoxide with free lime and solution of chloride of
calcium, or in such a mixture of these and other substances as is
obtained by adding more than an equivalent of lime to a solution of
chloride of manganese, which has been produced as a residual product
of the manufacture of chlorine, either by injecting air into such mixture

page_text: or by lifting the said mixture from one level to a higher one, and then
allowing it to fall through an atmosphere or column or current of air from
the said higher level to some convenient level below it (whether the
level from which the mixture was originally lifted or not), repeating
this treatment until the protoxide of manganese at first contained in
the mixture shall have been sufficiently peroxidized; or by placing the
:said mixture in any convenient "churn" and mechanically "churning"
it in contact with air until the desired end shall have been sufficiently
accomplished; or by placing the mixture in an open vessel of more or
less considerable depth at or near the centre but having sloping sides
of a large extent of surface, and then by means of any suitable dash
wheel or other mechanical appliance, duly adapted to the deeper part
of the vessel, agitating the mixture more or less violently, dashing it
about so as to bring all parts of it successively to the surface, and so
as to constantly fling portions of it on to the sides of the vessel, by
running down which sloping sides into the deeper part of the vessel
their contact with air will be advantageously prolonged; or by placing
the mixture in a hollow drum revolving on an axis placed horizontally,
having appertures in its sides near to its axis for the admission of air,
and being furnished interiorly with steps or dashboards from one to
another of which the mixture shall be kept constantly falling as the drum
revolves; or by combining together any two or more of these methods.
By any of these methods protoxide of manganese obtained from chloride
of manganese by means of lime may be very rapidly converted into a very
rich peroxide; but I believe that equally when working with lime as
when working with magnesia, the method of peroxidation by injection
of the air or other gaseous oxidizing agent will be found to be the
cheapest, the most rapid, and in all ways the most convenient.
30. The present Invention further includes some improvements in
the peroxidation of protoxide or other low oxides of manganese in the
wet way, which are equally applicable whatever the agent by means
of which such protoxide or other low oxide be obtained, and whatever
the substances in admixture with which it may be treated. These
further improvements consist in the use for the peroxidation of low
oxides of manganesc in the wet way of oxygen gas (which I believe
will shortly be producible cheaply enough to admit economically of
such application of it), either instead of atmospheric air, or in con-
junction with and in aid thereof; in the similar employment of gaseous

page_text: than in the latter. While, as stated in paragraph 29, the rule is that
artificial oxide of manganese which has been recovered by means of
lime, and is suspended in a solution of chloride of calcium, will be
raised to a higher state of oxidation by treatment with air at a given
rate for a given time the larger the proportion of free lime which is
associated with such oxide of manganese in such solution of chloride
of calcium. This rule is of course subject to such limitations as arise
from the circumstance that a richer peroxide of manganese than one
consisting wholly of Mn 0% cannot be obtained by the process
to which the rule refers, whence it follows that the differences
between the results obtained with an excess of lime and without, or
with different proportions of excess of lime, will be the smaller the
longer the periods for which the treatment with air be continued.
The rule, as above given, therefore holds good, the more especially
for short periods of treatment with air, and the differences between
the results obtained with an excess of lime and without by treatment
with air for only short periods are very remarkable. Let us suppose,
for example, a rate of treatment with air, the application of which
for two hours to a mixture consisting at the commencement simply
of protoxide of manganese and solution of chloride of calcium without
any free lime will raise the oxide of manganese in such mixture to
a state of peroxidation in which it will contain about forty to forty-
five per cent. of Mn 0%. Ten hours of such treatment will not yield a
richer peroxide than one containing about fifty-five per cent. of Mn O³
(being the proportion of Mn O contained in Mn 203), and a continuance
of the said treatment for twenty hours will scarcely raise the pro-
portion of Mn O in the said peroxide beyond if even up to sixty per
cenIf however there be present with the peroxide of manganese
from half an equivalent to three-quarters of an equivalent of free
lime, two hours treatment with air at the rate supposed will yield a
peroxide containing nearly seventy per cent. of Mn O, and four or
five hours of such treatment will yield a peroxide containing from
eighty to ninety per cent. of Mn O². Of course a peroxide of cighty
or ninety per cent. associated with from one-half to three-quarters of
an equivalent of free lime, or let us say, for the sake of the simpler
illustration, a peroxide of one hundred per cent. having associated
with it a full equivalent of free lime, will not liberate from a given
quantity of hydrochloric acid a larger quantity of free chlorine than
a peroxide containing only fifty-five per cent. of Mn Os, but having
E

page_text: no lime associated with it, will liberate therefrom. In the former
case the reaction will be that represented by the formula, 2 Mn 0²+
2 Ca O+6 H CI = 2 Mn Ol + 2 Ca Cl + 6 HO+ 2 Cl, while in the
latter case it will be that represented by the formula, Mn 20³+3H Cl=
2 Mn Ol +3 HO+ Cl, the yield of chlorine being in both cases just
one-third of the total quantity contained in the hydrochloric acid
employed. While, however, the yield of chlorine per given quantity
of hydrochloric acid will thus be exactly the same in both cases, the
yield of chlorine per given quantity of chloride of manganese treated
for the recovery of oxide therefrom will be twice as great in the case
of the oxide of a hundred per cent. associated with a full equivalent of
lime, as in the case of the oxide of fifty-five per cent. not associated
with any lime at all. An oxide of a hundred per cent. will rarely be
obtained in practice, but I believe that by using from half an equivalent
to three-quarters of an equivalent of excess of lime oxides of from
seventy to ninety, per cent. may be always obtained in from two to
five hours, the blast used being such as can be supplied by an engine
of from fifteen to twenty horse power, and the quantity of oxide
operated upon at once being (as reckoned in the state of protoxide)
about three-quarters of a ton. If that quantity of protoxide of
manganese be peroxidized up to each point that the result contains,
say, eighty per cent. of Mn 02 (such per-centage being of course
reckoned upon the total quantity of oxide of manganese simply, and
not upon the quantity of such oxide plus the quantity of any foreign
substance or substances that may be associated with it) the resulting
peroxide of eighty per cent. will liberate chlorine sufficient for the
production of about a ton and a half of bleaching powder; and supposing
the said peroxide to have associated with it about eight hundred pounds
of free lime, the mixture of lime and peroxide of manganese will
consume just about three times as much hydrochloric acid as contains
the quantity of chlorine which the peroxide of manganese in the said
mixture sets free. On the other hand, the same quantity of protoxide
of manganese if peroxidized only up to the fifty-five per cent., or
Mn Os point, which in cases in which free lime is wholly absent will
usually be quite as high a degree of peroxidation as it will be raised
to by from five to ten hours application of such a blast as that just
indicated, will liberate only chlorine enough for the production of one
ton of bleaching powder, for the generation of which quantity of chlorine
it also will require just three times the quantity of hydrochloric acid

page_text: containing the quantity of chlorine it sets free. The two peroxides
obtained as above set forth are thus on a level as regards the proportions.
of chlorine which they will liberate respectively from a given quantity
of hydrochloric acid; but the richer peroxide obtained when using the
excess of lime is obviously by far the more economical of the two,
the quantity of it as measured by the quantity of chlorine which can
be liberated thereby, which is producible in a given time by means of
an apparatus of a given size and a given amount of labour and attention,
being at least three times greater than the quantity similarly measured
that can be produced in the same time by means of an apparatus of
the same size and the same amount of labour of the less rich peroxide,
which alone can be obtained, except by very long continuance of the
treatment with air when an excess of lime is not used. The particular
proportion of excess of lime, the use of which will be found most
economical, must necessarily vary with circumstances, but I incline
to think that in all cases in which the manufacturer of chlorine shall
be content with obtaining in the free state one-third of the total
quantity contained in the hydrochloric acid which he consumes in his
manufacture thereof (and it is to be borne in mind that at present
manufacturers of chlorine but very rarely obtain in the free state more
than one-sixth of the total quantity contained in the hydrochloric
acid they consume), the proportion of free lime which it will be found
most advantageous to have associated with the oxide of manganese
regenerated at each operation will be from one-half to three-fourths of
an equivalent. Manufacturers desiring to obtain in the free state by
means of oxides of manganese regenerated from chloride of manganese
by means of lime in the wet way more than one-third of the total
chlorine in their hydrochloric acid must use smaller proportions of
excess of lime than that just stated, and must subject their recovered
oxide to the action of the peroxidizing blast for longer periods than
it will be needful to subject it thereto when using such proportion of
excess of lime as that indicated above.
32. Though perhaps not a matter of much practical importance it may
here be pointed out that while on the one hand the presence of free lime
tends so powerfully to promote the peroxidation in the wet way of
artificial oxides of manganese, on the other hand the presence of un-
decomposed chloride of manganese seems to have precisely the reverse
effect.
If to a solution of chloride of manganese less than an equivalen

page_text: lime, and especially when working with excess of lime, there will never
be any danger of the temperature during the peroxidation process being
too high if the peroxidation be performed by means of a blast of air at
its natural temperature, injected with moderate rapidity, however hot the
mixture into which the blast is injected may be at starting, and whether
or not it may be thought necessary, whether in order to hasten the
peroxidation or for any other reason, to inject steam into the mixture
simultaneously with the blast of air. Indeed, when working with lime,
and especially when working with excess of lime, the temperature must
approach 180° or even 200° Fahrenheit before one need begin to question
as to whether it is not so high as to be prejudicial to the richness of
the result.
34. When working with excess of lime the improvement which is
described above in paragraph 26 will obviously be of very special
importance, and what I accordingly consider to be a most important
part of the present Invention consists in the combination of the said
improvement with the said method of working with excess of lime.
35. When working with lime, equally as when working with
magnesia, the regeneration from chloride of manganese of oxides of
manganese to be used again in the manufacture of chlorine may be
performed either in the stills in which the recovered oxides will after-
wards be applied to the generation of chlorine, or in vessels distinct from
the stills and specially appropriated to the operations of the regeneration
process.
In cither case however it will be very desirable to purify
from sulphuric and sulphurous acids the hydrochloric acid from which
the recovered oxides are to be employed to liberate chlorine, as otherwise
there will be sulphate of calcium formed at every operation, for the
removal of which sulphate of calcium the "still liquor" will have
regularly to undergo a special treatment.
36. It will sometimes however be most convenient to work at once
with lime and with hydrochloric acid which has not been purified from
sulphuric acid, and in such case I take advantage for the separation of
the sulphate of calcium formed under such circumstances of the facts
that whereas sulphate of calcium is very considerably soluble both in free
hydrochloric acid and in hot solution of chloride of manganese, it is but
slightly soluble in solution of chloride of manganese when such solution
is both cold and neutral. By neutralizing any free acid which may be
associated with the chloride of manganese and letting the solution cool,

page_text: one can therefore cause the greater part of the sulphate of calcium to
crystallize out. It can then be readily eliminated either by filtration,
or by subsidence and decantation, or by a combination of both methods.
37. When working with lime, whether or not under circumstances
under which sulphate of calcium is formed, there will always be
impurities derived from the lime itself, which will require removal from
time to time. These will be chiefly silica and alumina, which last will
go into solution as cesqui-chloride of aluminium. The addition to the
still liquor of enough lime or other suitable agent (over and above the
quantity required to neutralize the free acid in it, if any) to decompose
the chloride of aluminium will enable both these impurities to be got
rid of in the same way as sulphate of calcium, and at the same time as
this last-mentioned compound, if it be formed.
38. As hydrochloric acid produced in the manufacture of alkalies
invariably contains iron, that element alike when working with magnesia
and when working with lime will accumulate in the still liquor unless
occasionally removed. It will always exist therein mainly if not
exclusively as sesqui-chloride of iron, which should be treated precisely
in the same way as the sesqui-chloride of aluminium.
39. The method to be adopted for the systematic separation, upon
the principle enunciated in paragraph 36, of the impurities spoken of in
that and the two following paragraphs, will depend upon whether the
decomposition of the chloride of manganese and the peroxidation of
the resulting oxide are performed in the stills or in separate vessels.
When these operations are performed in the stills I like to remove from
each still at every operation (after the first half dozen or so, more or less,
according to the amount of the impurities entering the still, or formed
within it at each working) such a proportion of the still liquor as shall
contain a quantity of the impurities to be eliminated as nearly as possible
equal to the quantity added to the still liquor during each operation,
each time replacing the quantity so removed by an equivalent quantity
of pure liquor. Suppose, for example, that I am working ten stills, that
I produce in each about a thousand cubic feet of still liquor at each
operation, that I have got accumulated in each still the impurities
resulting from ten operations, and that I now desire that impurities shall
not accumulate any further, I run off one hundred cubic feet of liquor
from each still and run in a like quantity of previously prepared pure
liquor; the impure liquor thus run off I purify while the next operation

page_text: in the still is being performed, and at the end of that operation I again
run off one hundred cubic feet of liquor from each still, this time
replacing the liquor run off by the now purified liquor run off at the end
of the preceding operation. Thenceforth I proceed in this way con-
tinually, at the end of every operation running off a portion of impure
liquor from each still and putting in its place a corresponding quantity
of the liquor which was run off at the end of the last preceding or some
other previous operation, but which has in the meantime been purified.
The purification on this plan may of course be performed less often than
at the end of every operation, but I prefer to perform it after every
operation excepting the first few, so that after the first few times the still
liquor with which operations are commenced shall be always in as nearly
as possible the same condition.
40. When purifying the still liquor on the plan thus set forth I
provide a reservoir, called a "purifier," into which I send the impure
liquor from every still. I prefer to place this purifier below the stills,
so that the impure liquor may run from the stills into it, but where this
is not convenient it may be placed above the stills and the impure liquor
be pumped or otherwise lifted into it. Where the number of stills is
considerable it may be necessary to have more purifiers than one, but
the mode of proceeding will of course be just the same as when only one
is employed. In the purifier the impure liquor is treated with either
magnesia or carbonate of magnesia, or else with either lime or carbonate
of lime, in just sufficient quantity to neutralize the free acid in it (if any)
and to decompose what chloride of iron and chloride of aluminium it may
contain. It is then either left at rest so that its impurities may subside
and the clear liquor be then run off or otherwise decanted into a second
reservoir or "cleared liquor tank," or, which I believe to be the pre-
ferable plan, it is run on to a filter bed and the clear liquor separated
by filtration. Whichever of these methods be adopted the clarified
liquor is lastly pumped up into a tank or reservoir suitably placed
above the level of the stills, and suitably connected with cach still, so
that the cleared or purified liquor can be run therefrom into the stills
as required.
41. When the working of my process of regeneration by the wet way,
as performed in the stills themselves, is conducted with proper care the
liquor in each still will always, after each operation, be at the same level
almost exactly. Each still should have a tap at that level, and another

page_text: tap at the level to which impure liquor is to be run off each time, and
the instructions to the workmen should be to open the lower of these
taps the moment the still has ceased to give off chlorine, and when this
tap has ceased running to close it and let liquor run in from the upper
reservoir of cleared liquor to the level of the upper of these two taps.
The running off of the right quantity of impure liquor and the running
in of the right quantity of purified liquor can thus be confided to
unskilled workmen with but little risk of any mistake being made.
42. When the decomposition of the chloride of manganese and the
peroxidation of the resulting oxide are performed in vessels other than
the stills the purification of the still liquor should be effected in appa-
ratus placed intermediately between the stills and the vessels in which
the recovery and peroxidation processes are thus conducted. This
apparatus may conveniently consist of three reservoirs, into one of which
liquor from the stills shall be constantly entering for a given period, in
another of which such liquor shall be treated with a suitable quantity
of lime, or magnesia, or carbonates thereof, and then be left at rest for
the same period, and into the third of which the clear liquor contained
in the second reservoir, after all solid impurities have subsided therein,
shall be pumped, run, syphoned, or otherwise decanted, the vessel or
vessels in which the recovery of oxide of manganese from the purified
liquor is effected being then supplied from this third reservoir.
43. In this case, however, equally as when performing the recovery
and peroxidation processes in the stills themselves, it is perhaps better
to effect the separation of the solid impurities contained in the liquor
after it has been treated with lime, or magnesia, or carbonates thereof,
as aforesaid, by filtration instead of by subsidence. In either case, if
the whole of the liquor be not filtered, the sediment left, after decan-
tation of the clear liquor, in the reservoirs in which the impurities
subside should be thrown on to suitable filter beds and there allowed
to drain thoroughly, the drainings running into the cleared liquor
reservoir. This sediment will usually be so retentive of liquid that
much manganese would otherwise be thrown away with it.
44. Or instead of filtering the sediment in question all associated
liquor may be separated from it by means of centrifugal hydro-
extractors.
45. The three reservoirs to be used as described in paragraph 42
should, when convenient, be placed at successively lower levels, so that

page_text: the liquor may run from the first of them unto the second, and from the
second into the third. The number of the reservoirs may be other than
three, but three will usually be found most advantageous. I prefer that
the vessel or vessels in which the liquor from the third or other final
reservoir is decomposed and the resulting oxide peroxidized should be
situated at a much higher level, so that while the liquor from this
"cleared liquor" reservoir will require pumping up into such vessel or
vessels the mixture of peroxidized oxide of manganese and solution of
chloride of other metal formed in such vessel or vessels may run from it
or them to the level of the stills, and so a single pumping be made
to suffice. A single pumping, however, will be equally sufficient if the
regeneration of the oxide be effected at or below the level of the cleared
liquor reservoir, and the mixture of oxide of manganese with either water
or solution of chloride of magnesium, chloride of calcium, or chloride
of other metal, be pumped therefrom to such higher level as may be
necessary.
46. The separation of the peroxidized oxide from as much as it may
be necessary to remove of the liquor in which it was formed should
be effected, when the oxide is regenerated in vessels other than the
stills, in vessels especially devoted to the purpose of such separation. A
good plan is to place at the back of or otherwise associate with each
still a reservoir (which may be of wood, iron, or any other convenient
material) capable of holding as much mixture of regenerated oxide of
manganese and liquor in which it was formed as shall contain oxide
enough for one charge of the still, and to run or pump or otherwise
propel or convey into each such reservoir such quantity of mixture of
oxide and liquor directly from the vessel or vessels in which the oxide
is formed, allowing one charge to settle in each such reservoir while
another charge is being worked in its associated still.
47. Another plan is to run or pump or otherwise convey the mixture
of oxide and liquor from the vessel or vessels in which it is formed into
a large tank to allow it to settle therein, to then decant off the clear
liquor, and to then run or pump or otherwise convey the oxide to the
stills in the state of the thick mud which is the state in which the oxide
remains after it has subsided as far as it will and the clear liquor has
then been decanted from above it. When adopting this plan it is well
to have three such tanks or reservoirs, into one of which mixture of
oxide and liquor can be constantly being put for some suitable period,

page_text: in a second of which the mixture of oxide and liquor can be left at rest
for the same period, and from the third of which, during the same
period, oxide can be supplied to the stills.
49. Other methods of separating the oxide from the proportion of
associated liquor which it is necessary to remove from it consist in
running the mixture of oxide and liquor on to filter beds, or into pits
on or in which it may remain until drained nearly or quite dry; or,
with or without previous washing, it may be dried more or less
completely by the direct application of heat.
50. When it is desired to wash the oxide, either as a preliminary to
drying it or otherwise, the washing may be performed either on filter
beds or in tanks or other vessels. In the last case water may be kept
constantly running in at the bottom of the vessel, and constantly
running out at the top, at such rate as not to carry with it any oxide;
or a hollow filter may be forced down into the mixture of oxide and
liquor, and be kept constantly nearly empty by means of a fixed syphon,
while water is run into the vessel containing the mixture of oxide and
liquor in proportion as liquor is removed by the syphon from inside
the hollow filter.
51. The stills used for the manufacture of chlorine from hydrochloric
acid by means of native oxides of manganese, and also those used for
the manufacture of chlorine by means of such artificial oxides as
have hitherto been in use, have invariably been more or less shallow,
either their width or their length, when not both their width and their
length also, being greater than their depth. Such stills, however, are not
convenient when working with artificial oxides regenerated in the
stills themselves. In that method of working it is better for obvious
reasons to employ stills whose depth is greater than either their length
or their width.
52. When thus employing stills whose depth is their greatest
dimension it is a good plan to sink them into the ground so far that
the lowest point to which it shall be necessary in ordinary working
to draw off liquor from them shall be just at the level of the ground,
or thereabouts. When the stills cannot be thus sunk in the ground I
recommend that they be partially buried in artificial embankments.
53. It will sometimes be found convenient to use stills only the lower
part of which shall be of stone or other substance not readily acted
upon by either hydrochloric acid or free chlorine, the upper part being

page_text: of iron or any other suitable material not specially capable of resisting
corrosion by acids. In such cases the arrangements must be such that
the contents of the still, when acid, shall never rise above the upper
limit of the stone portion of the still, the function of the portion
above that limit, and made of other material, being simply to afford
space for any liquor which in the particular system of working followed
it may be necessary to add to the "still liquor" proper after the
evolution of chlorine therefrom has ceased, and for whatever froth or
spray may be formed during the subsequent blowing. Stills of this
kind should have a moveable cover or lid admitting of being readily
fixed in its place just before running in acid upon the recovered oxide,
and of being as readily lifted out after the completion of the reaction
between the acid and oxide. The place of such moveable cover.
should be at or just below the upper limit of the lower portion of
the still.
54. Hitherto the pipe by which the oxidizing blast has been injected
into stills in which oxide of manganese has been recovered from chlorine
residues by my method has always been of iron, and so has had to be
removed before the running in of acid each time, and to be afterwards
replaced before the commencement of each peroxidizing operation. It
is far better to make this pipe of either stone, or earthenware, or ebonite,
or other convenient substance not readily attacked by either chlorine
or hydrochloric acid, so that it shall not need, as hitherto, to be removed
and replaced in the course of every operation.
55. It is sometimes a good plan to so arrange that the steam required
to be injected at one stage or other of the operations conducted in the
still shall enter by the same pipe as the oxidizing blast.
56. A very serviceable pipe by which to inject into the stills either the
steam required or the oxidizing blast may be made by placing an earthen-
ware pipe of the required bore inside another of larger bore, making the
joints in each pipe with lead, and either filling the whole space between
the outer pipe and the inner pipe with lead protected at any point at
which it would otherwise come in contact with either chlorine or acid
with a coating of the "black cement" which is ordinarily used in
chlorine manufactories, or else attaching the two pipes together by
means of lead only at the joints in each, and filling the rest of the
space between them with any other substance that may be preferred.
57. Good pipes for the purposes in question may also be made by

page_text: boring longitudinal blocks of red sandstone or other available silicious
stone. It is probable that suitable pipes could likewise be made of some
varieties of artificial stone.
58. Experience has shewn that stills in which oxide of manganese
is recovered and peroxidized in the wet way need not have false bottoms
to distribute the blast, provided that the blast be injected with sufficient
vigour. I sometimes prefer, however, to make the bottom of the still of
the shape of an inverted truncated cone, and to place a small false
bottom in the centre at the lower part of such inverted truncated cone,
and if I make such or any other false bottom used in my process of stone
or earthenware slabs I prefer to make the holes in it conical, each hole
being much wider at the under than at the upper side of the false
bottom.
59. It will sometimes be desirable when working with lime to take
advantage as follows of the fact stated in paragraph 12 together with
the further fact of the solubility of sulphate of calcium in hydrochloric
acid. Suppose that a peroxidizing operation has just been completed
in a given still, and that it is desired that the oxide produced shall be
caused to subside with the utmost possible rapidity, let hydrochloric
acid be immediately added to the contents of the still, but in quantity
insufficient to dissolve any peroxide of manganese. If the peroxidized
oxide be quite up to a hundred per cent. strength, which will probably
happen only very rarely, dilute hydrochloric acid will not dissolve any
of it, though it will very materially increase the rapidity with which
it will settle. The clear acid solution in such cases remaining above
the subsided oxide may either be thrown away, or its free acid may be
evaporated off and condensed for use or be turned to account in any
other convenient manner. If, however, the peroxidized oxide be at a
lower strength than a hundred per cent. the dilute hydrochloric
acid will dissolve protoxide from it, and the quantity of hydrochloric
acid used may easily be so regulated as to leave only peroxide of a
hundred per cent. undissolved. In such cases when the peroxide from
which all or part of the protoxide at first associated with it has been
dissolved, the supernatent solution will contain more or less chloride
of manganese, and so must not be thrown away until such chloride of
manganese shall have been decomposed. The mixed solution containing
this chloride of manganese should accordingly be run into a supple-
mentary vessel associated with the still, and be there treated with a

page_text: quantity of lime equivalent to the chloride of manganese contained in
it. The resulting protoxide of manganese should then be allowed to
settle, and the supernatent solution be then drawn off from it, all which
can be done while the oxide in the still is being digested with hydro-
chloric acid. Then on the cover of the still being removed for the
addition of lime and the commencement of a new recovery operation,
the protoxide in the supplementary vessel (which protoxide will now
be in the state of thick mud) should be pumped into the still, there
to undergo peroxidation together with the protoxide resulting from
the decomposition of the chloride of manganese formed by the reaction
together of the oxide which was left in the still and the hydrochloric
acid from which that oxide has liberated chlorine.
60. The plan just described is equally available when working with
magnesia, in which case also another similar plan will sometimes be
useful. Thus when a quantity of still liquor has been boiled in a still
or other vessel with an equivalent of magnesia until the greater portion.
but not the whole of the chloride of manganese in such liquor has been
decomposed and the resulting oxide of manganese has been allowed to
subside, and the supernatent mixed solution of chloride of magnesium
and chloride of manganese has been drawn off from it, instead of treating
that mixed solution as described in paragraph 4 it may be run into a
supplementary vessel, and boiled therein with an excess of magnesia until
the chloride of manganese contained it has been decomposed.
contents of such supplementary vessel will then consist of a mixture of
magnesia, protoxide of manganese, and solution of chloride of magnesium.
The latter having been more or less completely removed either by filtration.
or by subsidence and decantation, the remaining mixture of magnesia and
protoxide of manganese can be used instead of magnesia only in the next
recovery operation in the still, and so on continually.
The
61. As regards everything that has to be run off from the stills, it
will always be well to work by fixed taps in the sides of the stills upon
the plan suggested in paragraph 41. It will be a good plan also, at
least in some modes of working, to measure the acid put into the stills
by running it in from the level of one tap to that of another.
62. It will sometimes be desirable, when not convenient to separate
the sulphuric and sulphurous acids which may be contained in the
hydrochloric acid employed by the methods described in paragraph 25,
to separate it as sulphate of barium.

page_text: Occasionany
to use ammonia instead of either lime or magnesia as the agent by
means of which to decompose chloride of manganese, from which i
is desired to obtain by my method of regeneration and peroxidation
in the wet way oxides of manganese available for use in the manufacture
of chlorine.
64. Lastly, it is to be noted that, whereas when decomposing a mixture
of hydrated chloride of magnesium and chloride of manganese by heat, as
is recommended above in paragraph 4, access of air is of course essential
to the manganese being yielded up as peroxide, I have not found it
necessary when the proportion of chloride of manganese associated with
the chloride of magnesium has not been large to make any special
arrangements to secure such access of air. When decomposing the
mixture of chloride of magnesium and chloride of manganese in a
"blind" furnace, which is the plan I prefer, I have always found that
quite sufficient air gained access to the contents of the furnace although
all its doors were kept closed during the greater part of the operation,
the doors being opened only at intervals (and then only for brief
periods), in order that the contents of the furnace should be "worked"
or rabbled.
65. Having now particularly described and ascertained the nature
of my Invention, and the manner in which the same is to be performed,
I now finally point out that what I claim as my Invention, and desire
to be secured to me by the herein in part recited Letters Patent, is is
follows:-
(1.) The process or method of procedure for the obtainment from
chloride of manganese of oxides of manganese capable of being used
in manufacturing operations for the liberation of chlorine from hydro-
chloric acid, which process or method consists in either boiling or
otherwise treating together magnesia and solution of chloride of
manganese until the greater portion but not the whole of the chloride
of manganese has been decomposed, and in then peroxidizing the
resulting protoxide of manganese by treating with air or other gaseous
oxidizing agent a mixture of such protoxide of manganese with either
a mixed solution of chloride of magnesium and chloride of manganese
or a solution of chloride of magnesium only, or with water or any other
suitable liquid.

page_text: (2.) The method of treating the solution of chloride of magnesium
mixed with chloride of manganese, which is obtained together with
protoxide of manganese, when chloride of manganese in solution is
decomposed incompletely, by means of magnesia, which method consists
in boiling down this mixed solution, and then heating the residue with
moderate access of air, whereby the surplus water of such mixed
solution is driven off as steam, and the other constituents of it are
resolved into magnesia, a more or less rich peroxide of manganese,
and hydrochloric acid.
(3.) The method or process for the regeneration from chloride of
manganese by means of magnesia of oxides of manganese suitable for
use in the manufacture of chlorine, which method or process consists in
treating with air or other gaseous oxidizing agent a mixture of magnesia
with solution of chloride of manganese, or of magnesia and oxide of
manganese with a mixed solution of chloride of magnesium and
chloride of manganese, or the mixture, whatever its exact nature or
composition at any stage of the operation, which is got by adding
magnesia to the solution which is a residual product of the manufacture
of chlorine by the reaction of liquid hydrochloric acid upon oxides of
manganese, and then treating as aforesaid.
(4.) The decomposition into hydrochloric acid and magnesia of the
hydrated chloride of magnesium obtained as a bye-product of the decom-
position by magnesia of the residual chloride of manganese produced
in the manufacture of chlorine as aforesaid by subjecting such hydrated
chloride of magnesium to the action of heat alone, the water required
to afford oxygen to one of the elements of the chloride of magnesium
and hydrogen to the other being supplied by the water of hydration of
the chloride itself.
(5.) The decomposition of hydrated chloride of magnesium by heat
alone at temperature from about 310 degrees Fahrenheit to a point a
little below dull redness.
(6.) The regulation of the temperatures used for the decomposition
of hydrated chloride of magnesium obtained as a bye-product of the
decomposition by magnesia of the chloride of manganese which is
obtained as a residue of the manufacture of chlorine as at present usually
conducted according to the particular manner in which the magnesia
thereby recovered for use again is to be applied to the decomposition of
such chloride of manganese and the temperatures at which it is required

page_text: to react thereon, the temperatures used for the decomposition of the
chloride of magnesium being the lower the lower the temperatures at
which the resulting magnesia is required to be able to decompose
chloride of manganese.
(7.) The plan of decomposing each charge of chloride of magnesium
only partially, the chloride of magnesium contained in the mixture of
chloride of magnesium and magnesia which constitutes a partially
decomposed charge being made to form part (or the whole) of a
subsequent charge, or being otherwise applied, as may be more desirable
in any particular case.
(8.) The use for the decomposition, by heat alone, of hydrated chloride
of magnesium, and for the decomposition, whether by heat alone or by
heat aided by steam, of a mixture of chloride of magnesium and
chloride of manganese, of close or "blind" furnaces, similar to the
"blind roasters" used by manufacturers of soda for roasting their salt
cake, but preferably much longer than those "roasters" are.
(9.) The use for the decomposition of chloride of manganese obtained
as a residue of the manufacture of chlorine of magnesia obtained by
decomposing hydrated chloride of magnesium by heat alone; of
magnesia obtained by decomposing chloride of magnesium only partially,
whether by heat alone or by heat aided by steam; and of the magnesia
contained in the mixture of magnesia and peroxide of manganese,
or of magnesia, peroxide of manganese, and undecomposed chloride
or chlorides, which results from the complete or partial as aforesaid
of a mixture of hydrated chloride of magnesium and chloride of
manganese.
(10.) The plan of grinding very finely, with water or other suitable
liquid, magnesia (whether associated or not with peroxide of manganese)
which has been obtained by decomposing hydrated chloride of mag-
nesium, before adding it to the mass of the solution the chloride of
manganese in which it is required to decompose.
(11.) The use for the application of air or other gaseous oxidizing
agent to protoxide of manganese as obtained by an incomplete decom-
position of chloride of manganese by magnesia in the wet way, and also
for the application of air or other gaseous oxidizing agent to the mixture
of oxide of manganese and other substances which is treated of above
in paragraph 5, of the particular methods of applying such agents,
which are set forth above in paragraphs 15 and 30.

page_text: (12.) The various methods of proceedure for the regeneration from
chloride of manganese of oxides of manganese suitable for employment
in the manufacture of chlorine which are described above in paragraphs
17 to 23, both inclusive.
(13.) The systematic separation from the solution of chloride of
magnesium, associated or not with chloride of manganese, which is a
product of the reaction of magnesia upon chloride of manganese in the
wet way,
of the sulphate of magnesium which such solution will
always contain when the hydrochloric acid from which the chloride of
manganese was formed has contained either sulphuric or sulphurous
acids, or both.
(14.) The use for the purpose just indicated of the method and
arrangement which are described above in-paragraph 24.
(15.) The separation from hydrochloric acid which is to be employed
in the manufacture of chlorine, before applying to the purposes of that
manufacture, of any sulphuric or sulphurous acids which may be
associated with it.
(16.) The use for this purpose of such method and arrangements as
are described above in paragraph 25.
(17.) The separation from atmospheric air which is to be used for
the peroxidation of low oxides of manganese in the wet way of as much
as possible of the carbonic acid contained in it.
(18.) The use for the purpose of effecting such separation of carbonic
acid air which is to be employed as indicated of the methods and
arrangements which are described above in paragraphs 26 and 27.
(19.) The production of very rich artificial peroxides of manganese
by treating with air, by any of the methods mentioned above in
paragraph 29, a mixture of recovered oxide of manganese, free lime,
and solution of chloride of calcium, or any other suitable liquid.
(20.) The regulation of the proportion of free lime to be contained
in the mixture just mentioned according to what is set forth above in
paragraph 31.
(21.) The use of the peroxidation of artificial oxides of manganese
which have been recovered by means of lime of the particular methods
which are set forth above in paragraph 30, and of the agents other than
atmospheric air of which also mention is made in that paragraph.

page_text: (22.) The systematic separation of sulphate of calcium from the still
liquor obtained when manufacturing chlorine by means of artificial
oxides of manganese regenerated by means of lime and hydrochloric
acid containing either sulphuric or sulphurous acids, or both, and the
employment for this purpose of the method and arrangements described
above in paragraphs 36, 39, 40, 41, 42, 43, 44, and 45.
(23.) The separation also, by means of the same method and arrange-
ments, of the silica and alumina derived from the lime employed, and
of the iron derived from the hydrochloric acid used.
(24.) The various details relating to the apparatus, arrangements, and
modes of proceedure to be employed in various cases which are set forth
above in paragraphs 46 to 62, both inclusive.
(25.) The use of ammonia, when that reagent can be obtained
cheaply, and especially when the resulting chloride of ammonium can be
turned to useful account, for the recovery from chloride of manganese
of oxides of manganese, to be afterwards peroxidized by my process in
the wet way, and then employed for the liberation of chlorine from
hydrochloric acid.
(26.) The combination of any two or more of the improvements
which collectively constitute the Invention which is described in the
foregoing Specification, and the manufacture of chlorine by means of
oxides of manganese, in the recovery of which from chloride of man-
ganese any one or more of the said improvements has been employed.
In witness whereof, I, the said Walter Weldon, have hereunto
set my hand and seal, this Eighteenth day of August, in the
year of our Lord One thousand eight hundred and sixty-eight.

page_text: 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 under the Great Seal of Great Britain and Ireland, bearing
date at Westminster the Twentieth February One thousand eight
hundred and sixty-eight, in the thirty-first year of Her reign, did, for
Herself, Her heirs and successors, grant unto me, the said Walter
Weldon, my executors, administrators, and assigns, the sole privilege of
making, using, exercising, and vending an Invention of "IMPROVEMENTS
RELATING PRIMARILY TO THE MANUFACTURE OF CHLORINE BY MEANS OF REGE.
NERATED OXIDES OF MANGANESE, BUT PARTLY APPLICABLE TO OTHER PURPOSES,
BEING IMPROVEMENTS IN THE DECOMPOSITION OF CHLORINE RESIDUES IN THE
PEROXIDATION OF OXIDE OF MANGANESE RECOVERED THEREFROM IN THE TREAT-
MENT OF A BYE PRODUCT OF THE DECOMPOSITION OF THOSE RESIDUES IN THE
SEPARATION OF SULPHURIC ACID AND OTHER IMPURITIES FROM THE HYDROCHLORIC
ACID EXPLOYED, AND IN APPARATUS AND ARRANGEMENTS FOR SOME OF THOSE

page_text: PURPOSES," within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and the Isle of Man, for and during the term of
fourteen years thence next ensuing: And whereas in pursuance and
performance of a proviso in the said Letters Patent contained, I, the
said Walter Weldon, did, within six calendar months next after the date
of the said Letters Patent, cause a Specification in writing, under my
hand and seal, describing the said Invention, and in what manner the
same was to be performed, to be duly filed in the Great Seal Patent
Office: And whereas I, the said Walter Weldon, drew my said Specifi-
Ication myself, unaided by legal or other professional assistance, and I am
advised that I have crowded it with reasonings theoretical and chemical,
some of which are, as I now believe, erroneous, and which are altogether
so voluminous and involved as to be calculated to mislead: And whereas
I am also advised that some of the processes described and claimed in
the said Specification are of doubtful utility, and that there are several
clerical errors in the said Specification as filed: And whereas I am also
advised that the words following in the title to the said Invention, that
is to say,
"Improvements relating primarily, to the Manufacture of
Chlorine by Means of Regenerated Oxides of Manganese, but partly
applicable also to other Purposes, being," and also the words in the
said title noxt herein-after mentioned, that is to say, "in the Treatment
of a Bye Product of the Decomposition of those Residues in the
Separation of Sulphuric Acid and other Impurities from the Hydro-
chloric Acid employed, and in Apparatus and Arrangements for some
of these Purposes," relate to certain processes described in the said
Specification which are of doubtful utility, or as to some of such words,
appear to refer to matters which are not found in the said Specification
as filed, and I am therefore desirous of striking out the several words
herein-before mentioned from the title of the said Invention, and of
adding after the words "chlorine residues" the word "and": And whereas
I am desirous of disclaiming the various parts of the said Specification
herein-after particularly mentioned, and I am desirous, with the view
of making the Specification more intelligible, and in order that it
may
read continuously when altered by Disclaimer, as herein-after mentioned,
of altering the said Specification in manner herein-after set forth.
also
Λ
NOW KNOW YE, that I, the said Walter Weldon, by and with the
leave of Her Majesty's Attorney General, do hereby, for the reasons
aforesaid, disclaim the words herein-before lastly mentioned from the

page_text: title of the said Letters Patent, and I add after the words "chlorine
residues" in the said title the word "and," and for the reasons afore-
said I strike out from the printed copy of the said Specification, printed
by the Queen's printers, and published at the Great Seal Patent Office,
(which
copy
is herein-after referred to as the said printed copy, the word
"primarily," which occurs in the fourteenth line of the twenty-seventh
page of the said printed copy and alee the words "-principally-and-essen-
tially "
firstly" in the twenty-first and twenty-second lines of the same
and ending with
^
whole of the passage beginning with the
I also strike out the word "aforesaid," which occurs in the twenty-third line of the same page of the said printed copy,
pagc, and also the words "to the treatment of a bye product of such
decomposition of chloride of manganese. Thirdly," which occurs in
the twenty-fifth and twenty-sixth lines of the same page, and also the
whole of the passage commencing with the words "and to the separa-
tion" in the twenty-eighth line of the said twenty-seventh page of
the said printed copy, and ending with the words "made to me," in the
thirty-eighth line of the twenty-ninth page of the said printed copy.
And I am also desirous of striking out from the said printed copy the
word "thus" in the first line of the thirtieth page thereof, and of adding
in the last-mentioned line the words "granted to me" after the words
"previous Patents," and also of striking out from the second line of the
said thirtieth page the words "just named," and adding in the same
line the words "following the Twenty-sixth day of July One thousand
eight hundred and sixty six, the Eighteenth day of January One
thousand eight hundred and sixty-seven, and the Fourth day of
September One thousand eight hundred and sixty-seven," and of
substituting the figure 2 for the figure 3 in the third line of the said
thirtieth page. And I also strike out from the said printed copy the
whole of the passage commencing with the words "Chloride of manga-
nese" in the twelfth line of the thirtieth page of the said printed copy,
and ending with the words "is that" in the thirteenth line of the thirty-
second page thereof, and of changing the small "i" of the word "if" in
the last-mentioned line into a capital "I" so as to commence the
sentence with the word "If." And I strike out from the said printed
copy the whole of the passage of the said Specification commencing with
the word "The " in the twenty-first line of the thirty-second page of the
said printed copy, and ending with the word "sesqui-oxide" in the
thirtieth line of the same page. And for the purpose of amending a
clerical error I am desirous of substituting in the sixth line of the thirty-
third page the word "comes" for the word "came." And I strike out
said

page_text: from the said printed copy the whole of the passage beginning with the
word "When" in the ninth line of the thirty-third page of the said
printed copy, and ending with the word "charge" in the twelfth line of
the forty-second page thereof, and of insorting before the words "The
decomposition" in the last-mentioned line the figure "3" as the
number of the paragraph. And I strike out in the twenty-second line of
the said forty-second page of the said printed copy the word "go," and
substitute therefor the word "undergo;" and also strike out in the
twenty-fourth line of the last-mentioned page the word "place" and
insert therein instead the word "plan." And I strike out from the said
printed copy the whole of the passage commencing with the word
"The" in the thirty-third line of the forty-second page thereof, and
ending with the word "magnesia" in the third line of the forty-third
page thereof, and I substitute in the fourth line of the last-mentioned
page the figure "4" for the figure "10." And I strike out from the
said printed copy the whole of the passage commencing with the words
**The evaporation" in the cleventh line of the forty-third page thereof,
and ending with the words "16. I prefer that" in the fourteenth line of
the fiftieth page thereof, and I also substitute a capital M for a small
m in the word "magnesia" in the last-mentioned line, so as to com-
mence the sentence with that word; and I add before the said word
"Magnesia" in the last-mentioned line the figure "5" as the number of
the paragraph. And I also strike out from the twentieth line of the
said fiftieth page of the said printed-eepy the words "that it," and sub-
stitute in the twenty-third line of the said fiftieth page of the said
printed copy the figure "6" for the figures "17." And I strike out the
whole of the passage commencing "18. When the plan" in the twenty-
ninth line of the fifty-first page of the said printed copy, and ending with
the word "stills" in the thirty-seventh line of the fifty-second page
thereof; and I substitute in the last line of the last-mentioned page the
figure "7" for the figures "19," and the figure "6" for the figures "17."
And I also strike out from the said printed copy the whole of the
passage beginning with the words "In this case" in the fourth line of
the fifty-third page thereof, and ending with the words "are got" in the
twentieth line of the same page; and I obliterate the full stop after the
word "oxide" in the said fourth line of the same page, and substitute
a comma therefor, and add after the said word "oxide" in the said
fourth line the word "or," and substitute a full stop for the semi-colon
which occurs after the word "rapidity" in the twenty-seventh line of

page_text: said
sixtieth
the said fifty-third page. And I also strike out from the said printed
copy the whole of the passage commencing with the words " but this
method" in the twenty-seventh line of the fifty-third page thereof, and
ending with the words "paragraph 12" in the fifteenth line of the fifty-
fourth page thereof, and add before the word "when" in the last-
mentioned line the figure "8" as the number of the paragraph, and
substitute a capital letter W for a small w in the last-mentioned word
" when." And I strike out from the said printed copy in the said fifty-
fourth page thereof the passage commencing with the word "effecting"
in the twenty-sixth line thereof, and ending with the words and comma
"the beginning" in the twenty-eighth line of the same page. And I
also strike out from the said printed copy the whole of the passage
beginning with the words "When the former" in the thirty-first line of
the fifty-fourth page thereof, and ending with the words "for that
purpose in the eleventh line of the sixtieth page thereof; and I
substitute in the twelfth line of the same page the figure "9" for the
figures "28," and strike out from the said printed copy the whole of the
passage commencing "I believe that "in the fifteenth line of the
page, and ending with the word "lime" in the tenth line of the sixty-
second page; and I substitute in the eleventh line of the last-mentioned
page the figure "10" for the figures "29." And I also strike out from
the said printed copy the passage commencing with the words "and
will" in the twenty-second line of the said sixty-second page thereof,
and ending with the words "Mn2O3," in the twenty-third line of
the same page.
And also strike out from the said printed copy the
passage commencing with the words "and may be caused" in the twenty-
eighth line of the same page and ending with the words "Mn2O3"
in the twenty-ninth line of the same page, and change the comma
after the word "indeed" in the twenty-seventh line of the said sixty-
second page into a full stop, and I substitute a capital T for a small t
in the word "the" in the twenty-ninth line of the same page, and I add
after the word "formed" in the thirty-second line of the same page the
words "within the limits herein-after mentioned." And I also strike out.
from the said printed copy the whole of the passage commencing with
the words "By any "in the twenty-third line of the sixty-third page of
the said printed copy and ending with the word "cent." in the twenty-
eighth line of the sixty-fifth page thereof, and I insert the figures "11"
before the word "If" in the twenty-eighth line of the said sixty-fifth
page of the said printed copy, and strike out from the same line the word

page_text: 'however," and substitute in the same twenty-eighth line the word
'protoxide" for the word "peroxide to correct a clerical error, and
I strike out from the thirtieth line of the said sixty-fifth page the words
"two hours." And I also strike out from the said printed copy the
whole of the passage commencing with the words "at the rates
supposed" in the thirtieth line of the same page, and ending with the
words "such treatment in the thirty-second line of the same page. And
I also strike out the words "free" in the thirty-fifth and thirty-seventh
lines of the same page, and the words "I believe that" in the fourteenth
line of the sixty-sixth page of the said printed copy. And I also strike
out from the said printed copy the whole of the passage commencing
with the words "If that quantity" in the twentieth line of the sixty-
sixth page thereof, and ending with the words "or rabbled" in the
twentieth line of the seventy-eighth page thereof. And I strike out
the figures "65" in the twenty-first line of the last-mentioned page
and change the last word "is" in the twenty-fourth line of the same
page into "as" to correct a clerical error. And I also strike out from
the said printed copy the whole of the passage commencing with the
words "(1.) The process or method" in the twenty-sixth line of the
seventy-eighth page of the said printed copy, and ending with the words
"15 and 30" in the last line of the eightieth page thereof; and I
substitute in the first line of the eighty-first page of the said printed
copy the word "Firstly" for the Figure "(12)." And I also strike
out in the fourth line of the last-mentioned page the words and figures
"17 to 23, both inclusive," and substitute the words and figures " 6, 7,
and 8" therefor. And I also strike out from the said printed copy the
whole of the passage commencing "(13.) The systematic" in the fifth
line of the eighty-first page thereof, and ending with the words "para-
graphs 26 and 27" in the twenty-fifth line of the said eighty-first page,
and also the words "or any other suitable liquid" in the twenty-ninth
line of the same page, and the passage commencing "(21.) The use"
in the thirty-third line of the last mentioned page and ending with the
word "employed" in the twenty-third line of the eighty-second page
of the said printed copy. And I substitute in the twenty-sixth line
of the said eighty-first page the word "Secondly "for the figures
(19)," in the twenty-eighth line of the same page the figures "10"
for the figures "29," in the thirtieth line of the same page the word
"Thirdly" for the figures "(20)," and in the thirty-second line of
the same page the figures "11 for the figures 31."
66

page_text: from the chloride-of-manganese, which is a residual-product-of the-manufacture-of
ehlorine--whenever--that-manufacture is conducted--as--it--is--invariably--in this
country,-and-nearly, if-not-quite--se, in all other countries likewise,-by-causing
previously generated-hydrochlorie-acid-and-a-suitable oxide of manganese to react
directly-upon-each-other. The-said-improvements have reference to the decom-
position of the residual chloride of manganese aforesaid in order to the
transformation of the base of that compound from its state of com-
bination with chlorine to a state of combination with oxygen, secondly,
to the peroxidation of oxides of manganese obtained from chloride of
manganese.
the
^
The improvements constiting the present Invention are for the most
part further improvements of the process which is the subject of
three previous Patents granted to me of the dates following: Twenty-
sixth July One thousand eight hundred and sixty-six, Eighteenth
January One thousand eight hundred and sixty-seven, and Fourth
September One thousand cight hundred and sixty-seven.
day of
the
the
chlorine
day of
day of
2. One of the most important of those of the improvements collectively
constituting the present Invention which relate to the use of magnesia
for the regeneration of oxide of manganese in the wet way has reference
to the decomposion by means of that agent of the chloride of manganese,.
"ebleride
which is the essential constituent of what are known as
residues," being the mixture of various chlorides (in which however
chloride of manganese usually greatly predominates) which remains in the
stills used for the generation of chlorine after hydrochlorine, acid and
peroxide of manganese have reacted upon each other therein.. If hydrated

page_text: alone
^
chloride of magnesium have a portion of chloride of manganesc associated
with it, the subjection of the chloride of magnesium so associated with
chloride of manganese to a heat suitable to effect the decomposition of
the chloride of magnesium results in the decomposition not only of the
chloride of magnesium, but of the chloride of manganese as well, the
chlorine of both compounds flying off either wholly or chiefly as hydro-
chloric acid, and a mixture of magnesia with an oxide of manganeses
containing at least as much oxygen as is contained in sesqui-oxide or
MnO3 remaining behind. It follows that a chlorine manufacturer
desirous of decomposing his chloride of manganese by means of magnesia
in the wet way, and of then decomposing the resulting hydrated chloride
of magnesium into magnesia for use over again, and hydrochloric acid
for application to any purpose for which he may require it, need not be
anxious to obtain a complete decomposition in the wet way of his chloride
of manganese by his magnesia, but may be content to let a moderate
portion of his chloride of manganese remain unacted upon in the wet
way, and to allow this portion or as much of it as may be convenient to
pass round with the chloride of magnesium resulting from an incomplete
decomposition by magnesia in the wet way of the mass of the chloride
of manganese. By so doing he will incur no loss of materials, sceing
that, as just explained, both elements of such portion of the chloride of
manganese as may thus be submitted to the same treatment as the
chloride of magnesium come safely round, the chlorine either entirely as
hydrochloric acid or mainly as hydrochloric acid and partially as free
chlorine, and the manganese as a valuable oxide.
his
3. The decomposition of hydrated chloride of magnesium by heat
proceeds so much more rapidly at the earlier than at the subsequent
stages of the operation that two charges may each be half decomposed in
very much less time than is required for the decomposition of one charge
quite completely. It follows, firstly, that the plan of decomposing each
charge only partially is cheaper than the plan of decomposing each
charge completely; secondly, that the former plan by reason of its sub-
jecting the resulting magnesia to so much less prolonged exposure to
the heat employed than the greater portion of the magnesia obtained by
decomposing a charge of chloride of magnesium to completeness must
necessarily undergo yields, at whatever temperature it may be conducted,
a much more highly active magnesia than can be obtained by working
at the same temperature on the latter plan; and, thirdly, that it is

page_text: therefore the case not only, as already indicated, that when working in
both instances at the same temperature a given quantity of magnesia
can be obtained in much less time by half decomposing two charges of
chloride of magnesium than by completely decomposing one charge, but
also that for the decomposition of chloride of magnesium so as to obtain
therefrom magnesia of a given degree of chemical activity one may use
much higher temperatures when decomposing each charge only partially
than when decomposing each charge completely, thereby effecting a still
further economy alike of time, fuel, and apparatus.
4. The chloride of magnesium resulting from the reaction of magnesia
upon the chloride of manganese produced in the manufacture of chlorine
will always be obtained as a more or less dilute solution in water, which
solution may be used to dissolve out the undecomposed portion of a
partial decomposed previous charge of chloride of magnesium, and
whether first so used or not will require to be concentrated by evapo-
ration before the decomposition of the chloride of magnesium in it can
commence.
5. Magnesia which has been obtained by the decomposition of chloride
of magnesium, and which is to be used for the decomposition of chloride
of manganese before being added to the mass of the solution, the chloride
of manganese in which it is required to decompose should be first
ground or triturated cither with a portion of that solution itself or with
water, or with other suitable liquid, until it shall have been reduced to
the very finest possible state of division, and be thus added to the
solution of chloride of manganesc, or to the greater part thereof, in the
state of milk or paste, or more or less thick mud.
from chloride of manganeso
6. The method of proceeding in order to the regeneration of oxide of
manganese, by ineans of magnesia and the peroxidation of the oxide of
manganese so regenerated, both in the wet way, which I will first
describe, consists in boiling the "still liquor' (meaning thereby that
solution essentially of chloride of manganese which remains in chlorine
stills after any peroxide of manganesc has reacted upon hydrochloric acid
therein) with an equivalent or slightly more than an equivalent of
magnesia, until the greater portion of the chloride of manganesc at first
contained in the said liquor has been decomposed, then allowing the
protoxide of manganese which has been so formed to settle, until there
shall have become separated from it a quantity of clear solution (which.

page_text: will be solution of chloride of magnesium mixed with chloride of
manganese) equal in bulk to the volume of the hydrochloric acid which
will be required to dissolve the oxide after it shall have been peroxidized
combined with that of the water which will be condensed in the still in
which the oxide will be so dissolved if steam be used to heat together
therein the oxide and the acid which is to dissolve it, and that of the
milk or paste or mud of magnesia which will afterwards require to be
added to the solution of chloride of manganese, which by the recovered
oxide being thus dissolved in hydrochloric acid will be reproduced, then
drawing off the said quantity of the said clear solution from above the
settled protoxide, unless, which is a better plan, the decantation of this
clear solution be conducted simultaneously with the subsidence of the
protoxide, the clear solution being drawn off little by little as it forms,
and then when the required quantity of mixed solution of chloride of
magnesium and chloride of manganese has been removed commencing
the injection of the oxidizing blast. If before the boiling (which boiling
may conveniently be effected by injection of steam) a sufficient quantity
of magnesia have been put into the still or other vessel in which the
operations now being described are performed there will remain with the
protoxide of manganese after removal of the clear solution, as aforesaid,
enough magnesia to decompose the portion of the chloride of manganese
contained in the liquor remaining with the protoxide, and such chloride
of managesc will be decomposed by such magnesia almost immediately
after the injection of the blast has been commenced. The oxide may, if
nccd be, be allowed to settle again after peroxidation, and more solution
(which will now consist of chloride of magnesium only) be then run off
from it; usually however this will not be necessary, but the oxide
immediately upon the cessation of the blast may have acid run in upon
it if it have been regenerated and peroxidized in a still, or may itself, in
the state of more or less thin mud in which it will be at this stage, be
at once run into a still if it have been recovered, and peroxidized in
another vessel.
7. The plan described in paragraph 6 may be modified by commencing
the injection of the oxidizing blast immediately upon the cessation of

page_text: resulting mixture has been brought very nearly to the boiling point, and
then at once commencing the injection of the blast without waiting for
any actual ebullition. By this method, especially if the injection of
steam be continued during the injection of the blast, chloride of
manganese is transformed into Mn ³O* with most remarkable rapidity.
8. When it is desired to obtain from chloride of manganese by means
of magnesia in the wet way peroxides of manganese containing a
larger proportion of binoxide than is contained in Mn '0', I recommend
that the operation of peroxidation be performed at the temperature
of the atmosphere only or thereabout, though I would prepare the
operator to expect that he will be able to obtain such richer per-
oxides at temperatures as high as 100° Fahrenheit, or even higher.
The method of proceedure in order to the obtainment of such richer
peroxides may consist cither in boiling together the magnesia and
chloride of manganese and letting the resulting mixture cool before
commencing the oxidizing treatment, or in the peroxidizing operation
being commenced immediately upon the addition of the magnesia to the
chloride of manganese, and so without the magnesia and chloride of
manganese being first boiled together.
9. I now come to those of the improvements collectively constituting
the present Invention, which have reference to the regeneration of oxides
of manganese from chloride of manganese in the wet way when the
chloride of manganese is decomposed by means of lime.
10. A fact of the utmost practical importance in reference to the
regeneration of oxides of manganese in the wet way by means of lime
which I have discovered in the course of my endeavours to work out
on the large scale the said process of regeneration, as described in the
Specifications of my former Patents cited above is, that of the remarkable
power possessed by lime to promote the peroxidation of protoxide of
manganese in the wet way. Thus, if to a solution of chloride of man-
ganese there be added only just an equivalent of lime, and the resulting
mixture of protoxide of manganese with solution of chloride of calcium
be then treated with air by injection thereof or otherwise, the protoxide
of manganese in such mixture will peroxidize only very slowly indeed,
but if to a similar solution there be added more than an equivalent
of lime, and the resulting mixture of protoxide of manganese free lime
and solution of chloride of calcium be similarly treated with air the
protoxide of manganese in the latter mixture will peroxidize very

page_text: rapidly, indeed the state of oxidation to which it will be raised by a
given amount of treatment with air being the higher the larger the
proportion of free lime in the mixture in which it is formed within
the limits hercin-after mentioned. A very important part of the present
Invention therefore consists in peroxidizing the protoxide of manganesc
contained in a mixture of such protoxide with free lime and solution
of chloride of calcium or in such a mixture of these and other substances
as is obtained by adding more than an equivalent of lime to a solution
of chloride of manganese which has been produced as a residual product
of the manufacture of chloride, either by injecting air into such
mixture or by lifting the said mixture from one level to a higher one,
and then allow it to fall through an atmosphere or column or current
of air from the said higher level to some convenient level below it,
whether the level from which the mixture was originally lifted or not,
repeating this treatment until the protoxide of manganese at first
contained in the mixture shall have been sufficiently peroxidized; or by
placing the said mixture in any convenient "churn," and mechanically
"churning" it in contact with air until the desired end shall have
been sufficiently accomplished; or by placing the mixture in an open
vessel of more or less considerable depth at or near the centre, but
having sloping sides of a large extent of surface, and then by means
of any suitable dash wheel or other mechanical appliance duly adapted
to the deeper part of the vessel agitating the mixture more or less
violently dashing it about so as to bring all parts of it successively to
the surface, and so as to constantly fling portions of it on to the sides
of the vessel, by running down which sloping sides into the deeper
part of the vessel their contact with air will be advantageously
prolonged; or by placing the mixture in a hollow drum revolving on an
axis placed horizontally, having appertures in its sides near to its axis
for the admission of air, and being furnished interiorly with steps or
dash boards, from one to another of which the mixture shall be kept
constantly falling as the drum revolves, or by combining together any
two or more of these methods.
11. If there be present with the protoxide of manganese from half an
equivalent to three-quarters of an equivalent of free lime treatment
with air will yield a peroxide containing from eighty to ninety per cent.
of Mn 0. Of course a peroxide of eighty or ninety per cent. associated
with from ouc-half to three-quarters of an equivalent of lime, or let us

page_text: say, for the sake of the simpler illustration, a peroxide of one hundred
per cent. having associated with it a full equivalent of lime, will not
liberate from a given quantity of hydrochloric acid a larger quantity of
free chlorine than a peroxide containing only fifty-five per cent. of
Mn O, but having no lime associated with it, will liberate therefrom.
In the former case the reaction will be that represented by the formula
2MnO+2CaO+6HCl=2MnCl+2CaCl+6HO+2C1, while in the latter
casc it will be that represented by the formula Mn O³ + 3H Cl=
2MnCl+3HO+Cl, the yield of chlorine being in both cases just one-
third of the total quantity contained in the hydrochloric acid employed.
While, however, the yield of chlorine per given quantity of hydrocliloric
acid will thus be exactly the same in both cases, the yield of chlorine
per given quantity of chloride of manganese treated for the recovery of
oxide therefrom will be twice as great in the case of the oxide of a
hundred per cent. associated with a full equivalent of lime as in the
case of the oxide of fifty-five per cent. not associated with any lime at
all. An oxide of a hundred per cent. will rarely be obtained in practice,
but that by using from half an equivalent to three-quarters of an equiva-
lent of excess of lime oxides of from seventy to ninety per cent. may be
always obtained in from two to five hours, the blast used being such as
can be supplied by an engine of from fifteen to twenty horse power, and
the quantity of oxide operated upon at once being (as reckoned in the
state of protoxide) about three-quarters of a ton..
•
Having now particularly described and ascertained the nature of my
said Invention, and the manner in which the same is to be performed, I
now finally point out that what I claim as my Invention and desire to
be secured to me by the herein in part recited Letters Patent is as
follows:-
methods
^
Firstly. The various modes of proceedure for the regeneration from
chloride of manganese of oxides of manganese suitable for employment
in the manufacture of chlorine which are described above in paragraphs
6, 7,
and
8.
Secondly. The production of very rich artificial peroxides of man-
ganese by treating with air by any of the methods mentioned above in
paragraph 10 a mixture of recovered oxide of manganese, free lime, and
solution of chloride of calcium.

page_text: Thirdly. The regulation of the proportion of free lime to be contained
in the mixture just mentioned according to what is set forth above in
paragraph 11.
In witness whereof, I, the said Walter Weldon, have hereunto set
my hand and seal, this Twenty-first day of February One
thousand eight hundred and seventy.
חמותת
and seventy.
R. P. COLLIER,
Attorney General.