IMPROVEMENTS IN THE MANUFACTURE OF ALUMINA
Year: 1858

page_text: LETTERS PATENT to Alfred Vincent Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Mechanical Draughts-
man, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
ALUMINA." A communication from M. Le Chatelier, Mining Engineer,
residing at Paris, in the Empire of France.
Sealed the 11th February 1859, and dated the 1st September 1858.
PROVISIONAL SPECIFICATION left by the said Alfred Vincent Newton at
the Office of the Commissioners of Patents, with his Petition, on the
1st September 1858.
I, ALFRED VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane,
in the County of Middlesex, Mechanical Draughtsman, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OP
ALUMINA," to be as follows:-
For manufacturing alumina, various elementary compounds and various
processes are employed, but these processes are all grounded upon, the appli-
cation of a. general principle, that is, the artificial formation of a combination
between alumina and soda, or of aluminate of soda soluble in water mixed
with an excess more or less considerable of soda, or carbonate of soda. This
aluminate of soda being submitted to the action of a current of carbonic acid
gas, causes the alumina to be precipitated, and the carbonate of soda is
dissolved.

page_text: When the substances acted upon contain silica and alumina, an insoluble
combination of silica alumina soda and water, that is a silico-aluminate of
soda is formed, and silicate of soda or aluminate of soda in solution may be
obtained, the carbonic acid gas dividing the silica or alumina. The insoluble
residuum may be attacked by weak acids such as acetic acid, which dissolves
alumina and soda, forming acetates, and leaving gelatinous silica which com-
bines with other matters.
This Invention is more particularly applicable to the preparation of alumina
and silica, and of the new combination (hydrated silico-aluminate of soda).
The object of the present Invention is the artificial production of aluminate
of soda, and of silicate of soda, these substances being but an intermediary
product. If they were not obtained directly with their suitable composition,
they could be made to absorb alumina or silica precipitated during the
previous operations, otherwise the soda could be made partially into carbonates.
An important feature of the Invention is the application of potassa as a
substitute for soda in manufacturing alumina, silica, silico-aluminate of
potassa, aluminate of potassa, and silicate of potassa.
The following are the compounds the Inventor proposes to use in his pro-
cess: Iron ore from Beaux, near Arles, in France, and other similar ores,
either with silica or clay or without.
This ore contains water, oxide of iron, and alumina, up to and beyond 50
The varieties of ore which have been hitherto examined contain no
per cent.
silica either in the ore or vein which is calcareous.
Some similar ore is found in Africa towards the western coast, and also in
Italy and other places.
These ores may be treated in different ways:-1st, they may be digested in
a solution of caustic potassa for the purpose of more or less removing the
alumina.
2ndly, they may be digested at a high pressure with the same solution in
one of Papin's boilers, or in a boiler the valves of which would be more or
less heavily weighted; the solution of alumina is therefore more or less readily
and completely effected.
3rdly, they may be digested with the same solution in cast or wrought iron
pans, and the solution concentrated until it is brought to a syrup-like con-
sistence..
4thly, they may be melted or calcined when mixed with various sorts of
kelp in a reverberatory furnace or other apparatus, and the product when
submitted to the action of water yields aluminate of soda in the solution.
These various methods are highly beneficial at the same time for bettering

page_text: and purifying the ore from Beaux, so as to render an iron ore with a calcareous-
vein stone very rich.
5thly, the introduction of the ore from Beaux, in a more or less high pro--
portion amidst the mixture of sulphate of soda, chalk and charcoal does not
interfere with the operation, and yields, when the kelp is lixiviated, a certain.
quantity of aluminate of soda mixed with the carbonate of soda and soda.
Clays, Kaolins, and Feldspathic Rocks.-If these compounds are submitted'
to the action of a concentrated solution of caustic soda, or if they are melted.
or roasted with kelp they are easily acted on.
Some kinds of clays or claystone, such as the iron ore of Beaux, hold a
much larger proportion of alumina than the clays usually employed in the arts,
and by following the modus operandi above described, aluminate of soda is
obtained, and the silico-aluminate of soda is left as a residuum.
In the common clays silica prevails, and with the insoluble silico-aluminate
is found silicate of soda. Feldspar or granite is employed when gelatinous
silica, or an alkaline silicate is required, as the alkali in the feldspar counter-
balances the alkali which remains undissolved in combination with silica and
alumina.
The Inventor proposes to employ Fapin's boiler, or other boilers working
at high pressures, when using an unconcentrated caustic solution.
One of the essential features of this operation is, acting on quartzose rocks,
silica, and alkaline silicates, and likewise hydrate, alkaline, silico-aluminates,
by depriving them separately of their alumina and alkali.
Sulphates of Alumina.-The sulphates of alumina can be prepared either
directly by acting upon clays with sulphuric acid, or by roasting aluminous
pyritous slates, or earthy and pyritous lignites.
The sulphate of alumina is used instead of sulphuric acid for reacting
upon common sea salt, and producing sulphate of soda and muriatic acid.
This aluminous sulphate of soda is treated in the mixture for manufacturing
soda by the ordinary process, and when the rough soda is dissolved the liquor
contains caustic soda, or highly carbonated soda, and the aluminate of soda.
If any aluminate of lime is formed with the aluminate of soda, it is decom-
posed by digesting the insoluble residue which holds it with carbonate of soda.
The use of sulphates of alumina either pure or impure, instead of sulphuric
acid in the manufacturing of sulphate of soda, also constitutes a new process
for manufacturing soda with alumina as an additional produce.
By calcining aluminite, or alumstone previously sprinkled with sulphuric
acid if necessary, in order to render it entirely soluble with chloride of
potassium, a mixture of sulphate of potassa and of alumina is obtained, and this

page_text: mixture being treated with chalk and charcoal, aluminate of potassa is
formed, and will produce carbonate of potassa and alumina.
Various Compounds.-Various residues or compounds arising from manu-
factories may be used for preparing alumina. The residue supplied by the
manufacturing of aluminium, as also the residues of the sodium manufacture,
which metal reduces aluminium, may be mentioned.
.t
The latter contains sulphate of soda, and carbonate of soda. The residues
of the reduction of aluminium in the reverberatory furnace yield when the
common chloride of sodium has been removed, a substance consisting almost
.entirely, of fluoride of aluminium. Both these kinds of residues are mixed
together in variable proportions according to their composition; they are
calcined either with or without charcoal, and give a compound, from which a
simple lixiviation separates aluminate of soda. Kelp may be substituted for
the residues of sodium either with or without chalk.
In a former Patent relating to the application of acids derived from fluoriue;
to the preparation of soda and potassa, is included the production of alumina
by decomposing chloride of aluminium, and the purifying of the alumina thus
obtained by dissolving it in soda under the form of aluminate of soda.
The present Invention comprises the use of potassa whenever it is likely to
be preferred to soda.
The aluminate of soda, of potassa, or the alkaline silicate may be obtained
in the state of hot solution, which will divide by decanting, filtering, or drying.
the products or fixed residues. This solution must be submitted to the action
of carbonic acid.
When the soda or potassa is saturated by the carbonic acid, the alumina
will be entirely precipitated, and may be separated by decanting, filtering,
or drying, and lixiviating the brine waters, which will only hold carbonate of
soda, or potassa in solution; this latter may be made to crystallize, or be
evaporated to dryness.
•
By manufacturing at the same time silica and alumina, they may be s
made to combine in given proportions before they are separated from their.
mother waters. The product thus obtained will be free from iron or other
metallic oxides, and contain such quantity of alumina as is required, and can
be used at once in ceramic works.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alfred Vincent Newton in the Great Seal Patent Office on
the 1st March 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Mechanical Draughtsman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of September, in the year of our Lord One
thousand eight hundred and fifty-eight, in the twenty-second year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said Alfred Vincent Newton, Her special license that I, the said Alfred
Vincent Newton, my executors, administrators, and assigns, or such others as
I, the said Alfred Vincent Newton, 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 "IM-
PROVEMENTS IN THE MANUFACTURE OF ALUMINA," being a communication from
M. Le Chatelier, Mining Engineer, residing at Paris, in the Empire of
France; upon the condition (amongst others) that I, the said Alfred Vincent
Newton, by an instrument in writing under my hand and seal, should particu-.
larly 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 Alfred Vincent Newton, 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 thereof (that is to say):
:-
This Invention, as communicated to me by my foreign correspondent, relates
to the manufacture of alumina from various substances and by various pro->
cesses, which, however, are grounded upon the principle involved in the
artificial formation of a combination between alumina and soda, or of aluminatė.
of soda soluble in water, mixed with an excess, more or less considerable, of
soda or carbonate of soda.
This aluminate of soda, which results from the various reactions set up when
submitted to the action of a current of carbonic acid gas, causes the precipita-
tion of the alumina, the carbonate of soda being left in solution.. When the..

page_text: substances acted upon contain silica and alumina, an insoluble combination of
silica, alumina, soda, and water, that is, a hydrated silico-aluminate of soda; is
formed so as to permit (according to the proportions of silica and alumina) of
silicate of soda or aluminate of soda in solution being formed; the carbonic
acid gas separating the silica or alumina.
+
The insoluble residuum may be attacked by weak acids, and chiefly, by acetic
acid, which dissolves alumina and soda by forming acetates of alumina and
soda, and yielding gelatinous silica, which also forms one of the resulting
products.
This. Invention therefore, although more particularly applicable to the pre-
paration of alumina, relates accessorily to the preparation of silica, and of the
new combination (hydrated silico-aluminate of soda) which results from the
investigations of the Inventor directed to improve the manufacture of alumina.
The preparations of alumina and of silica cannot be made apart, as they
result from the application of the same processes, and either of the two sub-
stances can be obtained according to the composition of the ores employed..
'
The present Invention also includes the artificial production of aluminate of
soda and of silicate of soda, both of which, find already several applications in
the arts, these substances being but intermediary products of our manufacturing
process. When these substances are not obtained directly with their appro
priate chemical composition, the deficient amount of alumina or silica may be
supplied from that precipitated during the previous operations. As a substitute
for soda, potash may be used.
The following is an enumeration of the various compounds employed, with
a description of the process applicable to each:-
Iron Ore from Les Baux, near Arles, in France, and other similar Ores,
either with Silica or Clay, or, without.-The iron ore of Les Baux is found in
large quantities in France, in the Department of. Bouches du Rhône and Var,
and chiefly in the neighbourhood of Arles, by a place called Les Baux, where:
it was first noticed, and from which the name has been generically derived,
although it is found in many other places. It holds, according to its. proper
composition, but water, oxide of iron, and alumina, up to and beyond 50 per
cent. The varieties of ore which have been hitherto, examined, contain no
silica, either in the ore or in the gangue, which is calcareous. Some similar
ore is found in Africa towards the western coast, and it is shewn to be in Italy.
First, the ore is digested, when heated in a solution, sufficiently concentrated,
of caustic potash or soda, whereby more or less of the alumina is removed.
Secondly, the ore may be digested at a high pressure with the same soluțion
in one of Papin's boilers, or in a boiler, the valves of which being more or less

page_text: heavily weighted, will ensure the more or less complete dissolution of the
alumina..
Thirdly, the ore may be digested with the same solution in cast or forged
iron pans, this solution being concentrated until it is brought to a syrup-like
consistence.
Fourthly, the ore may be melted or energetically calcined when mixed
with various sorts of kelp in a reverberatory furnace or any other apparatus.
The resulting lump, when either fused or roasted, on being submitted to the
action of water yields aluminate of soda in solution.
Fifthly, the ore from Les Baux, if introduced in a greater or less proportion
into a mixture of sulphate of soda, chalk, and charcoal (which mixture is made
use of in order to manufacture soda by the ordinary process) does not interfere
with the operation, and yields, when the kelp is lixiviated, a certain quantity
of aluminate of soda mixed with the carbonate of soda, and soda which may
be in excess.
The Les Baux ore may be submitted to a different mode of treatment, which
will give pure alumina, but less soluble in acids, and more especially applicable
to the manufacture of aluminium. The ore is to be broken up into small pieces
and treated with weak muriatic acid, which will decompose the carbonate of
lime, which forms its gangue, or it may be calcined at a red heat in a rever-
beratory furnace or a lime kiln, and thrown into water on coming therefrom,
the calcareous cement being carried off by washing.
Thus prepared, and having added to it the quantity of charcoal necessary for
reducing the peroxide of iron to the state of protoxide or of metallic iron, the
ore is introduced into muffles or retorts or apparatus made of fire clay, similar
to gas or zinc retorts, and carried to a red heat and treated by a current of
muriatic acid gas, produced either by the decomposition of sea salt or common
salt (chloride of sodium) or in any other manner. Protochloride. of iron is
thus produced, which is volatilized and may be collected and pure alumina will
remain, which can only contain a small quantity of chloride of calcium arising
from the calcareous matter not removed by washing or by the action of the
weak acid. Simple washing will suffice to free the alumina entirely from it,
which remains pure and very white, or it may be of a grey color by reason of
a deposit of carbon on its surface from the organic matters contained in the
ore, or carried by the muriatic acid. The chloride of iron-being thrown into a
large chamber closed and heated to redness, the sides of which chamber must
be of fire clay, is decomposed by a current of either hot or cold air forced in at
the same time. Oxide of iron is, thus formed, which is deposited immediately,
and sesquichloride or perchloride of iron (which is afterwards decomposed)
:

page_text: and chlorine in a gaseous form also result. This latter, mixed with the-
azote of the atmospheric air, is conducted to apparatus, where it is condensed;
in slacked lime to form chloride of lime or employed for any other purpose for
which it may be applicable.
This mode of extracting alumina, therefore, leads as an accessory to the
production of chlorine, which may be effected simultaneously, and in apparatus
placed contiguous. to that in which the ore is decomposed; or this operation'
may be effected separately if the chloride of iron be condensed, in order to its
being subsequently operated upon.
The Les Baux ore may be treated with an excess of concentrated muriatic
acid; at a temperature of from 40 to 50 degrees centigrade. The ore will be
deprived of the greater part of the iron it contains; it is afterwards submitted
(after being washed and dried, and the necessary small quantity of charcoal
added) to the action of muriatic acid in a gaseous state, by which the remain-
ing traces of iron will be carried off. The solution of perchloride of iron
evaporated and calcined will restore the muriatic acid, which had served to
act upon the oxide of iron.
Clays, Kaolins, and Feldspathic Rocks.-These compounds being submitted
to the action of a caustic solution of soda, when this is concentrated by:
evaporating it to a syrup, are easily attacked, and likewise when they are
melted-or-roasted with a suitable proportion of the various descriptions of kelp
commercially sold.
:
:
Certain clays (among which is the remarkable clay to be found in large
strata geologically associated with the iron ore of Les Baux,) hold a much
larger proportion of alumina than the clays usually employed in the arts; the's
clay-from-Les Baux has yielded up to 72 per cent. of alumina. In this case,
by following the modus operandi 'above described, aluminate of soda is obtained
containing the largest proportion of alumina (60 per cent. in some varieties of
clay from Les Baux), and the silico-aluminate of soda is left as residuum!
In the common clays silica prevails, and with the insoluble silico-aluminate
is obtained soluble silicate of soda. Feldspar or granite is particularly useful'
when it is required to prepare gelatinous silica or to obtain an alkaline silicate;
for the alkali of the feldspar compensates for that which remains undissolved"
in combination with the silica and alumina; if there is no profit' with regard
tó alkali 'there is indeed no great loss. When the feldspar or granite has a
potash for its base the potash may be employed for acting upon the rock; the
product obtained will be silicate of potash with residuum of silico-aluminate of
potash, which if treated with sulphuric acid will give gelatinous silica and the
clements of alum, having potash for its base, which are to be crystallized.

page_text: Moreover, in order to avoid in this reaction the formation of insoluble sub-
sulphate of alumina, the silico-aluminate may be first treated with acetic acid
or hydrochloric acid, and the mixture of acetate or of chloride decomposed.by
means of sulphuric acid.
In treating argils or feldspathic rocks with soda or potash and the silico-
aluminate of soda (or, potash) with acetic acid by combining the processes
described in this Specification with those described in the Specification of the
Patent granted to me on behalf of the Inventor of the present improvements;
and bearing date Second March One thousand eight hundred and fifty-eight;
for manufacturing soda and potash; by means of the acids of fluor spar, the
three elements of the silico-aluminate may be separated, or products extracted
therefrom applicable to industrial purposes.
First. The alumina and, soda (or potash, if that substance has been
employed) may be saturated with acetic acid, and the gelatinous silica produced
thereby may be separated by filtration, compression, or drying in a centrifugal
machine, and the solution of acetate of alumina and soda collected, which.
may be employed in that state, or the soda precipitated therefrom by the fluo,
silicate of alumina, leaving only acetate of alumina, which must be concentrated
to such a degree as to fit it for the market.
:
Second. The silico-aluminate of soda or of potash may be treated with
muriatic acid,, and the soda precipitated from it by hydro-fluo-silicic acid, and
the chloride of aluminium may be employed for the production by evaporation
and calcination of muriatic acid and alumina; this latter will be purified after
calcination by a current of muriatic acid gas or treated by caustic soda, by
which it will be redissolved.
Third. The silico-aluminate of soda (or of potash) may be treated directly.
by hydro-fluo-silicic acid and a mixture of fluo silicate of soda, and of silica;
obtained which may be applied to the manufacture of silicate of soda, hydro-
fluo-silicic acid, and fluo silicate of alumina.
The clays may be completely, purified from the oxide of iron, that, they.
contain after having been calcined, if necessary, in order to drive off the
water by muriatic acid gas, as above explained, with reference to the Les.
Baux ore..
The silico-aluminate of soda resulting from the action of the soda.
will give in the different reactions to which it may be submitted, products free.
from iron. Argillaceous ores of iron may even be employed which will leave.
a pure argil suitable for the manufacture of white pottery ware, unless it be
employed for the preparation of silica and alumina, and at the same time the.
primary matter will become the source of chlorine which may be applied for..
various manufacturing purposes.

page_text: Sulphates of Alumina. The sulphate of alumina can be prepared either
directly by acting upon clays with sulphuric acid or by roasting aluminous
pyritous slates or earthy and pyritous lignates.
In the first case the sulphate of alumina may contain a more or less
considerable excess of acid, in the second it is mixed with a more or less
considerable quantity of sulphate of iron without any difficulty arising there-
from. The sulphate of alumina containing an excess of acid is used instead of
sulphuric acid for reacting upon common sea salt, and producing sulphate of
soda and muriatic acid; it is employed in the ordinary apparatuses, but then
the sulphate of soda is mixed with alumina. This aluminous sulphate of soda
is treated in the mixture for manufacturing soda by the ordinary process, and
when the rough soda is dissolved the liquor contains, besides caustic soda, or
carbonated soda, the aluminate of soda. If any aluminate of lime is formed
with the aluminate of soda it is transformed by getting the insoluble residue
which holds it to digest with carbonate of soda.
The use of sulphates of alumina, either pure or impure, instead of sulphuric
acid in the manufacturing of sulphate of soda, constitutes a new process for
manufacturing soda with alumina as an accessory product. Amongst sulphates
of alumina is included the aluminite or alumstone, which is a combination of
alum having potash for its base, and of sub-sulphate of alumina existing in a
native state in Italy, Auvergne, &c. By calcining this substance, previously
sprinkled with sulphuric acid, if necessary, in order to render it entirely soluble
with chloride of potassium, a mixture of sulphate of potash and of alumina is
obtained. This mixture of sulphate and alumina is treated according to the
ordinary process for manufacturing soda with chalk and charcoal to form
aluminate of potash, from which carbonate of potash and alumina are
produced.
J
Various Substances.-In various residues or accessory products arising from
manufactories a fit substance may be found for preparing alumina. Of these
the most important for preparing alumina and soda at the same time are the
residues obtained in the manufacture of aluminium.
The residues of the sodium manufacture, which metal reduces aluminium,
contain sulphate of soda, carbonate of soda and likewise lime which has been
carbonated through exposure to the open air and some of the fuel used.
The residues of the reductions of aluminium in the reverberatory furnace
yield, when the common chloride of sodium has been removed by water, a
substance made almost entirely of fluoride of aluminium. Both these descrip-
tions of residues are mixed together in variable proportions according to the
composition. When calcined either with or without charcoal a compound is

page_text: obtained from which simple lixiviation separates aluminate of soda; kelp may
be substituted for the residues of sodium, either with or without chalk.
The aluminate of soda, of potash, or the alkaline silicate, whenever it is
obtained by treating the compounds in which silica is present in excess may
be obtained in general in the state of a hot solution from which may be
separated, by decanting, filtering, or drying in a centrifugal machine, the pro-
ducts or fixed residues associated with it. This operation may be conducted
in an apparatus provided or not with a rotary spindle in which it will be
submitted to the action of carbonic acid.
It is preferred to employ an apparatus similar to a churn, composed of a
closed horizontal cylinder made of metal or wood, provided with a shaft
mounted in the two ends of the cylinder, and furnished with wings or beaters
worked by hand or by any other motive force. The carbonic acid and the
solution of alkaline aluminate enter at one end, so as to about half fill the
cylinder and mix in relative proportion with the carbonic acid, so that the
soda shall not take up too great an excess of carbonic acid and form too large
a quantity of bicarbonate of soda, which is not very soluble in water. When
the soda or potash has been saturated by the carbonic acid, the alumina will
be completely precipitated, and can then be separated by decanting, filtering,
or drying and washing the mother liquor, which will then only contain
carbonate of soda (or potash) in solution; this latter may be crystallized or
evaporated to dryness.
The alkaline carbonate may be sold as it is, or be used indefinitely for other
operations; only it will prove more profitable to use new kelp each time in
order to sell it to the trade in a greater state of purity.
The alumina precipitated by the carbonic acid contains a certain quantity of
carbonate of soda; repeated washings with boiling water will carry off the
greatest portion of this carbonate of soda, which would not, however, if it were
to remain with the alumina, interfere with its various applications, and would
present no other inconvenience than that of increasing the expense of the acid
when it is to be employed in the state of a salt, and more especially that of
acetate of alumina. If it be not an object to diminish the solubility of alumina
in acids, it may be heated in a stove, and even calcined in a reverberatory
furnace to a dull red heat; the combination of the carbonate of soda with the
alumina will then be destroyed, but aluminate of soda will be produced, which
may be employed for industrial purposes..
In order to obtain at once the gelatinous alumina as pure as possible, and
to facilitate the washing operation, the filtration may be effected by means of
a vacuum, produced either by a pneumatic pump or the condensation of steam.

page_text: •
Thus in a metallic cylindrical vessel open at the top, and with a bottom to it
such as to stand the atmospheric pressure, a filter is applied to the middle
part thereof. This filter consists of a metallic or wooden plate bearing upon
a rim which is secured to the sides of the vessel and to cross joints, so as to
be sufficiently firm against pressure. The plate is perforated, with small holest
and covered with a metallic gauże, above which is a filtering cloth of cotton,
linen, woollen stuff, or felt; the plate and cylinder being so tight as to allow
no passage to the filtering liquor. The substance is thrown upon the filter,
and by means of a stop-cock the vacuum is effected in the lower part of the
vessel with a pneumatic pump. The liquor passes rapidly through the filter
upon which the alumina remains deposited. This lower part of the vessel
may be heated externally, in order to prevent the crystallisation of the
carbonate of soda. Another stop-cock at the bottom, and a third one for
readmitting the air at the top of the cylinder, enable the filtered solution to be
run off. The vacuum may be formed likewise by introducing a jet of steam
through one of the cocks and leaving the others open, then shutting the three
when the whole of the air is driven out. As the vessel cools down, a partial
vacuum will be produced, and the filtration will be rapidly performed. When-
ever the precipitate collected upon the filter begins to dry, and before its
contraction makes it to split, water is to be poured over it, and the water
acting upon the principle of compelled displacement, a minimum amount will
combine with the product of filtration...
Having now set forth the nature of the Invention of "Improvements in the
Manufacture of Alumina," as communicated to me by my. foreign corre-
spondent, and explained the mode of carrying the same into effect, I wish it to
be understood that under the above in part recited Letters Patent, I claim the
production of alumina in the manner above described.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto
set my hand and seal, this Twenty-eighth day of February, in the year
of our Lord One thousand eight hundred and fifty-nine.
Witness,
J. W. MOFFATT,
66, Chancery Lane.:
A. V. NEWTON. (L.S.)