IMPROVE- MENTS IN APPARATUS, AND IN MATERIAL EMPLOYED THEREIN FOR FILTERING PURPOSES
Year: 1881

page_text: "
LETTERS PATENT to William Spence, of 8, Quality Court, Chancery Lane, in
the County of Middlesex, Patent Agent, for an Invention of "IMPROVE-
MENTS IN APPARATUS, AND IN MATERIAL EMPLOYED THEREIN FOR FILTERING
PURPOSES." A communication from abroad by Charles Piefke, of Berlin, in
the Empire of Germany.
PROVISIONAL SPECIFICATION left by the said William Spence at the Office
of the Commissioners of Patents on the 14th May 1881.
.
WILLIAM SPENCE, of 8, Quality Court, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN APPARATUS, AND IN MATERIAL
EMPLOYED THEREIN FOR FILTERING PURPOSES." (A communication from abroad
by Charles Piefke, of Berlin, in the Empire of Germany.)
This Invention consists in the construction of filtering apparatus composed of a
series of sieves arranged one above another, thereby giving an extended filtering
surface in proportion to the space occupied, and also in a special filtering paste to
be used in the apparatus.
The sieves are contained in a metal vessel, and are arranged one above another
round a central tube with inlets from the several sieves respectively, by means of
which the filtering paste with which the vessel is filled can be drained and deposited
on the sieves. The supply of filtering paste being stopped and the sieves being
thus covered with filtering material, the liquor to be filtered is admitted to the
vessel at the bottom and passes into the sieves and through the inlets therefrom
into the central tube, whence it escapes in a filtered state through a tap at the
bottom of the said tube.
The central tube and sieves are so arranged as to admit of their being drawn
upwards in order to clean the sieves and renew the filtering paste as required.
The mode of preparing the filtering paste is as follows:-Vegetable or animal
fibre is boiled with alkalies until it is nearly converted into cellulose, and its
specific gravity is increased so as to make it sink in water; then the fibre thus
treated is put into a solution of argillaceous earth, with which it becomes saturated.

page_text: By means of caustic alkalies the argillaceous earth is precipitated and adheres to
the fibre. To the fibre so treated and afterwards washed is added diluted lime
(which is afterwards made antisoluble by means of alum or tannic acid), or instead
of this lime jelly made of cellulose or tragacanth gum; the paste is then dried and
reduced to powder. The single particles mingled with water now form little flocky
bodies, which swelling and sinking form an adhering layer.
Instead of argillaceous earth gelatinous silicic acid or other colloidal substances
may be employed, and instead of vegetable or animal fibre asbestos may be used.
The revivification of the paste is effected by stirring it up with water, or if necessary
by boiling it with alkalies.
Before the apparatus is charged the filtering paste is stirred with water so as to
be in a fluid or semifluid state, in order to admit of its flowing into and filling the
filtering vessel as required.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Spence in the Great Seal Patent Office on the 12th November
1881.
WILLIAM SPENCE, of 8, Quality Court, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN APPARATUS, AND IN MATERIAL
EMPLOYED THEREIN FOR FILTERING PURPOSES." A communication from abroad
by Charles Piefke, of Berlin, in the Empire of Germany.
i
This Invention of "Improvements in Apparatus and in Material Employed
therein for Filtering Purposes," consists in the construction of filtering apparatus
composed of a series of sieves arranged one above another, thereby giving an
extended filtering surface in proportion to the space occupied, and also in a special
filtering paste to be used in the apparatus.
The sieves are contained in a metal vessel, and are arranged one above another
round a central tube, with inlets from the several sieves respectively, by means of
which the filtering paste with which the vessel is filled can be drained and deposited
on the sieves. The supply of filtering paste being stopped and the sieves being
thus covered with filtering material, the liquor to be filtered is admitted to the
vessel at the bottom, and passes into the sieves and therefrom through inlets into
the central tube, whence it escapes in a filtered state through a tap at the bottom
of the said tube.
The central tube and sieves are so arranged as to admit of their being drawn
upwards in order to clean the sieves and renew the filtering paste as required.
Also the apparatus may be so arranged that the liquor to be filtered can be
introduced so as to be caused to pass into the sieves from the centre, and pass out
at one side of the vessel.
The mode of preparing the filtering paste is as follows:-Vegetable or animal
fibre is boiled with alkalies until it is nearly converted into cellulose, and its specific
gravity is increased so as to make it sink in water; then the fibre thus treated is
put into a solution of argillaceous earth with which it becomes saturated. By
means of caustic alkalies the argillaceous earth is precipitated and adheres to the
fibre. To the fibre so treated and afterwards washed is added diluted lime (which
is afterwards made antisoluble by means of alum or tannic acid), or instead of this
lime jelly made of cellulose or tragacanth gum; the paste is then dried and reduced
to powder. The single particles mingled with water now form little flocky bodies,
which swelling and sinking form an adhering layer.
Instead of argillaceous earth gelatinous silicic acid or other colloidal substances
may be employed, and instead of vegetable or animal fibre asbestos may be
used.
The revivification of the paste is effected by stirring it up with water, or if
necessary by boiling it with alkalies.
Before the apparatus is charged the filtering paste is stirred with water so as to
be in a fluid or semifluid state in order to admit of its flowing into and filling the
filtering vessel as required.
In order however that the Invention may be fully understood, I will describe
more particularly in what manner the same is to be performed by the aid of
the accompanying Drawings, in which are represented the two arrangements of
2

page_text: Before the apparatus is charged the filtering paste (prepared in the manner
hereinbefore described) is stirred with water so as to be in a fluid or semifluid
state, and after the taps a and b in the apparatus, shewn in Fig. 1, have been
closed, the said filtering paste or fluid is quickly poured in through the aperture c
until the vessel is filled, and by means of the cover d the said paste or fluid is
deflected against the walls of the vessel; the flowing off tap a is then opened, and
a precipitation of the filtering paste or fluid upon the sieves f, f, is thereby effected.
The aperture c is now closed, and the tap bis opened for the admission of the liquor
to be filtered, and immediately the process of filtering begins.
As will be seen on reference to Fig. 1, the sieves f, f, and the bottom plates g, g,
are arranged one above another, and they may be enlarged and increased in number
without occupying a great increase of space. The separation of the unfiltered
liquor from the filtered is effected by the short tubes k, l, and the elastic rings or
washers 1, 1, by the latter of which the requisite tightness or impermeability is
obtained. The tube m at the upper part of the vessel is adapted for the escape of
air, and if necessary the tap n may also be used for the purpose.
If filtering with pressure be-not required the cover with the tap n may be
omitted. If after long use the flow of the filtering paste should cease, and if the
stirring with water be no longer effective, the central tube with the whole series
of sieves ff, and bottom plates g, g, are to be drawn upwards by the ring o, the
filtering paste is to be washed out by means of a jet of water and reserved
for revivification; then a second charge is to be made as before. Also the filtering
paste (in reference to Fig. 2) may be supplied to the central part of the vessel by
filling up the tube q provided with a funnel, as shown; thence the filtered liquor
flows off through the tube provided with a tap.
Having thus described the nature of the said Invention, and in what manner
the same is to be performed, (communicated to me from abroad as aforesaid),
I hereby declare that what I claim as of the said Invention is,-
First. The construction of filtering apparatus with the arrangement of separate
sieves one above another, whereby great filtering surface is obtained within a
comparatively small space, as herein before described.
Secondly. The manufacture or preparation of filtering paste, in the manner
herein before described.
Thirdly. The use of a filtering paste capable of being precipitated in a pulpy
state on to the filtering sieves resulting from the mode of its manufacture, as
herein before described.
Fourthly. The method of cleaning the filtering sieves, as hereinbefore
described.
And, Lastly. The method of revivifying the filtering paste herein before
described.
In witness whereof, I, the said William Spence, have hereunto set my hand
and seal, the Twelvth day of November, in the year of our Lord One-
thousand eight hundred and eighty one.
Witness,
FRANK REDMAN,
8, Quality Court,
Chancery Lane.
WILLIAM SPENCE. (L.S.)