Improvements in or applicable to Filters.
Year: 1896

page_text: Date of Application, 3rd Jan., 1896
PROVISIONAL SPECIFICATION.
Improvements in or applicable to Filters.
I EDWARD LUND of 22 Saint John Street, Manchester, in the County of
Lancaster, Surgeon, do hereby declare the nature of this invention to be as
follows:-
My invention consists principally in the construction and use of tubes of glass,
porcelain, earthenware, pure block tin, vulcanized rubber or of other suitable
substance open at both ends and constructed as hereinafter described and charged
with the filtering material prepared as hereinafter mentioned, for the purpose of
filtering and clarifying water or other liquids and to separate therefrom any
impurities therein contained.
Each tube so prepared and charged is a complete filter in itself and may be
used as a portable filter, for small quantities of water or liquid or any suitable
number thereof may be grouped or aggregated together by fixing them into holes
formed in the bottom of a suitable vessel or tank so that any larger quantity of
water or liquid can be filtered on a proportionate scale.
The tubes for this purpose may be made of a circular or other suitable form in
cross section, and when in use are preferably placed in a vertical position, but they
may also be placed in a more or less inclined position if desired.
I do not intend to confine myself to any particular length or diameter of filtering
tube, but for the sake of example I may here state, the size which I consider most
useful for general domestic purposes vist.: a tube of say about eight inches in
length, and of about one inch diameter inside open at both ends and at one of its
ends with the edges slightly flanged inwardly, so as to reduce the diameter for the
purpose of retaining the charge of filtering material, with, or without small holes
near the end of the tube.
My object in adhering to somewhere about these proportions in the length and
diameter is that the water or liquid to be filtered shall pass through a long narrow
channel of filtering material, rather than through a wide and shallow one, the
tubes being as before mentioned placed preferably in a vertical position when
in use.
When enlarging the filtering capacity of the filter, by grouping together a
number of these tubes as previously mentioned, I intend to pass each filtering tube
through a hole in the bottom of the tank or vessel (or in a horizontal position
therein) and to make a watertight joint round each tube by a packing of cork or
other suitable material, or to fix the tube by any other means. The upper end of
each tube will project upwards a short distance above the level of the bottom or
horizontal partition of the tank or vessel, so that the coarser contents of the impure
water or liquid will subside into this space and not enter the tubes (or very slightly
so) and by a side outlet and plug this stagnant impure water or liquid can readily
be removed from time to time without any disarrangement or injury to the filtering
tubes themselves.
In some cases, instead of effecting the filtration by descension as above described
I propose to effect the same by ascension, the water to be filtered being admitted
(under pressure) to the lower chamber or division of the filter below the horizontal
water-tight partition, and the filtered water drawn off from the upper chamber.
The filtering tube (or tubes) as abové described is (or are) inserted through

page_text: holes in this partition, and the water passes upwards through them they are fixed
with perfectly water tight joints.
This arrangement possesses this advantage, the water to be filtered being
introduced at or near the bottom of the lower chamber, the heavier portion of the
impurities will have a tendency to gravitate towards the bottom instead of
ascending, and therefore the filtering medium will not be so liable to become
fouled.
The lower chamber will be made with a sump fitted with a plug or otherwise so
arranged that it can readily be cleansed out when required.
The filtering medium with which I propose to fill these filtering tubes in all cases
is cotton wool prepared as hereinafter mentioned, which I find by my experiments
to possess the valuable properties of detaining in the extremely small spaces which
exist between the fibres of this material, any foreign matter suspended in the water
or fluid, and free it entirely from the finest particles of insoluble inatter even to
such a degree that they may be so minute as to be absolutely invisible to the naked
eye, like the microbes or infective germs which are said to be thus "water-borne."
Or other suitable pure vegetable fibre possessing the same properties might be
employed.
For this purpose I take cotton wool of the finest quality and steep it for several
days in a weak solution of about one per cent. of carbonate of soda or other suitable
alkali to remove all greasiness or oily nature which exists in the fibre, I then
remove and thoroughly wash it in pure distilled water to get rid of all traces of
free alkali, and lastly it should be dried perfectly by gentle heat afterwards raised
to a degree which shall "sterilize" it in a manner known to bacteriologists.
When it has arrived at this stage of its manufacture it ought to exhibit this
peculiarity, that when a small pledget of it is placed on the surface of cold water,
the prepared cotton wool will instantly sink to the bottom.
With the chject of carefully filling the filtering tubes with the cotton wool so
cleansed and dried, I propose (at the time of filling) to dip the said cotton wool
into distilled water, at the boiling point, for a few minutes so as to ensure its
absolute purity immediately before the packing of it into the tubes.
To avoid any air spaces being left in different parts of the cotton wool, as it is
removed from the boiling water and pressed into the tubes in its wet state, and to
preserve its uniform filtering power, I take only small tufts of it at a time and press
each one down separately rather than to force it at the same time in one large
pledget or mass.
These instructions relate to the best mode of filling the tubes.
As the cotton is being put in and pressed down into each tube at certain spaces
of say from half to three quarters of an inch, I introduce one or more circular
plates or discs perforated with small holes, such discs being made of thin sheet
block tin or other suitable substance and these resting at intervals between the
layers of cotton wool in the inside of the tubes, will divide the wool into separate
strata, and by the presence of these discs the cotton wool will be kept steady and
flattened, and will not be dislodged or disturbed by the entrance of a stream of
water into the filter, which might otherwise burrow out a large channel in the
wool, thus passing between masses of the same, instead of through only the minute
spaces existing between the fibres of the cotton as in the true filtering process. As
these perforated dises will divide the cotton wool into several distinct strata it will
be possible to remove one or more of the strata and replace the same by fresh
clean prepared cotton wool, without disturbing the strata which may have become
foul or have their filtering channels blocked up by foreign matter which may have
been caught up and detained therein and may require renewing from time
to time.
In dealing with very dirty or muddy water I should consider it advisable (to
prevent this condition as a cause of delay in the action of the filtering tubes) not
to pass the same into the filter until by subsidence or by coarse filtration through

page_text: layers of charcoal and sand or other suitable medium the water shall have been
somewhat cleansed from the grosser impurities.
Dated this 2nd day of January 1896.
GEO. DAVIES & SON,
4. St. Ann's Square, Manchester, Agents for the Applicant.
Improvements in or applicable to Filters,
1 EDWARD LUND of 22 Saint John Street, Manchester, in the County of
Lancaster, Surgeon, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
My invention consists principally in the construction and use of tubes of glass,
porcelain, earthenware, pure block tin, vulcanized rubber or of other suitable
substance open at hoth ends and constructed as hereinafter described and charged
with the filtering material prepared as hereinafter mentioned, for the purpose of
filtering and clarifying water or other liquids and to separate therefrom any
impurities therein contained.
Each tube so prepared and charged is a complete filter in itself, and may be
used as a portable filter, for small quantities of water or liquid or any suitable number
thereof may be grouped or aggregated together by fixing them into holes formed
in the bottom of a suitable vessel or tauk so that any larger quantity of water
or liquid can be filtered on a proportionate scale.
The tubes for this purpose may be made of a circular or other suitable form
in cross section, and when in use are preferably placed in a vertical position,
but they may also be placed in a more or less inclined position if desired.
The manner in which my said invention is to be performed or carried into
practical effect will be readily understood on reference to the two sheets of
drawings hereunto annexed and the following explanation thereof.
To carry out my invention there are the two principal ways in which I use the
filtering tubes herein described. One plan is as illustrated by Fig. 1 on the
annexed drawings (if the water or other liquid to be filtered does not contain
much foreign matter and if it is only slightly turbid) to make the tube a of glass
or other suitable substance into which the filtering material is to be packed, with the
upper part of it so expanded as to have a funnel-like form as at a and thus serve
as a reservoir for the unfiltered liquid. Below this part the tube is cylindrical in
section, and at the lower end the border of the tube is turned in so as to have an
internal flange a², and near to that part of the interior of the tube which is still
cylindrical where it joins on to the expanded funnel part a¹ I make three small
knobs or projections a³ in the glass or other substance placed at equal distances
around the inside of the tube as a means of fixing a circular metal disc b made of
pure block tin or other suitable material perforated with holes, and slightly concave
on one of its surfaces as shown, and having on the edge of the disc three
notches 61, 62, 63, placed at equal distances as shewn at enlarged plan view Fig. 2,
and each notch deep and wide enough to travel over the projections a³ when the
disc is passed down the length of the tube a. When this has been done, the disc
can be made to rest against the knobs by making a slight rotation of it in the
horizontal plane, and if previously pressed on to the filtering material it will tend
to prevent any displacement.
This form of filter I call a "gravitation filter," and it is suitable for the very

page_text: slow filtration of nearly pure water, where the particles of matter suspended in it
are very minute, and require careful separation and detention; and if the tube a is
made of pure block tin, with all the arrangements of packing-in the filtering
material, it can be screwed on or attached to a high pressure screw-down or other
tap and the water admitted into the filtering tube ready at any time to filter and
draw off small quantities of water, as illustrated at Fig. 5.
Although I do not confine myself to the use of any particular size or length of
filtering tube, yet, for domestic use the size which in my experiments I have
found to be most suitable, is to have the tube in its cylindrical portion of 1 inch
in diameter, 9 inches long, and the upper funnel part so expanded that it will hold
about twenty fluid ounces, and a bottle or other vessel c also of glass or other
suitable material, on which the tube is to rest and receive the filtered liquid as it
has passed through the filter.
To charge the filtering tube with the filtering material as shewn in Fig. 1, the
tube is to be placed on the receiving bottle e the greater part of the tube a being
inside the bottle, and the tube resting firmly on the mouth of the bottle by reason
of a strong projecting flange or collar a and there held vertically or nearly so.
Into this filtering tube a a metal disc b made of pure block tin or other suitable
material so fashioned that it has a convex and a concave surface, the surfaces being
of parallel curvature, is placed with the convex surface of it kept uppermost and
this is pressed down until it will rest on the internal flange a. The notches in
the edge of the dise allowing it to pass over the three knobs or projections a³.
The filtering material or medium e with which the tube a is charged and tightly
packed therein, is cotton wool, that preparation of it, well known to surgeons and
to the medical profession generally as absorbent cotton wool. It is cotton wool
which has been thoroughly washed and cleansed from all the impurities which
exist in the state of raw or undressed cotton, and from which by the use of a very
weak alkaline solution and by sufficient washing of it in pure water, all the greasy
matter has been removed.
It is then perfectly dried at a low temperature and the result of this process is
that when a small pledget of absorbent cotton wool when so prepared and well
dried is placed on the surface of pure distilled water it will instantly absorb water
and sink to the bottom of the vessel in which the water has been contained. This
is the only condition in which cotton wool should be used for charging the filtering
tubes and in filling the tubes it must be done in this manner. Small pledgets or
tufts of this absorbent cotton wool must be held by forceps dipped into boiling
water and then dropped into the filtering tube a and the cotton wool will fall down
easily in the tube if each piece of cotton has been well wetted. As soon as
sufficient quantity of the cotton wool so placed has filled up about two vertical
inches of the length of the tube, or even at shorter distances, the cotton wool
must be pressed down forcibly by hand pressure, by the cotton presser shown
at. Fig. 3 which consists of a perforated metal disc attached to a hand le
or rod g, the disc f being so curved as to direct the pressure on to the
mass of cotton in its central part, and force it outwards against the
inside walls of the tube. To give the right amount of pressure in so packing-in
the wool in its wetted state, a plunger Fig. 4, may also be used, to force
down the perforated discs by weights & placed on the flat top of the plunger, and
for this purpose at least 30 lbs. weight should be made to press on the cotton wool
and the water so squeezed out will rise up in the tube a and overflow it in
proportion as the cotton is compressed and reduced in volume. If about three
inches of length of cotton wool in the tube is thus produced, a second metal disc, of
rather less diameter (see Fig. 24) than the one placed at the end of the tube,
should be pushed down and laid upon the cotton with its convex surface down-
wards, and in this a third disc also of small size (Fig. 2) is laid on dise No. 2
with its convex surface upwards, towards the mouth of the tube through
which the tube is to be charged with the filtering material. A further
quantity of absorbent cotton wool is now put into the tube in small tufts

page_text: or pledgets, every one of them having been dipped in the boiling water
before it is dropped into the tube, the cotton presser Fig. 3 used with hand
pressure to expel as much water as can be pressed out of the wool, as well as any
air which might have been drawn in while the wetted cotton was falling down
the tube, and this process should be repeated until about six inches of length of
compressed cotton are in the tube, after this the plunger Fig. 4, is used with
weights up to 30 lbs. or even up to 40 lbs. if the fibre of the absorbent cotton wool
appears to be very resistant to pressure, and these weights should remain on the
plunger for 10 or 15 minutes or even longer after which the plunger may be
removed, and a disc of the smaller size put into the tube so as to rest upon the
surface of the compressed cotton wool with its convex surface downwards and on
it a disc of the smallest size with its convexity upwards, lastly, by the same
process of wetting the cotton in boiling water, dropping it into the tube followed
by hand pressure with the cotton presser, the entire length of compressed cotton
will fill the tube to about eight inches or one inch from the upper end of the nine
inch tube and it is near to this spot that the projections in the tube having been
placed a disc (of the same diameter and form as disc No. 1) is laid upon the
cotton with its convex surface downwards, and by means of the notches in the
edge of the disc it can be carried beyond the projections a³ when the disc can be
there fixed by a slight rotation, and this can be done not only by hand pressure
(which is very uncertain in its degree) but the fixing of the disc can be done with
30 or 40 lbs. of pressure so acting.
Sometimes instead of proceeding in the manner above described the preparod
cotton wool after being steeped in boiling water a small quantity of glycerine has
been added may be compressed by hydraulic or other competent pressure into the
form of a solid cylinder (either with or without the double convex discs) and this
compressed cylinder at once forced into the filtering tube a and the tendency of the
compressed cotton wool to expand on removal of the pressure will cause it to
make an absolutely water tight joint with the inside of the tube so that no water
can pass through between the two.
A filtering tube so charged with wetted and compressed absorbent cotton wool is
ready for use if the continuous filtering process is at once proceeded with, but, if the
compressed cotton is allowed to get perfectly dry which may take place in two or
three days, it will be found that water will not pass through the cotton and the
filter is useless, until, by placing the tube over an exhaust bottle or chamber air
pressure is then removed, and the weight of the atmosphere forcing the water
along the interstices of the cotton, its filtering power will be restored. A more
simple plan is, where it is thought that a filtering tube is not likely to be used for
some days, a weak mixture of glycerine with distilled water say about ten per cent.
being passed through the filter although the water may evaporate and dry up, the
glycerine will remain unchanged and at any future time water being applied to the
cotton the glycerine and water will mix together and the permeability of the
filtering medium will be restored. Glycerine in contact with absorbent cotton
fibre retains its affinity for water for many months of apparent dryness, and if a
small quantity of carbolic acid or any other suitable germicide has been previously
added to the glycerine the cotton wool will remain sterilized for a very long time.
Fig. 5 shows the method of applying one of my filtering tubes direct to a water
tap as hereinbefore referred to.
This may be called a "downward pressure filter."
The other way in which I use one or more filtering tubes when large quantities
of impure turbid water have to be dealt with for the purpose of filtering and
clarifying the water or other liquids is to effect the same by ascension, as
illustrated in section at Fig. 6 wherein is the filtering chamber and the vessel
from which the filtered water is drawn off. The water under a pressure of not
less than three pounds per square inch entering the chamber i at k and striking
against a partition (which breaks the force of the inlet stream) and passing
beneath the lower edge of the said partition ascends through a stratum m of fiuo

page_text: sand, charcoal, spongy iron or other suitable substance, as may be needful when
the water has been very impure, and passes through one two, or more filtering
tubes a of a construction similar to Fig. 1 into the upper chamber j from which it
can be drawn off as required. This may be called a "pressure filter by ascension."
The filtering tube (or tubes) as above described is (or are) inserted through
holes in the floor of the chamber i between the two vessels, and the water passes
upwards through them; where they must be fixed with perfectly water tight
joints.
This arrangement possesses this advantage; the water to be filtered being
introduced at or near the bottom of the lower chamber, the heavier portion of the
impurities will have a tendency to gravitate towards the bottom instead of
ascending, and therefore the filtering medium will not be so liable to become
fouled.
The lower chamber may be made with a sump fitted with a plug or otherwise so
arranged that it can readily be cleansed out when required.
I prefer that the top of the filtering tube or tubes a shall be raised somewhat
above the surface of the floor of the upper chamber, as shewn on the drawing,
but below the level of the draw off tap to keep the ends of the tubes below the
water.
The lower chamber i may be made of tinned iron or block tin, or of any other
suitable material, as may be desirable but the tubes a 1 prefer to make of pure
block tin and the upper chamber i must also be made of pure block tin or some
other suitable material which will not in any way render the filtered water impure
even after long detention.
In any or all of the above cases (and more especially when great pressure is
employed to compress the prepared cotton wool in the filtering tubes) in place of
the reversed curved discs of block tin which might possibly become flattened and
hence useless, I may sometimes employ spheres or double convex plates of block
tin or of glass, or other suitable substance, which may be either solid, or perforated
as may be preferred so as to allow the water to pass through, and in filling the
said tubes under pressure it may be advisable to support the lower surface of the
disc resting on the flange at the end of the tube by placing against it a block of
bard wood or other substance inside the flange and so curved or otherwise formed
as to exactly fit the bottom of the disc and prevent it from becoming flattened.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The improvements in or applicable to filters hereinbefore described and
illustrated by the annexed drawings and especially I claim the use of compressed
purified sterilized cotton wool as a filtering medium employed substantially under
the conditions and circumstances above mentioned.
Dated this 1ot dor of October 1900
GEO. DAVIES & SON,
4, St. Ann's Square, Manchester, Agents for the Applicant.