IMPROVEMENTS IN FILTERING AND PURIFYING WATER AND OTHER LIQUIDS, AND IN APPARATUS THEREFOR
Year: 1874

page_text: .
PROVISIONAL`SPECIFICATION left by Francis Thomas Bond at the
Office of the Commissioners of Patents, with his Petition, on the
30th April 1874.
I, FRANCIS THOMAS BOND, M.D., of Gloucester, in the County of
Gloucester, do hereby declare the nature of the said Invention for
."IMPROVEMENTS IN FILTERING AND PURIFYING WATER AND OTHER LIQUIDS, AND IN
APPARATUS THEREFOR," to be as follows:-
The object of this Invention is the construction of more efficient
forms of apparatus for filtering water and other liquids than are now in
use, and also the application of improved materials for the special purpose
of filtering and purifying water for drinking purposes.
I will first describe the nature of my improvements for separating
matters that are mechanically suspended in water or other liquids; it is
of two kinds, floating and fixed.
In the construction of my improved floating filters I take a cylinder
of metal, glass, or other suitable material, of a size which is appropriate
to the bulk of the liquid to be filtered. The bottom of this cylinder is
closed by a perforated plate which may be either flat or funnel-shaped.

page_text: In the centre of this plate is an aperture through which passes a tube
open at both ends. The lower end of the tube terminates a few inches
below the perforated plate, and the upper one may be carried up to
within a short distance of the top of the cylinder.
A short distance above the junction of the perforated plate and the
cylinder a projecting rim or flange is fixed on the inside of the cylinder
so as to support a circular perforated plate of metal or other material, in
the centre of which is a hole to enable it to be dropped over the tube
and to rest upon the projecting rim aforesaid, in which position it may
be fixed either by a cork with a hole in it which can be forced over
the tube, or by a screw or other simple means of fixture.
-The point
In order to put this filter in action I proceed as follows:-
where the tube enters the lower perforated plate having been made
water-tight, a piece of filtering paper, calico, muslin, or other appropriate
fabric is so shaped that it can be fitted upon the whole of the upper
surface of the lower perforated plate & be left projecting a little above
its junction with the botom of the cylinder; dry sand, powdered
charcoal, or other appropriate filtering material is then introduced into
the cylinder so as to closely press the filtering fabric to the upper
surface of the lower perforated plate, & the upper surface of the said
material is left flush with the projecting rim before mentioned. A
circular piece of the filtering fabric is then cut so that it can be dropped
over the tube and pressed close on the upper surface of the filtering
material & the rim, which is done by dropping the circular perforated
plate over the whole and fixing it by the means referred to before.
The filter thus completed is then connected by the lower end to the
upper end of a piece of india-rubber or other flexible tubing, the other
end of which is attached to a tap which is fixed near the bottom of
the vessel in which the liquid to be filtered is contained.
The action of the filter is as follows:-On opening the tap and
pouring turbid liquid into the vessel, as soon as the level of the liquid
rises above that of the perforated bottom of the filter the liquid is forced
through the filtering fabric & materials into the interior of the
cylinder, from which it runs off by the combined tube and tap.
If the filter is carefully fitted up and arranged as above directed no
liquid can get into the interior of the cylinder without passing through
the filtering materials.

page_text: In order to allow of the filter floating on the surface of the liquid it.
is only necessary to adjust the relative heights of the tube & the
cylinder, so that there shall be enough of the interior of the latter free
from liquid to give it the requisite flotation capacity. For this purpose,
and also to allow of the level of the liquid inside the cylinder being varied
so as to modify the pressure under which it is forced from without, it is
desirable that the tube should be capable of being readily moved up &
down through the perforated plates. The filter when thus at work can
never sink so long as the tap is open, and provided that the efferent
tube has been made large enough to carry off the liquid at a greater
rate than the perforated plates & filtering materials will admit it; but
in order to allow of the tap being kept closed if desired, it is only
necessary to adapt to the cylinder a lid like that of a saucepan, with a
rim of sufficient depth to hold enough air within it when closed to float
the whole apparatus, or the upper end of the cylinder may terminate in
a bottle-shaped neck into which a cork may be fitted when the level of
the liquid inside has been duly adjusted; the air which is retained.
inside will prevent the filter from sinking.
For some purposes it is desirable to give the filter an intermittent
action. In this case I bend the upper end of the tube so as to convert
it into a syphon, taking care that the neck of the said syphon does not;
rise above a sufficient distance below the upper edge of the cylinder to
allow the latter to continue floating when the liquid inside the cylinder
has risen above the neck of the syphon so as to set it in action.
Irrespective of the regulation of the flow of the liquid through the
filter, which may be effected by the adjustment of the tube above
described, the flow may be further regulated by more or less opening or
closing the tap.
When the filtering materials become clogged with foreign matters
they may be cleansed by lifting the filter out of the liquid & pouring"
'water into the cylinder, so that the action of the filter may be reversed.
My improved fixed filter I construct in every respect like the floating.
filter, except as follows:-The tube which passes through the perforated
plates, instead of being connected with a piece of flexible tubing, is
continued direct to the tap to which it is attached by a screw or other
simple water-tight connection; the cylinder also must be made in two.
parts which can be connected by a water-tight joint, & the upper part

page_text: must be terminated by a tube which should be long enough to rise to
the top of the vessel containing the liquid to be filtered..
The action of this form of filter is as follows:-On opening the tap &
pouring turbid liquid into the vessel, as soon as the level of the liquid
rises above the perforated bottom of the cylinder, pressure from without
begins to be thereby established which forces the liquid through the
filtering arrangement into the cylinder, whence it flows off either by the.
straight or syphon tube whichever may happen to be used. The
pressure is regulated in this case by the tap, which by rapidly draining
the cylinder may be made to establish a greater or lesser amount of
pressure according to the quantity of liquid contained in the external
vessel.
In order to clean this filter when it becomes at all choked by arrested
impurities, it is merely necessary to run off the liquid from the con-
taining vessel so as to bring it below the level of the perforated bottom 1
of the filter, & then to pour water into the cylinder through the upper.
tube. The pressure which can be thus established in a reverse
direction will soon clean the filter.
The two forms of filter above described are intended simply to
separate impurities which are mechanically suspended in water or other 2
liquids.
For the purpose of separating so far as is practicable organic matters
which are held in solution in water, I proceed as follows:- In the first
place I pack the space between the two perforated plates with powdered
charcoal, the oxydizing effects of which on organic matters dissolved in 2
water are well known. I also further increase this effect by filling the
inflexible tube which carries the water off from the interior of the cylinder
with fragments of charcoal, and the tube itself may be lengthened by
coiling or bending it on itself, so as thus to expose the water to as pro-
longed contact with the charcoal as possible. But I do not confine myself 3
to the use of charcoal either in the filter or the tube, and I prefer for this
purpose a special form of purifying material which I will now proceed
to describe. I take well dried pumicestone, charcoal, or other similar
porous & insoluble substance in small fragments, & introduce it. into.
a solution of chloride of platinum so as to saturate it therewith. This 3
object may be attained by placing the fragments in an open vessel with
sufficient of the platinum solution to cover them, and then heating the

page_text: whole until the water has evaporated, the fragments being kept con-
tinually stirred or agitated during the process so as to cover them as
evenly as possible with the evaporating solution; they are then treated
with solution of ammonia so as to convert the chloride of platinum with
which they are coated into the ammonio-chloride, & the process of
evaporation & agitation is then repeated as before. When evaporation
is complete the fragments thus coated with ammonio-chloride of platinum
are heated to redness so as to decompose the salt & leave in its place
the metal in a reduced or pulverulent condition. The fragments thus
covered with metallic platinum possess a high oxydizing power, and
when used to pack the filter and efferent tube will enable it to oxydize
and thus to destroy various matters held in solution by the water,
and thereby to greatly increase its purifying power. This oxydizing
effect of reduced platinum on organic matters in solution may be
much intensified by combining with it the influence of heat. For this
purpose I take the water after it has passed through the filter (or
without previous filtration if it be not necessary or convenient to do so)
and introduce it into a vessel which contains a number of platinised
fragments prepared as above mentioned and boil it. The time for
which it must be boiled will vary according to the proportion existing
between the quantities of platinised fragments and of water, and
to the amount & nature of the organic matter in the water.
boiled for about half an hour any ordinary amount of organic matter in
the water will be oxydized, and the water completely purified for
drinking purposes. I do not however confine myself to reduced
platinum as an oxydizing agent with which to pack my filters, but in
cases where for the sake of expense or other reasons this agent is
inadmissible I employ ferric oxide for the same purpose, covering the
pumicestone or charcoal with it by a process in every respect analogous
to that described above and which will be readily understood by
chemists.
If