Improvements in or relating to Filters.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to Filters.
A communication from ETIENNE LÉON DELSOL, of Coulommiers, in the Republic of
France.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved filter in which water, previously sterilized by
means of calcium aluminium permanganate, is filtered.
The filter consists chiefly of a tube or casing (made of some inoxidisable metal,
such for instance as aluminium, silver, nickel, enamelled or tinned sheet-metal etc.)
of sufficient size as to have a considerable thickness or extent of filtering material
through which the liquid to be filtered passes. The casing is provided at the top
with a cover through the centre of which passes a tube of small diameter the portion
of the latter tube inside the casing being sufficiently long to penetrate into the
filtering medium the constitution of which will be hereinafter described, so as to
receive only the water that has filtered through said material.
The lower part of the casing is arranged to receive a cap provided with a rubber-
washer in order to render the joint perfectly tight. The connection of the cap and
the casing may be by means of a bayonet joint, and the cap may be attached to the
body of the apparatus by means of a small chain.
The outer portion of the small tube is of suitable length and shape, according to
circumstances. This tube may be of short length and be arranged to receive a
rubber tube discharging the liquid into a receptacle placed on a lower level than the
filter or it may be sufficiently long to pass through the cork of a bottle or a soldier's
flask. The device may also be placed inside a receptacle or water container and from
the continuation of the cock of said receptacle, say, for domestic use.
Besides acting in a mechanical way as ordinary filters, the filter according to the
present invention is more particularly distinguished by its chemical action which
consists in reducing the excess of the permanganate which has been previously used
for sterilising the water, and in rendering said sterilized water perfectly colourless,
limpid, odourless and tasteless.
All organic matter is more or less suitable for producing this reduction, but all
cannot be used to effect at the same time the mechanical filtering action.
Fine prepared sponge would be a very suitable animal substance which would
advantageously fulfil the conditions if, beside being comparatively expensive, it were
not liable to rapid deterioration, and thereby imparting to the filtered water a
disagreeable flavour caused by this deterioration.
The inventor uses therefore woollen fabric with a long nap or fibre prepared
specially to render it suitable for the reduction of the permanganate, as being a
substance which fulfils in a tnost advantageous manner the desired conditions of being
unalterable, absorbent, supple, easily cleaned, durable, cheap and a good reducing
agent.

page_text: This reducing fabric is prepared as follows:-
1) Grey or white flannel or fabric, such as molleton with a long fibre is taken and
boiled in clean water for 30 minutes.
2) It is then withdrawn, pressed out and macerated for 12 hours in a cold solution
of potassium permanganate of 0.2% (using, say a litre of solution for 1000 squ.
centimetres of fabric).
3) If after 12 hours of maceration the bath is colourless, it ought to be macerated
again in acsimilar manner.
4) The woollen fabric thus saturated with Mn,O, which has been deposited on the
fibres and has coloured them brown, is washed in running water until the water
squeezed out becomes limpid and colourless. Then the fabric is again introduced into
a fresh bath of potassium permanganate of 0.1% strength and left there at a
boiling temperature for 30 minutes (a litre of solution for 1000 square centimetres
of fabric).
5) The fabric is then withdrawn from the bath, washed with water pressed out and
introduced into an alcohol bath at 90° for ten minutes. This bath serves to dissolve
any free potash that may have remained adhering to the fabric.
6) The fabric is then removed from the alcohol bath strongly pressed out and
left for say 8 days in a final bath of running water.
7) It is then withdrawn from the bath and dried, and is then ready for use and
fulfils the conditions herein before specified.
The colour of this fabric is then dark brown. It is perfectly clean, supple and
unalterable and it possesses a reducing power capable of decolourising a cubic
centimetre of solution of crystallised permanganate of potash of 0.1%, for each
square centimetre of fabric.
As already mentioned, water taken from any source is sterilised previous to being
filtered. This sterilization is effected by means of a powder of calcium-aluminium
permanganate, for which the following formulae have given good results.
1) For river water, and generally for turbid running or stagnant water:
Commercial crystallised sulphate of aluminium and natassium
giving a mixture sufficient for 100 litres of water.
This compound powder has a much more rapid action on the micro-organisms than
potassium or calcium permanganate used alone. Moreover, it assists and completes
clarification of muddy water, at the same time reducing very perceptibly the
hydrotimetric degree of calcareous water.
The construction of the filtering apparatus and the composition of the filtering
mass and of the microbe-destroying powder having thus been described, the operation
of the sterilisation and filtration will now be described.
Sterilisation of water: Water is at first treated with the powder as will be described
and ought to remain pink and have a bitter taste.

page_text: The cleaning is effected by withdrawing the flannel or fabric in order to rinse and
wash it either in pure water or in water reddened by means of aluminium calcium
permanganate of the strength of 0.50 grainmes for each litre of water. Having been
washed and squeezed by hand the fabric is again rolled up and replaced in its tube or
casing.
The fabric may be dried from time to time but even when damp, it remains unalter-
able and without smell in the casing; qualities which sponge does not possess.
To filter water for domestic use any receptacle such for instance as a tank made of
enamelled iron or porcelain may be used, and provided with a cock at the back of
which is fitted the filtering apparatus herein before described. The vessel is filled say
in the evening with water and 0.25 grammes of aluminium calcium permanganate
powder is added and the water stirred to dissolve the powder completely. The
chemical reaction goes on all night (although it takes place at once and water may be
drawn off even five minutes after the addition) and the next morning the cock is
opened as required and a perfectly safe and pleasant colourless limpid sterilised
water is obtained.
Besides other uses to which the filter according to the present invention can be
applied, there is one which is of great importance. It is the use of the filter in com-
bination with soldiers or travellers' water flasks. An ordinary military water-flask
may be provided in the interior with a filtering tube or casing of unoxidizable metal
or material.
The dimensions of this tube are chosen so that it easily enters through the large
opening of the flask and is capable of filtering about 10 litres of water without becoming
clogged up. A metal tube passes through the stopper of the flask and projects
slightly outside. The filter tube containing the woollen fabric may remain in the
flask closed by the cover.
In case of an epidemic, campaign and in the colonies when the order is given or
the necessity for filtering the water arises, the cover is removed and remains sus-
pended by the chain or cord in the flask and the flask then becomes a flask filter.

page_text: A vessel of unoxidizable metal and with a cover closing by bayonet joint or other-
wise may be suspended by means of a swivel or chain from a ring on the strap of the
flask and contains aluminium calcium permanganate powder for sterilising water.
To the inner side of the cover of this vessel may be secured a measure holding say
0.50 grammes of the powder, which is the quantity required for a full flask of ordinary
or regulation size.
A communication from ETIENNE LEON DELSOL, of Coulommiers, in the Republic of
France.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, 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 :-
This invention relates to an improved filter in which water, previously sterilised by
means of calcium aluminium perinanganate, is filtered. A filter according to the
present invention is illustrated, by way of example, in the accompanying drawings,
in which,
Figure 1 is a vertical section, the cap being shown separated from the
filter.
Figure 2 shows the filter applied to a soldier's flask.
Figures 3, 4 and 5 show various forms of its application for domestic or other
purposes.
The filter consists chiefly of a tube or casing A (Figure 1) made of some inoxidiz-
able metal or material, such, for instance, as aluminium, silver, nickel, enamelled or
tinned sheet-metal etc., of sufficient size as to have a considerable thickness or extent
of filtering material through which the liquid to be filtered passes. The casing A is
provided at the top with a cover B through the centre of which passes a tube C of
small diameter, the portion of the latter tube inside the casing A being sufficiently
long to penetrate into the filtering medium M, so as to receive only the water that
has filtered through said material.
The lower part of the casing A is arranged to receive a cap D provided with a
rubber or other washer E in order to render the joint perfectly tight.
This cap may be attached to the body of the apparatus by means of a small
chain F.
The outer portion of the small tube C is of suitable length and shape, according
to circumstances. This tube may be of short length as in Figure 1 and be arranged
to receive a rubber tube discharging the liquid into a receptacle placed on a lower
level than the filter as shown in Figures 3, 4 and 5 or it may be sufficiently long to
pass through the cork of a bottle or a soldier's flask as shown in Figure 2.
Besides acting in a mechanical way like ordinary filters, the filter according to the
present invention is more particularly distinguished by its chemical action which
consists in reducing the excess of the permanganate which has been previously used
for sterilising the water, and in rendering said sterilised water perfectly colourless,
limpid, odourless and tasteless.
Among the organic substances which are all more or less suitable for effecting this

page_text: If, however, the colour becomes paler or disappears another quantity of powder is
introduced and the bottle shaken again.
Besides other uses to which the filter according to the present invention can be
applied, there is one which is of great importance. It is the use of the filter in
combination with soldiers' or travellers water flasks. Figure 2 shows an ordinary
military water flask. G provided in the interior with a filtering tube or casing A of
unoxidisable metal or material.
The dimensions of this tube are chosen so that it easily enters through the large
opening of the flask and is capable of filtering about 10 litres of water without
becoming clogged up. A metal tube C passes through the stopper H of the flask
and projects slightly outside. The filter tube containing the woollen fabric may
remain in the flask closed by its cover D until required.
A vessel I of the unoxidisable metal and with a cover closing by bayonet joint or
otherwise may be suspended by means of a swivel or chain from a ring on the strap
of the flask, and contain aluminium calcium permanganate powder for sterilising
water. To the inner side of the cover of this vessel may be secured a measure
capable of holding say 0 50 grammes of the powder, which is the quantity required
for a full flask of ordinary or regulation size.
In order to obtain a great quantity of sterilised and filtered water during a
campaign, a canvas bucket L (Figure 3) is used as a water receptacle and suspended
in any suitable manner, say on rifles, said bucket being provided at the bottom with
a small pipe to which is connected a rubber hose t. At the other end of said tube t
is secured a small filter A provided with a cock R and having on its cover a nozzle or
branch for receiving said rubber hose.
In this arrangement the filter A is closed in an airtight manner by a cap with
rubber packing, and has inside a grating on which rests the reducing substance M.
The manner of use of these different constructions of filter is the same, viz. :-
powder of alumino-calcareous permanganate is introduced into the water reservoir in
the proportion of 0.25 grammes per litre, in order first to sterilise the water, and then
said water is passed through the filtering apparatus.
To apply the system of filtering according to this invention to domestic purposes
various forms of apparatus may be used which differ from one another only in the
arrangement of details, but are based on the same principle.
Thus the apparatus shown in Figure 4. is a sterilising and filtering fountain, with a
double compartment, made of sand stone, porcelain or unoxidisable metal. The upper
compartiment G receives the water to be filtered. It communicates with the lower
compartment G¹ through a tube to which is secured one end of a rubber tube C¹,
the other end of which is connected to the filtering apparatus A. This filtering
apparatus A is provided outside with a reducing fabric and is attached to a float A¹
which keeps it as near as possible to the surface of water. The upper portion of the
compartment G¹ is provided with an air-tube 0 bent at the top and carrying in the
bent portion fine carded cotton wool which filters the air entering the reservoir G¹
when the cock R is open.
For filters required to give a comparatively small quantity of water, a filtering
apparatus A may be placed at the bottom of a receptacle H of suitable shape (Figure 5)
communicating with the exterior through a pipe to which is connected a cock R. In
this construction the filter A containing the reducing substance, has at the top a mov-
able metallic cap 6 which admits water to the filter through small holes made round
its flange.
This arrangement is devised to prevent matter from entering which should be
precipitated to the bottom of the receptacle.
Having now particularly described and ascertained the nature of this said inven-
tion as communicated to me by my foreign correspondent and in what manner the
same is to be performed, I declare that what I claim is :-
1. A filtering device constituted by a casing containing a filtering substance and
having at one end a tube for the outlet of liquid and at the other a cover for closing

page_text: the casing when it is not in use, said filter being applicable to soldiers' flasks as well
as to military and domestic filters.
2. A filtering substance consisting of a layer or packing of wool, peat, hemp or flax
prepared by saturating it with permanganate of potash, washing in running water,
then placing in a second bath of permanganate of potash, at a boiling temperature
washed and immersed in alcohol of 90° and washed again for the purpose of rendering
said substance reductive.
3. A microbe destroying powder for use in combination with a filter of the kind
described consisting of sulphate of alumina and potash, carbonate of soda and
permanganate of potash, for the purpose of sterilising water previously to its
filtration.
4. A filtering device substantially as described and illustrated in Figure 1 of the
accompanying drawings.
Dated this 12th day of October 1898
BOULT & WADE,
Agents for the Applicant.