CERTAIN IMPROVEMENTS IN THE PROCESS AND APPA- RATUS FOR FILTERING WATER AND OTHER LIQUIDS
Year: 1842

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDRÉ
EUSTACHE GRATIEN AUGUSTE MAURRAS, of Cornhill, in the City of London,
Gentleman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Fifteenth day of November, in the sixth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said André
Eustache Gratien Auguste Maurras, Her especial licence, full power, sole
privilege and authority, that I, the said André Eustache Gratien Auguste.
Maurras, my exors, adñiors, and assigns, or such others as I, the said André
Eustache Gratien Maurras, my exors, admors, or assigns, should at any
time agree with, and no others, from time to time and at all times during the
term of years therein expressed, should and lawfully might make, use, exer-
cise, and vend, within England, Wales, and the Town of Berwick-upon-
Tweed, the Invention of "CERTAIN IMPROVEMENTS IN THE PROCESS AND APPA-
RATUS FOR FILTERING WATER AND OTHER LIQUIDS," partly of my own invention,
and partly communicated from a certain Foreigner residing abroad; in which
said Letters Patent is contained a proviso that I, the said André Eustache
Gratien Auguste Maurras, shall cause a particular description of the nature of
the said Invention, and in what manner the same is to be performed, to be
inrolled in Her said Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
André Eustache Gratien Auguste Maurras, do hereby describe the nature of
the said Invention.
The theory of the system of filtration to which the Invention applies consists
in the combination of the following principles:-
Firstly, in employing as a filtering medium none but inert substances; that
is to say, which exert no chemical action, on water, as sand, or pounded free-
stone or grit.
Secondly, in retaining and compressing the substances in a close vessel, so
as to form separate and compact beds or masses, to each of which the water
may be conducted on either the upper or under side alternately, or on both
sides at once, at pleasure.
Thirdly, employing pressure to any extent in order to render the filtration
more rapid, which pressure may be produced either by a column of water
pressing upon the filtering substances, or by means of a pump worked by any
suitable power.
Fourthly, the employment, according to circumstances, of one or more beds
of filtering materials, all concurring in the same operation.
Fifthly, the cleansing of the filter without its being necessary to take it to
pieces or relaying the filtering materials.
Sixthly, the application of the hydrostatic law by which fluids rise to their
level to the elevation of the filtered water to a height exceeding that of the
filtering vessel.
Such are the principles, apart from which I contend that no effectual filtra-
tion can be carried on on a large scale. To effect the perfect clarification of
thick or troubled water, as, for instance, river water holding in suspension a
certain quantity of foreign substances which impair its natural transparency, it
it is requisite to sift it, as it were, or to cause it to traverse a mass more or less
thick, of solid molecules, each distinct and separate, but so small, and so
closely pressed one against the other, that there exists only irregular capillary
passages between them, extremely narrow, permeable only to water, and
stopping the passage of all substances which are mixed with it, however
minute they may be. From this it will be seen that the clarification of water
by filtration is simply a mechanical operation. It is of importance that it
should retain this character, and therefore that no substance should be
employed which might impair the chemical purity of the water.
It is easy to
form and to maintain a bed of filtering materials when the water to be filtered
is. brought to the surface without pressure; but it is not so when the water is
driven with considerable force; then it becomes difficult to prevent the small-

page_text: grains of sand or freestone from being carried forward by the water, whereby
the mass loses its consistency, and finally becomes completely broken up. The
ruling principle, and that which alone renders the applications of most of the
others possible and effective, therefore, is, that of retaining and compressing the
filtering materials. This principle is the foundation of the system, and the
system must fall if the foundation fails. But this was not the only difficulty.
After discovering the means of preventing the filtering materials being carried
away by the force constantly acting with a tendency to produce that effect, it
still remained to simplify the apparatus, to render it easy to work and to put
together and to take asunder, durable in all its parts, and incorruptible in all
its materials. These points I have likewise attained, and the filter is as easy
of regulation as the most simple machines which have ever been employed in
manufactures. The turning of a few screws suffices either to take the parts
asunder or to reunite them so solidly that nothing can derange them.
DESCRIPTION OF THE APPARATUS.
The close vessel in which the filtration is effected may be of various forms
and dimensions; it may be made of wood, of stone, of iron, or copper; &c.
I therefore wish it to be understood that in the following description I do not
confine myself to either the forms, dimensions, or materials therein set forth, as
they may be altered or modified according to circumstances. I prefer, however,
the cylindrical, cubic, or rectangular forms, and also cast iron for the material.
It will likewise be readily understood that, although for simplicity of descrip-
tion and to avoid repetitions; I speak of water only, yet that my remarks apply
equally to all analagous liquids.
The Cylindrical Apparatus.-Figure 1 is a front elevation of that side
which contains the doors; Figure 2, a back elevation, shewing the pipes and
cocks; Figure 3, a side elevation, shewing the flanges; and Figure 4, a plan
of one of the bottoms. Note, that where any part occurs in several Figures,
it is denoted by the same letters in all of them. The case or vessel is of cast
iron. It is four feet high by four feet in diameter, and from five eighths to six
eighths of an inch in thickness. The vessel might be formed of as many lengths
as there are to be beds of filtering materials, the lengths being united in any
convenient manner; but it is preferable on many accounts to divide it from
top to bottom into two equal parts. The advantage of this method will pre-
sently be seen. (Figure 5 is a vertical section through the axis) shewing also
parts of the reservoirs, and of the side pipes in section. Around each portion
extends a flange pierced at equal distances with square holes to receive the
screw bolts, by which the two parts are united together. The front half

page_text: •
has three apertures A1, A2, A, corresponding exactly with the three beds
of filtering materials before spoken of. Upon the back half two tubes B, B,
are cast, extending from the top to the bottom of the vessel, and as close as
may be to the flanges. The internal diameter of these tubes is about three
inches, and they communicate with the interior of the vessel by means
of the cocks C, D, E, F, G, H, I, J, placed horizontally. Each half of
the vessel is cast with a top and bottom. The interior of the vessel is
arranged as follows, beginning at the upper part:-Immediately beneath the
top is a hollow space K', about two and a half inches high, communicating
with two external side pipes B, B, by two cocks C, G, of two inches diameter,
nearly diametrically opposite to each other; this space I call a vestibule.
Beneath this vestibule is placed a false bottom or disc L, about two inches
thick, which I call the retaining shelf or box; it is constructed as herein-after
described, and fixed in a
groove cast in and extending around the
side of the vessel, or formed by two small ledges cast upon the vessel or
fastened to it. This shelf constitutes the ceiling or top of a chamber M', eight
inches high, corresponding with the first door A' of the vessel, and intended to
receive a compact mass of sand of a certain fineness. A second shelf L
exactly like the first, forms the bottom of this chamber, descending towards the
bottom of the vessel; beneath the second shelf is seen a second vestibule K,
communicating in like mauner as the first with the pipes B, B, by the cocks
D, H; then a third shelf L, and a second chamber M, intended to receive a
mass of sand somewhat finer than that in the first chamber. Then follows a
fourth shelf L, and a third vestibule K³, communicating with the pipes B, B,
by the cocks E, I; then a fifth shelf L, and a third chamber M³, to contain a
mass of broken freestone of great fineness; then a sixth shelf L°, and lastly, a
fourth vestibule K', communicating with the pipes B, B, by the cocks F, J, the
bottom of which vestibule is formed by the bottom of the vessel. Thus the
vessel contains, first, four vestibules, each fitted with two cocks to admit and
discharge the water; secondly, six false bottoms, or retaining boxes or shelves,
fixed in circular grooves; and, thirdly, three chambers for holding the filtering
materials, and each having a door outside, of the same height as the chamber.
There should likewise be four other cocks N, O, P, Q, one at each end of the
side pipes B, B, to which they are connected by flanges and bolts, so as to be
readily united or detached. Lastly, all the metallic portions of the apparatus
which may require it should be protected as far as possible from oxidation, by
tinning, by galvinisation, by electro-galvanism, by painting, or any other

page_text: suitable means for effecting the object. The apparatus just described is
arranged for filtering downwards, but it is equally adapted to filtering upwards;
all that is necessary being to change the order of the filtering masses, placing
the coarsest in the lower filtering chamber, and the finest in the upper filtering
chamber. The shelves or retaining boxes are constructed as follows:-A hoop
of cast iron, of about two inches in depth (Fig. 6), is united to a metallic
bottom (preferably of sheet iron galvanised), which is pierced with a great
number of very small holes. The shelf is filled with sand, coarser than the
filtering materials, and very closely packed and covered with a metal plate
similar to the bottom plate, taking care that the holes in these plates are of
smaller diameter than the sand in the boxes; these plates are fastened to
the hoop by screws (see Figure 7). A shelf thus constructed will serve for
an apparatus of small diameter or exposed to little pressure, but for large
diameters or great pressure it is necessary, in order to obtain sufficient
strength, that the plates should be supported by a frame or grating attached to
the hoop, or that the interior of the hoop should be divided into compartments
(see Figs. 8 & 9), or the two plans may be combined. The utmost care
should be given to the perfect execution of these shelves, as the perfect
action of the filter depends upon them, and I believe that no substitute
could be found for them. In fact, it will be seen that although it is
impossible to retain the fine sand which is required for the perfect clarification
of the water merely by plates of metal pierced with holes, however fine they
may be, it is not impossible, nay, it is easy, by these same plates to retain sand
of six times the diameter of the holes, and consequently from one hundred
to two hundred times larger in volume. It will be understood likewise, that
in opposing to the extremity fine molecules of sand or freestone composing
the filtering materials, a thickness of two inches of sand, which, although
coarser, is very much compressed, it must be impossible for these molecules
to force a passage through such an obstacle, which only offers irregular and
winding capillary passages continually intercepted, one while enlarging, then
contracting, taking all forms and changing with the contact of every two
grains of sand. These boxes thus resolve, and in the most satisfactory
manner, the difficult problem of retaining and compressing the filtering
materials; and combined with the division of the vessel and the grooves in
which they are fixed, they give to the apparatus a degree of perfection never
before attained. It is simple and solid. It is now composed of but a small
number of parts, easy to take to pieces and to put together again, without
causing waste or wear. If thick or muddy water, such as river water is
generally, were turned directly on to a mass of filtering materials composed of

page_text: the finest molecules, and consequently very compact, there can be no doubt
that this mass would become choked up in a short time, that the filtration
would soon stop, and that the apparatus would require cleansing many times
a day; doubless also a single bed of materials of only eight inches in depth
(which depth should not be exceeded on account of facility of cleansing,
which is indispensable).having to sustain the whole pressure, the more minute
particles of dirt would at length force a passage through it, and, consequently, that
the water would remain more or less thick. Hence the necessity of affording
to the matters held in suspension by the water the space requisite for their
deposit; hence, consequently, the introduction of several filtering masses com-
posed of sand or freestone, which are finer in proportion as they are placed
lower down in the apparatus, if the filtration is effected downwards, or the
reverse if the filtration is effected by the ascent of the water. I have fixed
the number of these masses at three, experience having proved to me that
this number is sufficient, but there is nothing to prevent a fourth or even a
greater number, in those exceptional cases in which the water is very turbid.
On the other hand, only two, or even one, mass may be employed, if the
water contains but a small portion of foreign matter, or if, as in many cases
in manufactures, it is not required that the clarification of the water should
be carried out to the utmost extent. Lastly, the setting up of the apparatus
is an extremely simple operation, as it consists merely in placing the false
bottoms or shelves, complete in themselves, in the grooves of the vessel and in
connecting the two portions of the vessel together by means of screwed bolts.
To charge it with the filtering materials, the sand or freestone is introduced
by the openings or doorways in thin successive strata, taking care to wet
them slightly and to compress them firmly, so as to form a kind of artificial
porous stone. The vessel is then connected to the pipes by which the foul
water enters, and by which the clear water escapes, and it can then be set
instantly in operation by opening the four cocks O, G, F, and N, Figure 5.
The water from the reservoir R enters the upper vestibule K¹ by the cock G
under pressure, traverses the three filtering masses, leaves its impurities
therein, and runs off clear at the cock F to pass into the cistern or receiving
vessel S through the cock N. An apparatus thus constructed will act for a
long time without being taken asunder and without the least derangement.
As to the quantity of water which it will furnish, it is difficult to fix it exactly,
as circumstances vary so greatly; the quantity will always depend upon the
extent of the surface and upon the permeability of the filtering masses, upon
the greater or less impurity of the water brought on to these masses, and
likewise upon the pressure employed, always hearing in mind that when it is

page_text: required that the filtered water should rise to a given height above the
apparatus, that this column balances a corresponding column of dirty water,
and consequently reduces the pressure to that which results from the difference
in the height of the two columns.
Rectangular Apparatus.-The description of the details of construction of
a cylindrical filter will apply equally for the most part to a rectangular one, it
will therefore be sufficient for me to observe that this latter offers many
and important advantages over the former, which it is well to bear in mind
in many cases, and of which the following are the chief:-First, great economy
and simplification in the construction, since all the pieces which form the six
sides of the vessel are planes, and can be cast separately and fitted together
without difficulty. Secondly, a great facility in the placing the retaining boxes
in the grooves, in the putting together and disconnecting all the parts of the
filter by means of flanges and nuts and screws, in the removal from one
place to another, in consequence of the small space occupied by the apparatus
when taken to pieces. Thirdly, the increase of filtering surface, and consc-
quently of the product in filtered water in the proportion of more than twenty-
five per cent., without its being necessary for that effect in a large filtering
establishment to occupy a greater surface of ground, as a cylindrical filter of a
certain diameter occupies as much space as a square filter whose side is equal
to such diameter. Fourthly, the means of encreasing the size of the filters
more than is possible with filtering apparatus of a cylindrical form, and
thence effecting a reduction in the number of filters when a given quantity
of filtered surface is required, and a reduction in the expence of keeping in
order and working. In a large filtering establishment, two filtering vessels
may be placed back to back, as it were, which then form one vessel separated
into two departments by a cast-iron plate. With respect to the retaining
boxes, they must be made on the same principles, but square, as shewn in
Figures 10 and 11.
Cleansing the Filters.-It is a certain fact, that no filtration on a large
scale is possible, unless we have the means of cleansing the filters without
taking them to pieces, and without manipulating the filtering materials. To
effect this cleansing, I act on each filtering bed separately. Now, to effect
the cleansing of the first filtering bed I shut all the cocks of the filtering
vessel and the cock N, Figure 5, through which the filtered water passes away
after filtration, then I open the cock P and the cocks H and C, the water
then ascends through the filtering bed from below, that is to say, in the direc-
tion contrary to that which it follows during filtration. It is from this point
that I start to effect the cleansing movement. By means of the quadruple

page_text: key, hereafter described, fitting on the heads of the four cocks H, C, G, D, one
man can turn or work these cocks simultaneously, first one way then another,
in such a manner that by the first movement the cocks H and C shut and
G and D open, at the next movement G and D shut and H and C open. This
movement I make once or more times, one, two, one, two, and then for a
short interval of time allow the water and dirt it contains to pass away by
the cocks C and P. In this operation the filtering bed acted upon is rapidly
traversed by two strong currents in opposite directions, whose meeting has the
effect of producing shocks and agitation, which detach from the filtering
material the filthy matter which adheres to it and rejects such filth out of
the filter. This cleansing up and down movement is repeated during four or
five minutes, but care must be taken not to keep the cocks G and D too long
open at a time, as that would have the effect of forcing the filth, which it is
intended to remove, deeper into the filtering bed. After having cleansed the
first filtering bed I pass to the second bed, working the cocks L, D, H, E,
and then to the third bed, working the cocks J, E, I, F. The whole time
occupied thus in cleansing a filter with three filtering beds is about fifteen or
twenty minutes. As I have thus shewn the cleansing by the means of dirty
water is effected without any difficulty, but it has the inconvenience of soiling
the filtering material from below, that is to say, in a contrary direction to that
of filtration, whence it follows that on renewing the filtration it is necessary
to allow the water to run to waste for a moment until it passes clear. It
would be much more advantageous to effect the cleansing with filtered water,
provided it did not interrupt the working nor require a new pressure from any
source, nor cause the filtered water to return. Having given my attention
and researches to this important part of the art of filtration as well as to
the others, I have succeeded in overcoming the difficulty in the simplest
manner. Whenever there are several filters together in operation, and that the
filtered water is raised to an upper level, it suffices in such a situation to shut
the cock O, which allows the communication of the filter to be cleansed with
the pipe bringing the dirty water, and to keep the cock N, which allows its
communication with the filtered water, open. It is then evident that a part
of the filtered water supplied by the filters in operation will enter the filter to
be cleansed, under the effect of the first pressure, or of the column of dirty
water, and may be made use of in the same way as the column of dirty of
water, care being taken to keep open the cock Q, situated on the side opposite
to that by which the filtered water enters, and the cock P, shut. By these
means any filter may be cleansed without interrupting the filtration in any
way. The same operation may be effected even when the filtered water is

page_text: not raised above the filters by means of pipes and stopcocks, by which the
filtered water as it comes from other filters is stopped, and forced into the
filter requiring to be washed.
The quadruple key before mentioned is composed of four distinct keys,
Figures 12, 13, & 14, connected together two by two by jointed rods, which
are also connected together by another rod or handle intended to receive the
movement, and communicate it simultaneously to them. By means of this
movement one man is enabled to effect the cleansing. The operation is
rendered quite regular; there is no cause to fear any false movement or any
shocks given improperly, nor that one cock should be opened when it ought
to shut, or shut when it ought to open. In short, a common workman,
without any acquainiance with the subject, or previous apprenticeship, is in a
situation to manage thirty filters, and keep them perfectly cleansed.
On the direct application of pressure derived from any motive power to
filters, the means of regulating such pressure and of increasing or diminishing
it at pleasure: In all cases where circumstances will admit of it, it is doubtless
best to effect the filtration by means of pressure produced by a colunin of
water more or less elevated, and weighing upon the filtering materials, and
consequently to employ the motive power at command to produce such column
of water in case it does not exist naturally. In this case the pressure is
always uniform, and when once the vessels are made of the strength requisite
to sustain the pressure, no accident need be apprehended, whatever may.
be the resistance opposed by the filtering materials to the passage of the water,
according as they may be more or less compact, or more or less blocked up by
the impurities; but if, on the contrary, the water to be filtered is forced directly
through the filters, as it is impossible to regulate the action of the pump with
such precision as that it shall in all cases deliver only the exact quantity of
water which the filters can pass, it will necessarily happen, that when the
quantity of water supplied by the pump is too great, it will either force a
passage, carrying along with it a portion of the impurities, and thus render the
operation ineffectual, or else the vessel, the pipes, or some other parts of the
apparatus will at length give way, perhaps burst with great force, and cause
serious accidents. Let it be supposed, for example, that each stroke of the
piston furnishes one hundred gallons of water, if in the same space of time the
filters can only discharge ninety-nine gallons, it is clear that in the course of a
very few strokes one or other of the aforesaid events must take place. I have
remedied this danger by a safety valve, constructed as follows:-
Figure 15 represents a vertical section of the valve. To the pipe a, which

page_text: receives the water from the pump and conducts it to the filters, I attach the
vertical pipe b bored perfectly true and smooth inside, to receive the piston c.
The piston is connected by the rod d to a graduated lever e, furnished with a
moveable weight f. like a steelyard. In the tube bare a series of holes, round
which is placed a cup g, from which branches a tube h connected to the reser-
voir which supplies the pump. In its ordinary position the piston rests upon
the internal ring i, placed at the bottom of the tube b, at its junction with the
horizontal pipe which conducts the water. Before setting the filters to work,
the pressure at which they are to work is regulated by means of the weighted
lever. When this pressure is exceeded, that is, when the pump throws a
greater quantity of water than the filters can discharge, it will be seen that the
piston will gradually rise and will furnish an issue to the excess, by opening
in succession the holes made in the sides of the vertical tube in which it
moves. On the other hand the workman set to watch the apparatus will be
warned by the return of the water to the reservoir, and can diminish the force
of the machine without, however, its being absolutely necessary. By this
means the employment of any motive power to produce pressure directly is
rendered both possible and easy, the effect of this pressure upon the filters is
augmented or diminished at pleasure, and all dangers are avoided. It should
here be observed, that although all tending to the same end, each apparatus
in a large establishment has, as one may say, its own separate and independent
existence, that each can be connected with with or detached from the general
system, and that consequently there is no room to fear those serious accidents
which sometimes disturb or even suspend the operations of important
establishments.
Lastly, to give an idea of a large filtering establishment, I have annexed
the design, Figure 16, shewing an hydraulic tower and a series of twenty
filters, which series may be extended and multiplied at pleasure, in conforming
to the form and conveniences afforded by the ground at command.
I now proceed to state what I claim under my Patent aforesaid. I claim,
First, the division of the closed vessel which contains the filtering materials,
into several parts, and especially the division of the vessel of a cylindrical
form into two equal parts by a vertical section, and the division of the vessel
of a cubical form into as many parts as there are sides or faces, that is, into six
parts. Also, the manner of putting together and taking to pieces these
vessels, and of separating all the parts and putting them together in one body
of the greatest solidity.
Secondly, the two exterior pipes forming an integral part of the vessel,

page_text: either by being cast with the vessel, or placed on afterwards. Each of these
pipes convey water into or out of the apparatus, by means of horizontal cocks
communicating with the vestibules.
Thirdly, the false bottoms or shelves which I call retaining boxes. These
boxes are intended to retain and maintain, compressed in compact masses, the
beds of filtering materials. It is by their means alone that the use of pressure
in filtration is possible and efficacious, and consequently, that the problem
of filtration on a large scale, by means of pressure, is thus completely solved.
Fourthly, the simple and suitable manner of introducing and solidly fixing
in the filtering or closed vessel the retaining boxes, which is rendered easy
by the division of the vessel into several parts.
Fifthly, the placing and arranging in the vessel a series, more or less
extensive, of beds or masses of what I call inert filtering materials, such as
sand and pounded freestone or grit, progressively diminishing in coarseness;
these masses being separated from one another, but successively and gradually
contributing to the same operation, and dispensing with the use of all sub-
stances of a nature calculated to affect in any way the chemical quality of
water, or of any other analagous liquid submitted to filtration.
Sixthly, the cleansing of the apparatus with filtered water in establishments
where there are more than one filter, without using any other pressure than
that of the unfiltered water, which is done by closing the communication of the
vessels required to be cleansed against the said unfiltered water, and opening
their communication with the filtered water coming from the other filter or
filters in operation.
Seventhly, the method of cleansing the apparatus by one man and by means
of the quadruple key, which opens and shuts with regularity the necessary
cocks, and thus avoids the possibility of any irregular action or improperly
timed shocks.
Eighthly, the application of a safety valve in case of employing the direct
pressure of any other force than that of a column of water pressing on the
filtering materials, and the particular construction or arrangement before
described, by means of which safety valve all accidents are prevented, and the
pressure may be encreased or diminished at will.
In witness whereof, I, the said André Eustache Gratien Auguste
Maurras, have hereunto set my hand and seal, this Fifteenth day of
May, in the year of our Lord One thousand eight hundred and forty-
three.
A. E. G. A. (L.S.) MAURRAS.

page_text: AND BE IT REMEMBERED, that on the Fifteenth day of May, in the
year of our Lord 1843, the aforesaid André Eustache Gratien Auguste
Maurras came before our said Lady the Queen in Her Chancery, and
acknowledged the Specification aforesaid, and all and every thing therein
contained and specified, in form above written. And also the Specification
aforesaid was stamped according to the tenor of the Statute made for that
Par
Enrolled the Fifteenth day of May, in the year of our Lord One
thousand eight hundred and forty-three.