CERTAIN NEW AND IMPROVED MACHINERY AND OPERATIONS FOR THE PURPOSE OF SAVING FUEL IN THE PROCESS OF EVAPORATING WATER FROM SOLUTIONS OF SALTS, THE WASTE OR CAST-OFF LEYS OF SOAPMAKERS, AND WHICH MAY BE APPLICABLE ON OTHER OCCASIONS WHERE EVAPORATION OR A SEPARATION OF WATER, FORMING EITHER WHOLLY OR IN PART A. DISSOLVING FLUID, FROM THE SUBSTANCE OR SUBSTANCES HELD IN SOLUTION, IS RE
Year: 1792

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
FREARSON, of Liverpool, in the County Palatine of Lancaster, Merchant,
send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-first day of May, in the thirty-second year of His
reign, did give and grant unto me, the said David Frearson, His especial licence,
that I, the said David Frearson, during the term of years therein mentioned,
should and lawfully might use, exercise, and vend, within England, Wales,
and the Town of Berwick-upon-Tweed, my Invention of "CERTAIN NEW AND
IMPROVED MACHINERY AND OPERATIONS FOR THE PURPOSE OF SAVING FUEL IN THE
PROCESS OF EVAPORATING WATER FROM SOLUTIONS OF SALTS, THE WASTE OR CAST-OFF
LEYS OF SOAPMAKERS, AND WHICH MAY BE APPLICABLE ON OTHER OCCASIONS WHERE
EVAPORATION OR A SEPARATION OF WATER, FORMING EITHER WHOLLY OR IN PART
A. DISSOLVING FLUID, FROM THE SUBSTANCE OR SUBSTANCES HELD IN SOLUTION, IS
REQUIRED;" in which said Letters Patent there is contained a proviso obliging
me, the said David Frearson, by an instrument in writing under my hand and
seal, to cause a particular description of the nature of my said Invention, and in
what manner the same is to be performed, to be inrolled in His Majesty's H gh
Court. of Chancery within one calendar month after. the date of the said

page_text: recited Letters Patent, as in and by the same (relation being thereunto had)
may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
David Frearson, do hereby declare that my said Invention is described in
manner following (that is to say):-
The principles on which the Patentee rests his pretensions to His Majesty's
Letters of Licence for an exclusive right to the practice and emoluments of
his Invention are generally speaking these:-As oily, soapy, gelatinous, or
mucilaginous matter, when intermixed with aqueous solutions and gathering
upon their surface, would materially obstruct the progress of evaporation when
promoted by the principles to be proceeded on, all such are to be removed as
much as is possible and convenient by filtration, and at proper periods during
the process to be skimmed off. After having, when requisite, undergone such
filtration, either for the afore-mentioned purpose, or for removing other
impurities which it may be desirable to seperate, the solutions of salts, the
waste or cast-off leys of soapmakers, or other mixed solutions (from which
water, forming either wholly or in part a dissolving fluid, is required to be
evaporated or separated from the substance or substances held in solution,
and with which a part of the substance intended to be left behind may
occasionally fly off) are to be exposed to the atmosphere in shallow ponds or
reservoirs, which are to have various machinery affixed to them, by means of
which, a part of the solutions may be successively taken up and spread over
the surfaces of the machinery appropriated to that purpose, and thus have an
increase division or extension of their surfaces further exposed to the atmo-
sphere to be acted on by the sun and air, and are to be protected by such
machinery from rain or dew falling into or incorporating with them. The
operations and machinery he judges most proper to effect this purpose are as
follows, and though machinery of other forms and other materials than those
he points out may undoubtedly be constructed and contrived for the same use,
yet, as they must assuredly be some way or other imitations of these, and
operate upon the same general principles, he trusts and hopes that his study
and expence to accomplish this business will not be suffered to be lost to him
by attempts to evade his Patent on such grounds
"
(1st.) The receiving reservoirs for solutions required to be kept or filtered.
-The soapmakers' waste leys, or any other solutions of such description, will
require reservoirs for their reception of dimensions proportioned to the
quantity from whence the water is required to be evaporated, and which, along
with the succeeding reservoirs, may be sufficient to retain a considerable
portion during the winter, or any long continuance of wet unfavorable

page_text: weather. These dimensions will necessarily be regulated by circumstances,
as the extent of the reservoirs and machinery to which they are attached, the
quantity likely to be received in winter and during weather not favorable to
the progress of the evaporation, &c. They may be constructed of various forms
and materials, but must be so tight as not to admit the solutions in any
material quantity to penetrate or exude through them. If they are formed in
the ground with clay and bricks, clay, bricks, and cement, the best form will
be cylindrical, the base of the cylinder will be parralel with the horizon.
These I.will call, to distinguish them from the others, the receiving reservoirs.
(2dly.) Filtration and the filtring reservoirs.-When any solutions require
filtration to take from them any obstructions to evaporation, or earthly.
impurities, there must be another reservoir constructed similar to the former,
and adjoining thereto, over which must be placed large square-edged bags or
filterers, fastened to cords at their edges, the bottoms of which, when sus-
pended and containing the fluid, may incline towards a spherical or conoidical
form of a moderate depth. These square-edged filtring bags, formed of canvas,
hair, or other cloth or stuff fit for the purpose (into which the solutions must.
be pumped, or some other way run in), must be secured by nooses at the
angles to upright staffs or pegs placed at the end of rods running square with
each other in an horizontal direction, from which to the rods the nooses may
be at any time slipped, so that the two opposite points of each parallel side of
the square (or it may be oblong) horizontal line of direction of the nooses upon
the rods may be brought or drawn to approach each other, and the residuum in.
the filters pressed. In addition to the above mode of filtration, he proposes (when
the solutions are so impure as to require it) to divide these filtring reservoirs
into two parts by a partition, to put coarse sand at the bottom of each division,
so as to occupy a space of some inches left for the purpose between the
bottom of the dividing partition and the bottom of the reservoirs, and to come
up a little above the bottom of the partition. The bottom of the division over
which the filtring staffs are suspended must decline a little towards the bottom
of the other, and upon the sand in the former is to be placed coarse hair cloth,
canvas, or other stuff, fixed to poles by nooses with cords, so as to be drawn up
at pleasure, and the residium found upon it after the solutions have passed
into the other division taken away. These filtring as well as the receiving
reservoirs should have slight sheds or roofs to keep out the rain. The soap-
makers' waste leys will particularly require as perfect a filtration as can
conveniently be had, as the soapy and gelatinous matter they commonly
contain, if not separated, will gather upon the surface of the solutions, and in
great measure retard the progress of the evaporation of the water. Other

page_text: solutions to which the principles of this Patent are applicable may also require
an attentive filtration as well as these.
(3dly.) The evaporating reservoirs.-Either the solutions which have passed
filtration or those which do not require to be filtred are to be run or pumped
into shallow pits or reservoirs. These evaporating reservoirs are to range
and be placed so as to extend from east to west, or nearly in that direction, in
the longer or oblong side of their square, and from north to south in their
shorter side or breadth; they may be from about nine to about fourteen inches
deep, and are to be so constructed as to retain the solutions, and of such materials
as may be had on the cheapest terms and be effectual for the end in view (as
well as the other reservoirs before mentioned), which will of course vary in
different situations, circumstances, and places, respecting which I shall
endeavour to give some instructions, or at least hints, in my remarks on the
materials.
(4th.) The materials of which to construct the reservoirs in general.-There
being a great variety of materials of which all the afore-mentioned reservoirs
may be constructed, I shall endeavour to point out those which may be
generally the cheapest and most fit. If good clay be to be had in the ground
or near it, so as to be had at a low price, I would use it well tempered and close
rammed down as a retainer for the sides and bottom of all such of them as are
placed or sunk in the ground. The receiving and filtring reservoirs may be
formed of bricks set in such clay at about six inches thick from them, or, as before
intimated, these may be formed wholly of wood, in the way the workmen of
the city of London construct what they call backs, but will be expensive.
The bottoms and sides of the evaporating reservoirs may be covered with
boards and secured at the ends and middle upon frames or joists stretching the
length of the reservoirs, or with square-edged bricks on the flat on square tiles,
or with bricks or tiles covered with or set in tarras, or any such like good
cement or mortar. In the situation where it is first designed to apply his
machinery and operations, near the city of London, to the evaporation of water
from the soapmakers' waste or cast-off leys, there not being proper clay in the
ground or near at hand, and the ground lying rather low and disposed to be
damp, it is intended to form the evaporating reservoirs wholly of wood boards
close jointed so as to retain the solutions, to rest them upon logs of wood or
other pillars being supported from pillar to pillar by sufficient bearers at about
a foot from the ground, and to excavate and take away a part of the earth
underneath them, so as to leave room for a person to pass occasionally through
and examine whether they be so tight as not to admit of the solutions to exude
through the joints or any accidental opening or crevice. It is impossible to

page_text: ascertain minutely now by directions and description the greater eligibility of
one material rather than another of which to construct these reservoirs, the
choice depending so much on situation,, the value of the solutions, and other
circumstances observed on. The situation must be viewed and proper estimates
made of various articles by which the judgment may be guided. It may,
however, be remarked that reservoirs constructed of wood, if not objectionable
as to cost, will be better for retaining alkaline solutions than those made of
most other cheap materials; for alkaline compounds, in which there is an
excess of alkaline salt, will take up into solution (and so may be said to
corrode) silicious and argillaceous earths, of which common clay is almost
wholly composed, and also the silicious or sandy part of the cements called
morters or tarras in proportion to the excess of alkali, whether vegetable or
mineral. Weak or mild alkaline solutions will be long in corroding or taking
into solution clay, or the silicious part of well prepared cements or mortars;
but he would caution those who may follow him or use his Inventions, that an
exudation or loss of the solution may take place, when they not aware, for the
idea that the water may alone exude and the contained salts remain, is a
mistaken one. Salts will pass with their water of solution even through
glazed earthenware, as he has often experienced. Like remarks may be made
respecting some acid solutions. Reservoirs constructed with bricks and
common mortar, and well covered with pitch, or of wood covered either wholly
or only at the joints with pitch, may be very proper and cheap in some cases
for retaining such solutions as will not decompose or corrode the pitch. And
it may be observed that black, being the colouring material most heated by the
direction of the rays from the sun (as appears by its absorption of them and
from experience), may be applied in some instances to the evaporating reservoirs
and machinery, so that by increasing the heat the evaporation may be helped.
I come now to,
(5th.) The evaporating machinery, to promote evaporation and protect the
solutions from rain or dews falling into or incorporating with them.-And first,
the wheel machinery resembling the fly of a smoak jack, but placed vertically
and its covers. The use and dimensions of this, as well as of every other con-
trivance intended to effect the purpose, must necessarily be regulated by situa-
tion, and the quantity designed to be exposed to evaporation. Suppose the
evaporating reservoirs to be from about two to three hundred feet in length,
extending from east to west, and about fifteen feet in breadth from north to
south, which may be the most proper dimensions in many situations, where
the principles of the Patent are adopted; then, over these reservoirs are
to be placed roofs or frames formed of thin boards or framed canvas (or any

page_text: other coarse cloth or stuff fit for the purpose), from which the rain may run off,
as from an umbrella, and not penetrate through and mix with the solutions.
These are to be affixed by strong hinges to poles or pieces of wood, extending
from east to west, like the ridging of the roof of a house, and are to be sup-
ported by other posts, poles, or pieces of wood, placed perpendicular to the
horizon. I will call them
(6th.) The moveable roofs. If the evaporating reservoirs are about fifteen
feet broad and the wheels or flys (which will hereafter be described) are about
twelve feet diameter, these moveable roofs may be each about fifteen feet
long; and at the end of the frames (or the pieces of wood to which the boards
of the frames or the frame pieces formed of canvas, coarse cloth, or the like,
are secured) are to be fixed poles or staffs, by staples or hinges, so as to lift up
the roofs to a few degrees above the horizontal level of the solutions below, and
there support them, or to let them down that they may form a covering to
protect the solutions from rain or dew, for which they must be sufficient, and
must be made tight or be covered at the joints where the hinges are, so as not
to admit the rain to fall through at the ridges. Below these moveable roofs or
coverings must be fixed
(7th.) Wheels or flys, with their axles resting towards north and south in
proper bushes, on supporters rising from and fastened to the sides of the
evaporating reservoirs.-The diameter of the wheels will, of course, extend
towards east and west, and to the extremities of the parts composing the flys
or wheels are to be fixed thin boards, extending perpendicularly from the line
of their circumference towards north and south. To these must be affixed
other pieces, both at the ends and going lineally with the circumference of
the wheel, so as to form a kind of shovel to take up and disperse the so-
lutions. These fly wheels are to be so constructed as to be set in motion
by the wind, when blowing with a needful degree of strength and in cer-
tain directions, and are to be so hung upon their supporters, that the
shovels as they move may dip into the solutions, take up and disperse them
over the surfaces of the wheels, and the surfaces projecting from them, that
they may be exposed to the effects of the sun and air, and the aqueous parts
carried off in vapours or evaporated. The supporters, in which are placed
the bushes on which the axles of the wheels are to rest and move, must have
at the top frames or pieces of wood extending from them at right angles, into
each of which are to be inserted three or four bushes, that the axles of the
wheels may be occasionally moved and shifted into them, so that the lines of
their diameters (the wheels) may be placed from towards east and west to
towards north and south or south and north, that they may be properly ex-

page_text: posed to the direction of the wind, by which they may be kept in motion and
revolving upon the axles. The axles are to be fastened into the bushes by
proper hasps; when the. wind does not blow with sufficient force. or in a proper
direction to give motion to the wheels when loaded with the solutions adhering
to them, and to the projecting materials, designed to make an increase of the
surfaces of such solutions, they must be moved by some other power. These
fly wheels must have various other substances fixed to them, such as reeds, or
branching twigs of trees projecting from their surfaces, but they must not be
so numerous or so heavy, when loaded with the solutions taken up and dis-
persed, as materially to affect their being kept in motion, by the wind; nor
must they be obsured, but sufficiently and fully exposed to the effects of the
sun and air.
(8th.) Instead of, or in addition to; the above-mentioned fly wheels (designed
to be operated upon and set in motion by the wind), wheels may be placed in
like manner made of thin boards, framed cloth, &c. (of the full area and cir-
cumference of a circle) the diameters of which must necessarily depend on
circumstances (before alluded to), and these may be covered on both sides,
especially towards the south, with various substances, projecting out and fixed
to them, for the purpose of dividing and increasing the surfaces of the fluid,
and must have shovels fixed to them in the same manner as the fly wheels.
These wheels, as well as the former, must have at the north end of each of
the axles a projection of a few inches, into which cross staffs must be fixed at
right angles, that they may be turned round in succession, and the solutions
taken up and dispersed over the surfaces, to keep them wet and dripping,
which must also be done to the fly wheels when they are not kept in motion by
the wind. Various other mechanical powers may also be applied for this pur-
pose, and so as to keep the wheels in continual motion.
(9th.) The evaporating machinery, resembling a drawbridge or the frame
machinery. This class of machinery may succeed the others or not, situa-
tions and circumstances can alone determine; they may be constructed
cheaper than those before described of proportionable size, may be worked
where the fly wheels cannot for want of a sufficient current of air, unless
motion be given to them by some other power), and will for many reasons be
generally preferable to the plain wheels, and to both in respect that the
solutions may be more easily covered and uncovered by them, as the moveable
roofs will require more strength and labour to raise and let them fall, and of
course more time or more hands; hence it may be in many instances the best to
work with these alone. Whether they do or do not succeed the operation of the
former upon. the contents of the evaporating reservoirs, they are to be con-

page_text: structed thus: On the north side of the evaporating reservoirs pillars are to
be set up and fixed in the ground, of such heights and scantling as may be
conformable to the breadth of the reservoirs, the extent of surface wanted,
and the weight of the frames when loaded with the solutions. Suppose these
reservoirs to be from about two to about three hundred feet long, and about
fifteen feet wide, as has been supposed before to be generally most convenient.
Then he would have the pillars put down at about twelve or fifteen feet
distance from the centre of the perpendicular direction of each other, to be
about seventeen or eighteen feet high, about nine inches broad, and of strength
proportioned to the weight they are to support; they must be sunk in the
ground to such a sufficient depth that they may stand firm, and have stays on
the north side at the bottom. These pillars being placed at about six inches
distance from the evaporating reservoirs, in the space between them must be
put down other timbers of the breadth of the pillars, and so thick as exactly
to fill up the space, which are to be sunk into the ground about six or nine
inches deeper than the pillars; on the tops of each of these, on a level with the
north edge or brim of the reservoirs (which must be a little lower than the south
edge, that the solutions when the frames are dipped may not be thrown over
the latter), are to be affixed with bushes and forelocked bolts to iron eyes or
loopholes, projecting by strong iron straps from the south side of the pillars, two
posts or supporters to the frames, which I will call frame supporters, of such
length that they may exactly meet and fall into the opposite side of the reser-
voirs, and so, resting in part on those logs, which I will call frame logs, and
partly on the bolt like the pin of a hinge passing through them, they may be
raised towards a perpendicular height or let fall at pleasure to other frame logs,
or to other pillars. To the right hand and left, or east and west of these, are
to be affixed like frame supporters, and in the same manner; thus three pillars
will comprise in their extent two setts of this part of the machinery. To the
lower edge of two of these frames supporters are to be fastened, from pillar to
pillar, thin boards of wood, or frames of well-stretched canvas, or other cloth or
stuff. If boards be used they must lap or be fixed at the edges one over
another, so that when the frames, which I will call evaporating frames, are
suspended at an angle-suppose 30 of a quadrant-they may form a roof or
cover from which the rain as it descends may run off, and also the solutions as
they are taken up upon them. On the south or lower side the boards may be
strengthened and secured to each other by battens running across them. On
the tops of the pillars are to be fixed by stout hinges, with the pins of the
hinges on the north side of the pillars, and straps going round the tops of the
pillars, two bars or pieces of wood so as to constitute levers or balances;

page_text: when these are suspended horizontally, a cord or chain must drop from their
south ends vertically, and be secured to the frame supporters. These bars or
pieces of wood, which I will call evaporating levers, must be made tapering,
so that when they are suspended in an horizontal direction the south end of
the lever may be the smaller and lighter, and the north end the larger and
heavier. If the evaporating reservoirs be about fifteen feet wide, I would
have the south end of the evaporating levers from about twelve to fifteen feet
long, and the north end about seventeen to eighteen feet long, where they
must be joined by other pieces of wood of such weight that with the aid of
the strength of a man they may easily counterpoise the evaporating frames
loaded with the solutions, and move them. The south sides of these evapo-
rating frames are to have reeds, branching twigs of trees, or other light
materials, fastened to them, but not to project so far as to prevent their dipping
properly into the solutions. These will not produce an increase of surface by
their number, but occasion a dripping after being immerged. When the
solutions are very much concentrated these may be removed, or else they must
be afterwards washed with weaker solutions, or a part of the machinery may
be wholly without them for solutions in that state.
The operations with the frame machinery.-The evaporating reservoirs
and this part of the machinery being thus prepared, the reservoirs must be
nearly filled with the solutions from the receiving or filtring reservoirs, and
the frames let down and dipped into them by the levers, so that the extremity
of the upper surface of the south end may be dipped or plunged from two or
three inches, after which the frames are to be raised up and the levers fixed
by means of a cord or other such contrivance to the pillars, so as to support
the frames standing towards a perpendicular direction, but inclining a few
degrees to the south. Both the north and the south sides of the frames and
the projecting surfaces from the latter will thus be wetted and exposed to the
effects of the sun and air. At that which will be the lower end of the frames
when thus raised must be left an opening through its whole breadth, so that
when the fluid is taken up upon the north side as it runs down it may pass
through this opening into the reservoirs. And that this space may be made
the most of as to the effect of evaporation, there are to be reeds, branching
twigs of trees, or other things of that sort, suspended from the bottom of the
frame above, yet not in such number or so close to each other as either to
impede materially the passing of the fluid or cause it to fly forward to the
ground and be lost. When the wind blows with a great force these reeds, &c.
may be removed, that the solutions as they are divided in passing through
them may not be blown away.

page_text: The doing of this depends entirely on their value and the degree and force
of the wind. During fair weather people must thus proceed plunging, wetting,
and raising these frames successively till the evaporation be carried on to such
a degree that it is no longer prudent to attempt its continuance without the aid
of fuel, when the solutions must be run off into reservoirs, to be put into iron
pans, or run off directly into the pans that the evaporation may be perfected in
the usual way, and if any salts have chrystallized and fallen to the bottom of
the reservoirs they must be taken away and treated as is customary. As the
evaporation will proceed quicker when the solutions are weak and contain
much water than when they are concentrated and contain but little, the
evaporating reservoirs must be divided into compartments (the number
depending on the length of the reservoirs) by boards running across them, to
which the frame machinery must be so adapted where they are put that the
edges of the frame supporters may pass the edges of these dividing boards,
and dip with the frames into the contents of the reservoirs. The wheel or
fly machinery must also be adapted properly to these compartments. The
bottoms of each of the compartments into which the solutions are first put
must be nearly on a level with the surfaces of the adjoining ones, into which,
when the boards are lifted up, the solutions consentrated to a certain degree
may pass and be treated in the like manner; then passed or run into
a third, and so on, just as circumstances and their degree of strength may
point out. When rain or dew falls, the frames must be let down so as to
form roofs for the protection of the solutions from which the water may run
off, and the openings of the lower parts of the suspended frames must
then be covered up by light frames, as long as the evaporating frames
are broad, which may be placed upon stays fixed to the frame supporters,
and enter as into a groove below the bottom of the principal frames
where they may be secured, and so receive and carry off the water.
Or some solutions of little value may be covered up by letting fall a flap
either of thin boards or frame canvas, jointed by canvas or any other
proper material to the edges of the frames above. On the south side painted
or payed canvas or other coarse cloth or proper stuff must be raised and
fastened to that edge of the frames extending from the sides of the reservoirs
to protect the solutions on that side when the frames form a roof to carry off
the water. Before these frames for the openings are fixed, or the flaps let
down, some of the rain should be suffered to pass over the surfaces of the
frames (which will resemble a roof) through the openings into the reservoirs
to wash into them such part of the solutions as may be adhering, that they
may not be carried on to the ground and be lost, especially if they be concen-

page_text: trated and valuable.
In showery weather, when rain is often expected, it will
be proper to work only with the south or lower side of the frames, and omit
to dip the upper, keeping on the moveable frame or the flap down, but the
former a little shoved up into the grooves that the solutions may be more
effectually preserved, particular if they are strong in salts.
With the above general descriptions and directions are included such opera-
tions as more particularly belong to valuable solutions. I shall now observe
upon some particulars which may more especially relate to the evaporation of
water from the salt water of the sea. The sea water being let into large open
ponds or reservoirs, as is done at Lymington in the south of England and in
France, that the earthy impurities may subside to the bottom, and such part of
the water be evaporated in these open ponds as the state of the weather and
other circumstances may conveniently admit, must afterwards be passed into
evaporating reservoirs to which those principles, machinery, and operations
may be applied. The evaporating reservoirs for this purpose are to be con-
structed in much the same way as those before described, but it is not re-
quisite that so much care and expence should be employed to make the first
ranges of them tight for retaining the solutions while they are yet weak and
but little concentrated, because of the small value of sea water compared
with such solutions as the soapmaker's waste leys, or others, for which a consi-
derable price is or may be paid. These first ranges of reservoirs and
machinery designed for the reception of the sea water which has (or has
not) undergone a certain degree of concentration in the open ponds, may be
formed of clay only, or any other cheap material, which will pretty well retain
the fluid. But in this case they must either be of such sufficient depth that
the dipping of the evaporating frames or moving of the wheels may not cause
the close-rammed prepared clay or mud made use of to be mingled with the
solutions (sea water or salt brine), so as to make them muddy; or else, after
passing these, they must be run off into other large and deep reservoirs that
the earthy particles may subside, and the brine or solutions be cleared; and
filtration, as has been before described, may sometimes be employed to advan-
tage for this purpose. The succeeding reservoirs, especially those in which
the salt is designed to be formed (by the chrystallization which will take place
on the evaporation of the water), must be made with much the same care as
those described before in (4), and the fluid passed in the same manner from one
to another as the concentration advances, constant attention being paid to skim
off the impurities which may arise upon the surface, as before directed. In
sunimer, and when the seasons permit, as much salt will of course be suffered
to form or chrystallize and be taken up (or, as is termed, drawn) as is possible:

page_text: vv nen sait is not formed or chrystamzed in the evaporating reservoirs by une
operation of the sun and air, the salt brine solutions are to be brought, as near
as prudence will admit, to the point of saturation, and are then to be run off
into reservoirs, where they may be kept to be further purified by the subsiding
or precipitation of the earthy impurities, and afterwards put into iron pans (or
directly run off into the pans), to be boiled down to salt in the usual way;
and the salt brine which may remain in the reservoirs after salt has been
formed and drawn is to be treated in the same manner. But it may be
observed that if the boiling or evaporation of water from the salt by the aid of
fuel be conducted slowly or moderately, the salt will chrystallize in larger
grains, and be more perfect for the preservation of animal substances than
when they are small and produced by quick boiling to promote evaporation.
OBSERVATIONS.
Wood boards for the evaporating frames and moveable roofs may be pre-
ferred to canvas, or other cloth, for all those solutions which would tend.
to destroy the cloth, as all which contain an excess of alkaline salt cer-
tainly would. If canvas, or any sort of cloth, be used for such solutions, it
ought to be well painted or payed, which would be expensive, and even that
would secure it but imperfectly from their effects. This objection to framed
cloth or canvas does not extend to the salt water of the sea; for, as evaporating
frames or protecting covers constructed with such materials would be much
lighter than if of wood boards, they may be more eligible, as they would
require less power and strength to work and apply them.
For evaporating
water from the salt water of the sea, open cheap canvas, or such like cloth or
hair cloth stretched and fixed to wood frames, made no heavier than is neces-
sary, may be the best both for the moveable roofs and evaporating frames;
and the reeds, branching twigs, &c., may be attached to the wood frames of the
latter. These may very well be worked by single levers, fixed in the manner
of the double ones, but to pillars standing to face the middle of each frame, at
the distance of a few inches from the reservoirs; and the frames, in this case,
are to be hinged upon the frame logs in the way before described, but with
eyes or loopholes projecting by iron straps from the frame logs themselves.
These frames may also be hinged in many other ways. The evaporating
frames, of whatever material they be made, may be taken up and let down
by single levers, or by cords and pullies, fixed to posts,. high suspended rails,
&c., but he apprehends not with so much dispatch and steadiness as by the
double levers described in (9), particularly if they be wholly of wood, and con-
sequently heavy.

page_text: In a valuable treatise upon salt, the late Doctor Brownrigg has suggested
some principles and modes for promoting evaporation from the salt water of
the sea, or any salt brine, which have some conformity with a part of the
Patentee's machinery and operations. He has, therefore, solicited for an
exclusive right to the use of new and improved machinery and operations,
though he cannot learn that the ideas of Doctor Brownrigg have ever been
brought to use. He is informed, indeed, that such machinery and operations
as the Doctor has pointed out have been made trial of, for evaporating water
from sea water, but without success, as might be expected when the expence
is compared with the want of efficacy of his plan; and he takes notice of this
merely that no person may attempt the invasion of his Patent under pretext
that it is only an improvement. He trusts and believes that on the whole his
machinery and operations may be pronounced to be essentially new (and he
hopes useful), at least n relation to their object; but he has His Majesty's
Letters of Licence for new and improved machinery and operations, which he
has endeavoured to describe and make discovery of, as truly, fully, and openly
as he has had ability to do.
In witness whereof, I, the said David Frearson, have hereunto set my
hand and seal, this Twentieth day of June, in the year of our Lord
One thousand seven hundred and ninety-two.
Inrolled the Twenty-second day of June, in the year above mentioned.