CERTAIN IMPROVEMENTS IN THE MODE OF PROCESS AND FORM OF APPARATUS FOR MANUFACTURING SALT AND OTHER PURPOSES
Year: 1826

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
JOHNSON, of Droitwich, in the County of Worcester, Gentleman, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth did,
by His Letters Patent, under the Great Seal of His United Kingdom, bearing
date at Westminster, the Eighteenth day of December, One thousand eight
hundred and twenty-six, in the seventh year of the reign, give and grant
unto me, the said William Johnson, my exors, adiñors, and assigns, His
especial licence, full power, sole privilege and authority, that I, the said
William Johnson, my exors, adññiors, and assigns, during the term of years
therein mentioned, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "CERTAIN IMPROVEMENTS IN THE MODE OF PROCESS AND FORM OF APPARATUS
FOR MANUFACTURING SALT AND OTHER PURPOSES;" in which said Letters Patent
there is contained a proviso that if I, the said William Johnson, shall not
particularly describe and ascertain the nature of my said Invention, and in
what manner the same is to be performed, by an instrument in writing under
my hand and seal, and cause the same to be enrolled in His Majesty's High-
Court of Chancery, within six calendar months next and immediately after.
the date of the said Letters Patent, all liberties and advantages hereby granted
shall utterly cease, determine, and become void, as in and by the same; reference
being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said.
William Johnson, do hereby declare that the nature of my said Invention.
of certain Improvements in the Mode of Process and Form of Apparatus for

page_text: Manufacturing Salt and other Purposes, and the manner in which the same
is to performed, is particularly described and set forth as follows:-
Firstly, I employ the lower vessel of the treble evaporating boiler, described
under my Patents of the year One thousand eight hundred and twenty-three,
and One thousand eight hundred and twenty-four, for supplying heat by steam
to make the various common salt, using the steam of high temperature
generated in such lower boiler, and conveying.it by a pipe into a close vessel
aflixed under a common shallow-formed salt pan and trough, employing its
beat first to make from the brine in such pan fine salt, which pan and trough
must not be partially covered and trough exposed, but entirely.enclosed by a
strong cover united to it, for the purpose of employing the heat of the steam
from the brine of such fine salt at high temperature and pressure to go into a
vessel affixed under another salt pan, with sufficient power to force the heat more
rapidly and beneficially, for the evaporation of the brine charged in such pan,
for the making of broad salt then hitherto affected; the steam from which
broad salt brine I again enclose as hereafter to be directed, and employ it in
making British bay salt; and as the covered fine salt pan during the making
and drawing of the salt must be continued close, for the purpose of employing
its steam at high temperature, as stated, and that it is necessary that such
pan should be kept clean as possible from sediment adhering to it, I adopt
rakes to push or draw the salt across the pans into a trough, forming the lower
part of the pan within its enclosing cover, having their bandles made to pass
through stuffing boxes in the side of the pan cover to prevent waste of steam;
and that they may be kept in constant action, and save charge for hard labour,
I employ steam engine power, as will be further explained.
Secondly, I employ the heat from the same furnace, whilst generating steam
from the single or lower vessel of the treble boiler (when additional power is
wanted to generate steam from water in the two upper boilers, such heat
passing through the water of highest temperature in the lower boiler to the
upper boiler in succession (as is more fully described under the Patents men-
tioned), and I convey the steam from them, and employ its heat after the
same manner for making the different kinds of salt, as already described, of
the operations with the steam from the lowest boiler.
Thirdly, I employ the heat of fire direct to act under a common formed pan
or through a vessel of water under it, as in practice for making fine salt (with
permission if necessary to be obtained), but which pan I have close covered,
as already stated, for the purpose of obtaining high pressure steam from the
fine salt brine, to make by its heat broad salt in more beneficial manner, as

page_text: described, and again enclosing the steam from the broad salt brine, for the
making of large or British bay salt.
Fourthly, I make use of the steam, as stated, when evaporating from the
broad salt pan (by means of the heat of steam from the brine of fine salt)
to convey heat through other pans for making salt denominated bay salt,
to effect which the steam from the broad salt pans must be confined between
those, and the bay salt pans by means of thin boards surrounding them, or by
any other slight material, as it will not press with force against it, and that
the steam, when condensed against the bottom of the bay salt pan, should not
fall into the broad salt brine, the bottom of the bay salt pan should be made
sufficiently low in the centre, that the water from the condensed steam should
collect together and fall into troughs or in cloths placed in sloping direction
to carry it away.
Fifthly, during the manufacture of the broad salt by means of the heat of
steam from the fine salt pans, a large quantity of water arising from such steam
condensed under the broad salt pans, nearly or quite equal to the quantity
first evaporated from the steam boiler, will be constantly passing off at or
near boiling heat. This water I employ under pans immersed in it, when
placed in a frame of wood or brick or other material at a little distance
surrounding them, for making any description of large salt, or for heating
brine for the salt pans.
Sixthly, it being of great importance that the pans, whether employed in
making fine or large salt, should be kept free from sediment adhering to them,
which would prevent the heat from passing freely through them into the
brine, 1 employ steam engine power to work the rakes or shovels, that they
may be constantly in operation for drawing or putting the salt into troughs
enclosed within the pan cover.
Having stated the mode of process and arrangement and form of works
(sufficient for the instruction of those who are informed in operations by steam
heat, and in adapting machinery to carry such processes into effect), by which
I propose to convey and employ steam heat in improved manner, for the
manufacture of salt, and for drawing it at less charge for labour, I insert the
following sketches and explanations, which are only intended to illustrate and
assist in rendering my improved form of process, and means of carrying it
into effect, better understood. Let A, B, C, represent the end view of a
treble boiler for evaporating three distinct bodies of water at the same instant,
by means of heat from fire direct, acting only against the bottom of A, and to
operate on the upper boiler B, C, as described under my Patents of One
thousand eight hundred and twenty-three and One thousand eight hundred

page_text: and twenty-four. D, a pipe for conveying the steam from A into a close
vessel, as described by E, affixed under a shallow covered pan as F, for
making fine salt, which pan and trough must be entirely enclosed by a
strong cover, as described by line G, to retain the steam to considerable
pressure. The steam may also be made to operate with the same effect under
the brine in a continuation of pipe, as in the vessel E. H, a main and
branched pipe, shewn for conveying the steam arising from the brine in pan F,
into the close vessel as described, I, under pan K, for making broad salt. Let
the dotted lines L, L, represent the situation of some slight material for
enclosing the steam arising from the brine in pan K, to confine its heat to act
against the bottom of pan M, to evaporate brine for making large or British
bay salt. Let N, N, shew the position of troughs forming a part of the pans,
to be of good dimension, into which the salt is to be drawn or pushed by a
common or by a shovel-formed rake, the handles of which must pass through
stuffed boxes in the side of the pan cover to prevent waste of steam. The
door into the pan must be over the trough (of sufficient length to render the
opening convenient for taking out the salt, and for defending the salt men
from the steam from the pan when taking the salt from the trough. Perhaps
it will be sufficient to have a broad flap of wood or iron lodged within the
pan above the door, which, when let down, must rest against the farthest side
of the trough, which would sufficiently keep back the steam from the men if
the steam going under the pan from the boiler was for a short time turned off
to prevent its keeping up a pressure in the pan.
From the foregoing described nature of the plan and arrangement of the
apparatus for obtaining an improved manufactory for making salt by steam
heat, the progress of the heat from the furnice acting direct only against the
bottom of A, and its subsequent employment will be understood to be as
follows: A, B, C, having been charged with about half their depth of water,
and heated to a pressure of steam in A of about 25 lb. per inch, will raise a
pressure in B of about 12 lb. per inch, and in C to about 5 lb. per inch.
Supposing, then, the pans F, K, M, to be charged with brine, if the cock of
the pipe D be opened, the steam will pass with great force into E, and make
the fine salt brine in F to boil rapidly to make fine salt, the steam from which
being confined by the cover G will be soon raised to considerable pressure,
which, when in a state to act with force (seldom exceeding a pressure of five
pounds per inch), now let the cock of the pipe at H be opened, the steam
will then pass with sufficient power into vessel I, under a inore extensive pan
or pans as described K, which will raise the heat of the brine in them to the
temperature, if required, of one hundred and seventy. For making broad salt

page_text: again the steam arising at such heat from pan K being confined by any
description of material surrounding the pans and extending up to pan M (but
most properly with their boards) to act against the bottom of it; its heat I em-
ploy in making what is denominated British bay salt, the bottom of such pan
being sufficiently curved that the water from the steam condensed against it
should so collect as to fall into gutters or other convenient conductor for carry-
ing it away from falling into the broad salt pans again. As the sketches
describing a treble boiler and pans are not according to any scale of due
proportion, it will afford sufficient instruction to state, that from various trials
which I have made on a large scale, I have found that when the lower steam
boiler A was alone employed acting as a common boiler, and of ten feet by
seventeen extent, that steam was raised in it sufficient to supply heat to
support a temperature of one hundred and sixty-four degrees in the brine for
making broad salt in pans of lead of two thousand four hundred square feet
extent, the steam going direct from A into the vessel underneath the pans;
and that when the three boilers A, B, C, were employed together (the steam
having been raised in them as stated), they evaporated enough to support the
temperature of one hundred and sixty-four degrees in the brine in pans of four
thousand three hundred square feet extent, the steam going direct from thence
to the pans. But as by this improved process designed that the steam from A
(and also from B, C, if raised to sufficient temperature) should first make fine
salt in the close pan or pans as described, F, it is proper to be observed,
respecting the extent of pan for such purpose, that as by the rapidity of boiling,
when making fine salt, the evaporation will be far greater than when making
broad salt, it will not be necessary that the fine salt pan should be of more
than about three times the extent of the steam boiler, and will be most proper
to have such extent divided into three or four close covered pans, which will
afford the great convenience, that whilst the steam is turned off from one pan
to enable the men to cleanse it or take out the salt from the trough, the
other pans may continue at work; and respecting the extent of the broad salt
pans when receiving the steam from the fine salt pans and not direct from the
steam boiler, they must be nearly of the same extent as if it came direct from
the boiler, if the fine salt pans are properly enclosed from wasting heat; and
as the steam from the broad salt pans will not be raised to high pressure when
acting against the bottom of the bay salt pans (the extent of which to be
about one fourth the dimensions of the broad salt pans), it will only be required
that the lower part of the enclosing boards or cloth for about a yard in depth
should be constructed to be conveniently removed from resting on the outer

page_text: edge of the trough, to rest on its inner edge, to keep in the steam until the
salt is carried away.
Having stated that a part of my improved process in the manufacturing of
salt is to save labor and preserve the pans clear of sediment by the employ-
ment of steam engine power to draw or push the salt into the trough, by the
handles of the rakes or shovels passing through stuffed boxes in the sides of
the pan or cover, it will be sufficient to state that such rakes or shovels must
extend the whole length of the pans, and when it is necessary to have a great
length of them in one line with several handles to work them, it may be most
convenient to have a horizontal spindle or shaft extending the length of the
pans to be turned by a wheel on an axis of the steam engine, having upon
such shaft proper communicating small wheels to turn other wheels, placed on
each handle of the rakes or shovels, the centre of which last mentioned may
be screw-formed of wide thread, to be durable and fitted to turn on a corre-
sponding thread formed on the rake handles. Various modes may be adopted
for giving them motion, and for their proper operation the wheel on the steam
engine must be adapted to give motion to them as slowly as may be necessary,
and that the rakes or shovels may have the best effect in keeping the pans
clear of sediment, which is of the first importance. I propose that the pans
should be formed as adopted for other manufactories without having any rivett
or bolt head appearing in them, and to have the plates joined together by their
sides being bent to a proper angle to meet under the pan, and in that form to be
rivetted or bolted together, which will be farther explained by the following repre-
sentation :-
A, A, the plates, the sides of which are bent
to meet correctly to be bolted or rivetted together, and when designed for the fine
salt pans to have the lips of sufficient length to receive a link bolt to be key'd
to them. The bottom of the bolt to pass into a broad staple rivetted to the
bottom of the steam vessel under the pan, to render it sufficient to bear any
pressure of steam within it that may be required for rapidly boiling the brine,
but for the steam vessels under the broad salt pans none will be required.
Should the steam engine not be adopted to draw the salt and recharge the
steam boilers with the water from under the salt pans, in such case I employ
a common boiler of proper dimensions and strength, placed on the flue of the
steam boiler or on a furnace convenient for raising the water from the con-
densed steam; if, then, the water so obtained at nearly its temperature when
discharged be heated until the pressure of the steam in such boiler be raised
higher than the pressure of the steam in the treble boiler, then, by properly

page_text: regulated cocks affixed between them, they may be all served with water con-
veniently at any temperature desired.
Having described the mode of process and form of works for the employ-
ment of the steam generated in a common boiler, as from boiler A, when acting
alone, it will be sufficient to explain concerning the employment of the steam
coming from the upper boilers B, C, that the apparatus for such purpose must be
similar and for the same uses as described for employing the steam from A, if the
pressure and power of the steam in B and C be also raised sufficiently for the
making of fine salt; but if not wanted to be so raised for such purpose, their
evaporation I employ in the manner described to make only broad and bay salt.
I have very briefly mentioned, that instead of having vessels formed as
described at E for receiving the steam under the pans, that a continuation of
pipe closely laid in the brine may be substituted, which I adopt when preferred
(as this is a tried principle at Droitwich), and the vessels holding the brine
may be then made of stone or any other material; but by such principle no
more salt can be made in a given space or fuel saved (as may be wrongly
supposed), in consequence of the circumference of the pipe giving more surface
to the brine than a level pan, as can be easily explained.
To guard against being misunderstood, and to avoid the imputation of
claiming an exclusive right to use any distinct or combined part of the
described form of process or arrangement of apparatus for making salt that
does not constitute either a new or improved mode of process or a combi-
nation of apparatus employed under some new form or arrangement, I think
it proper to state in as clear a manner as I can the improvements which I
have designed to be comprehended under one of such descriptions :-
Firstly, the making of fine salt by rapid boiling under high-pressure heat in
a common shallow-formed salt pan and trough, entirely enclosed from the
access of the atmosphere acting on any part of the brine, whereby waste of
steam and heat is avoided, and evaporation accelerated.
Secondly, the drawing or pushing of the salt into a trough within pans,
enclosed as described, and effected by steam engine power.
Thirdly, the employment of and the obtaining from the brine of the fine salt
a greater quantity of steam in a given time from an entirely closed pan and
trough than when not so enclosed, and of more efficient power when raised to
pressure for passing the heat through the bottom of the pans for the making
of broad salt in pans (also enclosed as described), whereby a proper heat can
be maintained in the brine in such pans of much greater extent, and drawing
such broad salt by steam engine power.
Fourthly, the employment of the enclosed steam arising from the brine of

page_text: the broad salt obtained as described in the fourth particular first stated, for the
manufacturing of large or British bay salt.
Fifthly, the obtaining a greatly increased body of water at nearly boiling
heat from under the broad salt pans coming from the steam of the brine of the
fine salt, to be employed as described in the fifth particular first stated.
In witness whereof, I, the said William Johnson, have hereunto set my
hand and seal, this Seventh day of June, in the year of our Lord
Lunds and twenty-seven