CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF APPARATUS USED IN THE DECOMPOSITION OF COMMON SALT, AND IN THE MODE OR METHOD OF WORKING OR USING THE SAME
Year: 1836

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
Lutwyche, of Liverpool, in the County Palatine of Lancaster, Manufacturing
Chemist, send greeting.
WHEREAS His present most Excellent Majesty King William the Fourth,
by His Royal Letters Patent under the Great Seal of Great Britain, bearing
date at Westminster, the Thirteenth day of October, in the Seventh year of
His reign, and in the year of our Lord One thousand eight hundred and thirty-
six, did, for Himself, His heirs and successors, give and grant unto me, the
said Thomas Lutwyche, His especial license, full power, sole privilege and
authority, that I, the said Thomas Lutwyche, my executors, administrators, and
assigns, or such others as I, the said Thomas Lutwyche, my executors,
administrators, 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, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my Invention of "CERTAIN
IMPROVEMENTS IN THE CONSTRUCTION OF APPARATUS USED IN THE DECOMPOSITION OF
COMMON SALT, AND IN THE MODE OR METHOD OF WORKING OR USING THE SAME;
in which said Letters Patent is contained a proviso obliging me, the said
Thomas Lutwyche, by an instrument in writing under my hand and seal,
particularly to describe and ascertain the nature of my said Invention, and the
manner in which the same is to be performed, and to cause the same to be
inrolled in His Majesty's High Court of Chancery within six calendar months
"

page_text: 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Lutwyche, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, are particularly
described and ascertained in and by the following description thereof, reference
being had to the Drawing hereunto annexed, and to the letters and figures
marked thereon (that is to say):
My improvements in the construction of apparatus used in the decomposition
of common salt, and in the mode or method of working or using the same,
apply to the process or operation of decomposing common salt by means of
sulphuric acid and heat for the manufacturing of sulphate of soda, and have
for their objects the preventing the muriatic acid gas from escaping into the
atmosphere during the decomposition of the salt, and is effected by condensing
such gas in proper apparatus; and also the carrying on the said process or
manufacture in a better and more advantageous manner than is effected in the
apparatus now in common use, and at the same time saving a large portion of
the gas so condensed in the form of muriatic acid. The apparatus in common
use for the decomposition of common salt with sulphuric acid consists, firstly,
either of iron retorts or cylinders, or, secondly, of open furnaces composed of
brickwork. When the former is used, the heat is applied externally by a fire
at the bottom of the iron retort, and the object to be attained in this mode
beyond the making of the sulphate of soda is to collect the muriatic acid, which
is accomplished by receiving the gas evolved during the operation into double-
necked jars or carboys connected together, and to the retort at the top part by
earthenware pipes with proper luted joints; and when the latter mode is
used, the principal object is to obtain the salt cake or sulphate of soda of a
better quality and in a more perfect state than when made in close iron vessels.
By the second process the fire and flame is allowed to play directly upon the
materials under operation, and the gas is allowed to escape up the chimney
into the atmosphere. Imperfect decomposition of the salt, impurity of the
acid, and difficulty of condensation attends the first of these methods; and by
the second process of operation, viz*, decomposing in the open or reverberatory
furnace, the immense volumes of muriatic acid gas and other deleterious
vapours which are disengaged and liberated to the atmosphere are deemed
a nuisance. My improvements in the construction of apparatus for the
decomposition of common salt and condensation of the muriatic acid gas
consist, first, in a novel and peculiar construction of a closed oven or decom-

page_text: posing chamber with its fire-places and flues, and is composed chiefly of
bricks and mortar. Within this oven or decomposing chamber there are two
beds or floors, one about six inches lower than the other, and over them is formed
an arch of fire-bricks, or of fire tiles placed obliquely, which arch separates the
oven or chamber from the fire, and prevents the flame and smoke coming into
contact with the materials under operation, but admits of sufficient heat for
the purpose of decomposition. By this arrangement the muriatic gas evolved
from the salt and sulphuric acid is separated from the smoke and gaseous
products arising from the combustion of the fuel, and consequently is the
more easily condensed. A second arch is formed over the first, or fire tiles
are placed obliquely or horizontally, thereby forming the flue or flues, and one
or more fireplaces are placed at the end of the decomposing chamber. The
salt and acid are placed together into the lower bed of the chamber, in the side
of which there are two doors, one near the centre of the bed, the other close
to its end next the upper bed for the greater convenience of moving the
charge from the lower on to the upper beil when the materials become suffi-
ciently stiff to allow of this being done, which generally takes place in a few
hours. A fresh quantity or charge of salt and acid are put into the lower
bed, when that last introduced is changed to the upper, and at the expiration
of ten or twelve hours from the commencement of the operation the sulphate
of soda in the upper bed may be drawn out, when another removal of par-
tially decomposed salt takes place, and a fresh charge is put into the lower
bed, so that although the materials are kept in the furnace ten or twelve
hours, a fresh charge of salt and vitriol are put into the lower bed, and tho
decomposed salt or sulphate of soda is drawn out of the upper bed every five
or six hours. The acompanying Drawings will serve to further illustrate my
improvements in the construction of apparatus.
Fig. 1 is a perspective representation of the decomposing furnace and con-
densing apparatus, as seen looking toward the front of the fireplaces. Fig. 2
is a similar representation, looking at the side of the furnace. Fig. 3 is a
vertical section taken longitudinally through the furnace, to shew the closed
oven or decomposing chamber, its fireplaces and flues. Fig. 4 is another
similar section taken transversely. a, a, is the brickwork of the furnace;
3, the fireplaces; c, the fire doors; d, the ash pits; c, e, the flues leading to
he chimney; ff, the arch of fire bricks separating the flues from the oven
or decomposing chamber 9, 9; h is the lower floor or bed of the chamber,
and the upper; k, l, are the charging doors for introducing the salt and
acid, through the latter of which the partly decomposed salt is transferred to
he upper bed or floor, and m is the door for removing the sulphate of soda.

page_text: A slight variation to the foregoing is shewn in Figures 5 and 6, which are
similar sections to Figures 3 and 4, the same letters of reference being marked
on corresponding parts, the only difference of construction being that the
flues are in this instance separated from the decomposing chamber by means
of fire tiles or fire bricks placed at an angle instead of an arch or curve, and
the top of the flues are made flat or horizontal. Fig. 7 is a longitudinal
section of one of the condensing apparatus or troughs, which will be more
fully described hereafter. The condensing apparatus consists of a trough or
troughs constructed either of stone, slate, or wood, or of any other material or
materials which may be found best to resist the action of muriatic acid. Wood
well covered with boiled tar, pitch, or rosin, or a mixture of such substances,
I have found to answer well, and the most convenient size is from about nine
to twelve feet long by three feet wide, and from twelve to fifteen inches
deep. o, o, are the troughs, within which conducting pipes p, p, formed of
earthen or stone ware, are introduced as seen in the Drawings. A quantity
of water sufficient to rise within a few inches of the mouths or apertures of
the pipes p, p, is put into the troughs, and over the mouths of the pipes are
inverted earthen or stone ware jars or vessels q, q. These inverted jars form
water lutes or joints. The gas is conducted from the furnace by pipes r, r,
into the conducting pipes p, p, and is passed from vessel to vessel, until by the
time it reaches the fourth or fifth jar there is remaining little or no gas
uncondensed, the interior of the jars allowing a sufficient surface of water
exposed to the gas. The last conducting or exit pipes is connected with a
flue leading to the chimney, the draught of which contributes to bring the gas
forward from the furnace and assists the condensation. To the bottom part of
each of the condensing pipes p small branch pipes or nozzles t, t, are placed
(see Fig. 7). These nozzles pass through the bottom of the trough, and any
gas which becomes condensed in its passage is allowed to drop into a jar or
any suitable receptable placed below. The water in the trougbs may be
changed as often as is found desirable; and if there be a good supply of
water, and the acid be not required of any particular strength, it may be
allowed gradually to receive a fresh supply of water upon the upper surface at
one end of the trough, and may be drawn off from the bottom part at the
other end; but if the acid be required for manufacturing purposes, the water
may remain in the troughs until it acquires sufficient gravity, or until
the fumes arising therefrom become inconvenient or the condensation be
impeded.
Having thus described the nature of my Invention and the manner of
carrying the same into effect, I would remark that I do not confine myself to

page_text: the exact form and dimensions of the decomposing furnace shewn in the
Drawing, nor in the construction of the arches or the part which separates the
fireplaces and flues from the decomposing chamber, or the medium over
which the fire passes, as this medium may be of fire bricks or fire tiles, or
other fit and proper materials placed obliquely or horizontally or in curved
figures over the materials under operation for the formation of the sulphate
of soda. Nor do I confine myself to the size or number of the condensing
troughs, jars, vessels, or conducting pipes, the same being capable of modi-
cation, or being varied according to the quantity of salt required to be
decomposed in a given time. But I claim as my said Invention the improved
construction of decomposing furnace with the mode of applying the fire
through a medium of fire bricks, fire tiles, or other fit and proper materials in
the manner as before described, thus separating the muriatic acid gas from
the smoke and gaseous products arising from the combustion of the fuel.
And I also claim as my said Invention and improvements the improved
construction of condensing apparatus, and the application of the mode or
method of conducting the muriatic acid gas in pipes under water, and inverted
jars as before described in the said condensing troughs or apparatus.
In witness whereof, I, the said Thomas Lutwyche, have hereunto set my
hand and seal, this Eleventh day of April, One thousand eight hundred
and thints covon