IMPROVEMENTS IN THE MANU- FACTURE OF SODA AND THE CARBONATE THEREOF
Year: 1851

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, OR BE MADE
KNOWN, I, WILLIAM COOKE, of 18, Great George Street, Westminster, in the
County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Third day of May, in
the fourteenth year of Her said Majesty's reign, and in the year of our Lord One
thousand eight hundred and fifty-one, did, for Lerself, Her heirs and successors,
give and grant unto me, the said William Cooke, my exors, admors, and assigns,
Her especial license, full power, sole privilege and authority, that I, the said
William Cooke, my exors, adññors, and assigns, and to such others as I, the
said William Cooke, my exors, adññiors, and 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, the Town of Berwick-upon-Tweed, the
Islands of Guernsey, Jersey, Alderney, Sark, and Man, and all Her said
Majesty's Colonies and Plantations abroad, the "IMPROVEMENTS IN THE MANU-
FACTURE OF SODA AND THE CARBONATE THEREOF," communicated to me by a
certain foreigner residing abroad; and in which said Letters Patent is contained
a proviso, that I, the said William Cooke, should particularly describe and
ascertain the nature of the said Invention, and the manner in which the same
is to be performed and carried into practical effect, by an instrument in writing
under my hand and seal, and enroll or cause the same to be enrolled in Her

page_text: Majesty's High Court of Chancery in England within six calendar months
after the date of the said Royal Letters Patent, as in and by the same, reference
being had thereto, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Cooke, do hereby declare that the nature of the said Invention is
fully described and ascertained by the following description thereof, and con-
sists in obtaining caustic soda and carbonate of soda (soda ash) by the means
described, as follows:-I take common salt in solution, placing it between two
metals, iron and copper connected together, the decomposition being formed at
the expence of the iron. The chlorine of the salt combines with the iron, and
forms chloride of iron in solution. The sodium of the salt is set free, combines
with the oxygen of the water (hydrogen being liberated), and forms caustic
soda, which moves towards the copper, and in order to keep it there separated
from the chloride of iron, a porous diaphragma is placed between the two
metals, the salt solution being on the side where the iron is, and clean water
to receive the soda on the side where the copper is. The decomposition, how-
ever, will not take place unless the two following conditions be attended to;
firstly, the temperature must be kept up between 70 and 150° Fahrenheit;
and, secondly, the air must be excluded, that is, the vessel must be covered
air-tight to prevent the chloride of iron changing into oxide of iron, which it is
very apt to do, and in which case the soda reconbines with the chlorine set
free and forms salt again. The atmospheric air having free access to the
solution, the salt is continually decomposed and recomposed, the iron is
wasted with no beneficial result. To work this process on a manu-
facturing scale so as to make a ton of soda, a tank or cistern 11 feet
long, 6 feet wide, and 3 feet high, must be constructed of slate or stone,
or other material upon which caustic soda has no action. This tank must be
divided into three compartments by means of two porous diaphragmas, the
middle compartment being 11 feet long, and 1 foot wide; the two others being
also each 11 feet long, and 2 feet wide. The porous diaphragma must consist
of biscuit or unglazed earthenware, and may be constructed in the following
way-Two gutta percha frames, like window frames, each 11 feet long, and
3 feet high, containing, instead of glass panes, panes or tiles of the said biscuit,
must be fastened water-tight in the tank, the panes being not much thicker
than th of an inch. The tank being thus divided, pig iron (Scotch is pre-
ferred) is placed in the two outward compartments; the pieces so piled upon
each other that the salt water may touch as much of their surfaces as possible.
care being taken at the same time that all the pieces in each compartment
form as it were only one mass of iron, being in perfect metallic contact with

page_text: each other, which can be done by giving the pieces a small bright spot where
they touch each other in such a manner that a bright spot, however small it
may be, always touches another bright spot. The quantity of pieces must be
so regulated that in each compartment room be left for 324 gallons of salt
water. In the middle compartment, two copper plates, each 11 feet long, and
3 wide, are to be placed all along the two porous walls, at the distance of of
an inch from the said walls. The thickness of the copper is of no consequence,
thin copper foil will do as well as thick copper plate; it is only the surface
that is wanted, and the copper does not suffer by the action;
but each copper
plate must be connected with the next mass of iron by means of a slip of
copper bent over the porous wall, and fastened to some bright spot of
one of the pieces of iron, by means of a screw or otherwise, in such manner
that the closest metallic contact may exist between the copper plate and the
mass of iron, great care should be taken to do this well; the whole action
depends thereupon. To make a ton of soda ash, 2,489 pounds of salt are to be
dissolved in 747 gallons, 7,467 lbs., of water, which will make a saturated
solution (about 113 cubic feet of salt water); one half of this salt water is to be
poured upon the iron in one compartment, and the other half upon the iron in
the other compartment; the middle compartment wherein the copper plates are,
is to be filled up with clean water till it stands on a level with the salt water
in the other compartments. Things being now ready for action, the cover is to
be placed on the tank and luted thereon, to prevent the access of the atmospheric
air, in which cover a bent tube must be introduced, by which the hydrogen
may escape from the tank; the end of which tube must dip in a vessel of
water to prevent the air entering the tube. The temperature being now kept
abovo 70° Fabrenheit, the decomposition of the salt will be accomplished
within seven days, the salt water will be found changed into a green liquid,
(chloride of iron in solution,) and in the middle compartment will be found a
solution of caustic soda (with a little salt in it), which solution may be taken
out by means of a syphon, or drawn off by a cock. The strength of this
solution will depend on the quantity of water there was in that compartment;
but if all the salt is decomposed, then the solution will contain about
1,327 lbs. of dry caustic soda, that is about 40 lbs. in each cubic foot of water.
The caustic solution, if intended for soap-making, may at once be used for that
purpose; but if it is intended for the manufacture of soda ash, then it must be
boiled dry in an iron pot, and before it is dry, the salt which is in it, and which
has escaped the decomposition, may be taken out as soon as crystalized. The
caustic soda when dry must be kept hot and stirred for an hour or two, during
which time it will absorb the carbonic acid from the atmosphere with great

page_text: avidity; it will greatly increase in bulk, and will be finally converted into pure
carbonate of soda; soda ash of about 59 per cent. alkali, 2,489 lb. of salt, will
consume about 1,161 lb. of iron, producing about 1,327 lb. of dry caustic soda,
equivalent to one ton of pure carbonate of soda, which is soda ash of 59 per
centum alkali.
Having now described the nature of the said Invention, and the manner in
which I perform and carry it into practical effect, I desire it to be distinctly
understood, that the size and divising of the tank may be varied to suit
quantities required and other circumstances; and the metals may be alternate,
as iron, copper, iron, copper, iron, copper; but then the last copper must bo
connected with the first iron as in an ordinary galvanic battery; nor do I con-
fine myself to the precise limit of time in which the decomposition of the salt
will be effected, save that I state it as within seven days.
I claim the obtention of caustic soda and carbonate of soda (soda ash) by
the means or process or processes herein-before described.
In witness whereof, I, the said William Cooke, have hereunto set my
hand and affixed my seal, this First day of November, One thousand
night hundred and fifty-one