CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF PRUSSIATE OF POTASH AND PRUSSIATE OF SODA
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MILES
BERRY, of the Office of Patents, 66, Chancery Lane, in the County of
Middlesex, Patent Agent, 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 Twenty-first day of January, in the third year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said
Miles Berry, Her especial license, full power, sole privilege and authority, that
I, the said Miles Berry, my executors, administrators, and assigns, and such
others as
I, the said Miles Berry, my executors, administrators, and assigns,
at any time should 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 and Wales and the Town of Berwick-
upon-Tweed, an Invention of "CERTAIN IMPROVEMENTS IN THE MANUFACTURE
OF PRUSSIATE OF POTASH AND PRUSSIATE OF SODA," being a communication to
me from a Foreigner residing abroad; in which said Letters Patents is con-
tained a proviso that I, the said Miles Berry, shall cause a particular descrip-
tion of the nature of the said Invention, and in what manner the same is to
be performed, to be inrolled in Her 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
Miles Berry, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, is particularly described and
ascertained in and by the Drawings hereto annexed, and the following expla-
nation thereof (that is to say):-
This Invention of Certain Improvements in the Manufacture of the Prus-
siate of Potash and Prussiate of Soda, and for which the above in part recited
Letters Patent was granted, has been communicated to me in the following
words: Hitherto the prussiate of potash has only been obtained by incurring
the loss of a considerable quantity of azote or nitrogen gas, which when com-
bined with carbon forms cyanorgen, the generator of Prussian blue. This
azote is evolved by the distillation of organic substances contained in certain
vegetables, animal oils, &c., but it is obtained in larger quantities by the calci-
nation of animal substances, such as horn, blood, muscular flesh, skin, &c.
Sometimes the azoto is evolved under the form of subcarbonate of ammonia
and nitrogenous oils. To avoid the loss. generally incurred, which is of
serious consequence in the manufacturing of prussiate, it is necessary to treat
the primary matters in a different manner, so as to collect the azote which
escapes during the distillation, and to make it enter into combination with
carbon, iron, and potassium, and, moreover, to convert to useful purposes the
azote which has adhered to the carbonaceous residuum. This end is obtained
as follows: Instead of collecting the subcarbonate of ammonia in or by
an absorbent medium, it is made to pass through a quantity of charcoal, iron,
and potash placed in an iron tube kept at a red heat. The carbon on
the one part decomposes the subcarbonate of ammonia, and creates bicar-
buretted hydrogen, and at the same time gives up part of it to the azote
which proceeds from the decomposed ammonia, and thereby forms cyanorgen,
which, in its turn combining with the reduced potash, forms cyanoferruret
of potassium or prussiate of potash. To obtain the most complete reaction the
operator must divide or reduce the ingredients constituting the decomposing
compound. In order to effect such a division, either of the following means
may be used according to circumstances:-First method, or via humida,
is to reduce the charcoal into fragments of about the size of a nut or
walnut, then dissolve the potash or the salts of potash, such as carbonate
or nitrate, in an aqueous solvent, in urine, for example, if a great quan-
tity can be obtained easily and at little cost, otherwise use common water.
With respect to iron it is to be rendered soluble by the addition of an acid,
such as nitric or acetic acid. These preliminary preparations being made,
which are simple, the solution of potash and. nitre is then to be poured on

page_text: the charcoal; the saline lye is absorbed very soon; then pour in the solu-
tion of iron, stir the mixture with a spatula, evaporate the water which
has been used as a dissolvent, taking care that the compound does not become
calcined during the operation. The compound being dry is again pulverized
and introduced into cast-iron tubes, which I shall hereafter mention. The
other, or the dry method, has for its object the substitution of a mechanical
division instead of an atomical or chemical one. To effect this, introduce
the potash, nitre, and charcoal into a barrel with iron filings; place in the
barrel cannon balls. The barrel is then to be made to revolve on its axis,
and the balls will grind the compound and reduce it to small fragments, which
will thereby be mixed together. The compound is then removed from the
barrel and introduced at once into cast-iron pipes, or kept for use in a dry
place. It is not of importance to name any particular proportion in the
ingredients employed, as they may be varied according to the will of the
operator; but I will state for example such proportions as has been found to
give satisfactory results:-When the dry process is employed with the
mechanical division, take of ordinary potash 20 parts, saltpetre 10 ditto, iron
filings 20 ditto, coke or ordinary charcoal 45 to 55 ditto, dried blood 50 ditto,
and proceed as above stated. For the wet process, or the chemical division,
take of ordinary potash 30 parts, saltpetre 10 ditto, acetate or nitrate of iron'
15 ditto, coke or ordinary charcoal 45 to 55 ditto, dried blood 50 ditto, and
proceed as described. Whatever be the mode preferred, either the wet or the
dry process, for obtaining or effecting the mixture, the compound ingredients
must be introduced when perfectly dry in a series of pipes connected together
and contained in a furnace similar to that used for the manufacturing of car-
bonated hydrogen gas or coal gas employed for illumination. Instead of
placing the pipes in a horizontal position, which renders it somewhat difficult
to introduce and draw out or remove the charge, they may be placed vertically,
but then the heating is more expensive. When the pipes are placed vertically,
care must be taken not to pulverize completely the dry compound, in order that
the gases may be able to circulate through them without raising the internal
pressure to a dangerous pitch. The animal matter is placed in a separate
compartment and in a cast-iron retort, which is connected with the horizontal
or vertical pipes. On this retort is placed a safety valve to prevent accidents
which might arise from any obstacle obstructing the circulation of the gases
through the pipes. The heating of the furnace should be effected as follows:-
It is very essential to bring to a red heat the pipes containing the compound
or mixture before any fire is placed or introduced under the retort, in order
that from the beginning of the operation the decomposition of the gases may

page_text: take place. The gas which is evolved by the decomposition is inflammable
when issuing from the pipes, and the color of the flame will be a sufficient
indication of the progress of the operation. The color generally differs but
little from that of the heated cast-iron pipes in the furnace. When this color
approaches to pink the reaction is almost complete, so that very little, if any,
ammonia has escaped decomposition. When the jet of gas becomes smaller and
clearer while a good fire exists under the retort, one may consider that the
operation is near its end; the animal matter is reduced into azotated or nitro-
genated charcoal, which is used at present for the manufacturing of prussiate
of potash, and which is still to be employed in the same manner and treated
as usual. On the other hand, the azote, ammonia, and other gases, by com-
bining with the decomposing substances contained in the pipes, have been
transformed into prussiate of potash. The charge must then be rapidly
removed from the pipes, and it being at a red heat should be thrown at
once into water to extinguish it rapidly. The whole must be well stirred
and allowed to settle; the clear liquor is then to be drawn off, and this is the
strongest solution. Warm water is then to be poured on the carbonaceous
residuum, and well stirred, and allowed to settle, and then the liquid drawn off.
This operation is continued until the residuum be exhausted. The strong
solutions are to be evaporated, allowed to crystalize, and the prussiate extracted
according to the old process. The solutions which are not crystalizable contain
carbonated potash, which is extracted therefrom to be employed again. The
same is done with reference to the residuum of charcoal and of iron. All
this residuum is carried to the following operation, to which is added the
animal charcoal furnished by the first operation by the calcination of animal
matter. Besides this animal charcoal, a proper quantity of other or fresh
charcoal is added, in order to preserve, as far as possible, the same proportions
in the decomposing mixture. After some operations it may be found that the
animal charcoal is completely deprived of azote; a portion of it is in such case
to be laid aside, and a proper quantity of fresh animal charcoal to be sub-
stituted. It will thus be seen that after a little while the coke or vegetable
charcoal first employed is completely set aside, and the whole operation is
effected by two kinds of animal charcoal, of which one is almost deprived of
azote, and the other contains a great quantity of the same.
Though it is not essential to adopt exclusively one system of apparatus, as
the operation is more chemical than mechanical, I will nevertheless describe
an apparatus for carrying the Invention into effect, in order that the modus
operandi may be better understood.
Fig. 1. A, B, C, D, is a horizontal section of a furnace constructed to

page_text: receive four cliptical pipes, from five to six feet long. The largest diameter
may be supposed to be eighteen inches, and the smaller diameter ten inches.
The furnace is arched in the part A, C, B, in order to reverberate the heat.
and drive it back on the pipes W, W, W, W. These pipes are placed in a
position which is considered essential, they being placed on the focal plane E, F,
of the elypsoid. a, b, c, d, represents the grating or bars of the furnace to be
heated with coal or coke. I, I, is the pot or retort shewn in Figs. 2, 3, 4.
This pot or retort is placed in a separate compartment, as seen in Fig. 2.
Fig. 2, vertical section, taken through the line G, H, of Fig. 4. In this
Figure are shewn the pot or retort I and the pipe W. K, K', is a connecting
tube from the retort and the cliptical pipes. This tube K, K', is seen at
Fig. 3, and enters at S into the pipe W, and at S' in the pipe W. In the
section Fig. 2 the shape of the tube K, K, will be better seen, also its
cocks u and u, and the part S, S', by which it is connected with the
pipes W and W. 1, Fig. 2, indicates a safety valve. S is the cover of the
pot or retort. L is the ashpit, and a, c, the door of the furnace. X, X, is
an open space roofed over, or a kind of shed, close to the furnace, and under
which the pipes are emptied or charged. The arrows indicate the direction
of the current of heat. This current traverses the intervals left between the
pipes, and ascends behind them, passing through the aperture j in the brick-
work. This aperture j is provided with a valve or damper for closing it as
required. The heat passes through this aperture and strikes against the sides
of the pot when the valve is open. Another valve f, g, must also be open to
expose the pot or retort to the direct action of the fire. The smoke escapes
by a lateral passage into a chimney N. At I is placed a small valve to
prevent the smoke passing immediately through the aperture into the
chimney. It must also be remarked that there is a direct communication
between the chimney and that compartment of the furnace which contains
the pipes, so that the heat reflected from V and V strikes on the pot or retort
only when the pipes W, W, W", W, are sufficiently heated.
In Fig. 3 is shewn an inclined plane M, M. also represented in Fig. 2, and
the junction tubes which connects the four pipes with their gas burners Z, Z,
with their cocks m, m. rr, r² 1, 111, 111, are covers closing the pipes, and
having holes formed in them. These holes are shut by the stoppers e, e¹, ell,
elli;
whether the pipes are placed in the vertical or horizontal position, it is always
proper to be able to change the direction of the current of gas. This is
easily done by closing during one hour (if the operation is to last two hours)
the cocks u, n', and opening those u', m, then the gas passes through ',
in the branch k, and enters W, and passes through q into W through p into

page_text: u, and through O and W, and finally escapes by the burner Z. During the
following or other hour the cocks u, m, must be closed, the cocks u, m', being
opened, the current then goes from u into k, W, W, W, W, and escapes
by the burner Z, where it may be ignited. The changing of the direction of
the current dispenses to a certain degree with the labour required for stirring
with a spatula the matters contained in the pipes, nevertheless it is necessary
from time to time to pass an iron rod or poker amongst the substances
contained in the pipes. It is for this purpose that apertures are formed so as
to be easily opened and closed. I will here remark, that in the foregoing
Specification I have only mentioned the operation with reference to potash to
obtain prusiate of potash; it is quite clear that the same process is applicable
to soda, and when the above-mentioned ingredients are employed, soda being
substituted for potash, the result will be prussiate of soda. Finally, I would
remark, that whatever be the aparatus employed it is necessary it should be of
a sufficient thickness to resist the action of a continued ardent heat and an
internal pressure of one and a half atmospheres while the operation is
performed.
In witness whereof, I, the said Miles Berry, have hereunto set my hand
thousand sight hundred and
Inrolled the Twenty-first day of July, One thousand eight hundred and
forty.