IMPROVEMENTS IN THE MANU- FACTURE OF CYANOGEN AND ITS COMPOUNDS, PARTICULARLY THE PRUSSIATES OF POTASH AND SODA
Year: 1843

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
VINCENT NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Mechanical Draftsman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Thirteenth day of December, in the seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Alfred Vincent Newton, Her especial licence, full power, sole privilege
and authority, that I, the said Alfred Vincent Newton, my executors, admi-
nistrators, and assigns, and such others as I, the said Alfred Vincent Newton,
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
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, the Town of Berwick-upon-Tweed, and in all Her Majesty's
Colonies and Plantations abroad, and in the Islands of Jersey, Guernsey,
Alderney, Sark, and Man, an Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF CYANOGEN AND ITS COMPOUNDS, PARTICULARLY THE PRUSSIATES OF
POTASH AND SODA," being a communication from a Foreigner residing abroad
in which said Letters Patent is contained a proviso obliging me, the said
Alfred Vincent Newton, by an instrument in writing under my hand and
seal, particularly to describe and ascertain the nature of the said Invention,
and in what manner the same is to be performed, and to cause the same 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
רנס...rn

page_text: 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
Alfred Vincent Newton, 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 following description thereof, reference
being had to the Drawings hereunto annexed, and to the letters and figures
marked thereon (that is to say):-
The Invention for which I have obtained Letters Patent, and which has
been communicated to me from my Correspondent, consists in the application
of nitrogen gas, obtained by the decomposition of atmospheric air, or from the
waste gases of sulphuric acid chambers, to the manufacture of cyanogen and
the cyanides by the processes and apparatus hereafter described. This
operation, although simple in appearance, requires for its complete success
several essential conditions, without which it is impossible to obtain an econo-
mical and regular result, such as is required for manufacturing purposes. By
the means the Inventor has employed he has succeeded in surmounting every
difficulty in the way of carrying into practical and economical use the grand
principle of employing nitrogen obtained from the surrounding atmosphere.
The different materials which are employed in the process hereafter described,
according to the peculiar circumstances of the case are as follows:-First,
whatever may be the source from which the nitrogen is obtained, it may
always be employed, provided it is not accompanied by oxidating substances.
It is not necessary that it should be perfectly pure; it may be mixed with
carbonic oxide, hydrogen, carburetted hydrogen, and other gases, but the
presence of oxygen must be carefully avoided, as well as all matters capable
of affording it, as they would tend to destroy the cyanogen as fast as it is
formed. This essential point is effected and obtained in an economical
manner by using atmospheric air, taking the precaution to convert the oxygen
contained therein into carbonic oxide before it is permitted to come into
contact with the cyanides already formed. The means by which this is
accomplished are hereafter explained. Another source of nitrogen is the
waste gases of sulphuric acid chambers, after being washed in a solution of
sulphate of iron and of milk of lime, so as to deprive them of sulphurous and
nitrous vapour. The nitrogen so employed is employed in the same manner
as if obtained directly from atmospheric air, as is hereafter explained. Second,
the nature of the carbonaceous material that is employed in the process is not
of much consequence. Satisfactory results have been obtained with wood
charcoal, coke, pit coal, peat, spent bark wood, and other similar substances;

page_text: but as regards economy, produce, and convenience, wood charcoal, in pieces
of the size of a hazel nut, is preferable to any other. Third, with respect to
the potassa and soda, the carbonates are preferred; but any other salt capable
of being resolved ultimately into carbonate, oxide, or metal may be employed.
Although the choice of the materials is not of much consequence, it is not so
with regard to the mode in which they are employed. Thus the more or less
intimate mixture of the charcoal with the alkali, and the proportions of the
two, have a great influence. If the alkaline salt is easily fusible it may be
previously fritted with the charcoal, or the two substances may be carefully
mixed. It is, however, in general preferable to soak or steep the charcoal in
a concentrated alkaline solution, and to dry the mixture before using it; but,
whatever be the way of mixing the matters, it is of the greatest importance
that they should be perfectly dry before they are placed in the retorts. The
proportions of alkali and charcoal may be varied to a certain extent, but there
are limits which should not be passed. An excess of alkali renders the
chemical decompositions incomplete, and a too small proportion is not
economical; but, according to the difference in the density of the charcoal, it
may vary from twenty-five to one hundred parts of alkaline salts to one
hundred parts of charcoal. With hard wood charcoal the proportions which
have been found to answer best are from 30 to 50 parts of carbonate of pot-
ash to one hundred parts of charcoal, according to the intensity of the heat in
the retort. As regards the quantity of nitrogen gas, it must be used in
excess, to hasten the operations. Still, a too rapid current of gas must be
avoided, because it would carry off with it a part of the cyanides already
formed, and also a more or less proportion of unreduced alkali, and deposit
them beyond the sphere of action. The combination of the nitrogen is effected
most rapidly and completely when the gas is forced through a long column of
alkalized charcoal at a high degree of heat, and under a certain pressure; and
when itexperiences obstacles and considerable friction in penetrating through
the pores of the charcoal and interstices between the pieces, all these con-
ditions are combined in the most effective manner in the apparatus hereafter
described.
After having considered these general questions, it remains to determine
upon the most advantageous mode of constructing and working the apparatus.
The points most worthy of attention are the following:-First, heating the
mixture of charcoal and alkali to the highest possible degree, and in the most
uniform manner, and taking the proper precautions to recover the vapours of
potassium, sodium, and other alkaline and saline combinations that may be
carried off with the waste gases; second, to force through the pores and

page_text: interstices of the alkalized charcoal a steady current of air or nitrogen gas;
third, to protect the mass of cyanized carbon from all contact with oxygen
during the whole period of heating and cooling; fourth, a continuous operation,
which is generally so advantageous in manufacturing processes, becomes here
a necessity, or at least a most important consideration, because, setting aside
the waste of fuel, labour, and time, the dilatations and contractions caused by
interruptions of the work, occasion a speedy destruction of the apparatus. On
this account a perfect steadiness of firing and uninterrupted operations are
peculiarly desirable. The apparatus for carrying out these requisites may be
varied in dimensions and form, and may be modified to suit different car-
bonaceous matters. It may be mounted either vertically or diagonally (caking
coals, for instance, requiring stirring apparatus, and the diagonal position is
suitable for D retorts); but, without confining the Invention to the arrange-
ment of parts herein set forth, I will describe two applications, which combine
every practical and economical advantage, as has been found by experience.
Sheet I. of the accompanying Drawings represents the simplest form of
apparatus, in which only one retort is shewn.
Fig. 1 is a vertical section taken through the middle of the retort, and in
the dotted line 1, 2, of Fig. 2; and Fig. 2 is a sectional plan view, taken in
the dotted line 3, 4, of Fig. 1. A, A, represents the masonry of a furnace,
of which the part a, a, is heated intensely and as regularly as possible; B, B,
is a retort of fire clay, or other suitable material, capable of supporting a white
heat. It is open at the top C and bottom C¹. Its form may be elliptic, which
is preferable to any other and is best seen in Fig. 2. The lower end Cof
the retort stands upon and is supported by the flanch of a second retort or
refrigerator D, D, made of cast iron, and of a similar shape. At the bottom of
this is adapted an extractor E, which is mounted on suitable bearings, and is
worked periodically by an attendant for the purpose of conveying the cyanized
charcoal into the extinguisher or dip pipe, the mouth of which plunges in the
saline solution, which acts as a hydraulic valve, and closes the apparatus com.
pletely. F, F, is the waste gas pipes, which conducts the gases and vapours
into the hydraulic main G, G. The lower extremity of the pipe F is plunged
in water or in a solution of a salt of iron. H is a pipe by which the incon-
densible gases are drawn off by a pump or other convenient aspirating
machine. It is evident, that in place of producing the current of gas through
the apparatus by aspiration, the same purpose could be effected by forcing the
air or gas through the mass, but the above-described method of aspiration or
drawing has been found more convenient.
The Figures in Sheets II. and III. of the accompanying Drawings repre-

page_text: sent different views of an apparatus consisting of ten retorts working with one
air pump and one hydraulic main, and with all the other suitable apparatus
connected therewith.
Fig. 3 is a vertical section taken transversely through the apparatus, and
Fig. 4 is a horizontal section of the same. I, I, are pans or under backs of
iron which receive the cyanized charcoal. They are kept constantly charged
with a protosalt of iron, or with hydrate of protoxide of iron, diffused in the
liquor, which are intended to convert the simple cyanides into ferro-cyanides
the moment they fall into the liquor. If thought desirable, a fire may be
lighted beneath this pan to warm the liquor, as shewn in Fig. 3. J, J, are
fireplaces or furnaces for heating the retorts B, B. The conduct of the firing
requires much attention. If the fire be allowed to slacken, the retorts cool,
the chemical decomposition within cease, and the variations of temperature
may cause the retorts to crack. To prevent these accidents the magazine
or hopper J¹ is always kept full of fuel: coke is preferred, as it gives a
more intense and steady heat than bituminous coal. K, K, K, K, are the
fire flues the form and dimensions of these parts of the apparatus may be
varied according to circumstances. M, M, M, are horizontal flues, upon
which the pans P, P, P, for drying alkalised charcoal, are placed. The
waste heat of the retort furnaces may likewise be applied to boil down the
solutions of prussiates and for many other purposes. N, N, are the ash pits
of the fireplaces. R is a vessel (connected by means of a pipe S to the
hydraulic main) for the purpose of receiving the condensed gases.
The working of the apparatus will be easily understood:-The retort. B is
kept constantly full of alkalized charcoal, and the air pump L, Fig. 4 (or other
aspirating machine), is set to draw a steady current of air through the
materials in the retort. The gas drawn through, as above mentioned, may
be either burned air (consisting of nitrogen and carbonic oxide) or common
atmospheric air without any previous preparation, or hot air as supplied to
ordinary blast furnaces. In both the apparatus above described common
atmospheric air is used, and the oxygen contained therein is converted into
carbonic oxide by the upper layers of alkalized charcoal; but, as the charcoal
is in excess, this causes no other inconvenience than a corresponding waste of
charcoal. If it is considered worth while to save this waste, the atmospheric
air may be previously passed through a mass of burning coal or coke, so as to
deprive it of its oxygen before it is supplied to the alkalized charcoal. It
has been already mentioned that the nitrogen gas must be used in excess
to hasten the operations. For an apparatus of the dimensions of that
shewn in Figs. 1 and 2, from eight to ten cubic feet per minute are drawn

page_text: through. The firing being steady, and the current of gas regular, the retort
may be supplied with a fixed quantity of alkalized charcoal in a given period.
Both the feeding and extracting apparatus may be worked by machinery, if
found convenient, as represented in Sheet II.
In Fig. 3 a long shaft b extends the whole length of the apparatus, and
carries pullies c, which are driven by bands or straps d, d, passing oversimilar
pullies e mounted on the axle of the extractor E. If it is required to make the
feeding apparatus self-acting, a band or strap may be carried from pullies on
the long shaft b, b, over similar pullies connected with the feeding apparatus.
The time required for reducing the alkali, and converting it into cyanide, is in
the inverse ratio of the intensity of the heat. With a good white heat two or
three hours are sufficient to convert almost the totality of the alkali into
cyanide. Whether the retorts are fed by machinery or otherwise, care must
be taken to keep them constantly full, according to the working of the
extractor, which, as before mentioned, delivers the cyanized charcoal into the
dip pipe where it drops into the saline solution below, previous to which it
may be cooled in the iron retort by surrounding a part of the latter with a
cold-water chamber Q, as seen in Fig. 3. The waste gases and vapours are
drawn off by the air pump L, Fig. 4, through the pipes F, F, into the
hydraulic main G, where the vapours are condensed. Each pipe is furnished
with a stopcock f for the purpose of cutting off the communication when
required. The liquor in the under back should contain iron, either in the
state of hydrate of protoxide or in solution, which latter may be the nitrate,
sulphate, muriate, &c., according to the potassa salt which may be preferred, to
produce by double decomposition. There should always be a slight excess of
iron or ferro salts in the receiver, as without this precaution the simple
alkaline cyanides are rapidly decomposed into formiates of potassia and soda
and carbonate of ammonia. The liquor in the under back may be used either
warm or cold, according to circumstances. In the arrangement represented in
Sheet I. no method of warming is shewn, but in Sheet II. the under back is
furnished with a fireplace for the purpose. It is easy to ascertain when
sufficient iron is present by taking out a small quantity of the clear liquor, and
dropping it into a little weak solution of protosulphate or any other protosalt
of iron, a white precipitate will fall without any tinge of red; when, on the
contrary, the liquor gives a brown-red precipitate, or a mixture of red and
white, it wants iron. When it is certain that the liquor contains a slight
excess of iron the charcoal is taken out and thrown into vats or cisterns, and
washed either with cold or warm water until the salt is completely extracted.
The weak liquors are passed successively through new charcoal, by which they

page_text: are easily brought to 20° Beaumé's hydrometer. At this strength the liquors
may be thrown into evaporating pans, and be boiled down until the sulphate
of potassa falls down; this is separated as usual, and drained. The remainder
of the liquor is then drawn off into other vessels to crystallize; or, instead of
drawing it off, the evaporation may be carried still further, until the prussiate
also falls down and separates in a similar manner. The potassa mother-
liquors serve for fresh operations. The first rough crystals are washed and
crystallized a second time, as usual.
Having now described the Invention that has been communicated to me,
and the best manner with which I am acquainted for carrying the same into
effect, I wish it to be understood that I claim, as the Invention secured to ne
by the herein-before in part recited Letters Patent, the application of nitrogen
gas, obtained from the atmosphere or from the waste gases of sulphuric acid
chambers, to the manufacture of cyanogen and its compounds, in whatever
way or by means of whatever arrangement of apparatus the same may be
applied.
In witness whereof, I, the said Alfred Vincent Newton, have hereunto
set my hand and seal, this Thirteenth day of June, in the year of our
Lord One thongan