IMPROVEMENTS IN THE MANUFACTURE OF HYDROCYANIC ACID AND ITS COMPOUNDS, AND APPARATUS FOR THAT PURPOSE
Year: 1879

page_text: LETTERS PATENT to John Imray, of No. 28, Southampton Buildings, Chancery
Lane, in the County of Middlesex, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF HYDROCYANIC ACID AND ITS COMPOUNDS, AND
APPARATUS FOR THAT PURPOSE." A communication from abroad by the
Société Anonyme de Croix, of Croix, near Roubaix, France, an incorporated
Company.
PROVISIONAL SPECIFICATION left by the said John Imray at the Office of
the Commissioners of Patents on the 24th September 1879.
JOHN IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the County
of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF HYDROCYANIC ACID AND
ITS COMPOUNDS, AND APPARATUS FOR THAT PURPOSE." [A communication from
abroad by the Société Anonyme de Croix, of Croix, near Roubaix, France, an
incorporated Company.]
This Invention relates to a process and apparatus for the manufacture of hydro-
cyanic acid and its compounds, such as potassium, cyanide, yellow and red prussiates,
and Prussian blue. For this purpose the methylamine of commerce being vaporised
its vapour is passed through a retort heated to redness, whereby it becomes
decomposed, producing hydrocyanic acid in considerable quantity, as well as
ammonia, watery vapour, and inflammable gases. By passing these products through
an alkaline bath, such as a solution of caustic soda, or potass, the hydrocyanic acid
is separated, producing a sodium or potassium cyanide, as the case may be. The
ammonia is in like manner separated by means of an acid bath, and the inflammable
gases may be collected in a gas holder for use. The cyanides produced as above
described are treated in the ordinary way for production of the red or yellow
prussiates, Prussian blue, and other compounds of cyanogen.
The apparatus
employed for conducting the process above set forth may be variously arranged. A
convenient arrangement for continuous working is as follows:-From a cistern con-
taining the methylamine a regulated quantity flows into a vessel in which it is
vaporised by the heat of a steam coil or jacket. The vapour passes thence through
the heated retorts, of which a number are arranged in a furnace below. The pro-

page_text: ducts from the retorts are conducted by pipes up to closed vessels containing the
acid and the alkaline solutions, which are kept in agitation by revolving agitators.
The contents of these vessels, when they are sufficiently saturated, are allowed to.
flow down by pipes to evaporating and crystallising pans below. The inflammable
gases which are not absorbed in the acid or alkaline baths are conducted by a pipe
to a gas holder. It is of advantage to provide this pipe with a suction pump or
exhauster, so as to keep the pressure in the retorts and vessels somewhat below that
of the atmosphere, and thus prevent leakage therefrom. When it is desired to obtain
from methylamine only potassium-cyanide this may be effected by passing methyla-
mine vapour through caustic potass or saltpetre in a fused condition.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Imray in the Great Seal Patent Office on the 5th March
1880.
JOHN IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the County
of Middlesex. "IMPROVEMENTS IN THE MANUFACTURE OF HYDROCYANIC ACID AND
ITS COMPOUNDS, AND APPARATUS FOR THAT PURPOSE." A communication from
abroad by the Société Anonyme de Croix, of Croix, near Roubaix, France, an
incorporated Company.
This Invention relates to a process and apparatus for the manufacture of hydro-
cyanic acids and its compounds, such as potassium cyanide, yellow and red prussiates,
and Prussian blue. For this purpose the methylamine of commerce being vaporised
its vapour is passed through a retort heated to redness, whereby it becomes
decomposed, producing hydrocyanic acid in considerable quantity, as well as
ammonia, watery vapour, and inflammable gases. By passing these products through
an alkaline bath, such as a solution of caustic soda or potass, the hydrocyanic acid
is separated, producing a sodium or potassium cyanide, as the case may be. The
ammonia is in like manner separated by means of an acid bath, and the inflammable
gases may be 'collected in a gas holder for use. The cyanides produced as above
described are treated in the ordinary way for production of the red or yellow
prussiates, Prussian blue, and other compounds of cyanogen.
The apparatus employed for conducting the process above set forth may be variously
arranged. A convenient arrangement for continuous working is as follows:-From a
cistern containing the methylamine a regulated quantity flows into a vessel in which
it is vaporised by the heat of a steam coil or jacket. The vapour passes thence through
the heated retorts, of which a number are arranged in a furnace below. The pro-
ducts from the retorts are conducted by pipes up to closed vessels containing the
acid and the alkaline solutions, which are kept in agitation by revolving agitators.
The contents of these vessels, when they are sufficiently saturated, are allowed to
flow down by pipes to evaporating and crystallising pans below. The inflammable
gases which are not absorbed in the acid or alkaline baths are conducted by a pipe
to a gas holder. It is of advantage to provide this pipe with a suction pump or
exhauster, so as to keep the pressure in the retorts and vessels somewhat below that
of the atmosphere, and thus prevent leakage therefrom. When it is desired to obtain
from methylamine only potassium cyanide this may be effected by passing methyla-
mine vapour through caustic potass or saltpetre in a fused condition.
The accompanying Drawing represents apparatus arranged to operate as above
described. A is the reservoir containing methylamine of commerce, which flows
thence by a siphon pipe governed by a stop cock into a vaporising vessel B, where
it is heated and vaporised by coils of steam pipe. From B the vapour passes by
pipes into retorts Cheated to redness, wherein it is decomposed. The gaseous pro-
ducts of the decomposition pass by pipes D to condensers E, E', containing sulphuric
or hydrochloric acid, whereby the ammonia is fixed. The residual gaseous products
proceed to vessels F, F, containing caustic alkaline lye, soda, or potassa holding in
suspension iron oxide, which is kept stirred by agitators. In the vessels F, F¹, the
hydrocyanic acid is separated and retained. In order to prevent leakage outwards,
and to cause the flow of the gases through the apparatus, a pump or exhauster G is
employed which discharges the residual imflammable gases into a gas holder H,
whence they can be conducted for use in heating or lighting. Below the condensers
E, E¹, and F, F¹, are arranged evaporating pans I and R which receive the liquid
contents of these vessels by the pipes n and o for concentration, these when concen-
trated being discharged into crystallising vessels J, L. The contents of E, E¹, may
be heated by steam coils supplied by the pipe m.
•

page_text: Having thus described the nature of the said Invention, and in what manner the
same is to be performed, as communicated to me by my foreign correspondents, I
claim,―
First. The manufacture of hydrocyanic acid and its compounds by the herein
described treatment of methylamine.
Second. The herein described arrangement of apparatus for treating methylamine
for the production of hydrocyanic acid and its compounds.
J
In witness whereof, I, the said John Imray, have hereunto set my hand and
seal, this Fifth day of March, in the year of our Lord. One thousand eight
hundred and eighty.
JOHN IMRAY. (L.S.)