IMPROVEMENTS IN OBTAINING YELLOW AND RED PRUSSIATES."
Year: 1872

page_text: LETTERS PATENT to Robert Fraser Smith, of Glasgow, in the County'
of Lanark, North Britain, for the Invention of "IMPROVEMENTS IN
OBTAINING YELLOW AND RED PRUSSIATES."
PROVISIONAL SPECIFICATION left by the said Robert Fraser Smith
at the Office of the Commissioners of Patents, with his Petition,
on the 10th February 1872.
I, ROBERT FRASER SMITH, of Glasgow, in the County of Lanark,
North Britain, do hereby declare the nature of the said. Invention of
"IMPROVEMENTS IN OBTAINING YELLOW AND RED PRUSSIATES," to be as follows,
that is to say :-
This Invention has for its object the employment of the ammoniacal
liquor produced in the destructive distillation of coal, shale, and other
similar substances, as a source for the obtainment of the yellow and red
prussiates,, otherwise known as the ferro-cyanides and ferri-cyanides,
such, for example, as the yellow and red prussiates of potash or other
bases.
·

page_text: In carrying the Invention into practice the ammoniacal liquor is dis-
tilled over, the vapour being passed into sulphuric acid as at present,
when employed in the production of muriates or sulphates.
After the expulsion of the volatile ammonia the spent liquor is
evaporated until the chloride of ammonium crystallises out. The
mother liquor then contains chiefly sulphur, cyanide of ammonium, and
other nitrogenous substances which become available in the subsequent
process, and this consists in drying the mother liquor either by evapo-
ration or by centrifugal action. The solid residue thus obtained is
mixed with iron and carbonate of potash or other base, and placed in
iron vessels wherein they are subjected to a heat sufficient to decompose
the sulpho-cyanide into the ferro-cyanide or yellow prussiate; the resulting
product is lixiviated with water, and the solution is evaporated and
crystallized in the usual manner, from which the red prussiate may be
obtained by passing chlorine through the solution in the usual manner.
Or in place of treating the mother liquor as herein-before described, it
may be partly evaporated and the sulpho-cyanide precipitated by a salt
of copper and sulphurous acid or other suitable precipitant, after which
the supernatant liquid is drawn off and the precipitate treated with
sulphide of sodium or sulphide of potassium. Sulphide of copper remains,
and the concentrated solution of sulpho-cyanide of sodium or potassium
is then treated in the manner herein-before described for obtaining the
prussiates.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Fraser Smith in the Great Seal Patent 2
Office on the 10th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
FRAZER SMITH, of Glasgow, in the County of Lanark, North Britain,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 3
Letters Patent, bearing date the Tenth day of February, in the year
of our Lord One thousand eight hundred and seventy-two, in the
35th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Robert Frazer Smith, Her special

page_text: license that I, the said Robert Frazer Smith, my executors, adminis-
trators, and assigns, or such others as I, the said Robert Frazer Smith,
my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN OBTAINING YELLOW AND RED PRUSSIATES," upon the con-
dition (amongst others) that I, the said Robert Frazer Smith, by an
instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
'
NOW KNOW YE, that I, the said Robert Frazer Smith, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, that is to say :-
-
My said Invention has for its object the employment of the amino-
niacal liquor produced in the destructive distillation of coal, shale, and
other similar substances as a source for the obtainment of the yellow
and red prussiates, otherwise known as the ferro-cyanides and ferri-
cyanides, such, for example, as the yellow and red prussiates of potash or '
other bases.
The ammonical liquor produced in the manner mentioned is a watery
solution of di-carbonate, sulphide, chloride, and sulpho-cyanide of am-
monium. The first two of these substances, namely, ammonium di-
carbonate, and ammonium sulphide, have hitherto been distilled off the
liquor and treated for conversion into various compounds of ammonia,
after which it has hitherto been customary to run to waste the liquor
containing the chloride and sulpho-cyanide, as owing to the mass of.
water in which these substances are dissolved the extraction thereof has
been found to be unprofitable.
In carrying this Invention for the profitable recovery of the chloride
and sulpho-cyanide of ammonium into practice, the liquor is evaporated
until the ammonium chloride crystallizes out, and this salt then only
requires to be re-crystallized in order to be fitted for employment in.

page_text: .
manufactures. The mother liquid, after the extraction of the ammo-
nium chloride, is a nearly saturated solution of ammonium sulpho-
cyanide, and other nitrogenous substances, which, in further carrying
out this Invention are diluted with water to about twice their volume;
the supernatant fluid is then decanted or drawn off and made slightly
acid with hydrogen chloride or other acid. A solution containing
equivalent proportions of ferrous and cupreous sulphates is then added as
long as any precipitation occurs. The precipitate collects in the bottom
of the vessel as a granular deposit, containing the sulpho-cyanogen
in combination with copper. Mechanical agitation is used to assist this
process. The deposit is next washed once or twice with clean water
and the liquor drained off, which being effected a sufficient amount of
potassium sulphide is poured on the deposit, and steam being blown
through the mixture, sulphide of copper is precipitated and potassium
sulpho-cyanide remains in solution. The solution of this latter substance
is next dried, either by evaporation or by centrifugal action, and the solid
residue thus obtained is mixed with iron and carbonate of potash or
other base, or with iron merely, in which case the spongy iron is pre-
ferably employed and the mixed potassium sulpho-cyanide and metallic
iron is then mixed in an iron or other suitable retort and gently fused,
the mixture being constantly stirred during the time required to com-
plete the operation. The mass, which by this last described operation
has been decomposed into ferro-cyanide or yellow prussiate is then
withdrawn from the retort and lixiviated with water and the clear
solution decanted and evaporated to crystallization. The crystals thus
obtained are yellow prussiate of potash. The red prussiate may be
obtained by passing chlorine through the solution in the usual manner.
In lieu of concentrating the waste liquor by evaporating it until the
ammonium chloride contained therein crystallizes out as herein-before
described, the said liquor may be treated merely for the recovery of the
sulpho-cyanide which it contains. Under this process the waste liquor
from the ammoniacal liquor boilers is treated with a salt of copper and
sulphurous acid, or other suitable precipitant, by which the sulpho-
cyanide is precipitated, and thereafter the supernatant liquid is drawn
off and the precipitate treated with sulphide of sodium, or sulphide of
potassium, sulphide of copper remains, and the concentrated solution of
sulpho-cyanide of sodium or potassium is then treated in the manner
herein-before described for obtaining the prussiates.

page_text: The copper employed in the processes herein-before described is
recovered by roasting or otherwise treating the sulphide of copper by
well-known means at the conclusion of each operation, and is again
employed in fresh precipitations.
Having now described and particularly ascertained the nature of my
said Invention, and the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, I would observe
in conclusion that what I consider to be novel and original, and therefore
claim as the Invention secured to me by the herein-before in part
recited Letters Patent is, the manufacture by the processes herein-before
described, of yellow and red prussiates from sulpho-cyanides contained
in or recovered from waste ammoniacal liquor produced in the distillation
of coal, shale, and other similar substances.
In witness whereof, I, the said Robert Frazer Smith, have hereunto
set my hand and seal, this Ninth day of August One thousand