Sciencemadness Discussion Board - Ye Olde Potassium Ferrocyanide?

Ye Olde Potassium Ferrocyanide?

blogfast25 - 13-8-2011 at 08:12

Potassium ferrocyanide (and its slightly more expensive ferri counterpart) is now readily available and quite cheap too. But I’ve always been intrigued by how once long ago this complex salt was made from very basic resources, i.e. animal waste and potassium carbonate (potash), even though the chemistry is now quite well understood. It’s not so easy to find concise recipes for potassium ferrocyanide made ‘ye olde waye’ but here’s one I found recently. It’s a method for making the then so desirable Prussian Blue (the deep blue ferro ferri cyanide complex):

”Dry thoroughly in an iron vessel and powder grossly, any quantity of fresh blood. Dry thoroughly and powder also a quantity of pearl ash [K2CO3, my edit] equal to the powdered blood. Mix them, and calcine them in a low red heat in a crucible with a loose cover until all smoke and flame ceases: then make the cover fit close, and calcine in a full red or nearly white heat for half an hour. The crucible should not be more than two thirds full, as the mixture is apt to swell. Empty the contents of the crucible into warm water in the proportion of a quart to four oz. of the mixture. Pour on again as much warm water: mix and filter the solutions. Dissolve of sulphat of iron (green vitriol) and of alum, of each a quantity equal to one half of the pearl ash employed. Pour the solution of alum and green vitriol mixt together, gradually into the solution of blood and alkali: both solutions are better for being warm, but not boiling hot. Stir it well. Let the sediment settle. It will be of a dirty greenish colour: wash it. Then digest it for 2 or 3 days in diluted muriatic acid (spirit of salt one part, water two parts). The colour by this means gradually becomes blue, because the muriatic acid dissolves the yellow oxyd of iron which is not combined with the prussic acid. Wash it repeatedly. Dry it on chalk stones, paper, linen, or any other mode of draining off the water. Spread it thin to expose it to the air. I have kept the lixivium of blood and alkali (prussiat of potash) for a year and a half in bottles, and used it to make prussian blue with equal success as at first. Chippings of hoofs answer equally well with blood.”

By John Redman Coxe and Thomas Cooper (undated)

From: http://canopycanopycanopy.com/8/thirty_six_shades_of_prussia...

The first part, up to the introduction of ‘green vitriol’ (lol), seems indeed to be a simple synth of K4Fe(CN)6, from dried blood and potassium carbonate. Dried blood is readily available as garden fertiliser. Assuming this actually works, I wonder what kinds of yields can be expected.

Has anybody here had a go at this?

not_important - 13-8-2011 at 08:39

yes - it stinks most greatly, but if you have access to a cheap source of protein (old blood, leather scraps, small children,...) it might be useful. Takes several recrystallisations to get reasonable pure.

m1tanker78 - 13-8-2011 at 08:43

Quote from the Sheriff Of Rottingham (Robin Hood - MIT:)

"Looks like a Seder at Vincent Price's house"

IINM, dried blood is a major ingredient in fish food. I guess slitting one's wrist is out of the question, huh?

Tank

blogfast25 - 13-8-2011 at 08:52

Let me be clear that my post was neither an incitement to infanticide nor to suicide!

Dried blood (garden grade) is a couple of quid per kg. Not sure whether it's worth stinking out the neighbourhood for it though. Might do a small benchlab run for laughs and costing...

[Edited on 13-8-2011 by blogfast25]

m1tanker78 - 13-8-2011 at 09:06

Quote: Originally posted by blogfast25

Let me be clear that my post was neither an incitement to infanticide nor to suicide!

... Humor aside, I haven't seen dried blood sold as fertilizer in many, many years around here. That's why I brought up cichlid food as an alternative. It would be neat to try for the experience, if nothing else. To be honest, I'm more intrigued by what distills off from this mixture when heated - again, just for kicks.

Tank

blogfast25 - 13-8-2011 at 09:27

Tank, I'm lucky to have very nearby one of these Old World shops that should really be called 'Tangibles 'R Us': anything from quaint manual rotary apple peelers to zinc cladding, you name it! Quite a few useful chemicals too: 36 % HCl, 95 % H2SO4, NaOH, Na2CO3, NH3 sol., FeSO4, MgSO4, K2SO4, (NH4)2SO4. Not to mention... dried blood!

I don't know what I'm gonna do when that strange man retires...

[Edited on 13-8-2011 by blogfast25]

Didn't smell like roses!

The WiZard is In - 13-8-2011 at 10:21

Bet this didn't Smell like roses!

Ferrocyanide of potassium.

Present mode of manufacture.— It consist in introducing dry
nitrogenous animal matter, such as horns, hoofs, woolen rags,
leather, &c., into molten carbonate of potash contained in a
small, but very thick and heavy (15 cwt) cast-iron pot, heated
externally by a strong fire. The pot is provided with an iron
agitator, which is kept constantly in motion during the
operation. The nitrogenous material is introduced into the pot
slowly, and in small quantities at a time. The carbon and
nitrogen combine together forming cyanogen, which in turn
combines with the potassium, forming, some authorities say,
cyanide, others, ferrocyanide of potassium.

The mouths of the pots are practically open to the air, and at
each addition of nitrogenous material a flame shoots forth
carrying with it a large proportion of the nitrogen. It is at this
stage of the process that the chief waste of nitrogen takes
place.

Extracted from—
JB Readman, D.SC., F.R.S.E., F.C.S., Edinburgh
The Manufacture of Prussiate of Potash (Ferrocyanide of Potassium)
A paper read before the British Association, Newcastle-on-Tyne, 1889.
In:— The Journal of the Society of Chemical Industry
10:8 757-59. October 31, 1889.

------------
Frank Hall Thorpe
Outlines of Industrial Chemistry
MacMillian Co. New York 1919

Potassium ferrocyanide, K4Fe(CN)6 - 3H20, also called yellow prussiate of
potash, is made by fusing together potassium carbonate, iron borings, and
nitrogenous organic matter of any kind (horn, hair, blood, wool waste, and
leather scraps).* The potash is fused in a shallow cast-iron pan, set in a
reverberatory furnace, and the organic matter, mixed with from 6 to 8 per cent of
iron borings, is stirred in, in small portions at a time, until about 1 1/4 parts of the
mixture for each part of potash have been added. The temperature must be kept
high enough to keep the mass perfectly liquid, but not hot enough to volatilize
the cyanogen salts. The reaction is violent at first, and when the liquid remains in
quiet fusion the process is ended, and the melt is ladled into iron pans to cool.
The mass, containing a number of substances (KCN, K2CO3, K2S, FeS, metallic
iron, carbon, etc.), is broken up into. lumps the size of an egg, and digested with
water at 85o C. for several hours. During this process reactions take place
between the potassium cyanide and iron sulphide, by which the ferrocyanide is
formed: -

6 KCN + FeS = K2S + K4Fe(CN)6.

. Liebig explained the reactions during the fusion as follows: part of the carbon
and nitrogen of the organic matter combine to form cyanogen (CN)2, while some
of the potash is reduced by the excess of carbon to metallic potassium, which at
once unites with the cyanogen to form potassium cyanide. The sulphur in the
organic matter combines with the iron, forming ferrous sulphide. Finally, on
lixiviating, the formation of the ferrocyanide takes place. The solution is evapo-
rated in iron pans by the waste heat of the furnace, and clarified while hot; on
cooling, the crude ferrocyanide crystallizes, and is purified by recrystallization.
The mother-liquors yield more impure salt on further evaporation.

* The organic refuse is sometimes partially charred in retorts, by which much
ammonia is driven off and saved. But the yield of ferrocyanide is then less, since
the nitrogen content of the char is small.

----------
Sir Edward Thorpe
A Dictionary of Applied Chemistry
Longmans, Green, and Co.
London 1916

Potassium ferrocyanide K4Fe(CN)6,3H20 (Yellow prussiate of potash, Ger.
Blutlaugensalz).

The method of manufacture from nitrogenous organic matter is now only of
historical interest.

The sources of nitrogen were horn, dried blood, hair, waste wool, and feathers
(15-17 p.c. N), woollen rags (10-16 p.c. N), pigs' bristles (9-10 p.c. N), and old
leather (4-5-7 p.c. N). These materials were sometimes charred before use,
about 80 p.c. of the nitrogen being driven off in the form of ammonia,
hydrocyanic acid, and a complicated mixture of nitriles and organic bases.

The process was carried out at first in pear-shaped, cast-iron muffles, which
were replaced later by reverberatory furnaces, the beds of which were formed of
cast-iron pans, 5 feet long, 3 feet wide. 4 inches deep, and about 2 inches thick.
A charge of 2 cwt. of potash (usually made up of 2 parts of the ' blue salt '
recovered in a later stage of the process, and 1 part of fresh potash) was put into
the pan and fused with 18-20 lbs. of iron turnings ; 2 cwt. of the dry nitrogenous
materials were then stirred in gradually (2-5 to 3 cwt. of charred material could
be added without making the mass too pasty). The temperature was then raised
in order to complete the reaction, and the melt ladled out into iron moulds. After
solidification it was broken up and digested for 24 hours with water at 50o-60o,
and finally extracted completely with boiling water. The solutions obtained
contained potassium ferrocyanide, sulphocyanide, carbonate and sulphide. It
evaporated to sp.gr. 1.28, and allowed to crystallise. Further evaporation yielded
a second crop of impure crystals, the mother liquor of which was evaporated to
drynees, leaving a mixture of potassium carbonate and sulphide, known as ' blue
salt' which was returned to the fusion pan.

The black insoluble residue left from the extraction of the ' metal,' as the product
of the fusion is called, contained considerable quantities of potassium, mainly in
the form of potassium ferrous sulphide and of double potassium, calcium, and
aluminium silicates,

The quantity of ' metal ' produced was very little greater than the weight of
potash used, and 4 charges were put through in 24 hours, but practice varied
considerably : C. Karmrodt (Wagner's Jahresber. 1857, 3, 139) speaks of 6
charges of 500 lbs. each as the normal output of a pan in 24 hours.

The yield of ferrocyanide was seldom more than 20 p.c. of the quantity
theoretically obtainable from the nitrogen in the materials used when they were
not previously charred. Using charred materials, as much as 57 p.c. of the
remaining nitrogen was converted into ferrocyanide, corresponding with a yield
of about 12 p.c. on the nitrogen originally present.

The quantity and composition of the black residues varied greatly with the
kind of organic matter used. The main constituents were carbon (4-9 p.c.),
ferrous sulphide, iron, and in. organic substances derived from the ash of the
animal matters and adhering dirt, the principal being silica, lime, alumina, and
phosphoric acid. The quantity of potassium combined with these substances in
an insoluble form was considerable, According to Karmrodt (Wagner's
Jahresber. 1857, 3, 139), 100 parts of ' metal ' made (1) from horn gave 18.7
p.c. of dry residue, containing 12.2 p.c. of K20; (2) from rags, 28.3 p.c. of
residues, with 16.7 p.c. K20; (3) from leather, 35.1 p.c. of residue, with 10.2 p.c.
K20. These quantities represent about 4 1/2, 9, and 7 p.c. of the potassium
contained in the original charge, and since only some 10 p.c. of this is converted
into ferrocyanide at each operation (R. Brunquell, Wagner's Jahresber. 2, 102,
18565), the loss of potash in the residues appears to have been from 45 to 90
p.c. of that usefully employed. Potash was also carried away with the flue
gases. The iron pans survived several hundred operations.

Theory of the process was first given by Liebig (Annalen, 1841, 38, 20). Scheele
(Chemical Essays, London, 1786; reprinted 1901) had already shown that
lixivium sanguinis is essentially" a solution of potassium cyanide and that the
addition of a ferrous compound is necessary to convert it into prussiate. Liebig
confirmed this by extracting the ' metal ' with alcohol, which dissolves out
potassium cyanide, leaving a residue from which no ferrocyanide can be
obtained. He attributed the formation of the cyanide partly to the action of
ammonia (formed by destructive distillation of the organic matter) on carbon,
C+NH3=HCN+H2, and partly to the action of potassium on the nitrogenous
residue of carbon. It may be remarked that the temperature of the fusion could
not have exceeded 1000o, since cast iron melts about 1100o, and the pans
withstood some hundreds of fusions. The temperature, too, was lowered by the
addition of the organic matter, occasionally sufficiently to cause the charge to
solidify, so that the reaction between ammonia and carbon, which requires a
temperature of about 1000o, could not have occurred to any great extent. The
direct action of ammonia on potassium carbonate (p. 193) would, however, take
place, although, the ammonia being evolved on the surface of the mass, the
conditions were not favourable to it. As to the second of Liebig's reactions, the
writer has found that potassium is not formed from a mixture of charcoal and
potassium carbonate below about 1200o, certainly not at 1000o, so that the
greater part of the cyanide must have been formed by the action of potassium
carbonate itself on the nitrogenous charcoal. The role of sulphur in the process
was explained by Liebig thus : potassium sulphate, which is always present in
the potash, is reduced by carbon to sulphide, carbonate, and polysulphide. The
latter dissolves iron, forming a double sulphide of iron and potassium which,
when the product is lixiviated, dissolves in the potassium cyanide solution thus:

6KCN+FeS = K4Fe(CN)6 +K2S.

If insufficient iron is present in the fusion, the polysulphide, is not entirely
decomposed and potassium sulphocyanide is also formed. R. Hoffmann
(Annalen, 1860, 113, 81) investigated the behaviour of the sulphur compounds in
the process in some detail, and found that the sulphur of potassium sulphide is
rapidly and completely removed by iron alone in the fusion process, and that the
same is true of potassium sulphate in presence of carbon. When organic matters
are added to the sulphur free melt, however, sulphocyanide is produced in
proportion to the quantity added. Hoffmann, therefore, attributes its formation to
the organic sulphur.

The behaviour of potassium sulphocyanide in the fusion is not clearly
understood. Hoffmann found that it is completely decomposed by fusion with
excess of potassium carbonate, yielding cyanate and sulphide ; [1] but if the
mixture is again heated with carbon, the sulphocyanide is regenerated. It
appears, therefore, that, under the conditions of the process, sulphocyanide, is
not decomposed.

A part of the sulphide, of iron formed is present in the form of a potassium
ferrous sulphide, FeS.xK2S, which dissolves in hot water to a dark-green,
colloidal solution which is coagulated by cooling or by adding excess of
potassium carbonate. Another part is probably present in the form of the
crystalline potassium ferric sulphide K2S-Fe2S3, obtained y K. Preis (J. pr.
Chem. 1869, 107, 101), by fusing together finely divided iron, potassium
carbonate, and sulphur. He found that the crystalline sulphide was formed at
very high temperatures, and the amorphous one, yielding the green solutions, at
lower temperatures.

The reaction between potassium cyanide and ferric sulphide
13KCN+Fe2S3=2K4Fe(CN)6+KSCN+2K2S would give a ratio of cyanogen in the
form of sulphocyanide to cyanogen in the form of ferrocyanide of 1:12, whilst
Hoffmann, in 10 experiments, found ratios varying from 1 : 5 to I : 18.

The improvements in the process which were proposed, aimed at saving the
ammonia evolved in the early stages by distilling the organic matters separately
and passing the ammonia through a red-hot mixture of potash and charcoal
(Brunquell, Wagner's Jahresber, 1856, 2, 102), or a similar mixture with iron
added (Karmrodt, ibid. 1857, 3, 139), or over red-hot charcoal forming
hydrocyanic acid which was to be absorbed, together with the unchanged
ammonia, in a solution of ferrous sulphate, (Brunquell). These proposals,
unfruitful at the time are interesting as foreshadowing processes which came into
successful operation nearly half a century later.

The commonly accepted view that cyanogen compounds are more easily
produced from potash than from soda, is not entirely in accordance with the older
experimental evidence. The truth appears to be that equally good results can be
obtained with sodium carbonate under suitable conditions, but the conditions are
not so easily realised.

L. Possoz (Compt. rend. 1858, 47, 209) obtained, under manufacturing
conditions, 5 parts of sodium prussiate, instead of 25 parts of the potassium salt,
from 100 parts of horn. R. Hoffmann (AnDalen, 1860, 113, 81), using a very high
temperature and sodium carbonate, got the equivalent of 11 parts of potassium
ferrocyanide from 100 parts of woollen rags, against 10 to 14 parts with potash,
and S. Tanatar (Dingl. poly. J. 1880, 237, 234) obtained the results tabulated
below, as the means of 3 to 5 experiments:-

Blood
charcoal

K2CO3

Na2CO3

NaCl

CaCO3
Prussiate
obtained
10
25
——
——
——
2.15
10
——
25
——
——
0.2
10
——
5
25
——
2.17
10
——
5
25
3
2.3

[1] I can confirm the accuracy of this observation. Equal molecules of
potassium carbonate and sulphocyanide were fused together in a closed
aluminium crucible at 500o—580o for 1 1/2 hours, a little more than half of the
materials had reacted in accordance with the equation
KSCN+K2CO3=KCNO+K2S+CO2.-T. E.

--------
&c., &c., &c.

djh
----
Next up — Manufacture of Cyandies from Schlempe.

cyanureeves - 13-8-2011 at 10:35

i just came from a garden shop and saw a bag of dried blood and iron sulphate,zinc sulfate, ammonium sulphate,muriate of potash,potassium nitrate,sulfur,magnesium sulfate,urea and more stuff. the potassium chloride makes coffee filters flammable when i filter the stuff before even turning it to chlorate in a cell. i tried ye olde way before and made great prussian blue but never got close to the cyanide. Gmelin literature called for blood and carbonate and iron filings then after isolating the ferrocyanide to repeat in a closed vessel with just carbonate. this last step has been difficult for me because of too much oxygen and little heat. they had to marvel way back in afore days how this formula that looks like a soup recipe could dissolve gold. i used deer hooves instead of blood so you can imagine the smoke and stench

The WiZard is In - 13-8-2011 at 12:13

Quote: Originally posted by cyanureeves

i used deer hooves instead of blood so you can imagine the smoke and stench

Suffocating Balls
[No doubt -- these did not smell like roses. /djh/]

Are made in the same way as the smoke balls. The composition contains
in addition, rasped horses’ and asses’ hoofs, burnt in the hoof, assafatida,
seraphine gum &c.

Manual of Military Pyrotechny: For use of the Cadets of
the U.S. Military Academy, West Point 1831

[Edited on 13-8-2011 by The WiZard is In]

blogfast25 - 13-8-2011 at 12:39

Thanks Wiz!

Clearly living near these stink factories won't have been the plight of the privileged...

m1tanker78 - 14-8-2011 at 06:07

So, who's going to give this a shot (test tube scale)? Bonus points for creative implementation of a cold finger or cold trap of some sort. Extra bonus for a crude ID of the distillate (if any).

Tank

blogfast25 - 14-8-2011 at 07:41

I'm thinking about it, Tank, but for those temperatures I need to get my charcoal fired mini-furnace out: that's a bit if a major op in my lab!

unionised - 14-8-2011 at 12:37

I think this
http://en.wikipedia.org/wiki/Dippel's_oil
is a rough ID of the volatiles.
The bone oil is full of pyridine, phenol and their homologues. It smells roughly as bad as you would expect.

blogfast25 - 14-8-2011 at 12:41

Dippel's oil is apparently what lead to the accidental discovery of Prussian Blure (Berlin Blue), so that kind of fits...

[Edited on 14-8-2011 by blogfast25]

cyanureeves - 14-8-2011 at 17:14

ID of the volatile distillates? does that mean like find the liquid substitutions for all the solid parts? would be freakin wicked.

m1tanker78 - 14-8-2011 at 18:14

IMO, it'd be a treat to condense some of the flue gas - even if it's just temporary (as long as the dry ice or wvr keeps it liquified). Condense, photo, ID (any bits of info to make a semi-informed guess), so on. Keeping in the spirit of yestercenturies, the first [al]chemists to perform this must have asked, "I wonder what makes the smoke stink?"

Blogfast, I'll bet you have one or two other projects on the 'back burner' that require you to fire up the furnace. Kill 2 with 1? Just a thought. Yeah, I'm trying to egg you on.

Reeves and Blog, you all are lucky to have those things at your disposal. I did find a farm/ranch supply house today that sells a few things no longer found in the big box stores. Walked out with a few goodies and the owner said he could probably order a few more not on the shelves.

Tank