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Presence of Cyanides in Gassing Facilities and Apparent Absence
of Prussian Blue
Markiewicz, Gubala, and Labedz of the Institute for Forensic Research,
Cracow demonstrated that HCN was present in the homicidal gas chambers,
i.e., Krema I, Krema II, Krema III, Krema IV, Krema V, and
the cellars of Bunker 11, at levels above other facilities in the AB
complex. 3 They took
several samples from Bunker 11, and Kremas I-V. They found levels
of cyanide significantly higher than background levels in all of these
sites of homicidal gassing. They used a carefully calibrated method
in which their calibration curve was checked with known standards in the
process of running the sample. The analysis was conducted by a
separate team from the sample collection team to insure objectivity.
Unlike the Holocaust-deniers, they used a carefully calibrated method
that discriminated against the iron blue compounds, such as Prussian
blue , that are believed to be responsible for the above-mentioned
staining.
The purpose of this essay is to look closer at this blue staining, what
it is, how it could have formed, and whether its absence in the
homicidal gas chambers of AB can reasonably be interpreted to mean that
homicidal gassings did not take place there. Owing to the fact that
Rudolf and Leuchter did not discriminate against iron blue compounds,
the fact that they measure more cyanide compounds in the delousing
chambers than in the homicidal gas chambers is functionally no different
than the observation that the blue-staining is present in the delousing
chambers and not in the homicidal chambers. In other words, they have
found nothing by measurement that is not apparent without measurement.
By a carefully thought out experiment, Markiewicz, Gubala, and Labedz
have provided real information.
The fact that there is obvious blue-staining in the delousing chambers
and not in the homicidal chambers of AB is not in dispute here. It
should be mentioned, however, that at the Majdanek death camp there is
indeed blue-staining on the homicidal gas chambers. 4,5 Additionally, the staining is
not present on all known delousing chambers. One is left immediately to
ponder why it would be argued that such staining is a necessary
consequence of the use of hydrogen cyanide (HCN).
Owing to the fact that he cannot think of a mechanism by which the
Prussian blue could form from iron in its third oxidation state (as
present in brick), Bailer 6
speculates that the presence of iron blues may be because of paint
rather than exposure to HCN vapor (iron blues are commonly used as
pigments in paints). Bailer's speculation, although it is certainly more
reasonable than the claims of Rudolf that homicidal gassings did not
occur at AB, must still be viewed with skepticism. If paint was indeed
used on these facilities, it should be possible to find evidence that
such paint was purchased and applied. The paint hypothesis needs more
evidence to support it, if it is to be believed.
A few points should be made clear:
- Some of the delousing chambers exhibit blue-staining, whereas
some of the homicidal gas chambers do not. Because Rudolf and Leuchter
chose to include this blue-stained material in their samples, their
measurements do not provide more information than visual inspection
except as an exercise in fooling the public by putting numbers to what
is apparent to the eye. In other words, by not discriminating against
Prussian blue they have introduced a bias into using the delousing
chambers as a control. They have not thereby contributed to
understanding why a discrepancy in the level of Prussian blue exists.
- The blue-stained material is characteristic of a class of
compounds called the iron blues, of which Prussian blue is a member.
Although Bailer4 has
suggested that the blue color may come from paint, that explanation
seems unlikely. Observers of the staining at Majdanek describe it as
splotchy and saturated deep within the building materials.
- In order for Prussian blue to form, it is necessary either to
have a source of Fe(II), Fe(0), or an agent that can reduce Fe(III) to
Fe(II). If a reducing agent is present, the conditions must be right to
cause reduction. This point is explained further in some depth, below.
- The Institute for Forensic Research, Cracow, discriminated
against Prussian blue compounds so as not to introduce a bias in the
control. They found unequivocally, that all buildings said to have been
in contact with HCN at Auschwitz-Birkenau had traces of cyanides
significantly above the background of other buildings at
Auschwitz-Birkenau.
Prussian
blue once formed is much less susceptible to weathering than
are other forms of cyanides. Rudolf himself acknowleges this fact:
4
If the hydrocyanic acid from the Zyklon B had bonded with the
brickwork only through the process of adsorption, then due to the
volatility of hydrocyanic acid (boiling point: 25.7C) it would no longer
be possible today to detect any hydrocyanic acid residues in the
remaining walls.
This argument neglects the fact that hydrogen cyanide is a weak acid
that can form salts, such as potassium cyanide, fails to address the
binding of chemisorption, or the formation of other cyanide compounds;
yet the point is not completely without merit. More significant,
perhaps, is the fact that cyanide salts are highly water soluble unlike
Prussian blue. Markiewicz et al. report that they were not
optimistic at being able to detect cyanides so many years after exposure
to HCN. Owing to the fact that they had legal access to their samples,
however, they were able to plan sample collection in a manner likely to
detect cyanides in locations that were relatively sheltered from the
elements. The fact that they measured traces of cyanide not bound to
iron in the homicidal gas chambers at levels above those observe in
other buildings disproves the claims that such traces would not be
measurable
In order for Leuchter or Rudolf to demonstrate the significance of their
findings, it is necessary for them to prove the necessity of Prussian
blue formation under the conditions that the homicidal gas chambers were
operated. Showing that the delousing chambers have Prussian blue and
that the homicidal gas chambers do not, proves nothing, if it cannot be
shown that conditions in the gas chambers were such as to produce
Prussian blue. I shall therefore turn my attention to Prussian blue,
its formation and the conditions present in the gas chambers.
The Iron Blues and Their Industrial Preparation
There are a number of compounds known colloquially as the "iron blues."
Insoluble Prussian Blue, for example, is
Fe4[Fe(CN)6]3. It can be
formed by the addition of Fe(II) to
[Fe(III)(CN)6]-3. 7 It should be noted here
that the distinction between soluble and insoluble is a matter of the
ease with which the compound forms colloidal suspensions rather than any
real difference in solubility. 7 This point is important
when addressing the possible degradation of Prussian blue. While I will
not argue that degradation of Prussian blue is the cause of its absence
from the homicidal gas chambers, this hypothesis should not be rejected
as a possibility out of hand.
There are 3 methods generally used for the preparation of soluble iron
blues described by Holtzman. 8 Insoluble blues can be
prepared by subsequent reaction of soluble blues with various metal
cations (see table II in Holtzman).
The three methods are
- mixing a ferric (Fe(III)) salt with a ferrocyanide Fe(II),
- mixing a ferrous (Fe(II)) salt with ferricyanide Fe(III), and
- mixing a ferrous salt
with a ferrocyanide, followed by oxidation.
It should be noted that it is necessary to produce iron in a mixture
of oxidation states or perhaps in a resonance structure of mixed states.
Bailer argues for the improbability of Prussian blue formation for
exactly that reason.
Rudolf's Proposed Mechanism
Rudolf, 1,4 in his own persona and also under
the alias 9 "E. Gauss," 10 has with some bombast
criticized Bailer for not noting the possibility that HCN itself could
be the reducing agent responsible for converting iron (III) into iron
(II). Even stranger synthesis of iron blues have been reported. 11
Rudolf cites in support of his claim a paper by Alich, Howarth, and
Johnson.12 Apparently, he did
not read this paper very carefully. The authors investigate the
reduction of [Fe(CN)6]3- by aqueous and ethanolic
solutions of CN-. They suggest that CN- is indeed
the reducing agent, but their inability to observe CNO- must
suggest that this claim is inconclusive. DeWet and Rolle have claimed
that Fe(III)Fe(III)(CN)6 can be reduced to a Prussian blue
compound with water. 13
The observation by Alich et al. that addition of water inhibits
the reaction, perhaps, makes the supposition that HCN is the reducing
agent more plausible despite their inability to observe
CNO-.
What the reducing agent is, however, may be academic.
The relevant question is whether such a mechanism to form Prussian blue
would necessarily have been operative in the gas chambers.
Alich et al. show that Prussian Blue does not form in water
unless there is an excess of CN- ions compared to Fe(III) or
very basic conditions.
14
The dilution of the absolute stock solutions of Fe(III) and
Fe(CN)63-with absolute ethanol gave the red
complex which persisted for about 1 hour, as compared to the
disappearance of the red complex in the aqueous media at a dilution of
3.3 * 10-4 M. The red complex in ethanol darkened within the
hour and reduction to Prussian Blue was complete in 2 days (Fig. 3).
Now comes the important part:
It is to be noted that the complex in aqueous solution, under the same
conditions, decomposes immediately, the spectrum reverting to that of
the Fe(CN)63- ion. Furthermore, addition of as
little as 13% water (by volume) caused the red complex to decompose,
giving a spectrum of the Fe(CN)63-
ion.
Conditions in the Homicidal Gas chambers at Auschwitz Birkenau.
In other words, Prussian blue only forms with very high
concentrations of CN-. The concentrations in the gas
chambers were such that ambient water, given time to reach equilibrium,
might theoretically have approached concentrations of 0.2 or 0.3
M - but more likely on the order of 0.1 M or below - as shown in
Appendix I.
That such an equilibrium concentration could have been reached
during the time span of an actual gassing is doubtful. This
concentration is the equilibrium value. Absorption of HCN by water
would undoubtedly be kinetically limited, i.e., the
concentration would be limited by how fast the absorption process can
occur. The equilibrium concentration assumes that the water has been
exposed to HCN long enough that the rate of HCN leaving solution into
the gas phase is equal to the rate at which HCN from the gas phase is
being absorbed by the water.
Most importantly one must recall that the gas chambers were hosed down
with water after gassings to clean up blood and excrement.15 Considering that the ambient
water would have been quite small, providing 100 times dilution
would have been trivial. This effect may actually be the
explanation for the presence of Prussian blue in the delousing
chambers yet its absence in the homicidal chambers. Some further
research will be necessary to support this supposition
conclusively.
Prussian blue formation is exceedingly sensitive to concentration and
also to pH. Very small effects could tip the balance between whether
Prussian blue forms or not. Alich et al. found a strong pH
dependence to the reaction. The presence of human beings in the gas
chambers could also help tip the balance. CO2 is an acid
anhydride and there would have been a lot of it in the homicidal
chambers. An acid anhydride is a substance that increases the acidity
of a solution when it becomes solvated. Even atmospheric concentrations
of CO2 (at 360 ppm today, about 330 ppm then) are sufficient
to cause pure rain water to have a pH of 5.6. Human beings exhale about
4% CO2, so the pH could be quite a bit lower.
For example at 2% CO2 the pH would be below 4.8.
Appendix II derives the relationship between
carbon dioxide concentration and pH.
Low pH inhibits the reaction. Additionally, a lower pH will drive the
HCN from solution, making the CN- more dilute at the outset.
For completeness, it should be added that these factors may be
somewhat mitigated by the use of limewash (Ca(OH)2)
which is slightly water soluble and could boost the pH. A pure
solution of Ca(OH)2 can reach a pH as high as 12 (see
the Merck Index), but coatings with limewash hardly provide such
conditions.
Another point should be noted here. The conditions outlined
here are for the formation of Prussian blue in the presence of
cyanide ions and Fe(CN)63-. In the gas
chambers Fe(III) would have been present in the brickwork and
cyanide ions from the HCN itself, but Alich et. al. note:
"The spectra of solutions containing only Fe(III) and
CN- ion indicated only the acid hydrolysis of Fe(III)."
16 Prussian blue did
not form.
The experimental evidence that Prussian blue formation is not a
necessity with the presence of HCN and construction materials is
strong. Markiewicz et al. 17 were not able to produce
such pigments in experiments with HCN and building materials.
Additionally, Rudolf did an experiment in which he exposed a brick to
HCN and yet found no detectable level of cyanides within the sensitivity of his
analytical method. 18 These failures to produce
Prussian blue are sufficient to demonstrate that its formation at
detectable levels is not a necessary result of exposure to HCN.
Conclusion
Whereas it would be premature to claim that I have explained why
Prussian blue is present in the delousing chambers and not in the gas
chambers, I have certainly shown that Rudolf's proposed mechanism is
unlikely to have been operative in the homicidal gas chambers. More
importantly, I have shown that the formation of Prussian blue is subject
to very subtle influences of the conditions present. Slight changes in
condition may have been sufficient to push the balance one way or the
other. Yet the burden of proof here lies with the deniers. They claim
to prove that gassings could not have occurred in the gas
chambers. To make such an argument, they need to demonstrate that their
proposed mechanism of Prussian blue formation must be operative
in the gas chambers under the precise conditions under which they were
operated. Their task is daunting. Any claim made on the basis of the
absence of Prussian blue is at best empty speculation. Add to that the
evidence that cyanides were indeed present in the homicidal gas
chambers, that witnesses claim that gassings took place there, that the
perpetrators admitted to their crimes, and that 1 to 1.5 million people
were deported to Auschwitz-Birkenau and never returned, and we can label
Rudolf's work willful distortion of the evidence.
Appendix I: Absorption
by Water and Henry's Law
Appendix II: The
Effect of Carbon Dioxide on pH
back to
The Chemistry of Auschwitz
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