INSTITUTE OF FORENSIC RESEARCH
In the name of Prof. Dr. Jan Sehn, Krakow
Division of Forensic Toxicology

Krakow, 24 Sept. 1990
Westerplatte 9 / Code 31-033
Tel. 505-44, 592-24, 287-50
Telex 0325213 eksad ...

The hydrocyanic acid (HCN) that is released from the Zyklon B
preparation is a liquid with a boiling point of about 27 degrees
Celsius. It has an acidic character, and therefore forms
compounds with metallic salts, which are known as cyanides. The
salts of alkaline metals (such as sodium and potassium) are
water soluble.

Hydrocyanic acid is a very weak acid, and accordingly its salts
dissolve easily in stronger acids. Even carbonic acid, which is
formed as a reaction of carbon dioxide with water, will dissolve
ferro-cyanide.

Stronger acids, such as sulfuric acids, easily dissolve the
cyanides. The compounds of cyanide ions with heavy metals are
longer lasting. This includes the already mentioned Prussian
blue, although this will also slowly dissolve in an acidic
environment.

Therefore, one can hardly assume that traces of cyanic compounds
could still be detected in construction materials (plaster,
brick) after 45 years, after being subjected to the weather and
the elements (rain, acid oxides, especially sulfuric and
nitrogen oxides). More reliable would be the analysis of wall
plaster [samples] from closed rooms which were not subject to
weather and the elements (including acid rain).

The discovery of hydrocyanic acid compounds in samples of
material which had been subject to the elements can only be
accidental.

The original plaintext version of this file is available via ftp.

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