This article is from the Holocaust FAQ, by Ken McVay firstname.lastname@example.org with numerous contributions by others.
Two German firms, Tesch/Stabenow and Degesch, produced Cyclone
B gas after they acquired the patent from Farben. Tesch
supplied two tons a month, and Degesch three quarters of a ton.
The firms that produced the gas already had extensive experience
in fumigation. "In short, this industry used very powerful
gases to exterminate rodents and insects in enclosed spaces;
that it should now have become involved in an operation to kill
off Jews by the hundreds of thousands is not mere accident."
(Hilberg, Commandant, 567) After the war the directors of the
firms insisted that they had sold their products for fumigation
purposes and did not know they were being used on humans. But
the prosecutors found letters from Tesch not only offering to
supply the gas crystals but also advising how to use the
ventilating and heating equipment. Hoess testified that the
Tesch directors could not help but know of the use for their
product because they sold him enough to annihilate two million
people. Two Tesch partners were sentenced to death in 1946 and
hanged. The director of Degesch recieved five years in prison."
(Feig) (See also Breitman, 203-204, for a discussion of the early
involvement of Heerdt-Lingler)
From the statement of Hans Stark, registrar of new arrivals,
Auschwitz (Klee, 255):
At another, later gassing -- also in autumn 1941 -- Grabner*
ordered me to pour Zyklon B into the opening because only one
medical orderly had shown up. During a gassing Zyklon B had to
be poured through both openings of the gas-chamber room at the
same time. This gassing was also a transport of 200-250 Jews,
once again men, women and children. As the Zyklon B -- as
already mentioned -- was in granular form, it trickled down over
the people as it was being poured in. They then started to cry
out terribly for they now knew what was happening to them. I
did not look through the opening because it had to be closed as
soon as the Zyklon B had been poured in. After a few minutes
there was silence. After some time had passed, it may have been
ten to fifteen minutes, the gas chamber was opened. The dead
lay higgledy-piggedly all over the place. It was a dreadful
* Maximillian Grabner, Head of Political Department, Auschwitz
Zyklon-B is a powerful insecticide which serves as a carrier for the
gas Hydrocyanic acid, or HCN. It usually comes in the shape of small
pellets or disks. (See Breitman, 203, for more detail about the
early use of the gas at Auschwitz) HCN is the cause of death
following the application of Zyklon-B. While interacting with iron
and concrete, it creates Hydrocyanic compounds, which Leuchter
admitted were found in the ruins of the gas chamber in Krematoria II.
His finding was confirmed by findings of the Polish government.
HCN is *extremely poisonous* to humans. It is used in execution gas
chambers in the US; the first was built in Arizona in 1920.
Holocaust denial often includes the claim that Germany in the 1940's
could not handle the "technical difficulties" inherent in using HCN
for execution - "difficulties" that were easily solved in 1920.
Moreover, the Germans had a lot of experience with HCN, as it was
extensively used for delousing.
There were two types of gas chambers in Auschwitz: those used for
delousing clothes ("delousing gas chambers") and those used for
killing people on a massive scale ("extermination gas chambers").
The delousing gas chambers were a standard feature, and were left
intact by the SS (the extermination gas chambers were dynamited in an
effort to conceal criminal traces).
Holocaust denial asserts that because more Hydrocyanic compounds were
found in the delousing chambers in Auschwitz than in the ruins of the
extermination gas chambers, mass murder using the gas could not have
taken took place within, because the reverse would be true.
HCN is much more effective on warm-blooded animals, including humans,
than it is on insects. The exposure period (to HCN) is much greater
in delousing operations than in homicidal gassings. This means that
a much lower concentration is necessary to kill people than to get
rid of lice, etc. In delousing, concentrations of up to 16,000 ppm
(parts per million) are sometimes used, and exposure time can be up
to 72 hours; while 300 ppm will kill people in fifteen minutes or so.
Therefore, the HCN in the extermination chambers hardly had time to
form compounds on the walls. While some claim that the gas
would need a lot of time to kill, because it would have to spread all
over the chamber, it simply is not true; the gas chambers were not
that large (those in Krematoria II and III were about 210 square
meters), and the Zyklon-B was dropped from four openings (still
visible in the ruins of the gas chambers). Since the concentration
used was higher than the lethal one, death was very swift.
Furthermore, the delousing chambers are intact while the
extermination chambers were blown up (a .GIF picture of the one of
Krema II is available). Therefore, their walls have been exposed to
the elements for the last 50 years. The ruins of the gas chamber of
Krema II are covered with about 3 feet of water during certain
periods of the year; HCN compounds easily dissolve in these
surroundings. Nonetheless, so much gassing took place that some of
the compound remained.
Summarizing, the walls of the extermination gas chambers were in
contact with HCN for a much shorter time then those of the delousing
chambers, and for the last 45 years were exposed to surroundings
which dissolve the compounds, while the delousing rooms were not.
Therefore it is obvious that less traces of compounds would remain in
This fact - that all, or most, of the compounds would vanish during
45 years of exposure - is clearly stated in the report written by the
experts of the Cracow Institute of Forensic Research.
Holocaust deniers once claimed that the gas chamber in Krema I was
left intact, and therefore its walls were not exposed to the
elements. But - as they admit themselves - the gas chamber of Krema
I was used only for a short time, and than it was changed to an
air-raid shelter. After the liberation of the camp, it was
reconstructed to its original shape. This, and the fact that "only"
about 10,000 people were murdered inside it (compared to 350,000 and
400,000 in Kremas II and III) explain why relatively small amounts of
cyanide compounds remain. As for Kremas IV and V, they were
completely destroyed by the SS before the Soviets liberated the camp.
Finally, cyanide compounds were found on the ventilation grills of
the extermination chambers, proving beyond doubt that gassing did
take place inside them.
The claim that it would have been impossible to use the gas chambers
for killing, because they were too close to the furnaces, and the gas
would explode, is often found in Holocaust denial literature, and is
one of the assertions of the Leuchter report.
The concentration of HCN necessary to cause death is nearly 200 times
lower than that which causes explosion. Although the SS used a
concentration higher than the lethal one, it was far below that
As a reference, one can look at "The Merck Index" and the "CRC
handbook of Chemistry and Physics", or consult any manual dealing
with toxicity and flammability of chemicals. For HCN, a
concentration of 300 ppm (parts per million) kills humans within a
few minutes, while the minimal concentration that can result in an
explosion is 56,000 ppm.
Another common claim is that it takes 20 hours to air a room which
has been disinfected with Zyklon-B, and therefore the eyewitness
accounts giving a time of 20-30 minutes from when the gassing started
to when the bodies where carried out is impossible, because the
people carrying out the bodies would perish.
If one disinfects a building in ordinary commercial use, it should
not be reentered within 20 hours. That figure, however, has no
meaning in relation to the extermination chambers, because they were
forcibly ventilated. Fifteen minutes were enough to replace the air.
When ventilation was not used, the Sonderkommando (prisoners used as
forced labor) who took the bodies out had gas masks on. The Germans
had plenty of experience with gas, especially HCN, which was widely
used for delousing. They knew how to work with it without getting
hurt. It is absurd to use the 20 hour figure in this context, which
does not assume forced ventilation and takes a huge safety factor
into account. The SS didn't care much for the safety of the
Sonderkommando who had to enter the gas chambers to take the corpses
Furthermore, what makes ventilation difficult and lengthy is the
presence of rugs, furniture, curtains, etc. Needless to say, these
were not present in the gas chambers - there was just bare concrete,
making ventilation fast and efficient.
If the "20 hours ventilation period" above was true, this would mean
that the corpses of people executed using cyanide gas in US gas
chambers would remain tied to the chair 20 hours after they were
Another common claim is that the "alleged" extermination chambers are
actually morgues, and that Zyklon-B was used in them as a disinfectant.
This claim stems from the fact that Hydrocyanic compounds were found
on the ventilation grills of the gas chambers in Krematoria II and
III (the chemical analysis was carried out by Dr. Jan Robel of the
Cracow Forensic Institute in December 1945, and was part of the
evidence in the trial of Auschwitz commander Hoess). This proves
that gassing did take place in that chamber. Zyklon-B cannot kill
anaerobic bacteria - it kills only aerobic organisms. That means it
would be useless for disinfecting corpses.
In closing, consider the testimony of SS private Hoeblinger:
I was detailed to the transport service and I drove the Sanka
[abbreviation for Sanitatskraftwagon/medical truck] which was to
carry the prisoners....
Then we drove to the gas chambers. The medical orderlies
climbed a ladder, they had gas masks up there, and emptied the
cans. I was able to observe the prisoners while they were
undressing. It always proceeded quitely and without them
suspecting anything. It happened very quickly.
Note Pvt. Hoeblinger's mention of gas masks - some Holocaust deniers
insist that the SS-men dropping the gas would be killed by it, which
leads one to speculate about their reading ability.
Finally, the undeniable evidence that the SS ordered Degesch to
remove the indicator odor, mandated under German law, which was added
to the Zyklon B in order to provide a warning to human beings that
the lethal stuff was nearby. I believe this demonstrated clear
criminal intent - the SS would hardly have removed the indicator odor
if they had intended, as the denial set insists, to use the gas only
on insects and corpses... (get pub/orgs/german/farben.ig/farben.001 for
more information about this demand from the SS. Borkin, 123)
Barrington,J.H., ed. The Zyklon B Trial: Trial of Bruno Tesch and
Two Others. London, 1948, and Borkin (see Work Cited).
Harmon, Brian. Technical Aspects of the Holocaust: Cyanide, Zyklon-B,
aand Mass Murder. (get pub/camps/auschwitz/cyanide.001), 1994
United Nations War Crimes Commission. Law Reports of Trials of War
Criminals. Vol. 1, London, 1947. See pp. 93-104