The Holocaust Historiography Project

The gas chambers of Auschwitz

Zyklon B is a hydrocyanic acid that is given off by evaporation.

It used for the disinfection of ships, silos, and dwellings, as well as for the destruction of pests. It is still manufactured today in Frankfurt-on-Main.

It is sold in Western Europe, in Eastern Europe, in the United States and nearly everywhere else in the world. Hydrocyanic gas is highly poisonous and very dangerous. One milligram per kilogram of body weight is sufficient to kill a man. In a closed place it will poison a man in several seconds and will kill him in several minutes. A man can lose consciousness and die by absorbing the gas through the skin.

This gas sticks to surfaces. It sticks not only to the skin and to the mucous membranes to the point of penetrating them, but it also sticks to wood, to plaster, to paint, and to cement, and it penetrates them. In an ordinary place where these materials are encountered, the gas cannot be ventilated after use; it is necessary to be content with a natural airing-out process, which lasts nearly 24 hours.

Only specialized personnel, having gone through a period of instruction and having been awarded a diploma, can use this product or gas. They must wear gas masks with special filtering cartridges for hydrocyanic acid. The preparations necessary for the gassing of a place, for example a dwelling place, are long and meticulous, especially in order to obtain a good air-tightness.

The granules of Zyklon from which the hydrocyanic gas is released are not thrown at random, are not scattered by chance. This would be too dangerous later on. It is necessary to assure a calculated distribution. The granules are set down on display napkins.

When the gas is thought to have ended its destructive work, it is necessary that specialized personnel enter the place in order to open everything that would permit a natural airing-out. This is the most critical moment. The airing out presents the greatest danger for participants as well as for nonparticipants. It is therefore necessary to proceed with it with special prudence and always wearing gas masks. As a rule it is necessary to air out the place in such a way as to be able to reach the open air as soon as possible and in such a way that the gas will be evacuated from a side where every risk for nonparticipants is excluded.

The airing-out lasts at least twenty hours.

At the end of twenty hours, the specialized personnel come back into the place, while still wearing their masks. If it is possible, they raise the temperature of the place to 15 degrees centigrade. They leave, returning at the end of an hour, still with their masks, in order to test for the disappearance of the gas. If the test is favorable, the place is declared to be accessible without wearing a gas mask. But, if it is a dwelling place, people will not be able to sleep inside for the first night and the windows ought still to remain open during that first night. Mattresses, bed rolls and cushions must be beaten or shaken for at least an hour because they are impregnated with gas.

This gas is flammable and explosive; there must not be any naked flame in the vicinity and, most definitely, it is necessary not to smoke.

In a more general way, in order to enter a place where there is some hydrocyanic gas, it is necessary always to wear a gas mask with a particularly strong filter cartridge; two cases then present themselves:

  1. The masked man will be exposed to concentrations lower than 1 percent in volume of hydrocyanic gas; or
  2. He will be exposed to concentrations equal to or higher than one percent.

In the first case, he will be able to devote himself to some light work; for example, he will be able to open windows that are easy to open, but on condition that after each step he goes outside in order to remove his mask there and to breathe the open air for at least ten minutes. In the second case, the exposure of the man to those concentrations must be tolerated only in case of necessity and for a period of time not to exceed one minute.

This gas can be used in depressurized fumigation chambers. It is used in the United States for the execution of a person condemned to death in the gas chamber. One must see one of these chambers and be acquainted with the process of their use in order to realize the extent to which it is difficult and dangerous to use hydrocyanic gas in order to kill a single man.

During the First World War, combat gasses had been used, but with very many disappointments and with nearly as much danger for one’s own troops as for the enemy; gas is the least controllable of all weapons. Many suicidal or accidental poisonings prove it. But since the end of the war some Americans who wished for a more humane method of putting condemned prisoners to death believed that nothing would be at the same time more humane and easier than to use a powerful gas to put the man to sleep until death would result. It was when they put their idea into practice that they realized the difficulties. The first execution of a condemned man by hydrocyanic gas took place in the penitentiary at Carson City, Nevada, in 1924; it narrowly missed turning into a catastrophe for the entourage.

It was necessary to wait until 1936-1938 in order to obtain more reliable gas chambers. But even today, this method of execution remains dangerous for the executioners and for the entourage.

The small cockpit called a gas chamber is made entirely of glass and steel in order to avoid having the gas stick too much to the surfaces or penetrate them. The glass and steel are very thick for various technical reasons and especially in order that a partial vacuum can be created in the cockpit with a view to assuring it a good air-tightness; but a partial vacuum thus created brings some risks of implosion. The construction is thus very strong.

Once the condemned person is killed by the emission of the gas the real difficulties begin. It is in effect necessary to enter into a place which, for the moment, is full of deadly gas and it is necessary there to handle a corpse impregnated with that gas.

The gas is not evacuated toward a chimney in the direction of the air outside; this would be too dangerous. In fact, it is driven back in the direction of a mixer where it is neutralized by a chemical base (ammonia). The acid thus gives way to a salt which will be washed away with a great deal of water. Nevertheless, the place still remains dangerous for a long time, as does the corpse. For the doctor and his aides who will have to enter the place and drag out the body, some precautions remain necessary. They will wait until a warning product (phenolpthalein) signals them that the deadly gas has been neutralized, at least for the most part. They wear masks with special filtering cartridges. They wear gloves and rubber aprons. They wash the corpse very carefully with a hose, particularly in the mouth and in all of the folds of the body.

Beforehand, preparating the gas chamber for an execution requires two days of work for two specialized men. The machinery is relatively important.

To use hydrocyanic gas to kill only one man is thus much more complicated and dangerous than one would generally imagine.

One must not confuse the complicated gas chambers that the use of this dangerous gas demands with the rudimentary buildings that all the armies in the world use to train recruits in the wearing of gas masks with ordinary filter cartridges. These places are also called gas chambers. The gas used is not very poisonous and is ventilated easily; the air-tightness of such buildings is quite relative.

When one knows all this, one is quite surprised at reading the testimonies or confessions about the use that the Germans are supposed to have made of Zyklon B to execute not one man at a time but hundreds or thousands of human beings at a time. The most complete of those testimonies or confessions is that of the first of three successive commandants of Auschwitz: Rudolf Höss (who must not be confused with that of Rudolf Hess, the prisoner of Spandau). Rudolf Höss is supposed to have drawn up for his jailers and for his communist judges a confession whose text is supposed to have been reproduced in 1958, or eleven years later, in its original language by Dr. Martin Broszat, a member of the Institute for Contemporary History in Munich. That confession is known to the general public under the title The Commandant of Auschwitz. First on page 126, then on page 166 of the German edition of the book one learns this:

Half an hour after having released the gas [i.e. Zyklon B], the door [of the gas chamber where there are several thousands of victims] would be opened and the fan turned on. The bodies immediately began to be removed.

He goes on to say that this tremendous job of taking out thousands of bodies, from which they removed the gold teeth or cut the hair, was carried out by resigned and indifferent people who during all that time did not cease to smoke and to eat.

That description is surprising. If those people smoked and ate, they were not even wearing gas masks. How could they smoke in a place with vapors from a flammable and explosive gas? How could all of that be done near the doors of the crematory ovens in which they were burning thousands of bodies? How could they enter into a gas chamber still full of gas to handle those bodies that were saturated with gas, and that immediately after the opening of the door? How could they devote themselves to such a gigantic job for hours when specialists, equipped with masks, can only remain in such an atmosphere for several minutes and on condition that they only devote themselves to efforts that do not go beyond the effort required to open windows that are easy to open? How could they, with bare hands, extract teeth and cut hair when one knows that, in an American gas chamber, the first concern of the doctor who enters into the cockpit with mask involves tousling the hair of the corpse with his rubber-gloved hands in order to expel from it the molecules of hydrocyanic gas which have remained in the hair of that corpse in spite of all of the precautions taken? Who are these beings endowed with supernatural powers? From what world do these tremendous creatures come? Do they belong to our world which is ruled by inflexible, known laws of the physicist, the doctor, the chemist, the toxicologist? Or do they indeed belong to the world of the imagination where all those laws, even the law of gravity, are overcome by magic or disappear by enchantment?

If Rudolf Höss still lived, we would be able to pose these questions to him. Unfortunately, after his confession to the communists he was hanged. It remains for us therefore to pose these questions to other persons who have borne witness before the courts and who say they have seen these “gas chambers” functioning. No court has yet posed questions of this type, for example, to a Dov Paisikovic or to a Filip Müller. Fortunately, what the judges have not done, an American historical institute did on 3 September 1979 at Los Angeles. The Institute for Historical Review has even promised a reward of $ 50,000. But, for nearly a year, no candidate has made himself known, not even Filip Müller, who lives in West Germany (68 Mannheim, Hochuferstrasse 31). His book, recently published in German, in English, and in French, does not bring any element of an answer to the questions posed. In truth, furthermore, it accumulates still more mysteries and the affair becomes inextricable.

No proof of gassings

I keep at the disposal of every witness or of every court a study that ends with the following question: “What proof is there demonstrating the evidence of 'gassing' at Auschwitz that did not already demonstrate the evidence of 'gassing' at Dachau?”

We know today that there was never any “gassing” at Dachau, but for many years they presented a host of proofs and testimonies thanks to which they claimed to demonstrate the reality of those “gassings.” It seemed to me to be a good idea to refer back to the proofs and testimonies that there had been some “gassings” at Ravensbrück where we likewise know that there were none. My conclusion is the following: between on the one hand the documents about Dachau (or about Ravensbrück) and, on the other hand, the documents about Auschwitz, there is no difference in quality, but only in quantity. On those first “gas chambers” or on the first “gassings,” they have made up stories only during some 15 years, while on the others they have made up stories for 35 years.

Without gas masks

According to R. Höss' statement in Kommandant in Auschwitz, pages 126 and 166, one can see that the Jewish Sonderkommando members did not have gas masks when they took bodies of gassing victims from the chambers. Mark Weber made me aware that, during Höss' pretrial interrogation on 2 April 1946, Höss had said specifically that these Sonderkommando Jews did not wear gas masks “because they did not need them.”

Questions by Mr. S. Jaari to the witness [R. Höss] through the interpreter [Mr. Leo Katz]:

Question: But was it not quite dangerous work for these inmates to go into these chambers and work among the bodies and among the gas fumes?

Answer: No.

Question: Did they carry gas masks?

Answer: They had some, but they did not need them, as nothing ever happened. (John Mendelsohn (ed.). The Holocaust. 1982. XII, page 113, “From the pretrial interrogation of R. Höss, 2 April 1946.")


On Zyklon, see the Nuremberg documents NI-9098 and, especially, NI-9912.

On the necessary gas mask, see a work of the French Army, translated from an American Army manual: The Gas Mask, Technical Manual No. 3-205, (1-2), War Department, Washington, 22 September 1943, a manual drawn up under the direction of the Chief of the Chemical Warfare Service, U.S. Government Printing Office, 1943, 154 pages. See, in particular, page 55.

On the testimony attributed to Rudolf Höss, see: Kommandant in Auschwitz, Autobiographische Aufzeichnungen, eingeleitet und kommentiert von Martin Broszat, 1958, Stuttgart, Deutsche Verlagsanstalt, especially pages 126 and 166.17

On Filip Müller, see: Sonderbehandlung, Drei Jahre in den Krematorien und Gaskammern von Auschwitz. Deutsche Bearbeitung von Helmut Freitag. München: Verlag Steinhausen; 1979; 287 pages. Translated into English: Eyewitness Auschwitz, Three Years in the Gas Chambers. Literary collaboration of Helmut Freitag, foreword by Yehuda Bauer. New York: Stein and Day; 1979; 180 pages. Translated into French: Trois ans dans une chambre à gaz d' Auschwitz: Le Témoignage de l'un des seuls rescapés des commandos spéciaux. Pygmalion/Gérard Watelet; 1980; 252 pages; with a preface by Claude Lanzmann.