Zyklon B


 * This article is about the cyanide-based gas used during the holocaust. For the Norwegian black metal band see Zyklon-B (band).



Zyklon B (, also spelled Cyclon B) was the tradename of a cyanide-based insecticide notorious for its use by Nazi Germany to kill over one million people in the gas chambers of Auschwitz and Majdanek during the Holocaust. It consisted of hydrocyanic acid (prussic acid, Blausäure in German, hence B), a stabilizer, and a warning odorant that were impregnated onto various substrates, typically small absorbent pellets, fiber discs, or diatomaceous earth. It was stored in airtight containers; when exposed to air, the substrates evolved gaseous hydrogen cyanide (HCN).

History and production
Zyklon B was originally developed as a pesticide by Fritz Haber, a German Jew who emigrated in 1933. It was first produced in World War I by TASCH (Technischer Ausschuss für Schädlingsbekämpfung, or Technical Committee for Pest Control) as a delousing agent. Out of TASCH emerged DEGESCH (Deutsche Gesellschaft für Schädlingsbekämpfung GmbH, or German Corporation for Pest Control), which played a key role in the manufacturing of Zyklon B in World War II. Many German companies had a stake in DEGESCH, but all eventually sold their shares to the chemical giant Degussa in the early 1920s. Degussa developed the process to manufacture Zyklon B in crystals, as it was used during World War II. To raise capital, Degussa split its controlling interest of DEGESCH with IG Farben in 1930: both companies held a 42.5% share in DEGESCH, with the remaining 15% held by the Th. Goldschmidt AG of Essen.

DEGESCH's role at this point was limited to acquiring patents and intellectual properties: it did not itself produce Zyklon B. The manufacture of Zyklon B was handled by the Dessauer Werke für Zucker and Chemische Werke, which acquired the stabilizer from IG Farben, the warning agent from Schering AG and the prussic acid from Dessauer Schlempe and assembled them into the final product. This company extracted prussic acid from the waste products of the sugar beet refining process. From 1943 to 1945, the Kaliwerken, from the Czech town of Kolin, also supplied prussic acid to the Dessauer Werke. When Zyklon B became used in the gas chambers, the Nazis ordered the warning agent removed.

Upon production, Zyklon B was sold by Degesch to Degussa. To cut costs, Degussa sold the marketing rights of Zyklon B to two intermediaries: the Heerdt and Linger GmbH (Heli) and Tesch and Stabenow (Tesch und Stabenow, Internationale Gesellschaft für Schädlingsbekämpfung m.b.H., or Testa) of Hamburg. Both suppliers split their territory along the Elbe river, with Heli handling the clients to the west and Testa doing the same in the east.

Zyklon B is still in production in the Czech Republic in the factory Draslovka Kolín a.s. in the city Kolín under the tradename Uragan D2, sold for eradicating insects and small animals.

Use on humans


From 1929 onwards the U.S. used Zyklon B to disinfect the freight trains and clothes of Mexican immigrants entering the US.

The pesticide was used by Nazi Germany as a chemical weapon to poison prisoners in the gas chambers of the largest extermination camp, Auschwitz Birkenau, and also at Majdanek, one of the Operation Reinhard camps. At the other extermination camps, engine exhaust was used in the gas chambers. The victims were primarily Jews and the Zyklon B gas became a central symbol of the Holocaust.

Zyklon B was used in the concentration camps initially for delousing to control typhus. The chemical used in the gas chambers was deliberately made without the warning odorant.

In January or February 1940, 250 Gypsy children from Brno in the Buchenwald concentration camp were used as guinea pigs for testing the Zyklon B gas. On September 3, 1941, 600 Soviet prisoners of war and 250 sick Polish prisoners were gassed with Zyklon B at Auschwitz camp I; this was the first experiment with the gas at Auschwitz. The experiments lasted more than 20 hours.

After the war, two directors of Testa – Bruno Tesch and Karl Weinbacher – were tried by a British military court and were executed for their part in supplying the chemical.

The use of the word Zyklon (German for cyclone) continues to prompt angry reactions from Jewish groups. In 2002, both Bosch Siemens Hausgeräte and Umbro were forced to withdraw from attempts to use or trademark the term for their products.

Modern Holocaust deniers assert that Zyklon B gas was not used in the gas chambers, relying as evidence on the low levels of Prussian blue residue in samples of the purported gas chambers found by Fred A. Leuchter, which Leuchter dismissed as the results of general delousing of buildings. However, Leuchter's negative control, a sample of gasket material taken from a different building in the camp, registered as having no such cyanide residue. The manager of the analytical laboratory hired by Leuchter states in an interview in Errol Morris' film Mr. Death: The Rise and Fall of Fred A. Leuchter, Jr., that Leuchter's thick samples of brick would have greatly diluted the cyanide residue, which forms only an extremely fine layer on the walls and cannot penetrate.

In 1994, the Institute for Forensic Research in Kraków re-examined this claim on the grounds that formation of Prussian blue by exposure of bricks to cyanide is not a highly probable reaction (Amoklauf gegen die Wirklichkeit. Praca zbiorowa; B. Gallanda, J. Bailer, F. Freund, T. Geisler, W. Lasek, N. Neugebauer, G. Spenn, W. Wegner; Bundesministerium fuer Unterricht und Kultur Wien, 1991). Using more sophisticated microdiffusion techniques, they tested 22 samples from the alleged gas chambers, delousing chambers (as positive controls), and living quarters (as negative controls), finding cyanide residue in both the delousing chambers and the ruins of the suggested gas chambers but none in the ruins of the living quarters, thus supporting the identification of the gas chambers as correct.