Zyklon B

Zyklon B was the trade name of a cyanide-based pesticide invented in Germany in the early 1920s. It consists of hydrogen cyanide, as well as a cautionary eye irritant and one of several adsorbents such as diatomaceous earth. The product is notorious for its use by Nazi Germany during the Holocaust to murder approximately 1.1 million people in gas chambers installed at Auschwitz-Birkenau, Majdanek, and other extermination camps.

Hydrogen cyanide, a poisonous gas that interferes with cellular respiration, was first used as a pesticide in California in the 1880s. Research at Degesch of Germany led to the development of Zyklon, a pesticide that released hydrogen cyanide upon exposure to water and heat. It was banned after World War I, when Germany used a similar product as a chemical weapon.