. "Zyklon B (German pronunciation: [tsyklo\u02D0n \u02C8be\u02D0]; anglicized /\u02C8za\u026Akl\u0252n \u02C8bi\u02D0/ or translated Cyclone B) was the trade name of a cyanide-based pesticide invented in Germany in the early 1920s. It consisted of hydrogen cyanide (prussic acid), a warning eye irritant, and one of several adsorbents such as diatomaceous earth."@en . . .