Zyklon B:hydrogen cyanide adsorbed on or released from a carrier in the form of small tablets, used as an insecticidal fumigant.
(A fumigation team in New Orleans, 1939)
Even in their preferred choice of mass killing the Nazis used a poison which was originally designed to kill insects and other pests, and that is the clearest indication what they thought of their victims.
Hydrogen cyanide, a poisonous gas that interferes with cellular respiration, was first used as a pesticide in California in the 1880s.Research at Degesch(German Corporation for Pest control) led to the development of Zyklon (later known as Zyklon A), a pesticide which released hydrogen cyanide upon exposure to water and heat.
It was banned after a similar product was used by Germany as a chemical weapon in World War I. In 1922, Degesch was purchased by Degussa, where a team of chemists that included Walter Heerdtand Bruno Tesch developed a method of packaging hydrogen cyanide in sealed canisters along with a cautionary eye irritant and adsorbent stabilizers.
The new product was also named Zyklon, but it became known as Zyklon B to distinguish it from the earlier version. Uses included delousing clothing and disinfesting ships, warehouses, and trains.
During the killing process, prisoners at Auschwitz and other killing centers were forced into the air-tight chambers that had been disguised by the Nazis to look like shower rooms. The Zyklon pellets were then dumped into the chambers via special air shafts or openings in the ceiling.
The pellets would then vaporize, giving off a noticeable bitter almond odor. Upon being breathed in, the vapors combined with red blood cells, depriving the human body of vital oxygen, causing unconsciousness, and then death through oxygen starvation.It could take up to 20 minutes before the victims died.