Neutralized Zyklon B (also spelled Cyclon B) – the infamous gas that was used by the SS troops in the holocaust to gas their prisoners in the concentration camps. Ironically, it was developed as an arsenic-based insecticide by Dr. Fritz Haber, a German-Jew in 1920. Just a couple of years before, he was awarded with the Nobel prize in chemistry! He died in 1934, one year after he had to leave Germany because of his jewish roots. See more about it on Wikipedia