Zyklon-B is a powerful insecticide which serves as a carrier for the gas Hydrocyanic acid, or HCN. It usually comes in the shape of small pellets or disks. (See Breitman, 203, for more detail about the early use of the gas at Auschwitz) HCN is the cause of death following the application of Zyklon-B. While interacting with iron and concrete, it creates Hydrocyanic compounds, which Leuchter admitted were found in the ruins of the gas chamber in Krematoria II. His finding was confirmed by findings of the Polish government.