The containers above hold Zyklon-B pellets (hydrocyanic acid) that vaporize
when exposed to air. Originally intended for commercial use as a disinfectant
and an insecticide, the Nazis discovered through experimentation the gas
could be used to kill humans.
The brand of Zyklon-B used by the Nazis contained substances which gave
the pellets a blue appearance and left blue stains inside gas chambers
which can still be seen today in chambers that were left intact.
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.