
For comparison here is Müller's textual description, as reproduced in Sonderkommando Auschwitz I.
It's apparent Müller never understood that the Zyklon pellets had to be removed or cleaned up (see also his descriptions of Crema I) -- rather, for him it was a "crystal" which totally sublimated into gas. His two-sentence description of the column could be interpreted in multiple ways, but the most apparent plain reading of it is that the "crystals" were meant to be distributed through the "perforations". Else there could be no purpose to the spiral design.The Zyclon B gas crystals were inserted through openings into hollow pillars made of sheet metal. They were perforated at regular intervals and inside them a spiral ran from top to bottom in order to ensure as even a distribution of the granular crystals as possible.
[...]
When some room had been made behind the door, the corpses were hosed down. This served to neutralize any gas crystals still lying about, but mainly it was intended to clean the dead bodies.