Winkler’s Bed
The accidental discovery that led to fluidisation
A few days ago a colleague came into my office. A Wittig reaction wasn’t working properly; could I help him and his student purify some potassium t-butoxide? Up in the lab we poured the greyish material into a glass tube, chased it with a plug of glass wool and after evacuating the tube on a Schlenk line, we placed it inside a small glass tube furnace. As the temperature passed 200˚C, the powder suddenly came alive and the particles began to dance as if driven by a powerful but unseen wind while white crystals grew a few inches further along tube. Tapping the tube and inclining it gently, the powder flowed smoothly, its surface remaining horizontal. It was a beautiful example of fluidisation, a phenomenon discovered accidentally by a German industrial chemist in the 1920s.