Fluidization tests on pure silver and silver catalyst powder show that agglomeration occurs when the bed is heated, which finally results in bed collapse at a comparatively low temperature. If the bed temperature is held constant in the agglomerating temperature range, an induction period is observed before fluidization ceases. A study of the induction period as a function of temperature (10–60°C.) leads to an activation energy of 18 kcal. for the overall agglomeration process for pure silver. Agglomeration is believed to be due to sintering.