To determine whether experiments performed by robots yield the same results as humans, we carried out manual tracer experiments using the same stirrers and glassware. Contrary to our initial expectations, there were apparent differences in the appearance of the particles obtained by robots and by manual processes (Fig. , Table ). We had anticipated that particles produced by automated experiments would be more homogeneous, but the opposite was true. In every run, while the average size of the particles did not differ significantly between the robotic and manual experiments, the size distribution was smaller in the human experiments. SEM observations also showed that in robotic experiments, there were many small or agglomerated particles (Fig. ).