Figure 3. Dripping a solution of methylene blue C16H18N3SCl (right) into water - clearly no diffusion experiment

From

Understanding Diffusion and Demonstrating it Correctly – A Critical Look at a Transport Process often Incorrectly Taught in Schools

Philipp Meyer

International Journal of Physics. 2024, 12(5), 238-246 doi:10.12691/ijp-12-5-7