Sedimentation of a single soluble particle at low Reynolds and high Péclet numbers

We report experiments on the dissolution of a single particle during its sedimentation in a quiescent aqueous solution in the regime of low Reynolds and high P\'eclet numbers. We use butyramide, a chemical which does not change the density of water when it dissolves. The particle shrinks at a rate independent of its initial radius, in agreement with the model that we derive assuming Stokes drag and a mass transfer rate given by Levich (1962). This model becomes quantitative when including two correction factors to account for the non-sphericity of the particle and for the inclusions of air bubbles inside the particle.