Allegre et al. recently presented new experimental data regarding the
dependence of the streaming potential coupling coefficient with the
saturation of the water phase. Such experiments are important to model
the self-potential response associated with the flow of water in the
vadose zone and the electroseismic/seismoelectric conversions in
unsaturated porous media. However, the approach used to interpret the
data is questionable and the conclusions reached by Allegre et al.
likely incorrect