Perturbation techniques are applied to dispersion relations for nucleon-deuteron scattering. It is shown that additional Coulomb effects account for the pd quartet scattering parameters and in particular for the large difference in pd and nd quartet scattering lengths. Results for the doublet, ɭ=0 phase seem to disagree with current inaccurate data. Another datum of the same channel, namely the Coulomb energy, appears close to the observed 3H 3He mass difference.