The additivity in the influence of cations and anions on the rate of relaxation of the nuclei of the solvent (water) molecule is studied. The dissociation of a number of electrolytes is studied. In some cases, the dissociation may be considered complete up to the limits of solubility (NaCl, NaNO₃, RbCl, NaF). However, for a number of simple electrolytes, such as CaCl₂, CaBr₂, Na₂SO₄, etc., a deviation from the additivity rule is observable at moderate concentrations. The conclusion is made that contact or separated ionic pairs are formed.