  This paper is aiming at presenting some relevant contributions of Jean-Pierre
Badiali during the first ten years of his growing scientific activity. This
presentation does not contain new materials but is based on a number of
selected papers published in the seventies, a part of them written in French.
The presentation is organized around three points. The first point,
corresponding to his PhD thesis, is concerned with the study of ion-solvent and
ion-ion interactions in a solution using complex dielectric permittivity
measurements in the Hertzian and microwave frequency range. The second one is
concerned with an analysis of the ion pair absorption band observed in the far
infrared region in terms of an interionic potential energy. The third one is
concerned with the metal-solution interface and his significant advances on (i)
the Lippmann equation linking electrocapillary and electrical measurements and
(ii) the contribution of the metal to the differential interfacial capacity.
