RESEARCH concerning bonding conditions for tritium and deuterium in micaceous minerals, as formerly mentioned by us1, indicated the presence of apical OH in di-octahedral hydro micas. Burns and White2 conclude from infra-red examination after hydrogen saturation and heating of LiNO3-treated muscovite that hydronium ions H3O+ replace interlayer cations, giving rise to an infrared absorption band at considerable bathochromic shift from the normal OH band of the mica (3,472 cm-1 respectively 3,600 cm-1). In order to elucidate the bonding problem of the protons of hydrogen micas we have examined the very pure dioctahedral montmorillonite from Skyrvedalen, already described by one of us (I. Th. R.)3. As acid treatment tends to attack the silicate lattice we have obtained the desired hydrogen-substituted minerals by introduction of NH4+ in the exchangeable positions and subsequent dissociation of NH3 by heat treatment.