Satellite gravity inversion incorporating a lithosphere thermal gravity correction has been used to map crustal thickness and lithosphere thinning factor for the NE Atlantic. Predicted oceanic crustal thicknesses in the Norwegian Basin are between 4 and 7 km on the extinct Aegir Ridge, increasing to 9 – 14 km at the margins, consistent with volcanic margin continental breakup at the end of the Paleocene. The observation (from gravity inversion and seismic refraction studies) of thin oceanic crust produced by the Aegir Ridge in the Oligocene may have implications for the temporal evolution of asthenosphere temperature under the NE Atlantic during the Tertiary. Thin Oligocene oceanic crust may imply cool (normal) asthenosphere temperatures during the Oligocene in contrast to elevated asthenosphere temperatures in the Paleocene and Miocene‐Recent as indicated by the formation of volcanic margins and Iceland respectively.

On evaporated films of W, Mo, Ta, Nb, Cr and Fe, nitrogen, like hydrogen, shows both weak reversible and strong irreversible chemisorption. However, unlike hydrogen, there is discontinuity in the adsorption isobar, so that separate mechanisms are operating.On all metals fast irreversible chemisorption covers only part of the surface, and approximate fractional coverages are Mo and Cr, 0.42 ; W, 0.36 ; Ta, 0.25 ; Nb, 0-15 ; Fe, 0.02. Hydrogen may be adsorbed on some though not all of the residual surface. The results suggest a relative scarcity of unpaired electrons in the metal surface for covalent bond formation and on Mo, Cr and W there may be only 1.5 such electrons per surface atom.Slow sorption follows rapid adsorption, and on Fe, Cr and Ta the rate is proportional to p k This may indicate lattice penetration, in which case interstitial nitrogen atoms may be active in catalytic ammonia synthesis. The bearing of the result on synthesis kinetics is briefly discussed.

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