William D. Scott

Previous theoretical studies of the formation of sulfate in the SO2-NH3-liquid H2O system have not considered in a rigorous manner the chemical equilibrium equations, and have failed to provide a satisfactory explanation for the catalytic action of the ammonia. In the present paper the equilibria involved are derived. By assuming that the limiting mechanism in the rate of production of sulfate is the oxidation of the sulfite ion, the observed catalysis of the oxidation by ammonia is explained. The theory also predicts a rate of production of sulfate which is in qualitative agreement with experimental results.

A new ceramic‐metal composite with continuous interconnected ceramic and metal phases has been fabricated from sintered aluminum nitride infiltrated with aluminum metal. A dense, lightweight, hard material with high strength has been obtained. Advance of the infiltration front was linear with time. The activation energy of the process was very high (330 kJ/mol), suggesting that a chemical interaction rather than viscous flow was rate‐controlling. The infiltration rate was observed to be inversely proportional to the pore size. Thermal and mechanical properties of the composite were promising.

A punctuated 103.3 m thick succession of upper Palaeogene to Quaternary sediments has been recovered in a borehole from the upper Hebrides Slope, west of Britain. The borehole proved 11.2m of upper Oligocene, carbonate-rich muds at the base, unconformably overlain by 2.85 m of middle to upper Miocene, glauconitic sands. This is in turn unconformably overlain by 89.25 m of predominantly Plio-Pleistocene sands and muds, with a Holocene sea-bed veneer. The post-Miocene succession is subdivided into two units: the sand-dominated, Pliocene to lower middle Pleistocene, Lower MacLeod sequence between 89.25 and 67.82 m, and the mud-dominated, middle Pleistocene to Holocene, Upper MacLeod sequence above 67.82 m. Regional mapping indicates that these sequences are commonly associated with large-scale shelf-margin progradation and slope-front fan construction. The borehole core provides an excellent record of the transition from pre-glacial to glacial conditions in the mid-latitude NE Atlantic Ocean. Climatic conditions warmer than present prevailed in the late Oligocene, mid- to late Miocene and Pliocene, although the influx of ice-rafted detritus in the late Pliocene marks the onset of climatic deterioration. This deterioration continued, in a fluctuating manner, until the early mid-Pleistocene (0.44 Ma) when fully glacial conditions were established on the Hebridean Margin.

Alumina single crystals were deformed in compression along the c axes at T= 625 to 1373 K. Large‐scale deformation by rhombohedral twinning was observed at a constant resolved shear stress of only 12.6 MPa between ∼900 and 1373 K. Below 900 K, the twinning stress for specimens with ground surfaces rose rapidly to 227 MPa at 625 K. A model for twin growth in the absence of dislocation slip is proposed.