The kinetics of the reaction of gaseous chlorine with metallic nickel has been investigated in a constant pressure flow system in the temperature range from 1200° to 1700°K, and at chlorine pressures between 0.08 and 0.4 mm Hg. Nickel chloride produced in the over-all reaction, Ni(s)+Cl2(g)→NiCl2(g), is highly volatile at these temperatures, and the reaction thus takes place on the exposed metal surface. The process whereby nickel is removed from the surface is first order in chlorine pressure, very rapid with a collision efficiency between 0.5 and 0.2, and is temperature independent, i.e., Eact<2 kcal. The rate constant for the removal of nickel is found to be 1.85 × 103 cm sec—1, the units corresponding to moles of nickel per cm2of surface per unit density (M/cm3) of chlorine. An experimental technique employing time lapse photography is described which is particularly well suited to the study of the kinetics of high temperature surface reactions with volatile reaction products.

Near-infrared emission spectrograms of vibrationally excited hydroxyl radicals in the ground state have been obtained upon mixing H atoms and ozone. A recent interpretation of a particular source of the night-sky radiation has been verified. A nonequilibrium distribution of energy between the reaction products is indicated.

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This paper examines the performance of unsaturated soils under repeated loading. As part of the research, a triaxial system was developed that incorporates small-strain measurements using Hall effect transducers, in addition to suction measurements taken using a psychrometer. Tests were conducted on samples of kaolin under constant water mass conditions. The results address the effects of compaction effort and water content at the time of compaction on the overall performance of unsaturated soils, under different amplitudes of loading and different confining pressures. The results show that suction in the sample reduced with increasing number of loading cycles of the same magnitude. The resilient modulus initially increased with increasing water content up to approximately optimum water content, and then reduced substantially with further increase in water content.

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