The distribution of a-c resistance throughout the thickness of oxide film on aluminum specimens, conditioned by pre-exposure to 1.0N solutions of sodium chloride and sulfate, has been determined by an electrical method. This method involves measurement of series capacitance and dielectric loss of the oxide covered aluminum as the surface films thin slowly in a slightly alkaline, passivating, sodium chromate solution. Results show that chloride ions become included at certain selected locations in the oxide film, create additional current carriers, and lower the ionic resistance of the film. Sulfate ions do not appear to become included in aluminum oxide films under these conditions and do not lower the film resistance. Aluminum oxide films containing chloride ions dissolve more rapidly in the chromate solution than similar untreated films or films that have been treated in sodium sulfate solution. These observations are held to throw new light on the well defined tendency of oxide covered aluminum to pit severely in nearly neutral sodium chloriae solutions. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-05-25 to IP Vol. 112, No. 1 EFFECTS OF CHLORIDE IONS ON ALUMINUM ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-05-25 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.215.225.9 Downloaded on 2015-05-25 to IP

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A new approach to sewage treatment which involves rapid clarification of raw sewage with fine magnetite particles is described. The process, which is essentially a greatly accelerated chemical coagulation, provides a quick separation of the sewage into two liquid streams, one clarified, the other highly concentrated. Development of the process up to and including operation of a fully continuous pilot is outlined and potential advantages and disadvantages identified.

The electrochemical behavior of aluminum alloyed with selected Group IV elements has been investigated in 0.1N sodium chloride solution. Of the group IV elements studied only tin had a major effect on aluminum; Al‐Sn alloys carried surface oxide films of very low ionic resistance, exhibited potentials more active than −1.0v on the hydrogen scale and gave very large galvanic currents when coupled to mild steel cathodes. The conditions permitting entry of a group IV alloying addition from the metal into the surface oxide film have been partly clarified.

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