Abstract: In an electrolytic cell for the production of aluminum from alumina, having an anode-to-cathode gap of from 1 to 5 cm, the flow of electrolyte through the interelectrode gap is induced by positioning the cathode at an inclination of from about 2 to about 15 degrees from the horizontal, and operating at an anode current density of from about 0.5 to about 3.0 A/cm.sup.2. The cathode surface is a Refractory Hard Material which is wetted by aluminum.

Abstract: An ultrasonic liquid jet probe for coupling ultrasonic waves with a structure. The probe includes an ultrasonic transducer for emitting or receiving ultrasonic waves, a housing disposed about the transducer and in fluid communication with a source of liquid under pressure, and a nozzle for shaping the flow of liquid into a round jet column and guiding the ultrasonic waves between the transducer and the liquid jet column. The interior of the housing includes first and second chambers fluidly connected by elongated conduits to impart a substantially laminar flow to the liquid flowing into the nozzle which promotes the stability of the liquid jet column discharged from the nozzle.