This report discusses two methods used for experimental determination of the interfacial tension of an immisible aqueous-organic system where the density of the organic phase is less than that of the aqueous phase. The methods discussed are the falling drop method and the Donnan modification/rising drop method.

From abstract: "A comparison has been made of methods for producing Fe59 of higher specific activity than that obtainable by irradiating natural iron in the Clinton pile. Five processes have been considered, (1) irradiation of natural iron in the Hanford piles, (2) irradiation of enriched F58 in the Clinton and Hanford piles, (3) Szilard-Chalmers enrichment using ferrocyanides in the Clinton pile, (4) collection of recoils in a phase separable from the bulk of the iron, and (5) the Co59 (n,p) Fe59 reaction in the Clinton and Hanford piles."