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A further study has been made on the application of the chemical exchange reaction between ammonia gas and ammonium nitrate in water to the problem of securing high concentrations of the nitrogen isotope of atomic weight 15. The apparatus consists of several glass packed columns filled with efficient packing materials arranged in cascade, such that a smaller second column operates on the product from the first and a third column operates on the product from the second. With this arrangement of columns we have secured 72.8 percent N15 and have produced sufficient quantities of concentrated material to investigate many of the physical properties of N15 and its compounds.
Thode et al. (Sun,) studied this question.