Concentration of isotopes of mercury in countercurrent molecular stills.

Mercury was refluxed in countercurrent molecular stills in order to concentrate 204Hg. Two glass sti lls , with heater and cooler placed outside the distillation columns, and one still, consisting of a glass column heated externally and a stainless-steel cooler placed concentrically inside the column, were used . As compared with a lO-cell steel column described previously, these columns showed poor performance, mainly because the hold-up was too small. There are definite indications, however, that with liquids having a lower surface tension than Hg, these columns will perform as well as the lO-cell steel column. Mass-spectTometer analyses of isotope Tatios of the Hg-isotope concentrates were in good agreement with density determinat.ions.