Partial Separation of the Oxygen Isotopes by Thermal Diffusion and the Deuteron Bombardment ofO17

With an eighteen-meter column, ${\mathrm{O}}^{18}$ has been enriched from the ordinary concentration of 0.2 percent to 17 percent and ${\mathrm{O}}^{17}$ from 0.04 percent to 0.8 percent. The former increase was determined by the mass spectrometer, the latter by the increased activity of ${\mathrm{F}}^{18}$ produced in the nuclear reaction ${\mathrm{O}}^{17}\mathrm{}(d,n)\mathrm{}{\mathrm{F}}^{18}$. The time rate of increase of the concentration of ${\mathrm{O}}^{18}$ was characterized by a step-wise nature, which arises from the staggering of the six three-meter tubes convectively coupled in series. A qualitative discussion of staggering is given.