from zirconium by precipitation as fluorides. Cerium was sep- arated from trivalent rare earths by precipitation as ceric lodate. In analysis of Rojoa dredged sand an attempt was made to separate trivalent rare earths from yttrium by precipitating them on lanthanum carbonate, but absorption curve study showed that this separation was not complete. A large fraction of other trivalent rare earth isotopes had carried on yttrium instead of on lanthanum. The two results were added together and reported as trivalent rare earths. This separation was not attempted in other analyses. Trivalent rare earths were counted together on yttrium carrier. The rare earths were weighed as oxalates. Zirconium was recovered from the flouride supernate by precipitation first as barium fluozirconate and than as zirconium mandelate, which was ignited and weighed as zirconium oxide. The supernate from the hydroxide precipitation contained barium, strontium, and calcium which were precipitated as carbonates. Barium was separated as barium chromate and strontium and calcium precipitated together as oxalates. Chem- ical separation of strontium and calcium was not attempted. A separate aliquot of Rojoa dredged sand solution was analyzed for cesium by the standard cesium perchlorate method and no de-_ Since rubidium also is carried tectable radiocesium was found. on this precipitate it is evident that rubidium was also absent. In most samples the absence of cesium was indicated by the absence of activity in the solution remaining after precipitation of rare earth hydroxides and alkaline earth carbonates. -~ 81 - Ruth-