Troe 015 Cid 0-05 45 55 65 LIGHT ABSORBANCE AT 440 my i oa iT) 020 er —> 765m. _[i2N___Heo| mm. ‘Dowex-1° of bismuth carrier weparated on @ ‘Dowex-s0" fone de of alga eotlected at Mniwetok shed Hoe is the ehition curve for levels of bismuth were determined &. in The solid line indicates the the eluted fractions. The Is tor colnting error are viven from the anion fraction of ruthentum-106-rhodiumper cent of the hismuth-207 ‘action, and the remaining in the oxalate fraction. uthentum from the anion ith perchloric acid only the Z07 were present in the test for bismuth was made henium!, The sample was ‘sulphuric acid. Five ml. of ‘ogether with 1 ml. of 1 per hen 1 ml. of 10 per cent dded to three drops of the ulphurie acid. The solution ur of iodobismuthite. A ‘Dowex-I resin column (100-200 mesh) 56 mm. by 8 em. was converted to the Cl- form with 6 N hydrochloric acid then treated with 25 mi. 2 N hydrochloric acid. The fraction which contained the bismuth was dissolved in 15 ml. 2 N hydrochlorie acid and passed through the resin column at a flowrate of 0-1 ml./min. The columnwaseluted with 15 ml. 2N,20 ml. 6 N, 20 ml. 12 N hydrochloric acid, and 10 ml. distilled water. The eluates were collected in 5-ml. fractions, dried in test tubes, then treated with heat and sulphuric acid to remove the chloride. Gamma counts for bismuth-207 were made from each fraction and the stable hismuth determined by the iodide colorimetric method. The amounts of iodobismuthite in the fractions were determined by light absorbance measurements at 440 mu. The y-radioactivity and the light absorbance in the fractions are shown in Fig. 1. Bismuth is known to be strongly adsorbed on to ‘Dowex-l’ resin at molarities of hydrochloric acid from 0-6, but is desorbed by 12 N hydrochloric acid?. In the separation described above both the y-activity and the stable bismuth remained on the ‘Dowex-1? during elution with 2 N and 6 N hydrochioric acid but were removed by 12 N hydrochloric acid. A 20-mgm. sample of bismuth-207 made in tho University of Washington eyelotron in 1956 was subjected to the same ion-cxchange procedures used for the algal sample. Of the bismuth-207 introduced into the ‘Dowex-50’ column, 99:98 per cent was recovered in the anion fraction (sample eluate + 0-2.N hydrochlorie acid wash}. In the ‘Dowex-1 column’, the bismuth-207 remuined attached to the resin during elution with 2 N and 6 N hydrochloric acid but was quantitatively removed by 12 N_ hydroehloric aeid. (The conversion of bismuth to a chloride complex in ash from biological material which is then separated by successive elutions from ‘Dowex-50’ and ‘Dowex-l’ columns would be an efficient method for separation of stable bismuth from these samples. The amount of stable bismuth separated may be determined with a colorimetric test. If carrier-free hismuth-207 were added to the sample before ashing, the yield for the stable element could be accurately determined by > counting the added spike and the purified bisnmruth separation.) Bismuth-207 in radioactive fall-out would be in the oxide form, which is insoluble in sea water. In the lagoon, therefore. it would be expected to oceurin the bottom sediments. The bismuth-207 found in the sample of Dictyota was probably adsorbed to the surface of the plant and not incorporated in its living material. Algae are