. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. 66 ADVEXTURES IX RADIOISOTOPE RESEARCH tain some information on the then not entirely elucidated nature of the natural radioactivity of potassium. We bombarded a few grams of very pure scandium oxide prepared by Prof. Sterba-Bohm and used by Prof. HoNiGSCHMiDT in his work on the atomic weight of scandium. After neutron bombardment the scandium oxide was dissolved in dilute hydro- chloric acid and 100 — 150 mgm of sodium chloride as a carrier of ^^K and the same amount of calcium oxide was added. The filtrate obtained af
. Adventures in radioisotope research;. Radioactive tracers; Radiobiology. 66 ADVEXTURES IX RADIOISOTOPE RESEARCH tain some information on the then not entirely elucidated nature of the natural radioactivity of potassium. We bombarded a few grams of very pure scandium oxide prepared by Prof. Sterba-Bohm and used by Prof. HoNiGSCHMiDT in his work on the atomic weight of scandium. After neutron bombardment the scandium oxide was dissolved in dilute hydro- chloric acid and 100 — 150 mgm of sodium chloride as a carrier of ^^K and the same amount of calcium oxide was added. The filtrate obtained after precipitation with carbonate-free ammonia was treated with oxalic. ^ 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 36 40 42 days Fig. 2. Dec;iy Curve of the Potassium Precipitate. acid and the calcium oxalate formed was removed. The sodium chloride which had been added to the solution of the scandium chloride compound was recovered after the removal of the ammonium chloride content of the last filtrate by evaporation. The activities of the three fractions, namely scandium oxide, sodium chloride, and calcium oxalate, were then determined. Only the two first preparations mentioned were found to be active. The activity of the scandium oxide decayed very slowly while the various sodium chloride fractions obtained in different ex- periments lost half of their slight activity within 10 and 18 hours. We had just finished the experiment mentioned when a note was published by Fermi and his collaborators (1) concerning the action of neutrons on potassium. They found that potassium captured neutrons by giving birth to a potassium isotope decaying with a half-life of 16 hours. The values found by us for the period of the slight activity of different potassium preparations obtained from irradiated scandium showed a half- life between 10 and 18 hours; we thought it justifiable, therefore, to identify the element found by us with that found by Fermi and his collaborators. The initial acti
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