Crossword-Solution: ACTINIUM 8 letters, 13 clues 🏆 scrabble score: 12

Evidence gradually accumulated that the amounts of actinium in radio-active minerals were, roughly at any rate, proportional to the amounts of uranium.

Separating a quantity of actinium from a kilogramme of ore, Boltwood observed a growth of 8.5 x (10 to the power -9) gramme of radium in 193 days, agreeing with that indicated by theory within the limits of experimental error.

Turning to the other end of the radium series we are led to ask what becomes of radium-F when in turn it disintegrates? What is the final non-active product of the series of changes we have traced from uranium through actinium and radium? One such product has been indicated above.

This is true also of the two other elements found in the ores of uranium and thorium, viz., polonium and actinium.

Recent advances in the chemistry of the radioactive elements has brought out evidence that all three lines of radioactive descent known to us--_i.e._ those beginning with uranium, with thorium, and with actinium--alike converge to lead.[1] There are difficulties in the way of believing that all the lead-like atoms so produced ("isotopes" of lead, as Soddy proposes to call them) actually remain as stable lead in the minerals.