Astatine is - besides radon and francium - the only natural radioelement which only has short-Lived isotopes, thereby excluding experiments with . . weighable" amounts of the element. This implies that all available data on physics and chemistry of this element are 12 16 based on experiments on the tracer scale with 10- to 10- g - and this will also not change in future because no longer-Lived isotopes as yet known are to be expected. Due to the fact that the only isotope of At occurring in the natural decay series, 219At, results from the 0. 005% a-branching of 223Fr which itself is produced...