19K43 and the Radioactivity of Potassium

IT has recently been suggested by Newman and Walke¹ and Klemperer² that the natural β-radioactivity of potassium is due to an isotope ₁₉K⁴⁰ present in very small abundance. Sitte³, however, has come to the conclusion that another relatively rare isotope of potassium exists which is the source of the β-particles, and this, he states, can only be ₁₉K⁴³.