ABSTRACT
Dr. Aston discusses the probable mass of new isotope, which for convenience called as actino-uranium. It seems simplest to suppose that its mass is 235, and that it undergoes first an α and then a β ray transformation into protactinium. An estimate of the period of transformation of the new isotope of uranium can be deduced on certain probable assumptions. The measurements made by Dr. Aston of the relative intensities of the lead isotopes in the mineral, it may be considers its bearing on the origin of actinium. He first discusses the probable mass of this new isotope, which for convenience will be called actino-uranium. He supposes for the purpose of calculation that t is 10 years-an average estimate of the age of old primary uranium minerals. It is natural to suppose that the uranium in our earth has its origin in the sun, and has been decaying since the separation of the earth from the sun.
