-particles ought to be to leave the atomic weight unchanged while increasing the atomic number by one. The result of one emission of
-particles followed by two of
-particles is thus to deprive the nucleus of a helium nucleus and two electrons, without, in the end, changing the atomic number. Thus uranium has two very stable forms, called uranium I and uranium II. Uranium I is the great-grandfather of uranium II. Uranium I, by means of
-rays, gives rise to uranium
, of which half decays in little less than 24 days. Uranium