The half-value period for thorium X is much shorter, namely, a little over four days, and this is also the recovery period for thorium X. The plotted decay and recovery curves will intersect at this point.
The consecutive disintegration series, with the half-value periods, for the uranium and thorium series as given by Soddy are seen in the following tables. They are probably subject to some changes on further and more accurate determination. The nature of the rays emitted is also given.
Fig. 6.—Disintegration Series for Uranium, Actinium, and Thorium, as Given by Soddy.
CHAPTER IV
NATURE OF THE ALPHA PARTICLE
Disintegration of the Elements
The remarkable disintegrations related in the last chapter, in which the heaviest known elementary atom—that of uranium (at. wt. 238)—is by successive stages changed into others of lower atomic weight, afford a clue to the nature of the atom and to that goal of the chemist, the final constitution of matter. The composite nature of the atom and some sort of interrelation of the elements had previously been made apparent from a study of the Periodic System and data gathered still earlier, but all attempts at working out a so-called genesis of the elements had proved vague and unsatisfactory.