The first-named constitutes the beta, and the second the alpha rays.
The emanation is certainly composed of alpha ions with a few molecules agglomerated round them.

Professor Rutherford has, in fact, demonstrated that the emanation is charged with positive electricity; and this emanation may, in turn, be destroyed by giving birth to new bodies.
After the loss of the atoms which are carried off by the radiation, the remainder of the body acquires new properties, but it may still be radioactive, and again lose atoms.

The various stages that we meet with in the evolution of the radioactive substance or of its emanation, correspond to the various degrees of atomic disaggregation.
Professors Rutherford and Soddy have described them clearly in the case of uranium and radium.

As regards thorium the results are less satisfactory.

The evolution should continue until a stable atomic condition is finally reached, which, because of this stability, is no longer radioactive.