Radioaktivitat_, i.p.358, 1904).

Since the above was written, another product has been found to intervene between the X substance and the emanation in the case of actinium and thorium.

They have been named radio-actinium and radio-thorium respectively .-- ED.] It is not possible to give a complete table which should, as it were, represent the genealogical tree of the various radioactive substances.
Several authors have endeavoured to do so, but in a premature manner; all the affiliations are not at the present time yet perfectly known, and it will no doubt be acknowledged some day that identical states have been described under different names.[39] [Footnote 39: Such a table is given on p.

169 of Rutherford's _Radioactive Transformations_ .-- ED.] Sec.4.THE DISAGGREGATION OF MATTER AND ATOMIC ENERGY In spite of uncertainties which are not yet entirely removed, it cannot be denied that many experiments render it probable that in radioactive bodies we find ourselves witnessing veritable transformations of matter.
Professor Rutherford, Professor Soddy, and several other physicists, have come to regard these phenomena in the following way.

A radioactive body is composed of atoms which have little stability, and are able to detach themselves spontaneously from the parent substance, and at the same time to divide themselves into two essential component parts, the negative electron and its residue the positive ion.