From the results of the investigations on zinc and copper and on the regularities existing in the anomalous temperatures of iron, it was inferred that the "structure levels", E_1 and E_2, of the valence electron in this metal might be denoted by (A_1, B_1)^7G_ and (A_2, B_2)^5D_, respectively. Of these notations, (A_1, B_1) and (A_2, B_2) respectively represent two pairs of atoms forming diatomic molecules, and suffix numbers, being the values of J, were written in order of the energy positions. Further, assuming that iron crystal is built up of equal numbers of the above molecules, the electronic origins of the transformations of A_3, A_4 and the melting, and the phenomena allied to them were explained by attributing them to the transitions between two adjacent components of the above multiplets. The spontaneous magnetism of iron crystal was explained to be due to the term (3d)^6 ^5D_4 of the atoms in the molecule (A_2, B_2)
