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By properly separating the extraordinary Hall effect due to magnetization from the ordinary Hall effect due to a uniform field (the magnetizing force H), a well-behaved Hall constant for ferromagnetics can be measured which should provide considerable information concerning the band structure of ferromagnetics.

Glendenin 4 (0.06 Mev) leads to the ground state or to an excited state of Nb 93 . Further evidence for the proposed rule can be obtained from the behavior of nuclei with isotopic numbers other than those shown in Fig. 1. One finds that in all cases of nuclei with N>5Q>Z and N somewhat larger than 82, the &~ decay energies of the odd Z nuclei lie systematically higher than those of the odd N nuclei. It may be noted that the unexpected instability and comparatively high decay energy of In 115 fit well into this picture. A similar, but presumably smaller, "split" seems to occur at N > 126, though the lack of 0-decay data makes it impossible to predict the ^-instability of the isotopes of At (85) or Fr (87) from /3-decay systematics. In the region of N>2& and Z<40 a similar abnormality seems to hold, but here the 0~ energies of the odd N nuclei seem to be systematically higher than those of the odd Z nuclei.The proposed picture can be described in other words by saying that the line of maximum stability (the Gamow line) is shifted towards a region of smaller neutron excess when the number of neutrons exceeds 50 or 82 but that this shift is larger for the odd Z than for the odd N nuclei, so that in the region of N >50 >Z and for N somewhat larger than 82 the Gamow line is split in two lines referring to odd Z and odd N nuclei, respectively (Fig. 2).The numerical values for the lowering of the binding energies of the last neutron at 7^=50 and 82 as derived from Fig. 1 are as follows (in Mev): N: 50 82 paired neutron: 2.4 2.0 unpaired neu tron: 1.8 1.3. These figures are in good agreement with the first estimate made by Mayer 2 of about 2 Mev for all cases.There are several possible ways of explaining these abnormalities, but it seems premature to the writer to give any one of them final preference. Thanks are due to Maria Mayer for extensive discussions of these possibilities. 1 January 15, 1951 S INCE the interpretation of the measurements on n-irradiated Hf has been shown to be complicated because of the presence of different activities, 1 * 2 we have separated electromagnetically the Hf isotopes of a pile-irradiated sample. Besides the known activity of Hf 181 there was also one corresponding to mass number 175, amounting to about 2.5 percent of the total activity as measured by a G-M counter with a 2.2 mg/cm 2 window. JLA*JU^-~A .,/°" Lv\>~v Ey-342kev-i r-Ej«344.5llev fEj«48tkev 0/45* 6000 6100 6200 6300 8200 Pot. reading 6300 8400 FIG. 1,0-spectra of the separated mass numbers 181 and 175 isotopes. The intensities are not drawn to the same scale. FIG. 2. The high energy photo-lines of unseparated Hf.The separated isotopes, collected on 2.5 mg Al/cm 2 , were used as samples for /S-spectrometer investigations, the results of which are shown in Fig. 1. The letters K\, K 2 -• -L h L 2 -• • indicate the K and L conversion lines of the well-known 7-rays of energies 132, 135, 345, and 481 kev, respectively. Because of the presence of small amounts of the strong mass 181 activity in mass 175 source this spectrum also ...