The Energy Content of the Heavy Nuclei

A packing fraction curve is constructed from the atomic masses previously measured and from new measurements for tin, lanthanum and neodymium. The curve is also drawn to agree with the differences in packing fractions for the twenty-five pairs previously reported. The curve has the general shape of Aston's curve, but has a higher minimum value of -7.2×${10}^{-4\mathrm{}}$ in place of -10×${10}^{-4\mathrm{}}$ and is from 2×${10}^{-4\mathrm{}}$ to 3×${10}^{-4\mathrm{}}$ higher for the heavy elements. For the elements below lead the curve is much less steep than above. This gives an energy content to these elements, such that $\alpha$-ray emission is impossible. With the values given by the curve for tin and palladium, the differences between the masses of lead and thorium, and lead and uranium are greater than the total mass of the $\alpha$- and $\beta$-rays emitted in the transformations from thorium or uranium to lead, but agree with the differences to be expected if the mass equivalents of the energies of the $\alpha$- and $\beta$-rays are allowed for. The effect of the packing fractions on the computed atomic weights of the elements cassiopeium, neodymium thorium and uranium is discussed. The masses of gold and tin isotopes have been compared, and the masses of neodymium, lanthanum and tin isotopes have been compared with titanium.