The Isotopic Weight ofH2

The mass of neutral ${\mathrm{H}}^2$ was measured on a mass-spectrograph as 2.01351±0.00006 referred to He and 2.01351±0.00018 referred to ${\mathrm{O}}^{16}$=16. The equivalent packing fraction of ${\mathrm{H}}^2$ is 67.5 parts in 10,000. On the assumption that the nucleus is composed of two protons and one electron the energy of binding is approximately 2×${10}^6$ electron-volts. If the ${\mathrm{H}}^2$ nucleus is made up of one proton and one Chadwick neutron of mass 1.0067 then the binding energy of these two particles is 9.7×${10}^5$ electron-volts. ${\mathrm{H}}_3^{1+}$ and ${\mathrm{He}}^{+}$ provided the dispersion measurements for the spectra. The presence of ${\mathrm{H}}^1$ ${\mathrm{H}}^{2+}$ can only introduce in the mass determination a possible maximum error of 0.00003 mass units. Lines of mass 4.02852 on the spectra were attributed to ${\mathrm{H}}_2^1$ ${\mathrm{H}}^2$ ions because: (1) no lines of comparable intensity appeared in this position when commercial hydrogen of low ${\mathrm{H}}^2$ content was used; (2) under the conditions existing in the discharge tube the abundance of ${\mathrm{H}}_2^{2+}$ was negligibly small compared to the abundance of ${\mathrm{H}}_2^1$ ${\mathrm{H}}^{2+}$; (3) the mass is less than the mass of ${\mathrm{H}}_4^{1+}$ by an amount outside of the limits of error. Two samples of enriched hydrogen were used which had been prepared by Brickwedde; both had been tested spectroscopically by Urey and Murphy, and one of them was identical with Bleakney's Sample III. From the value for the mass of ${\mathrm{H}}^2$, the energy balance is calculated for one process of noncapture disintegration of ${\mathrm{N}}^{14}$ by neutron impact, suggested by Feather, which would result in ${\mathrm{C}}^{12}$ and ${\mathrm{H}}^2$. It is concluded that this disintegration could not possibly occur under the conditions of his experiments.