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Hydrogen was electrolyzed into flat ring cathodes of magnetically soft iron in 0.5 N solutions of H2SO4 or of KOH. The design of the electrolytic cell permitted magnetic testing at intervals. Magnetic hardening began after many hours provided the electrolytic current density was kept above a lower limit depending on the electrolyte. This hardening proceeded, at adequate current density, to an end point beyond which longer charging at any current density rarely produced any further changes in magnetic properties. Removal of hydrogen by storage in air at room temperature for 5 months, or by annealing at 400°C in vacuum for 17 hours, did not diminish the magnetic hardness produced during electrolysis. It is suggested that the iron is locally cold-worked by non-uniform distribution in it of hydrogen in excess of the solubility limit at room temperature, and that uniformly distributed hydrogen up to this limit has very little effect on the ferromagnetic properties.

An apparatus has been constructed for measuring at elevated temperatures and at independently controlled pressures the magnetic susceptibility of vapors of substances which are normally in the liquid or solid state. Besides greatly increasing the range of substances for which such measurements can be made, the measurement at elevated temperatures is believed to permit considerably greater accuracy than has been attained previously in the susceptibility measurements on vapors. Determinations of the susceptibilities of the vapors of benzene and carbon tetrachloride have been carried out at 110°C. The extreme limits of uncertainty in the results are estimated to be 3 percent. The values found for the mass susceptibilities of the vapors are in very close agreement with values which have been obtained for the liquids.