The Magnetic Susceptibility of Metallic Neodymium

gurface or one which is covered by such a thin oxide film as to be unable to prevent iupture and intermetallic welding.This view is supported by the fact that the film on aluminium oxidized at higher temperatures (5OO"c for 30 minutes) exceptional in that it retained the surface topography of the underlying metal and exceptional also in that it alone, of the metals examined, gave better protection against frictional damage than did the thinner oxide film forming at room temperature.-ACKNOWLEDGMENTS 'I'he authors wish to thank Mr. M.