Mass attenuation coefficients have been determined for titanium, vanadium, iron, nickel, and copper over an energy range 17.5 to 2.3 kev and for praseodymium, gadolinium and erbium over the range 26.3 to 4.5 kev. Agreement within experimental error with recent measurements on the transition metals was obtained. There appears to be no published experimental data in the pertinent energy range for comparison with the coefficients determined for the rare earth elements. The precision of the measurements as determined by the relative standard deviation varied from 0.5 per cent to 2.4 per cent. The variation in the precision can be accounted for by non-uniform absorbing foils. The accuracy of the measurements was judged to be in the range two to four per cent of the coefficients reported.

The thesis contains a brief description of the theoretical aspects of the phenomena of absorption and describes the X-ray and ancillary instrumentation used for the investigation, the assessment of error in the measurement techniques and the results of the project.