Abstract
The Fricke ferrous sulphate dosemeter has been calibrated against a plane-parallel extrapolation chamber for 60 kvp x-rays, HVL 0.20 mm Al, apparent quantum energy 12 kev. The energy absorbed in the Fricke dosemeter was assessed by the `relative effective density' method of Loevinger and Yaniv. A tabulation of errors, systematic and random, inherent in these measurements, has been made, end their effects evaluated. A value of GFe+++ = 14.63 ± 0.26 was obtained.