An approximate method is developed for deducing the dielectric loss factor of a solid dielectric from the charging current that flows after the sudden application of a direct voltage. It is shown that, subject to certain conditions, the loss factor at a frequency f cycles per second can be deduced from the charging current at a time 0.1/f seconds after applying the direct voltage. The range of application of the method is discussed, and its use in correlating d.c. measurements with a.c. bridge measurements on the same sample is illustrated by experimental results.