Balloon-borne measurements of atmospheric electrical parameters made during the last several years indicate that there has been a significant change in the average small-ion mobility. In addition, on some soundings abrupt changes in the ion mobility profile have been noted. These variations provide an unusual opportunity to experimentally study the functional relationships between mobility, ion density, conductivity, and the recombination coefficient in the stratosphere. Within the uncertainties involved it is found that the measurements support the simple, predicted theoretical relationships between these various parameters. If fluctuations in ion mobility are in fact a usual occurrence, then this work indicates that variations frequently observed in the ion concentration are probably related to changes in ion mobility rather than aerosol variations, as is usually assumed. One somewhat surprising result predicted by the functional relationships between the electrical parameters indicates that the ambient conductivity may be relatively insensitive to mobility variations.