The empirical quantity defined by \[i=\frac{i_{\rm{d},l}}{c_{\rm{B}}\ m^{\frac{2}{3}}\ t_{1}^{\frac{1}{6}}}\] the equation where \(i_{\rm{d},l}\) = limiting diffusion current, \(c_{\rm{B}}\) = bulk concentration of the substance B whose reduction or oxidation is responsible for the wave in question, \(m\) = average rate of (mass) flow of mercury (or other liquid metal) and \(t_{1}\) = drop time.