Carrier Mobility Spectra of Liquids Electrified by Bubbling

Abstract

The mobility spectra produced by bubbling water and various aqueous solutions of salt, acid, base, sugar, and soap have been investigated with an Erikson mobility tube under conditions of high resolving power. Curves of current against mobility show that for water there are five distinct negative groups of carriers having mobilities 1.80, 0.95, 0.45, 0.32, and 0.20 cm/sec. per volt/cm. There are two definite positive groups at mobilities 1.0 and 0.40 (varying between 0.44 and 0.34). Few carriers are produced with mobilities less than 0.1. Depending on the size of the bubbling capillary, the ratio of the total amount of positive electrification to negative varies from one to three (small capillary) to one to one hundred (12 mm tubing). Addition of salts to water favors production of slow carriers at the expense of fast ones; the curves degenerate to continuous distributions of mobilities from mobilities roughly 0.5 to 0.01. Medium concentrations (${10}^{-3\mathrm{}}$ molal) produce more total electrification than distilled water, high concentrations (1 molal) less. With the addition of sugar to water, several groups of carriers appear whose mobilities lie between 0.1 and 0.001. There are large numbers of carriers in these groups, so that the total amount of electrification increases to about 12 times that for water. The use of air blasts of high humidity favors production of slow carriers, and gives heterogeneous spreads of mobilities. From new experiments on spraying water and salt solutions, some weak groups previously unobserved have been detected. Comparisons have been made between curves of bubbling and curves of spraying.