Abstracts of Technical Articles from Bell System Sources (01 January 1932)

2. The current is proportional to the voltage only so long as the current is small; otherwise the products of electrolysis alter the conductivity. 3. Polarization currents are caused by the Ba and O which are produced by electrolysis. 

These currents decrease rapidly even at temperatures near 500° K., thus showing that Ba and O diffuse at low temperatures.