U-Tube-RVFM-CA1007-A-device-that-is-used-for-the-observation-of-the-migration-of-coloured-ions-Consists-of-a-central-loading-tube-with-funnel-attached-to-a-U-tube-Two-carbon-electrodes-are-mounted-in-holed-rubber-bungs-closing-the-mouth-of-the-U-tube-U-Shaped-Test-Tubes