This item is a vintage Manhattan Electrical Supply Company (MESCO) polarity indicator, patented around October 24, 1905.    Hard rubber with a steel eclipse cover.  There are supposedly? platinum electrodes inside the vial. Marked ManhattanIt appears to be in good condition with the fluid still inside the glass tube.  Missing a nut on one end.  Measures approximately 4" long.  Please refer to the photos as they are part of the description.

D. Tote