Electropoion \E*lec`tro*poi"on\, n., or Electropoion fluid \Electropoion fluid\ [NL.; electro- + Gr. poiw^n, p. pr. of poiei^n to make.]

(Elec.) An exciting and depolarizing acid solution used in certain cells or batteries, as the Grenet battery. Electropoion is best prepared by mixing one gallon of concentrated sulphuric acid diluted with three gallons of water, with a solution of six pounds of potassium bichromate in two gallons of boiling water. It should be used cold.

Source: Webster's Revised Unabridged Dictionary (1913)