Procedure:

Take sufficient quantity of a representative sample of bitumen emulsion in the glass container. Immerse two stainless steel plates 25 mm x 75 mm which are connected to a 12 V battery circuit through a switch, a rheostat and an ammeter, to a depth of 25 mm and mark the +ve and –ve plates. Close the switch and adjust the rheostat so that the current in the circuit is more than 4 mA. Open the circuit after 30 min and remove the plates. Gently wash the plates, if necessary with distilled water to remove unbroken emulsion and then examine.