Perform the experimental set-up according to Figs. 1 and 2.
Insert the two nickel electrodes into two holes in the threehole
rubber stopper and fix the terminal screws to the lower
ends of the electrodes. Screw two pieces of chrome nickel
wire, which are each about 15 cm long, into the clamps
between these two electrodes so that they are electrically
connected in parallel. The wires must not touch each other.
Insert the one-way stopcock into the third hole of the stopper
and insert the thus-prepared stopper in the lower opening of
the bottle.