THE HEATING EFFECT OF THE CURRENT.
With a piece of very fine platinum wire (No. 36 or 40), placed in the circuit of the battery, the heating effect of the current may be shown. A half inch of No. 36 platinum wire will serve for the experiment. If the battery is in good condition it will heat from 1/8 to 1/4 inch of the wire red hot. This is sufficient to light gas or an alcohol lamp, also to ignite powder or gun cotton.
A short piece of a watch hair spring, or a piece of very fine iron wire, if placed in the circuit will be made very hot.