the process, and the chemical action keeps it up. Oxygen, being an
"electro-negative" element in chemistry, is attracted to the zinc,
and hydrogen, being "electro-positive," is attracted to the
copper.

The difference of electrical condition or "potential" between the
plates by which the current is started has been called the
electromotive force, or force which puts the electricity in
motion. The obstruction or hindrance which the electricity
overcomes in passing through its conductor is known as the
RESISTANCE. Obviously the higher the electromotive force and the
lower the resistance, the stronger will be the current in the
conductor. Hence it is desirable to have a cell which will give a
high electromotive force and a low internal resistance.

Voltaic cells are grouped together in the mode of Leyden jars.
Figure 13 shows how they are joined "in series," the zinc or
negative pole of one being connected by wire to the copper or
positive pole of the next. This arrangement multiplies alike the
electromotive force and the resistance. The electromotive force of
the battery is the sum of the electromotive forces of all the
cells, and the resistance of the battery is the sum of the
resistances of all the cells. High electromotive forces or
"pressures" capable of overcoming high resistances outside the
battery can be obtained in this way.

Figure 14 shows how the zincs are joined "in parallel," the zinc
or negative pole of one being connected by wire to the zinc or
negative pole of the rest, and all the copper or positive poles
together. This arrangement does not increase the electromotive