[Illustration: FIG. 234.--An ammeter.]
In marking the scale, an ammeter is placed in the circuit of an
electrolytic cell and the position of the pointer is marked on the
blank card which lies beneath and which is to serve as a scale (Fig.
235). After the current has flowed for about an hour, the amount of
silver which has been deposited is measured. Knowing the time during
which the current has run, and the amount of deposit, the strength of
the current in amperes can be calculated. This number is written
opposite the place at which the pointer stood during the experiment.
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