Fig. 332 shows one couple of the battery. S is artificial antimony
sulphide; M is German silver; m is a protecting plate of German silver
to save the sulphide from wasting in the flame.
Fig. 332. ELEMENTS OF BECQUEREL'S THERMOELECTRIC BATTERIES.
Clamond's pile has been used in practical work. The negative element is
an alloy of antimony, 2 parts, zinc, 1 part. The positive element is tin
plate. Mica in some parts, and a paste of soluble glass and asbestus in
other parts are used as insulators. They are built up so as to form a
cylinder within which the fire is maintained. The air is relied on to
keep the outer junctions cool. The temperature does not exceed 200° C.
(392° F.)
Sixty such elements have an electro-motive force of 300 volts and an
internal resistance of 1.5 ohms. Such a battery requires the consumption
of three cubic feet of gas per hour. (See Currents, Thermo-electric. )