LITHIUM BY ELECTROLYSIS.^29

In carrying out electrolytic preparations, the apparatus is usu-

ally arranged in accordance with the following scheme (Fig. 9),

which is, in principle, identical with that employed in electro-

analysis. The decomposition cell, an ammeter, and a regulating-

resistance are introduced in series into an electric circuit. The

binding clamps of the cell may also be connected with wires from

a voltmeter in order to determine the difference in potential

between the two poles during the electrolysis. The ammeter

should remain in the circuit throughout the whole of the elec-

trolysis; the voltage is measured only from time to time, and

has less value for determining the course of the reaction when

Batteryh

Resistance

Decomposition Cell

Fia. 9.

one is working according to well-tested directions. A stor-
age battery may serve as the source of electricity; for measuring
the current and voltage the simpler and inexpensive instruments
suffice, and their reliability can be determined easily by comparison
with standard instruments.
In all cases where a metal which decomposes water is to be
prepared, a fused compound rather than its aqueous solution must
be used for the electrolyte. The melting-point of the salt may be
lowered by admixture with some other suitable salt.

Mix together 30 g. of dry lithium chloride and an equal weight

of dry potassium chloride in a porcelain crucible, 6 to 8 cm.

high and 9 cm. in diameter. Melt the mixture and then after