the stock must be thoroughly cleaned and is then passed between copper
rollers which act in the same capacity as the copper dies.

_Other Applications._--Hardening and tempering can be done by clamping
the work in the welding dies and setting the control and time to bring the
metal to the proper color, when it is cooled in the usual manner.

Brazing is done by clamping the work in the jaws and heating until the
flux, then the spelter has melted and run into the joint. Riveting and
heading of rivets can be done by bringing the dies down on opposite ends of
the rivet after it has been inserted in the hole, the dies being shaped to
form the heads properly.

Hardened steel may be softened and annealed so that it can be machined by
connecting the dies of the welder to each side of the point to be softened.
The current is then applied until the work has reached a point at which it
will soften when cooled.

_Troubles and Remedies._--The following methods have been furnished by
the Toledo Electric Welder Company and are recommended for this class of
work whenever necessary.

To locate grounds in the primary or high voltage side of the circuit,
connect incandescent lamps in series by means of a long piece of lamp cord,
as shown, in Figure 43a. For 110 volts use one lamp, for 220 volts use two
lamps and for 440 volts use four lamps. Attach one end of the lamp cord to
one side of the switch, and close the switch. Take the other end of the
cord in the hand and press it against some part of the welder frame where
the metal is clean and bright. Paint, grease and dirt act as insulators and
prevent electrical contact. If the lamp lights, the circuit is in