The welding flame should be played on the work around the crack and
gradually brought to bear on the work. The bottom of the bevel should be
joined first and it will be noted that the cast iron tends to run toward
the flame, but does not stick together easily. A hard and porous weld
should be carefully guarded against, as described above, and upon
completion of the work the welded surface should be scraped with a file,
while still red hot, in order to remove the surface scale.

_Malleable Iron._--This material should be beveled in the same way
that cast iron is handled, and preheating and slow cooling are equally
desirable. The flame used is the same as for cast iron and so is the flux.
The welding rod may be of cast iron, although better results are secured
with Norway iron wire or else a mild steel wire wrapped with a coil of
copper wire.

It will be understood that malleable iron turns to ordinary cast iron when
melted and cooled. Welds in malleable iron are usually far from
satisfactory and a better joint is secured by brazing the edges together
with bronze. The edges to be joined are brought to a heat just a little
below the point at which they will flow and the opening is then
quickly-filled from a rod of Tobin bronze or manganese bronze, a brass or
bronze flux being used in this work.

_Wrought Iron or Semi-Steel._--This metal should be beveled and heated
in the same way as described for cast iron. The flame should be neutral, of
the same size as for steel, and used with the tip of the blue-white cone
just touching the work. The welding rod should be of mild steel, or, if
wrought iron is to be welded to steel, a cast iron rod may be used. A cast
iron flux is well suited for this work. It should be noted that wrought