produced by suitable burners and require no special preparation except
adjustment of the heat to the proper degree for the size and thickness of
the metal being welded so that it will not be burned.

A coal fire used for ordinary forging operations should not be used for
welding because of the impurities it contains. A fresh fire should be built
with a rather deep bed of coal, four to eight inches being about right for
work ordinarily met with. The fire should be kept burning until the coal
around the edges has been thoroughly coked and a sufficient quantity of
fuel should be on and around the fire so that no fresh coal will have to
be added while working.

After the coking process has progressed sufficiently, the edges should be
packed down and the fire made as small as possible while still surrounding
the ends to be joined. The fire should not be altered by poking it while
the metal is being heated. The best form of fire to use is one having
rather high banks of coked coal on each side of the mass, leaving an
opening or channel from end to end. This will allow the added fuel to be
brought down on top of the fire with a small amount of disturbance.

_Preparing to Weld._--If the operator is not familiar with the metal
to be handled, it is best to secure a test piece if at all possible and try
heating it and joining the ends. Various grades of iron and steel call for
different methods of handling and for different degrees of heat, the proper
method and temperature being determined best by actual test under the
hammer.

The form of the pieces also has a great deal to do with their handling,
especially in the case of a more or less inexperienced workman. If the
pieces are at all irregular in shape, the motions should be gone through