Here
the presence of the solid carbon, mixed with the ore, prevents any
oxidizing action, and the temperature of the mass is raised to a point
at which the cinder begins to form. Then the charge is carried forward
by the workmen to the front hearth, in which the temperature of a
puddling furnace prevails. Here the cinder melts, and at the same
time the solid carbon reacts on the oxygen remaining combined with the
ore, and forms metallic iron; but by this time the molten cinder is
present to prevent undue oxidation of the metal formed, and solid
carbon is still present in the mixture to play the same role, of
reducing protoxide of iron from the cinder, as the carbon of the cast
iron does in the ordinary puddling process. I have said that the cast
iron used as the material for puddling contains about 3 per cent. of
carbon; but in this process sufficient carbon is added to effect the
reduction of the ore to a metallic state, and leave enough in the mass
to play the part of the carbon of the cast iron when the metallic
stage has been reached.
It would be interesting to compare the Wilson with the numerous other
direct processes to which allusion has already been made, but there
have been so many of them, and the data concerning them are so
incomplete, that this is impossible. Two processes, however, the Blair
and the Siemens, have attracted sufficient attention, and are
sufficiently modern to deserve notice.
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