he 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. In the Blair process a metallic
iron sponge was made from the ore in a closed retort, this sponge
cooled down in receptacles from which the air was excluded, to the
temperature of the atmosphere, then charged into a puddling furnace
and heated for working. In this way (and the same plan essentially has
been followed by other inventors), the metallic iron, in the finest
possible state of subdivision, is subjected to the more or less
oxidizing influences of the flame, without liquid slag to save it from
oxidation, and with no carbon present to again reduce the iron oxides
from the cinder after it is formed. The loss of metal is consequently
very large, but oxides of iron being left in the metal the blooms are
invariably "red short."

In the Siemens process pieces of ore of the size of beans or peas,
mixed with lime or other fluxing material, form the charge, which is
introduced into a rotating furnace; and when this charge has become
heated to a bright-red heat, small coal of uniform size is added in
sufficient quantity to effect the reduction of the ore.

The size of the pieces of the material employed prevents the intimate
mixture of the particles of iron with the particles of carbon, and
hence we would, on theoretical grounds, anticipate just what practice
has proved, viz., that the reduction is incomplete, and the resulting
metal being charged