is not out of place here.

The material operated on in puddling is iron containing from 21/2 to 4
per cent. of carbon. During the first stage of the process this iron
is melted down to a fluid bath in the bottom of a reverberatory
furnace. Then the oxidation of the carbon contained in the iron
commences, and at the same time a fluid, basic cinder, or slag, is
produced, which covers a portion of the surface of the metal bath, and
prevents too hasty oxidation. This slag results from the union of
oxides of iron with the sand adhering to the pigs, and the silica
resulting from the oxidation of the silicon contained in the iron.

This cinder now plays a very important part in the process. It takes
up the oxides of iron formed by the contact of the oxidizing flame
with the exposed portion of the metal bath, and at the same time the
carbon of the iron, coming in contact with the under surface of the
cinder covering, where it is protected from oxidizing influences,
reduces these oxides from the cinder and restores them to the bath in
metallic form. This alternate oxidation of exposed metal, and its
reduction by the carbon of the cast iron, continues till the carbon is
nearly exhausted, when the iron assumes a pasty condition, or "comes
to nature," as the puddlers call this change. The charge is then
worked up into balls, and removed for treatment in the squeezer, and
then hammered or rolled. In the Wilson process the conditions which we
have noted in the puddling operation are very closely approximated.
Iron ore reduced to a coarse sand is mixed with the proper proportion
of charcoal or coke dust, and the mixture fed into upright retorts
placed in the chimney of the puddling furnace. By exposure for 24
hours to the heat of the waste gases from the furnace, in the presence
of solid carbon, a considerable portion of the oxygen of the ore is
removed, but little or no metallic iron is formed. The ore is then
drawn from the deoxidizer into the rear or second hearth of the
puddling furnace, situated below it, where it is exposed for 20
minutes to a much higher temperature than that of the deoxidizer. 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 t