Fluxes yield slags; reducing
agents give buttons of regulus or of metal. The action of a reducing
agent is the separation of the oxygen or sulphur from the metal with
which it is combined. For example, the mineral anglesite (lead sulphate)
is a compound of lead, sulphur, and oxygen; by carefully heating it with
charcoal the oxygen is taken away by the charcoal, and a regulus of lead
sulphide remains. If the regulus be then fused with metallic iron the
sulphur is removed by the iron, and metallic lead is left. The charcoal
and the iron are reducing agents. But in defining a reducing agent as
one which removes oxygen, or sulphur, from a metallic compound so as to
set the metal free, it must be remembered that sulphur itself will
reduce metallic lead from fused litharge, and that oxygen will similarly
set free the metal in fused lead sulphide. There is no impropriety in
describing sulphur as a reducing agent; but it is absurd to call oxygen
one. Some confusion will be avoided if these substances and those which
are opposite to them in property be classed as oxidising and
de-oxidising, sulphurising, and de-sulphurising agents. Most oxidising
agents also act as de-sulphurisers.
_The de-oxidising agents_ most in use are the following:--
~Charcoal.~--Powdered wood charcoal; it contains more or less
hygroscopic moisture and about 3 or 4 per cent.
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