ur is introduced by the
coke and fuel used. Sulphur is very difficult to get rid of in
steel making; in fact the resulting metal usually contains a little
more than the raw materials used. Only the electric furnace is
able to produce the necessary heat and slags required to eliminate
sulphur, and as a matter of fact the sulphur does not go until
several other impurities have been eliminated. Consequently, an
electric steel with extremely low sulphur (0.02 per cent) is by
that same token a well-made metal.

Sulphur is of most trouble to rolling and forging operations when
conducted at a red heat. It makes steel tender and brittle at that
temperature--a condition known to the workmen as "red-short." It
seems to have little or no effect upon the physical properties
of cold steel--at least as revealed by the ordinary testing
machines--consequently many specifications do not set any limit
on sulphur, resting on the idea that if sulphur is low enough not
to cause trouble to the manufacturer during rolling, it will not
cause the user any trouble.

Tool steel and other fine steels should be very low in sulphur,
preferably not higher than 0.03 per cent. Higher sulphur steels
(0.06 per cent, and even up to 0.10 per cent) have given very good
service for machine parts, but in general a high sulphur steel
is a suspicious steel. Screw stock is purposely made with up to
0.12 per cent sulphur and a like amount of phosphorus so it will
cut freely.

Manganese counteracts the detrimental effect of sulphur when present
in the steel to an amount at least five times the sulphur content.

PHOSPHORUS is an element (symbol P) which enters the metal from
the ore. It remains in the steel when made by the so-called acid
process, but it can be easily eliminated down to 0.06 per cent
in the basic process. In fact the discovery of the basic process
was necessary before the huge iron deposits of Belgium and the
Franco-German border could be used. These ores contain several
per cent phosphorus, and made a very brittle steel ("cold short")
until basic furnaces were used. Basic furnaces allow the formation
of a slag high in lime, which takes practically all the phosphorus
out of the metal. Not only is the resulting metal usable, but the
slag makes a very excellent fertilizer, and is in good demand.

SILICON is a very widespread element (symbol Si), being an essential
constituent of nearly all the rocks of the earth. It is similar to
carbon in ma