Among the steels, those that are softer are more serviceable and
reliable than the harder ones, especially whereever shocks and
concussions or rapidly alternating strains are to be endured. In other
words, the more nearly steel resembles good wrought iron, the more
certain it is to render lasting service when used within appropriate
limits of strain. Indeed, a wrought iron of fine quality is better
calculated to endure fatigue than any steel. This is particularly
noticeable in steam hammer pistons, propeller shafts, and railroad
axles. A better quality of wrought iron, therefore, has long been a
desideratum, and it appears now that it has at last been found.

Several years since, a pneumatic process of manufacturing wrought iron
was invented and patented by Dr. Chapin, and an experimental plant was
erected near Chicago. Enough was done to demonstrate, first, that an
iron of unprecedentedly good qualities was attainable from common pig;
and second, that the cost of its manufacture would not exceed that of
Bessemer steel. Nevertheless, owing to lack of funds properly to push
the invention against the jealous opposition which it encountered, the
enterprise came to a halt until quite recently, when its merits found
a champion in Gustav Lindenthal, C.E., member of this club, who is
now the general manager of the Chapin Pneumatic Iron Co., and under
whose direction this new quality of iron will soon be put upon the
market.

The process of manufacture is briefly as follows: The pig metal, after
being melted in a cupola and tapped into a discharging ladle, is
delivered into a Bessemer converter, in which the metal is largely
relieved of its silicon, sulphur, carbon, etc., by the ordinary
pneumatic process. At the end of the blow the converter is turned down