Queries. [Volume: 8, Issue: 1, 1888, pp. 21-28]

22

UNITED STATES ASSOCIATION OF

[VOL. 8,

plants of more modern construction. The use of a portion of coke
has made the management, also, somewhat easier and consequently
enabled the percentage of foundry iron produced to be increased.
The difficulties attending the production of a large percentage
of foundry iron from all magnetic ores, are due to several causes.
Mention will only be made of the leading ones. Within certain
limits, the greater the ease with which the iron of an ore parts with
its oxygen, the more regularly and rapidly will the furnace perform its work of reduction and melting, and the hotter will be the
crucible with the same weight of fuel. That the reduction of
magnetic ores proceeds more slowly than of brown hematites, or
red oxides, is probably due as much to their mechanical structure,
as to any difference in chemical composition. Most of magnetic
ores available in the Schuylkill and Lehigh Valley districts of
Pennsylvania, are dense, close, compact ores. These ores, even
when entirely free of sulphur, are more or less difficult to work,
especially when filled into furnace in large pieces or masses, too
heavy for one man to conveniently lift into a charging barrow.
The writer has seen the dense New Jersey magnetics so filled into
furnaces and at the same time the managers were complaining of
the impossibility of making foundry grades, and the tendency of
the furnace to work irregularly, or to run off on white iron, without (to them) any apparent cause.
The furnace gases experience more or less difficulty in penetrating, breaking up and de-oxidizing dense ores; they canl be
broken down more cheaply with hammers, open porous ores, or
ores containing considerable combined water, are quickly and thoroughly permeated, in consequence, with magnetites there is a
greater consumption of heat in the lower parts of the furnace and
from the presence of ore, only partially reduced, there is apt to be
sudden variations in the temperature of crucible. One of the conditions requisite to the production of a large proportion of the
higher grades of foundry iron is almost absolute uniformity of
temperature of the lower parts of the furnace. The crucible and
boshes seem to acquire certain shapes or proportions, by graphitic
accumulations, without which uniform soft grades of No. 1 and
No. 2, x iron can scarcely be made. Time is required to form
these accumulations of graphite, &c., but they are quickly and
easily disturbed, and the disturbing cause seriously affecting the