result that steel-plant
construction for many years past has been largely open-hearth. The
open-hearth process is favored also because it allows closer control of
phosphorus content in the steel.

Small but increasing amounts of steel are also made in the electric
furnace; for the most part, however, this process is more expensive than
the others, and it is used principally for special alloy steels.

Iron ores are seldom so uniform in quality that they can be shipped
without careful attention to sampling and grade. In the Lake Superior
region the ores are sampled daily as mined, and the utmost care is taken
to mix and load the ore in such a way that the desired grades can be
obtained. Ordinarily a single deposit produces several grades of ore.
When ores are put into the furnace for smelting the mixtures are
selected with great care for the particular purpose for which the
product is to be used. The mixture is compounded as carefully as a
druggist's prescription. An ore salesman, after ascertaining the nature
of the iron and steel products of a plant, has to use great skill in
offering particular ores for sale which not only will meet the desired
grade in regard to all elements, but also will meet competition in
price. In some respects, the marketing of different grades of iron ore
is as complex as the marketing of a miscellaneous stock of merchandise.
With ores, as with merchandise, custom and sentiment play their
part,--with the result that two ores of identical grade mineralogically
and chemically may have quite a different vogue and price, simply
because of the fact that furnace men are used to one and not to the
other and are not willing to experiment.

The geologist is ordinarily concerned merely with finding an ore of as
good a general grade as possible; but he often finds to his surprise
that his efforts have been directed toward the discovery of something
which, due to some minor defect in texture, in mineralogical
composition, or in chemical composition, is difficult to introduce on
the market. There is here a promising field, intermediate between
geology (or mineralogy) and metallurgy, for the application of
principles of chemistry, metallurgy, and mineralogy, which is occupied
at the present time mainly by the ore salesman. Both the mineralogist
and metallurgist touch the problem but they do not cover it. With
increasingly precise and rapidly changing metallurgical requirements,
this field calls for scient