serve only as a supplement to the current undertaking.

Certain other metals, such as nickel, vital to the

production of jet engine parts, are employed in relatively

small quantities and their uses are specific enough to

be handled as particular problem areas.

 Iron and copper, on the other hand, are repre-

sentative of two broad classes of metals, ferrous and
 4
non-ferrous. They are important not only because of

their use in many different kinds of production, but

also because they are used in great quantities.

 Iron is the material out of which most machines

and heavy structures are built. Copper has been an

important building block of our electrically oriented

technology, used in the production of electrical

circuitry and electrical parts. These metals represent

the bulk metals used for production in a modern economy

and careful analysis of their supply and disposition

will serve us well in determining the role metals have

played in the growth of the United States economy.



 In analyzing the relation between production

and the extraction of metals, we shall first consider


 Metals generally are divided into categories
which include the ferrous metals (those related to the
production of steel), and the non-ferrous metals. Non-
ferrous metals are further divided into the "base metals,"
copper, lead, tin, and zinc; and the "light metals,"
including aluminum and magnesium. The most important of
these in terms of volume are, of course, iron, copper, and
aluminum, with extensive use of aluminum being a relatively
recent development.