76
under other circumstances would have been of importance
to those metals. Due to its electrical properties, alumi
num has come to replace copper in many large transmission
lines and in other uses where added bulk is not a crucial
factor. Lightness and wearability have allowed it to
replace steel in a few uses, notably in containers.
Prestressed concrete has taken some of the market
formerly reserved for structural steel, and even plastic
44
warships now are being launched. Fibreglass automobile
bodies and aluminum engine blocks and radiators already
have been used and found successful in many instances
and might find more widespread use in the future were
price and technological advances favorable to such
substitution.
Finally, metals production has been affected
by the recovery of metal contained in obsolete imple-
45
ments. In lplO production of refined copper from
scrap amounted to 17.5 percent of the apparent consumption
of new copper; by i960 that figure had grown to 37.5
percent.^
44
In 1971 two small plastic warships were
launched; pending success of the experiment, future plans
call for production of plastic warships to frigate size.
The principal difficulty at this time is one of cost.
45
See Appendix B for data and information relat
ing to scrap generation, availability, and use.
^Minerals Yearbook, 19^5 p. 122; Minerals
Yearbook, 1965. p. 356.