Illustration: FINE WIRE DRAWING.
Different metals have different powers of “ductility,” that is to
say, some can be drawn much finer than others. Dr. Turner says, “The
only metals remarkable in this respect are gold, silver, platinum,
iron, and copper. Walliston devised a method by which gold wire may
be obtained so fine that its diameter shall be only the 5000th part
of an inch, and 550 feet of it are required to weigh one grain; he
obtained a platinum wire so small that its diameter did not exceed
the 30,000th of an inch. It is singular that the ductility and
malleability of the same metal are not always in proportion to each
other. Iron, for example, cannot be made into thin leaves, but it may
be drawn into very small wires.”