7 The 100 Most Influential Inventors of All Time 7use of rubber. Though subsequent discoveries have refined
Goodyear’s original techniques, the vulcanization process
remains fundamentally the same as it was in his day.
Goodyear began his career as a partner in his father’s
hardware business, which went bankrupt in 1830. He then
became interested in discovering a method of treating
india rubber so that it would lose its adhesiveness and
susceptibility to extremes of heat and cold. He developed
a nitric acid treatment and in 1837 contracted for the
manufacture by this process of mailbags for the U.S. gov-
ernment, but the rubber fabric proved useless at high
temperatures.
For the next few years he worked with Nathaniel M.
Hayward (1808–65), a former employee of a rubber factory
in Roxbury, Mass., who had discovered that rubber treated
with sulfur was not sticky. Goodyear bought Hayward’s
process. In 1839 he accidentally dropped some India
rubber mixed with sulfur on a hot stove and so discovered
vulcanization (after Vulcan, the Roman god of fire).
Goodyear found that a mixture of rubber with about 8
percent by weight of sulfur and some white lead as an
accelerant was transformed, on heating, to an elastic solid
that remained elastic and resilient at high temperatures
and yet stayed soft at low temperatures. It is now known
that sulfur atoms react to form interlinks between the
long, chainlike rubber molecules, making a loose molecular
network. The original rubber liquid is thus converted into
a solid that will not flow even when warm because the
molecules are now permanently tied together. Moreover,
the addition of a small amount of sulfur in various forms
makes the rubber molecules sufficiently irregular that
crystallization (and, hence, hardening at low temperatures)
is greatly impeded.
Goodyear was granted his first patent in 1844 but had
to fight numerous infringements in court; the decisive