A
list of Seven Noble Metals is that which obtained in the most ancient
times : Gold, Electrum (clearly an alloy of gold and silver), Silver,
Copper, Tin, Lead, Iron.
The
subject of Metallurgy is just now attracting to itself special
scientific attention. At Sheffield, to wit, there is a school
established for the particular study of this science. Its chief,
Professor J. 0. Arnold, has recently delivered a lecture at the same on
the "Internal Architecture of Metals," January 25th, 1907. Speaking
there about a metal rod, as used in the construction of a motor-car, he
explained that the metal forming this bar consists of crystals ; " upon
the nature of which towards one another depend nearly all those
metallic properties that are of such great practical importance for
working purposes." And it is an undoubted fact that these aggregated
crystals are liable to fatigue from too prolonged, or too arduous a
strain ; which so-called " fatigue " of metals is a generic term now
used to explain all cases of fracture, such as may be thus understood.
It bears likewise on " repose in the living animal, as in the not
living metal, or mineral." For, " there is more than a superficial
resemblance between so-called ' fatigue ' in a metal, and the fatigue
of an overwrought literary man;"—"only the metallurgical explanation
would be expressed in vastly different terms from the physiological
explanation."
