  ApSimon considered the problem of deciding by a process of two weighings on
which of a known number of mints emit either coins of a known genuine weight or
emit coins of a different secondary but unknown weight. The combinatorial
problem consists of finding two sets of coin numbers to be loaded on the tray
for each of the weighings, and then to minimize the total count of coins to be
drawn from all mints for these two weighings.
  This work yields numerical results for the generalized problem which allows
three or more weighings to settle which of the mints produce either sort of
coins.
