The Collaborative International Dictionary of English v.0.48:

Manhes process \Man`h[`e]s" proc"ess\ (Copper Metal.)
   A process by which copper matte is treated by passing through
   it a blast of air, to oxidize and remove sulphur. It is
   analogous in apparatus to the Bessemer process for
   decarbonizing cast iron. So called from Pierre Manh[`e]s, a
   French metallurgist, who invented it.
   [Webster 1913 Suppl.]