The Collaborative International Dictionary of English v.0.48:

Copygraph \Cop"y*graph\, n.
   A contrivance for producing manifold copies of a writing or
   drawing; -- made obsolete by later developments in copying
   technology; see xerography.
   [1913 Webster +PJC]

   Note: The writing or drawing is made with aniline ink on
         paper, and a reverse copy transfered by pressure to a
         slab of gelatin softened with glycerin. A large number
         of transcripts can be taken while the ink is fresh.
         [1913 Webster]

               Various names have been given to the process [the
               gelatin copying process], some of them acceptable
               and others absurd; hectograph, polygraph,
               copygraph, lithogram, etc.         --Knight.
         [1913 Webster]