COPYGRAPH
Etymology
Noun
copygraph (plural copygraphs)
(dated) An early means of producing multiple copies of a document by means of pressing it against a slab of gelatin softened with glycerin and making further copies from the resulting reversed image.
Source: Wiktionary
Cop"y*graph, n.
Definition: A contrivance for producing manifold copies of a writing or
drawing.
Note: The writing or drawing is made with aniline ink on paper, and a
reverse copy transferred by pressure to a slab of gelatin softened
with glycerin. A large number of transcripts can be taken while the
ink is fresh.
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.
Source: Webster’s Unabridged Dictionary 1913 Edition