Celluloid keytops smell like camphor when cut because they contain
camphor.  Cellulose nitrate is, I believe, cellulose dissolved in
nitric acid, so no camphor there.  I once tested the flammability of
old nitrate film by putting a can of it to the match.  It burned, but
not explosively or violently.

Philip Jamison
West Chester, PA

 [ I've been told that celluloid is not a plastic, so I checked the
 [ big dictionary of 1927 (before modern plastics).  It indicates that
 [ a 'plastic' material is capable of being molded.  Elsewhere it says
 [ that celluloid is essentially soluble guncotton and camphor, and
 [ was also called xylonite.  -- Robbie