LINKS and useful information:
http://www.alternativephotography.com/process_gumbichromate.html
http://www.alternativephotography.com/articles/art121.html
http://www.nationmaster.com/encyclopedia/Gum-bichromate
http://www.gumphoto.co.uk/technical.html
http://www.pacifier.com/~kthayer/html/size.html
http://unblinkingeye.com/AAPG/Gum/gum.html
http://www.artic.edu/~fendsley/altProc_GumPrint.html
http://unblinkingeye.com/Articles/3CG/3cg.html