A MMD reader found this compendium article on the 'Net:

 >> Hide Glue
 >>
 >> by Craig Deller, historic furniture conservator,
 >> The Deller Conservation Group Ltd.
 >>
 >> This article is adapted (with permission) from an unofficial
 >> FAQ prepared for the rec.woodworking newsgroup.

It's at URL  http://www.woodforum.com/hideglue.htm